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Sample records for two-dimensional fast spin-echo

  1. Evaluation of the chondromalacia patella using a microscopy coil: comparison of the two-dimensional fast spin echo techniques and the three-dimensional fast field echo techniques.

    Science.gov (United States)

    Kim, Hyun-joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung-Ja; Cho, Woo Shin

    2011-01-01

    We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast field echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FS-PD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p chondromalacia patella.

  2. Evaluation of the Chondromalacia Patella Using a Microscopy Coil: Comparison of the Two-Dimensional Fast Spin Echo Techniques and the Three-Dimensional Fast Field Echo Techniques

    International Nuclear Information System (INIS)

    Kim, Hyun Joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung Ja; Cho, Woo Shin

    2011-01-01

    We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast fi eld echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FSPD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p < 0.01). The iw-FS-FSE images obtained with a microscopy coil show best diagnostic performance among the 2D and 3D GRE images for evaluating the chondromalacia patella

  3. Evaluation of the Chondromalacia Patella Using a Microscopy Coil: Comparison of the Two-Dimensional Fast Spin Echo Techniques and the Three-Dimensional Fast Field Echo Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung Ja; Cho, Woo Shin [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

    2011-02-15

    We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast fi eld echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FSPD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p < 0.01). The iw-FS-FSE images obtained with a microscopy coil show best diagnostic performance among the 2D and 3D GRE images for evaluating the chondromalacia patella

  4. Fast spin-echo imaging

    International Nuclear Information System (INIS)

    Mackey, K.; Zoarski, G.; Bentson, J.R.; Lufkin, R.B.; Melki, P.; Jolesz, F.

    1991-01-01

    This paper reports on a partial radio-frequency (RF) echo-planar pulse sequence called contiguous slice fast spin echo (CSFSE) which is undergoing clinical trials for spine MR imaging. In this variation of rapid acquisition relaxation enhanced (RARE) spin-echo imaging, rapid 180 degrees RF pulse generated refocused echoes, producing T2-weighted images in about one-third the time of conventional double-echo technique. Forty patients with suspected pathology of the spine were imaged with conventional double-echo and closely matched CSFSE techniques on a GE Signa 1.5-T Advantage system. Cases were reviewed by two board-certified neuroradiologists. In all cases the CSFSE images were of equal or superior quality compared with those obtained with the conventional double-echo technique. Pathologic processes that were imaged consisted of inflammatory, neoplastic, posttraumatic, and degenerative conditions

  5. Comparison of two-dimensional fast spin echo T2 weighted sequences and three-dimensional volume isotropic T2 weighted fast spin echo (VISTA) MRI in the evaluation of triangular fibrocartilage of the wrist.

    Science.gov (United States)

    Park, Hee Jin; Lee, So Yeon; Kang, Kyung A; Kim, Eun Young; Shin, Hun Kyu; Park, Se Jin; Park, Jai Hyung; Kim, Eugene

    2018-04-01

    To compare image quality of three-dimensional volume isotropic T 2 weighted fast spin echo (3D VISTA) and two-dimensional (2D) T 2 weighted images (T2WI) for evaluation of triangular fibrocartilage (TFC) and to investigate whether 3D VISTA can replace 2D T 2 WI in evaluating TFC injury. This retrospective study included 69 patients who received wrist MRIs using both 2D T 2 WI and 3D VISTA techniques for assessment of wrist pathology, including TFC injury. Two radiologists measured the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) of the two sequences. The anatomical identification score and diagnostic performance were independently assessed by two interpreters. The diagnostic abilities of 3D VISTA and 2D T 2 WI were analysed by sensitivity, specificity and accuracy for diagnosing TFC injury using surgically or clinically confirmed diagnostic reference standards. 17 cases (25%) were classified as having TFC injury. 2 cases (12%) were diagnosed surgically, and 15 cases (88%) were diagnosed by physical examination. 52 cases (75%) were diagnosed as having intact TFC. 8 of these cases (15%) were surgically confirmed, while the others were diagnosed by physical examination and clinical findings. The 3D VISTA images had significantly higher SNR and CNR values for the TFC than 2D T 2 WI images. The scores of 3D VISTA's total length, full width and sharpness were similar to those of 2D T 2 WI. We were unable to find a significant difference between 3D VISTA and 2D T 2 WI in the ability to diagnose TFC injury. 3D VISTA image quality is similar to that of 2D T 2 WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment. Advances in knowledge: 3D VISTA image quality is similar to that of 2D T 2 WI for TFC evaluation and is also excellent for tissue contrast. 3D VISTA can replace 2D images in TFC injury assessment.

  6. Evaluation of shoulder pathology: three-dimensional enhanced T1 high-resolution isotropic volume excitation MR vs two-dimensional fast spin echo T2 fat saturation MR.

    Science.gov (United States)

    Park, H J; Lee, S Y; Kim, M S; Choi, S H; Chung, E C; Kook, S H; Kim, E

    2015-03-01

    To evaluate the diagnostic accuracy of three-dimensional (3D) enhanced T1 high-resolution isotropic volume excitation (eTHRIVE) shoulder MR for the detection of rotator cuff tears, labral lesions and calcific tendonitis of the rotator cuff in comparison with two-dimensional (2D) fast spin echo T2 fat saturation (FS) MR. This retrospective study included 73 patients who underwent shoulder MRI using the eTHRIVE technique. Shoulder MR images were interpreted separately by two radiologists. They evaluated anatomic identification and image quality of the shoulder joint on routine MRI sequences (axial and oblique coronal T2 FS images) and compared them with the reformatted eTHRIVE images. The images were scored on a four-point scale (0, poor; 1, questionable; 2, adequate; 3, excellent) according to the degree of homogeneous and sufficient fat saturation to penetrate bone and soft tissue, visualization of the glenoid labrum and distinction of the supraspinatus tendon (SST). The diagnostic accuracy of eTHRIVE images compared with routine MRI sequences was evaluated in the setting of rotator cuff tears, glenoid labral injuries and calcific tendonitis of the SST. Fat saturation scores for eTHRIVE were significantly higher than those of the T2 FS for both radiologists. The sensitivity and accuracy of the T2 FS in diagnosing rotor cuff tears were >90%, whereas sensitivity and accuracy of the eTHRIVE method were significantly lower. The sensitivity, specificity and accuracy of both images in diagnosing labral injuries and calcific tendonitis were similar and showed no significant differences. The specificity of both images for the diagnosis of labral injuries and calcific tendonitis was higher than the sensitivities. The accuracy of 3D eTHRIVE imaging was comparable to that of 2D FSE T2 FS for the diagnosis of glenoid labral injury and calcific tendonitis of SST. The 3D eTHRIVE technique was superior to 2D FSE T2 FS in terms of fat saturation. Overall, 3D eTHRIVE was inferior

  7. Imaging of the brain using the fast-spin-echo and gradient-spin-echo techniques

    International Nuclear Information System (INIS)

    Umek, W.; Ba-Ssalamah, A.; Prokesch, R.; Mallek, R.; Heimberger, K.; Hittmair, K.

    1998-01-01

    The aim of our study was to compare gradient-spin-echo (GRASE) to fast-spin-echo (FSE) sequences for fast T2-weighted MR imaging of the brain. Thirty-one patients with high-signal-intensity lesions on T2-weighted images were examined on a 1.5-T MR system. The FSE and GRASE sequences with identical sequence parameters were obtained and compared side by side. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, signal-to-noise, contrast-to-noise, and contrast ratios and were determined. The FSE technique demonstrated more lesions than GRASE and with generally better conspicuity. Smaller lesions in particular were better demonstrated on FSE because of lower image noise and slightly weaker image artifacts. Gray-white differentiation was better on FSE. Ferritin and hemosiderin depositions appeared darker on GRASE, which resulted in better contrast. Fatty tissue was less bright on GRASE. With current standard hardware equipment, the FSE technique seems preferable to GRASE for fast T2-weighted routine MR imaging of the brain. For the assessment of hemosiderin or ferritin depositions, GRASE might be considered. (orig.)

  8. Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study.

    Science.gov (United States)

    Abdulhadi, Mike A; Perno, Joseph R; Melhem, Elias R; Nucifora, Paolo G P

    2014-01-01

    In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

  9. Fast spin echo MRI techniques. Contrast characteristics and clinical potential

    International Nuclear Information System (INIS)

    Melki, P.; Mulkern, R.V.; Dacher, J.N.; Helenon, O.; Higuchi, N.; Oshio, K.; Jolesz, F.; Pourcelot, L.; Einstein, S.

    1993-01-01

    Based on partial RF echo planar principles, Fast Spin Echo techniques (FSE) were implemented on high field systems. These methods produce image quality and contrast which resemble to conventional spin echo (SE) techniques. By reducing acquisition times by factors between 1.4 and 16 over SE methods, FSE allows for several imaging options usually prohibitive with conventional spin echo (SE) sequences. These include fast scans (especially breathold acquisitions); improved T2 contrast with longer TR intervals; increased spatial resolution with the use of larger image matrices and/or smaller fields of view; and 3D volume imaging with a 3D multislab FSE technique. Contrast features of FSE techniques are directly comparable to those of multiple echo SE sequences using the same echo spacing than FSE methods. However, essential contrast differences existing between the FSE sequences and their routine asymmetric dual SE counterpart can be identified. Decreased magnetic susceptibility effects and increased fat signal present within T2 weighted images compared to conventional dual SE images are due to the use of shorter echo spacings employed in FSE sequences. Off-resonance irradiation inherent to the use of a large number of radio frequency pulses in shown to results in dramatic magnetization contrast transfer effects in FSE images acquired in multislice mode

  10. Isotropic three-dimensional fast spin-echo Cube magnetic resonance dacryocystography: comparison with the three-dimensional fast-recovery fast spin-echo technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Chen, Lang; Wang, Qiu-Xia; Zhu, Wen-Zhen; Luo, Xin; Peng, Li [Huazhong University of Science and Technology, Department of Radiology, Tongji Hospital, Wuhan (China); Liu, Rong [Huazhong University of Science and Technology, Department of Ophthalmology, Tongji Hospital, Wuhan (China); Xiong, Wei [GE Healthcare China Wuhan Office, Wuhan (China)

    2015-04-01

    Three-dimensional fast spin-echo Cube (3D-FSE-Cube) uses modulated refocusing flip angles and autocalibrates two dimensional (2D)-accelerated parallel and nonlinear view ordering to produce high-quality volumetric image sets with high-spatial resolution. Furthermore, 3D-FSE-Cube with topical instillation of fluid can also be used for magnetic resonance dacryocystography (MRD) with good soft tissue contrast. The purpose of this study was to evaluate the technical quality and visualization of the lacrimal drainage system (LDS) when using the 3D-FSE-Cube sequence and the 3D fast-recovery fast spin-echo (FRFSE) sequence. In total, 75 patients with primary LDS outflow impairment or postsurgical recurrent epiphora underwent 3D-FSE-Cube MRD and 3D-FRFSE MRD at 3.0 T after topical administration of compound sodium chloride eye drops. Two radiologists graded the images from either of the two sequences in a blinded fashion, and appropriate statistical tests were used to assess differences in technical quality, visibility of ductal segments, and number of segments visualized per LDS. Obstructions were confirmed in 90 of the 150 LDSs assessed. The technical quality of 3D-FSE-Cube MRD and 3D-FRFSE MRD was statistically equivalent (P = 0.871). However, compared with 3D-FRFSE MRD, 3D-FSE-Cube MRD improved the overall visibility and the visibility of the upper drainage segments in normal and obstructed LDSs (P < 0.001). There was a corresponding increase in the number of segments visualized per LDS in both groups (P < 0.001). Compared with 3D-FRFSE MRD, 3D-FSE-Cube MRD potentially improves the visibility of the LDS. (orig.)

  11. Proton T2 relaxation effect of superparamagnetic iron oxide. Comparison between fast spin echo and conventional spin echo sequence

    International Nuclear Information System (INIS)

    Tanimoto, Akihiro; Satoh, Yoshinori; Higuchi, Nobuya; Izutsu, Mutsumu; Yuasa, Yuji; Hiramatsu, Kyoichi

    1995-01-01

    Superparamagnetic iron oxide (SPIO) particles have been known to show a great T 2 relaxation effect in the liver, which contributes to significant liver signal decrease and detection of hepatic neoplasms. Recently, fast spin echo (FSE) sequence with less scanning time than conventional spin echo (SE) sequence has been rapidly introduced in clinical MR imaging. To investigate whether SPIO would show decreased T 2 relaxation effect on FSE, we obtained T 2 relaxivity (R2) of SPIO in vitro and liver signal decrease caused by SPIO in vivo. SPIO showed 20% less R2 on Carr-Purcell-Meiboom-Gill (CPMG) sequence than on SE. Relative liver signal-to-noise ratio (SNR) decrease caused by SPIO was significantly smaller (p 2 relaxation effect on FSE than on SE. However, further studies will be required to assess the diagnostic capability of SPIO on FSE, in the detection of hepatic neoplasms. (author)

  12. Fast spin-echo MR imaging of the eye

    International Nuclear Information System (INIS)

    Hosten, N.; Lemke, A.J.; Bornfeld, N.; Wassmuth, R.; Schweiger, U.; Terstegge, K.; Felix, R.

    1996-01-01

    Magnetic resonance imaging of the eye usually includes T2-weighted images both for screening purposes and for characterization of melanoma. Conventional T2-weighted spin-echo (SE) imaging suffers both from long acquisition times and incomplete recovery of the virteous' signal. A fast SE sequence was therefore compared prospectively with conventional sequences in 29 consecutive patients with lesions of the eye. Fast SE images delineated melanoma and other lesions of the eye from vitreous better than conventional T2-weighted images. Image quality and lesion conspicuity were improved on the fast sequence. Whereas melanoma appeared hypointense to vitreous on both types of images, subretinal effusion was hypointense on fast images and hyperintense on conventional T2-weighted images. Ghosting of the globe, which, however, did not decrease diagnostic value, was more pronounced on fast images. Conventional T2-weighted images may be replaced by fast SE images in MR studies of the eye with a gain in lesion conspicuity and significant time saving. (orig.)

  13. High signal intensity of fat on fast spin echo imaging

    International Nuclear Information System (INIS)

    Ogura, Akio; Yamazaki, Masaru; Hongoh, Takaharu; Inoue, Hiroshi; Ishikuro, Akihiro

    2000-01-01

    The fast spin echo (FSE) technique of producing T 2 -weighted images in greatly reduced imaging times has recently been used for routine clinical study. FSE images show contrast that is very similar in most tissues to that of conventional SE images. However, fat shows a high signal intensity that is influenced by j-coupling and the magnetization transfer effect. The purpose of this study was to assess whether the higher signal intensity of fat is different among MRI systems and to examine the effects of j-coupling and magnetization transfer on the high signal intensity of fat on FSE. The contrast in signal intensity between fat and water was measured for various echo train lengths (ETL) with and without multislicing on FSE using a contrast phantom. Measurements were obtained with four different MRI systems. In addition, the effective T 2 values of fat were calculated for the above conditions. Results indicated that contrast for fat and water was reduced with increased ETL and by using multislicing and was different among the four MRI systems. The effective T 2 values of fat were extended for increased ETL and were not dependent on multislicing. They also differed among the four MRI systems. The extent of effective T 2 values was affected by j-coupling. In this study, it was indicated that the degree of the high signal intensity of fat on FSE differed for different MRI systems. In addition, the reasons for the high signal intensity of fat on FSE were related to the effects of j-coupling and magnetization transfer. (author)

  14. Fast spin echo MRI techniques. Contrast characteristics and clinical potential. Techniques d'IRM en fast spin echo. Caracteristiques de contraste et potentiels cliniques

    Energy Technology Data Exchange (ETDEWEB)

    Melki, P.; Mulkern, R.V.; Dacher, J.N.; Helenon, O.; Higuchi, N. (Harvard Medical School, Boston, MA (United States)); Oshio, K.; Jolesz, F. (Keio Univ., Tokyo (Japan)); Pourcelot, L. (Hopital Bretonneau, 37 - Tours (France)); Einstein, S. (General Electric Medical System, Milwaukee, WI (United States))

    1993-03-01

    Based on partial RF echo planar principles, Fast Spin Echo techniques (FSE) were implemented on high field systems. These methods produce image quality and contrast which resemble to conventional spin echo (SE) techniques. By reducing acquisition times by factors between 1.4 and 16 over SE methods, FSE allows for several imaging options usually prohibitive with conventional spin echo (SE) sequences. These include fast scans (especially breathold acquisitions); improved T2 contrast with longer TR intervals; increased spatial resolution with the use of larger image matrices and/or smaller fields of view; and 3D volume imaging with a 3D multislab FSE technique. Contrast features of FSE techniques are directly comparable to those of multiple echo SE sequences using the same echo spacing than FSE methods. However, essential contrast differences existing between the FSE sequences and their routine asymmetric dual SE counterpart can be identified. Decreased magnetic susceptibility effects and increased fat signal present within T2 weighted images compared to conventional dual SE images are due to the use of shorter echo spacings employed in FSE sequences. Off-resonance irradiation inherent to the use of a large number of radio frequency pulses in shown to results in dramatic magnetization contrast transfer effects in FSE images acquired in multislice mode.

  15. Application of fast spin-echo T2-weighted imaging for examination of the neurocranium. Comparison with the conventional T2-weighted spin-echo sequence

    International Nuclear Information System (INIS)

    Siewert, C.; Hosten, N.; Felix, R.

    1994-01-01

    T 2 -weighted spin-echo imaging is the standard screening procedure in MR imaging of the neutrocranium. We evaluated fast spin-echo T 2 -weighted imaging (TT 2 ) of the neurocranium in comparison to conventional spin-echo T 2 -weighted imaging (T 2 ). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher than TT 2 than in T 2 (with the exception of grey-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT 2 , Parkinson patients have to be examined by conventional T 2 . If these limitations are taken into account, fast spin-echo T 2 -weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T 2 -weighting achieved in a short acquisition time. (orig.) [de

  16. Fast triple-spin-echo Dixon (FTSED) sequence for water and fat imaging

    Czech Academy of Sciences Publication Activity Database

    Kořínek, Radim; Bartušek, Karel; Starčuk jr., Zenon

    2017-01-01

    Roč. 37, APR (2017), s. 164-170 ISSN 0730-725X R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : fast triple-spin-echo Dixon * sequence * MRI * fat fraction * water-fat * ultra-high field * 9.4 T * FTSED Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Radiology, nuclear medicine and medical imaging Impact factor: 2.225, year: 2016

  17. MR cholangiography using a fast spin-echo technique: prospective evaluation in 20 patients

    International Nuclear Information System (INIS)

    Rondeau, Y.; Meduri, B.; Spelle, L.; Gouhiri, M.; Aubert, A.; Scherrer, A.; Soyer, Ph.; Rymer, R.

    1998-01-01

    To evaluate a MR cholangiographic technique using a non breath-hold fast spin-echo technique in patients with suspected bile duct obstruction. Twenty patients with suspected bile duct obstruction were prospectively investigated with MR cholangiography using a T2-weighted non breath-hold fast spin-echo technique (TR 8000-9000 msec, effective TE 120-266 msec, ETL = 16-32, acquisition time = 1-3 min) with a body coil. Results of MR cholangiography were compared to those obtained with endoscopic retrograde cholangiography (n = 20 patients) and endoscopic sonography (n 12 patients) that were considered as reference. MR cholangiography provided high-quality images in 19 out of 20 cases (95 %). MR cholangiography had 100 % sensitivity, 100 % specificity and 73 % accuracy in the diagnosis of bile duct obstruction. MR cholangiography failed to depict small stones (< 3 mm) of the main bile duct in 4 cases in which no bile duct dilation was found. MR cholangiography using a non breath-hold fast spin-echo technique depicts bile duct dilatation with a degree of accuracy comparable to that achieved with endoscopic examination. In the absence of bile duct dilatation, small stones of the main bile duct may be undetected with MR cholangiography. (author)

  18. Diagnostic equivalence of conventional and fast spin echo magnetic resonance imaging of the anterior cruciate ligament of the knee

    International Nuclear Information System (INIS)

    Munk, P.L.; Hilborn, M.D.; Vellet, A.D.; University of Calgary, Calgary, Alberta,; Romano, C.C.; University of Calgary, Calgary, Alberta,

    1997-01-01

    Many techniques and pulse sequences have been devised for the assessment of the anterior cruciate ligament. The present study compares fast spin echo (FSE) imaging to conventional spin echo imaging at a field strength of 1.5 T in an effort to determine if these sequences are diagnostically equivalent. Where available, arthroscopy was also done. A total of 52 patients were imaged using both FSE and conventional spin echo sequences. Eight volunteers were used as controls. Arthroscopy was performed on 10 patients. The anterior cruciate ligament was assessed in a blinded fashion by three radiologists. The Kappa statistic was then used to determine the percentage agreement between FSE and conventional spin echo imaging. Fast spin echo sequencing demonstrated a sensitivity of 100%, a specificity of 94.8% and an accuracy of 96.3% when compared to arthroscopy. Conventional spin echo imaging and arthroscopy had a sensitivity of 100%, specificity of 84.6% and an accuracy of 88.9%. The remaining 34 patients who did not undergo arthroscopy were followed clinically because clinical and imaging findings were not suggestive of ACL tears. These demonstrated 72% agreement between FSE and conventional spin echo imaging using the Kappa statistic, with regards to calling ACL normal or having only a low-grade partial tear. Fast spin echo imaging produces images of the anterior cruciate ligament that have similar diagnostic accuracy to conventional spin echo images (P<0.05) within a much shorter scan time. These results however, require further validation in a larger group, preferably with arthroscopic correlation. (author)

  19. Contrast-enhanced dynamic MR imaging of parasellar tumor using fast spin-echo sequence

    International Nuclear Information System (INIS)

    Kusunoki, Katsusuke; Ohue, Shiro; Ichikawa, Haruhisa; Saito, Masahiro; Sadamoto, Kazuhiko; Sakaki, Saburo; Miki, Hitoshi.

    1995-01-01

    We have applied a new dynamic MRI technique that uses a fast spin-echo sequence to parasellar tumors. This sequence has less susceptible effect and better spatial resolution than a gradient echo sequence, providing faster images than a short spin-echo sequence does. Image was obtained in the coronal or sagittal plane using a 1.5T clinical MRI system, and then, dynamic MR images were acquired every 10 to 20 sec after administration of Gd-DTPA (0.1 mmol/kg). The subjects were 12 patients (5 microadenomas, 5 macroadenomas and 2 Rathke's cleft cysts) and 5 normal volunteers. As for volunteers, the cavernous sinus, pituitary stalk and posterior pituitary gland were contrasted on the first image, followed by visualization of the proximal portion adjacent to the junction of the infundibulum and the anterior pituitary gland, and finally by contrasting the distal portion of the anterior pituitary gland. There was a difference with respect to tumor contrast between microadenomas and macroadenomas. In the case of the macroadenomas, the tumor was contrasted at the same time as, or faster than the anterior pituitary gland, while with the microadenomas the tumor was enhanced later than the anterior pituitary gland. No enhancement with contrast medium was seen in Rathke's cleft cysts. In addition, it was possible to differentiate a recurrent tumor from a piece of muscle placed at surgery since the images obtained by the fast spin-echo sequence were clearer than those obtained by gradient echo sequence. (author)

  20. Comparison of respiratory-triggered 3-D fast spin-echo and single-shot fast spin-echo radial slab MR cholangiopancreatography images in children

    Energy Technology Data Exchange (ETDEWEB)

    Chavhan, Govind B.; Almehdar, Abeer; Gupta, Sumeet [The Hospital for Sick Children and University of Toronto, Department of Diagnostic Imaging, Toronto (Canada); Moineddin, Rahim [University of Toronto, Department of Family and Community Medicine, Toronto (Canada); Babyn, Paul S. [Royal University Hospital, Department of Medical Imaging, Saskatoon (Canada)

    2013-09-15

    The two most commonly performed magnetic resonance cholangiopancreatography (MRCP) sequences, 3-D fast spin-echo (3-D FSE) and single-shot fast spin-echo radial slabs (radial slabs), have not been compared in children. The purpose of this study was to compare 3-D FSE and radial slabs MRCP sequences on a 3-T scanner to determine their ability to show various segments of pancreaticobiliary tree and presence of artifacts in children. We reviewed 79 consecutive MRCPs performed in 74 children on a 3-T scanner. We noted visibility of major ducts on 3-D FSE and radial slabs. We noted the order of branching of ducts in the right and left hepatic ducts and the degree of visibility of the pancreatic duct. Statistical analysis was performed using McNemar and signed rank tests. There was no significant difference in the visibility of major bile ducts and the order of branching in the right hepatic lobe between sequences. A higher order of branching in the left lobe was seen on radial slabs than 3-D FSE (mean order of branching 2.82 versus 2.27; P-value = 0.0002). The visibility of pancreatic duct was better on radial slabs as compared to 3-D FSE (mean value of 1.53 vs. 0.90; P-value < 0.0001). 3-D FSE sequence was artifact-free in 25/79 (31.6%) MRCP exams as compared to radial slabs, which were artifact-free in 18/79 (22.8%) MRCP exams (P-value = 0.0001). There is no significant difference in the visibility of major bile ducts between 3-D FSE and radial slab MRCP sequences at 3-T in children. However, radial slab MRCP shows a higher order of branching in the left hepatic lobe and superior visibility of the pancreatic duct than 3-D FSE. (orig.)

  1. Detection of renal arteries with fast spin-echo magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tello, R.; Mitchell, P.J.; Witte, D.J.; Thomson, K.R. [University of Melbourne, Parkville, VIC (Australia). Department of Radiology

    1998-08-01

    With the increasing use of non-invasive imaging with MR and volumetric CT to evaluate renal arteries, the ability to accurately detect the number and state of native renal arteries becomes critical if conventional angiography is to be supplanted in these settings. The present study evaluated the utility of a fast spin-echo (FSE) T2-weighted sequence to detect the number and course of renal arteries and their ostia compared to conventional angiography. Ten patients underwent conventional catheter angiography either for renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with FSE MR (TR = 4000 ms, TE = 102 ms, eight- echo train length, 5-mm-thick interleaved 128 phase encodes, superior and inferior saturation pulses, number of excitations (NEX) = 4, on a 1.5-T superconducting magnet). Images were reviewed by two `blinded` radiologists and renal arteries were counted and their ostia were evaluated. Results were compared with angiography and inter- and intra-observer statistics were calculated. All 10 patients underwent MR successfully, nine for renal artery stenosis (RAS) evaluation and one was a renal donor. A total of 24 renal arteries were imaged in 19 kidneys. Fast spin-echo MR is 95% accurate (95%CI: 88-100%) in detection of renal arteries, with no statistical difference between FSE MR and catheter angiography (McNemar P = 0.0). Inter- and intra-observer statistics demonstrate good-to-excellent agreement in renal artery detection (kappa: 0.63-0.90). In one case of RAS evaluation an incidental adrenal mass was detected as the aetiology of the patient`s hypertension. Fast spin-echo MR can be a useful adjunct as part of the imaging for renal arteries with MRI. Copyright (1998) Blackwell Science Pty Ltd 16 refs., 1 fig.

  2. Detection of renal arteries with fast spin-echo magnetic resonance imaging

    International Nuclear Information System (INIS)

    Tello, R.; Mitchell, P.J.; Witte, D.J.; Thomson, K.R.

    1998-01-01

    With the increasing use of non-invasive imaging with MR and volumetric CT to evaluate renal arteries, the ability to accurately detect the number and state of native renal arteries becomes critical if conventional angiography is to be supplanted in these settings. The present study evaluated the utility of a fast spin-echo (FSE) T2-weighted sequence to detect the number and course of renal arteries and their ostia compared to conventional angiography. Ten patients underwent conventional catheter angiography either for renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with FSE MR (TR = 4000 ms, TE = 102 ms, eight- echo train length, 5-mm-thick interleaved 128 phase encodes, superior and inferior saturation pulses, number of excitations (NEX) = 4, on a 1.5-T superconducting magnet. Images were reviewed by two 'blinded' radiologists and renal arteries were counted and their ostia were evaluated. Results were compared with angiography and inter- and intra-observer statistics were calculated. All 10 patients underwent MR successfully, nine for renal artery stenosis (RAS) evaluation and one was a renal donor. A total of 24 renal arteries were imaged in 19 kidneys. Fast spin-echo MR is 95% accurate (95%CI: 88-100%) in detection of renal arteries, with no statistical difference between FSE MR and catheter angiography (McNemar P = 0.0). Inter- and intra-observer statistics demonstrate good-to-excellent agreement in renal artery detection (kappa: 0.63-0.90). In one case of RAS evaluation an incidental adrenal mass was detected as the aetiology of the patient's hypertension. Fast spin-echo MR can be a useful adjunct as part of the imaging for renal arteries with MRI. Copyright (1998) Blackwell Science Pty Ltd

  3. Fast method of NMR imaging based on trains of spin echoes

    International Nuclear Information System (INIS)

    Hennel, F.

    1993-01-01

    A theoretical introduction to Fourier NMR imaging and a discussion of fast methods are presented. Then an application of the method of echo-planar imaging (EPI) with spin echoes in a micro-imaging system is described together with introduced modifications of the sequence. A new technique for the measurement of flow profiles in liquids which results from a modification of x-pulsed EPI is presented. The development of new software for a NMR micro-imaging system is described, too. 51 refs, 29 refs

  4. Fast FLAIR MR imaging finidngs of cerebral infarction : comparison with T2-weighted spin echo imaging

    International Nuclear Information System (INIS)

    Kong, Keun Young; Choi, Woo Suk; Kim, Eui Jong

    1997-01-01

    To evaluate the utility of FLAIR(Fluid Attenuated Inversion Recovery) MR imaging in cerebral infarction by comparing its results with those of T2-weighted spin-echo imaging. We retrospectively evaluated fast FLAIR images and conventional spin echo images of 82 patients (47 men and 20 women ; median age 60.9 years) with cerebral infarction. MR imaging used a 1.5T MR unit with conventional T2(TR 3900, TE 90) and fast FLAIR sequence (TR 8000, TE 105, TI 2400). We analysed the size of the main lesion and number of lesions, and discrimination between old and new lesions and between small infarction and perivascular space. When T2-weighted and FLAIR imaging were compared, the latter showed that the main lesion was larger in 38 cases (46%), similar in 38 (46%), and smaller in six (7%). The number of lesions was greater in 23 cases(28%), similar in 52 (63%), and fewer in seven (9%). FLAIR images discriminated between old and new lesions in 31 cases ; perivascular space and small infarotion were differentiated in eight cases, and CSF inflowing artifact was observed in 66 (80%). In the diagnosis of cerebral infaretion, fast FLAIR provides images that are equal or superior to T2-weighted images. The fast FLAIR sequence may therefore be used as a part of routine MR brain study in the diagnosis of cerebral infarction

  5. Application of fast spin-echo T[sub 2]-weighted imaging for examination of the neurocranium. Comparison with the conventional T[sub 2]-weighted spin-echo sequence. Die Anwendung der T[sub 2]-gewichteten Turbo-Spin-Echo-Sequenz zur Untersuchung des Neurokraniums. Vergleich mit der konventionellen T[sub 2]-gewichteten Spin-Echo-Sequenz

    Energy Technology Data Exchange (ETDEWEB)

    Siewert, C. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany)); Hosten, N. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany)); Felix, R. (Strahlenklinik und Poliklinik, Universitaets-Klinikum Rudolf Virchow, Standort Wedding, Freie Univ. Berlin (Germany))

    1994-07-01

    T[sub 2]-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neutrocranium. We evaluated fast spin-echo T[sub 2]-weighted imaging (TT[sub 2]) of the neurocranium in comparison to conventional spin-echo T[sub 2]-weighted imaging (T[sub 2]). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher than TT[sub 2] than in T[sub 2] (with the exception of grey-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT[sub 2], Parkinson patients have to be examined by conventional T[sub 2]. If these limitations are taken into account, fast spin-echo T[sub 2]-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T[sub 2]-weighting achieved in a short acquisition time. (orig.)

  6. A comparison between fast and conventional spin-echo in the detection of multiple sclerosis lesions

    International Nuclear Information System (INIS)

    Thorpe, J.W.; Halpin, S.F.; MacManus, D.G.; Barker, G.J.; Kendall, B.E.; Miller, D.H.

    1994-01-01

    Long repetition time (TR) spin-echo (SE) with T 2 - or proton density weighting is the sequence of choice to detect the brain lesions of multiple sclerosis (MS). Fast spin-echo (FSE) permits the generation of T 2 -weighted images with similar contrast to SE but in a fraction of the time. We compared the sensitivity of FSE and SE in the detection of the brain lesions of MS. Six patients with clinically definite MS underwent brain imaging with both dual echo (long TR, long and short echo time (TE) SE and dual echo FSE. The SE and FSE images were first reviewed independently and then compared. A total of 404 lesions was detected on SE and 398 on FSE. Slightly more periventricular lesions were detected using SE than FSE (145 vs 127), whereas more posterior cranial fossa lesions were detected by FSE (77 vs 57). With both SE and FSE the short TE images revealed more lesions than the long echo. These results suggest that FSE could replace SE as the long TR sequence of choice in the investigation of MS. (orig.)

  7. Comparison of spin echo T1-weighted sequences versus fast spin-echo proton density-weighted sequences for evaluation of meniscal tears at 1.5 T

    International Nuclear Information System (INIS)

    Wolff, Andrew B.; Pesce, Lorenzo L.; Wu, Jim S.; Smart, L.R.; Medvecky, Michael J.; Haims, Andrew H.

    2009-01-01

    At our institution, fast spin-echo (FSE) proton density (PD) imaging is used to evaluate articular cartilage, while conventional spin-echo (CSE) T1-weighted sequences have been traditionally used to characterize meniscal pathology. We sought to determine if FSE PD-weighted sequences are equivalent to CSE T1-weighted sequences in the detection of meniscal tears, obviating the need to perform both sequences. We retrospectively reviewed the records of knee arthroscopies performed by two arthroscopy-focused surgeons from an academic medical center over a 2-year period. The preoperative MRI images were interpreted independently by two fellowship-trained musculoskeletal radiologists who graded the sagittal CSE T1 and FSE PD sequences at different sittings with grades 1-5, where 1 = normal meniscus, 2 = probable normal meniscus, 3 indeterminate, 4 = probable torn meniscus, and 5 = torn meniscus. Each meniscus was divided into an anterior and posterior half, and these halves were graded separately. Operative findings provided the gold standard. Receiver operating characteristic (ROC) analysis was performed to compare the two sequences. There were 131 tears in 504 meniscal halves. Using ROC analysis, the reader 1 area under curve for FSE PD was significantly better than CSE T1 (0.939 vs. 0.902, >95% confidence). For reader 2, the difference met good criteria for statistical non-inferiority but not superiority (0.913 for FSE PD and 0.908 for CSE T1; >95% non-inferiority for difference at most of -0.027). FSE PD-weighted sequences, using our institutional protocol, are not inferior to CSE T1-weighted sequences for the detection of meniscal tears and may be superior. (orig.)

  8. Meniscal tear evaluation. Comparison of a conventional spin-echo proton density sequence with a fast spin-echo sequence utilizing a 512x358 matrix size

    International Nuclear Information System (INIS)

    Hopper, M.A.; Robinson, P.; Grainger, A.J.

    2011-01-01

    Aim: To determine the sensitivities, specificities, and receiver-operating characteristics (ROCs) for sagittal conventional spin-echo proton density (SE-PD) and fast spin-echo proton density (FSE-PD) sequences in the diagnosis of meniscal tears when compared to arthroscopic findings utilizing increased FSE matrix acquisition size. Method and materials: Magnetic resonance imaging (MRI) studies of 97 knees (194 menisci) were independently and prospectively interpreted by two experienced musculoskeletal radiologists over four separate readings at least 3 weeks apart. Readings 1 and 2 included images in all three planes in accordance with the standard protocol with either a SE or FSE sagittal PD, at readings 3 and 4 just the SE or FSE sagittal PD sequences were reported. The FSE sequence was acquired with an increased matrix size, compared to the SE sequence, to provide increased resolution. Menisci were graded for the presence of a tear and statistical analysis to calculate sensitivity and specificity was performed comparing to arthroscopy as the reference standard. ROC analysis for the diagnosis of meniscal tears on the SE and FSE sagittal sequences was also evaluated. Reader concordance for the SE and FSE sequences was calculated. Results: Sixty-seven tears were noted at arthroscopy; 60 were detected on SE and 56 on FSE. The sensitivity and specificity for SE was 90 and 90%, and for FSE was 84 and 94%, respectively, with no significant difference. ROC analysis showed no significant difference between the two sequences and kappa values demonstrated a higher level of reader agreement for the FSE than for the SE reading. Conclusion: Use of a FSE sagittal PD sequence with an increased matrix size provides comparable performance to conventional SE sagittal PD when evaluating meniscal disease with a modern system. The present study indicates an increased level of concordance between readers for the FSE sagittal sequence compared to the conventional SE.

  9. Meniscal tear evaluation. Comparison of a conventional spin-echo proton density sequence with a fast spin-echo sequence utilizing a 512x358 matrix size

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, M.A.; Robinson, P. [Leeds Teaching Hospitals NHS Trust, Leeds (United Kingdom); Grainger, A.J., E-mail: andrew.grainger@leedsth.nhs.u [Leeds Teaching Hospitals NHS Trust, Leeds (United Kingdom)

    2011-04-15

    Aim: To determine the sensitivities, specificities, and receiver-operating characteristics (ROCs) for sagittal conventional spin-echo proton density (SE-PD) and fast spin-echo proton density (FSE-PD) sequences in the diagnosis of meniscal tears when compared to arthroscopic findings utilizing increased FSE matrix acquisition size. Method and materials: Magnetic resonance imaging (MRI) studies of 97 knees (194 menisci) were independently and prospectively interpreted by two experienced musculoskeletal radiologists over four separate readings at least 3 weeks apart. Readings 1 and 2 included images in all three planes in accordance with the standard protocol with either a SE or FSE sagittal PD, at readings 3 and 4 just the SE or FSE sagittal PD sequences were reported. The FSE sequence was acquired with an increased matrix size, compared to the SE sequence, to provide increased resolution. Menisci were graded for the presence of a tear and statistical analysis to calculate sensitivity and specificity was performed comparing to arthroscopy as the reference standard. ROC analysis for the diagnosis of meniscal tears on the SE and FSE sagittal sequences was also evaluated. Reader concordance for the SE and FSE sequences was calculated. Results: Sixty-seven tears were noted at arthroscopy; 60 were detected on SE and 56 on FSE. The sensitivity and specificity for SE was 90 and 90%, and for FSE was 84 and 94%, respectively, with no significant difference. ROC analysis showed no significant difference between the two sequences and kappa values demonstrated a higher level of reader agreement for the FSE than for the SE reading. Conclusion: Use of a FSE sagittal PD sequence with an increased matrix size provides comparable performance to conventional SE sagittal PD when evaluating meniscal disease with a modern system. The present study indicates an increased level of concordance between readers for the FSE sagittal sequence compared to the conventional SE.

  10. MR contrast of ferritin and hemosiderin in the brain: comparison among gradient-echo, conventional spin-echo and fast spin-echo sequences

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Tabassum Laz; Miki, Yukio; Kanagaki, Mitsunori; Takahashi, Takahiro; Yamamoto, Akira; Konishi, Junya; Nozaki, Kazuhiko; Hashimoto, Nobuo; Konishi, Junji

    2003-12-01

    Objective: To compare the magnetic resonance image contrasts due to ferritin and hemosiderin in the brain tissue among different pulse sequences. Materials and methods: Fourteen patients with cavernous hemangioma in the brain prospectively underwent MR imaging with T2*-weighted gradient-echo (GRE), T2-weighted conventional spin-echo (SE) and fast spin-echo (FSE) sequences. The relative contrast ratios (CRs) of the hypointense part of cavernous hemangioma, globus pallidus and putamen to the deep frontal white matter were measured on each pulse sequence and statistically analyzed using analysis of variance followed by paired t-test. Results: In the hypointense part of cavernous hemangioma, relative CRs were significantly lower on T2*-weighted GRE than on T2-weighted SE images (P=0.0001), and on T2-weighted SE than on T2-weighted FSE images (P=0.0001). In the globus pallidus, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.002), and on T2*-weighted GRE than on T2-weighted FSE images (P=0.0002). In the putamen, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.001), and there was no significant difference between CRs on T2-weighted FSE and T2*-weighted GRE images (P=0.90). Conclusion: Hemosiderin showed best image contrast on T2*-weighted GRE images but ferritin showed more prominent image contrast on T2-weighted SE than on T2*-weighted GRE images, which may help to determine an appropriate pulse sequence in neurological diseases associated with excessive ferritin accumulation.

  11. MR contrast of ferritin and hemosiderin in the brain: comparison among gradient-echo, conventional spin-echo and fast spin-echo sequences

    International Nuclear Information System (INIS)

    Haque, Tabassum Laz; Miki, Yukio; Kanagaki, Mitsunori; Takahashi, Takahiro; Yamamoto, Akira; Konishi, Junya; Nozaki, Kazuhiko; Hashimoto, Nobuo; Konishi, Junji

    2003-01-01

    Objective: To compare the magnetic resonance image contrasts due to ferritin and hemosiderin in the brain tissue among different pulse sequences. Materials and methods: Fourteen patients with cavernous hemangioma in the brain prospectively underwent MR imaging with T2*-weighted gradient-echo (GRE), T2-weighted conventional spin-echo (SE) and fast spin-echo (FSE) sequences. The relative contrast ratios (CRs) of the hypointense part of cavernous hemangioma, globus pallidus and putamen to the deep frontal white matter were measured on each pulse sequence and statistically analyzed using analysis of variance followed by paired t-test. Results: In the hypointense part of cavernous hemangioma, relative CRs were significantly lower on T2*-weighted GRE than on T2-weighted SE images (P=0.0001), and on T2-weighted SE than on T2-weighted FSE images (P=0.0001). In the globus pallidus, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.002), and on T2*-weighted GRE than on T2-weighted FSE images (P=0.0002). In the putamen, relative CRs were significantly lower on T2-weighted SE than on T2*-weighted GRE images (P=0.001), and there was no significant difference between CRs on T2-weighted FSE and T2*-weighted GRE images (P=0.90). Conclusion: Hemosiderin showed best image contrast on T2*-weighted GRE images but ferritin showed more prominent image contrast on T2-weighted SE than on T2*-weighted GRE images, which may help to determine an appropriate pulse sequence in neurological diseases associated with excessive ferritin accumulation

  12. Kinematic MRI using short TR single shot fast spin echo (SSFSE) in evaluating swallowing

    Energy Technology Data Exchange (ETDEWEB)

    Isogai, Satoshi; Takehara, Yasuo; Isoda, Haruo; Kodaira, Nami; Masunaga, Hatsuko; Ozawa, Fukujirou; Kaneko, Masao [Hamamatsu Univ. School of Medicine, Shizuoka (Japan); Nozaki, Atsushi; Kabasawa, Hiroyuki

    1999-03-01

    The utility of short TR single shot fast spin echo (SSFSE) MR imaging for evaluating swallowing was determined. Five healthy volunteers underwent kinematic MR imaging of swallowing with a 1.5 T MR scanner using the short TR (300 ms) SSFSE sequence. Twenty phases of sagittal sections were acquired within 6 sec, where the temporal resolution was 300 ms. For oral contrast medium, we used prune yogurt juice with Fe added. The image contrast of short TR SSFSE was found to be somewhere like that of T1-weighted images. In all cases, both the buccal and pharyngeal stages of swallowing were successfully depicted. The Fe-added prune yogurt juice performed as a positive contrast medium and helped determine anatomical structures in the buccal stage. Short TR (300 ms) SSFSE was useful in evaluating swallowing. The combined use of Fe-added prune yogurt juice was helpful in enhancing the surface of the oropharynx. (author)

  13. Kinematic MRI using short TR single shot fast spin echo (SSFSE) in evaluating swallowing

    International Nuclear Information System (INIS)

    Isogai, Satoshi; Takehara, Yasuo; Isoda, Haruo; Kodaira, Nami; Masunaga, Hatsuko; Ozawa, Fukujirou; Kaneko, Masao; Nozaki, Atsushi; Kabasawa, Hiroyuki

    1999-01-01

    The utility of short TR single shot fast spin echo (SSFSE) MR imaging for evaluating swallowing was determined. Five healthy volunteers underwent kinematic MR imaging of swallowing with a 1.5 T MR scanner using the short TR (300 ms) SSFSE sequence. Twenty phases of sagittal sections were acquired within 6 sec, where the temporal resolution was 300 ms. For oral contrast medium, we used prune yogurt juice with Fe added. The image contrast of short TR SSFSE was found to be somewhere like that of T1-weighted images. In all cases, both the buccal and pharyngeal stages of swallowing were successfully depicted. The Fe-added prune yogurt juice performed as a positive contrast medium and helped determine anatomical structures in the buccal stage. Short TR (300 ms) SSFSE was useful in evaluating swallowing. The combined use of Fe-added prune yogurt juice was helpful in enhancing the surface of the oropharynx. (author)

  14. The evaluation of fat saturation fast spin-echo T2W1 for patients with acute spinal trauma

    International Nuclear Information System (INIS)

    Kim, Sung Gyu; Lee, Chang Jun; Lee, Myung Joon; Kang, Ik Won; Yoo, Jeong Hyun

    2002-01-01

    To determine the usefulness of fat saturation fast spin-echo T2W1 for patients with mild acute trauma of the spine. Between July 1998 and June 2002, 36 patients with acute spinal trauma underwent MRI within four months of injury. One, whose clinal symptoms indicated neurological paralysis, was excluded form our study. A superconductive 1.0-T MRI scanner was used, and conventional T1W1, T2W1, and additional fat-saturation fast spin-echo T2W1 were performed. Two radiologists compared conventional T2-weighted sagittal imaging and fat-saturation T2-weighted sagittal imaging in terms of the extension of increased high signal intensities in soft tissue and vertebral bodies, bone marrow signal change, disk herniation, and signal change of the disk. The detection rate of focal high signal intensities in soft tissue and bone marrow was significantly higher at fat-saturation fast spin-echo T2W1 than at conventional T2W1. Fat-saturation fast spin-echo T2W1 is useful for the evaluation of patients with mild acute spinal trauma without neurological impairment

  15. Comparison of single-shot fast spin-echo sequence and T2-weighted fast spin-echo sequence in MR imaging of the brain

    International Nuclear Information System (INIS)

    Cha, Sung Ho; Seo, Jeong Jin; Jeong, Gwang Woo; Kim, Jae Kyu; Kim, Yun Hyeon; Jeong, Yong Yeon; Kang, Heoung Keun; Oh, Hee Yeon; Yoon, Jong Hoon

    1998-01-01

    The purpose of this study was to evaluate the usefulness of the single-shot fast spinecho (SS-FSE) sequence in comparison with the T2-weighted fast spin-echo (T2-FSE) sequence in brain MR imaging. In 41 patients aged 15-75 years with intracranial lesion, both SS-FSE and T2-FES images were obtained using a 1.5-T MR system. Lesions included cerebral ischemia or infarcts (n=3D23), tumors (n=3D10), hemorrhages (n=3D3), inflammatory diseases (n=3D2), arachnoid cysts(n=3D2), and vascular disease (n=3D1), and the MR images were retrospectively evaluated. To calculate contrast-to-noise ratio (CNR), percentage contrast, and signal-to-noise ratio (SNR)-and thus make a quantitative comparison-the mean signal intensities of lesions, normal brain tissue, and noise out-side the patient were measured. For qualitative comparison, the visibility, margin, and extent of the lesions were rated using a five-grade system, and the degree of MR artifacts was also evaluated. Wilcoxon's signed ranks test was used for statistical analysis. The mean CNR of lesions was significantly higher on SS-FSE (31.3) than on T2-FSE images (27.5) (p=3D0.0131). Mean percentage contrast was also higher on SS-FSE (159.0) than on T2-FSE images (108.5) (p=3D0.0222), but mean SNR was higher on T2-FSE (80.3) than on SS-FSE images (53.5) (p=3D0.0000). No significant differences in lesion visibility were observed between the two imaging sequences, though margin and extent of the lesion were worse on SS-FSE images. For MR artifacts, no significant differences were demonstrated. For the evaluation of most intracranial lesions, MR imaging using the SS-FSE sequence appears to be slightly inferior to the T2-FSE sequence, but may be useful where patients are ill or uncooperative, or where children require sedation.=20

  16. Reduction of respiratory ghosting motion artifacts in conventional two-dimensional multi-slice Cartesian turbo spin-echo: which k-space filling order is the best?

    Science.gov (United States)

    Inoue, Yuuji; Yoneyama, Masami; Nakamura, Masanobu; Takemura, Atsushi

    2018-06-01

    The two-dimensional Cartesian turbo spin-echo (TSE) sequence is widely used in routine clinical studies, but it is sensitive to respiratory motion. We investigated the k-space orders in Cartesian TSE that can effectively reduce motion artifacts. The purpose of this study was to demonstrate the relationship between k-space order and degree of motion artifacts using a moving phantom. We compared the degree of motion artifacts between linear and asymmetric k-space orders. The actual spacing of ghost artifacts in the asymmetric order was doubled compared with that in the linear order in the free-breathing situation. The asymmetric order clearly showed less sensitivity to incomplete breath-hold at the latter half of the imaging period. Because of the actual number of partitions of the k-space and the temporal filling order, the asymmetric k-space order of Cartesian TSE was superior to the linear k-space order for reduction of ghosting motion artifacts.

  17. Diagnostic performance of the three-dimensional fast spin echo-Cube sequence in comparison with a conventional imaging protocol in evaluation of the lachrymal drainage system

    International Nuclear Information System (INIS)

    Zhang, Jing; Chen, Lang; Wang, Qiu-Xia; Zhu, Wen-Zhen; Luo, Xin; Peng, Li; Liu, Rong; Xiong, Wei

    2015-01-01

    To compare the three-dimensional (3D)-fast spin-echo (FSE)-Cube with a conventional imaging protocol in evaluation of dacryostenosis. Thirty-three patients with epiphora underwent examinations using Cube magnetic resonance dacryocystography (MRD) and a conventional protocol, which included 3D fast-recovery fast spin-echo (FRFSE) MRD and two-dimensional (2D)-FSE sequences at 3.0 T. Using lachrymal endoscopic findings as the reference standard, we calculated the sensitivity and specificity of both protocols for detecting lachrymal drainage system (LDS) obstruction and their accuracies in depicting the level of obstruction. Comparable coronal and axial images were selected for bot sequences. Two neuroradiologists graded paired images for blurring, artefacts, anatomic details, and overall image quality. The two methods showed no significant difference in sensitivity (89.5 % vs. 94.7 %; p =0.674), specificity (64.3 %; p =1) or accuracy (86.8 %; p =1) in detecting or depicting LDS obstruction. Blurring and artefacts were significantly better on 2D-FSE images (p 0.05). In comparison with the conventional protocol, Cube MRD demonstrates satisfactory image quality and similar diagnostic capability for cases of possible LDS disease. (orig.)

  18. High-spatial-resolution isotropic three-dimensional fast-recovery fast spin-echo magnetic resonance dacryocystography combined with topical administration of sterile saline solution

    International Nuclear Information System (INIS)

    Jing, Zhang; Lang, Chen; Qiu-Xia, Wang; Rong, Liu; Xin, Luo; Wen-Zhen, Zhu; Li-Ming, Xia; Jian-Pin, Qi; He, Wang

    2013-01-01

    Objective: This study aims to investigate the clinical performance of three-dimensional (3D) fast-recovery fast spin-echo (FRFSE) magnetic resonance dacryocystography (MRD) with topical administration of sterile saline solution for the assessment of the lacrimal drainage system (LDS). Methods: A total of 13 healthy volunteers underwent both 3D-FRFSE MRD and two-dimensional (2D)-impulse recovery (IR)-single-shot fast spin-echo (SSFSE) MRD after topical administration of sterile saline solution, and 31 patients affected by primary LDS outflow impairment or postsurgical recurrent epiphora underwent 3D-FRFSE MRD and conventional T1- and T2-weighted sequences. All patients underwent lacrimal endoscopy or surgery, which served as a standard of reference for confirming the MRD findings. Results: 3D-FRFSE MRD detected more visualized superior and inferior canaliculi and nasolacrimal duct than 2D-IR-SSFSE MRD. Compared with 2D-IR-SSFSE MRD, 3D-FRFSE MRD showed more visualized segments per LDS, although the difference was not statistically significant. Significant improvements in the inferior canaliculus and nasolacrimal duct visibility grades were achieved using 3D-FRFSE MRD. 3D-FRFSE MRD had 100% sensitivity and 63.6% specificity for detecting LDS obstruction. In 51 out of the 62 LDSs that were assessed, a 90% agreement was noted between the findings of 3D-FRFSE MRD and lacrimal endoscopy in detecting the obstruction level. Conclusion: 3D-FRFSE MRD combined with topical administration of sterile saline solution is a simple and noninvasive method of obtaining detailed morphological and functional information on the LDS. Overall, 3D-FRFSE MRD could be used as a reliable diagnostic method in many patients with epiphora prior to surgery

  19. Three-dimensional fast recovery fast spin-echo imaging of the inner ear and the vestibulocochlear nerve

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, K.; Morikawa, M.; Ishimaru, H.; Ochi, M.; Hayashi, K. [Department of Radiology, Nagasaki University School of Medicine, 1-7-1 Sakamoto, Nagasaki 852-8501 (Japan); Kabasawa, H. [GE Yokogawa Medical Systems, Tokyo (Japan)

    2002-11-01

    The aim of this study was to assess the performance of three-dimensional fast recovery fast spin-echo (3DFRFSE) for imaging of the inner ear as well as the facial and vestibulocochlear nerves. We evaluated 3DFRFSE sequences, comparing it with 3D fast spin-echo (3DFSE) in a water phantom and in 12 normal volunteers. We also examined 66 patients using 3DFRFSE sequence and assessed the visualization of their pathologies. In a water phantom study, signal intensity (SI) on 3DFRFSE was higher than that on 3DFSE at the same TR ranging from 1500 to 6000 ms. In normal volunteers, 3DFRFSE with TR of 2800 ms showed comparable SI, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) superior to those on 3DFSE with TR of 5000 ms. In clinical setting, 3DFRFSE was useful in demonstrating anatomic details in the labyrinth and pathologic findings of inner ear. The 3DFRFSE can provide high-resolution heavily T2-weighted images (T2WI) with shorter scan time than 3DFSE without significant disadvantage. The 3DFRFSE is a beneficial technique for evaluation of lesions in the inner ear as well as the facial and vestibulocochlear nerves. (orig.)

  20. Spatial resolution properties in 3D fast spin-echo using variable refocusing flip angles

    International Nuclear Information System (INIS)

    Ozaki, Masanori; Mizukami, Shinya; Hata, Hirofumi; Sato, Mayumi; Komi, Syotaro; Miyati, Tosiaki; Nozaki, Atsushi

    2011-01-01

    A new 3-dimensional fast spin-echo (3D FSE) method that uses a variable refocusing flip angle technique has recently been applied to imaging. The imaging pulse sequence can inhibit T 2 decay by varying the refocusing flip angle. Use of a long echo train length allows acquisition of 3D T 2 -weighted images with less blurring in a short scan time. The smaller refocusing flip angle in the new 3D FSE method than in the conventional method can reduce the specific absorption rate. However, T 2 decay differs between the new and conventional 3D FSE methods, so the resolution properties of the 2 methods may differ. We investigated the resolution properties of the new 3D FSE method using a variable refocusing flip angle technique. Varying the refocusing flip angle resulted in different resolution properties for the new 3D FSE method compared to the conventional method, a difference particularly noticeable when the imaging parameters were set for obtaining proton density weighted images. (author)

  1. MR cisternography with three-dimensional fast advanced spin-echo (FASE)

    International Nuclear Information System (INIS)

    Ohgi, Kazuyuki; Yamamoto, Hidefumi; Yokote, Hiroyuki

    2000-01-01

    To evaluate the usefulness of MR cisternography (MRC) combined with various postprocessing techniques and three-dimensional (3D) time-of-flight (TOF) MR angiography, MR cisternograms in 212 patients with various cranial nerve symptoms were retrospectively evaluated. MR examinations were performed with a 1.5 T MR imager using a 3D fast advanced spin-echo (FASE) sequence. Maximum intensity projection (MIP) had the advantage of demonstrating fluid-filled structures such as cerebrospinal fluid (CSF)-internal auditory canal (IAC) and Meckel's cave. Minimum intensity projection (Min IP) was especially useful in delineating neurovascular structures (NVS) in wide CSF space. Addition provided the most well-balanced images of NVS, and was superior to Min IP in the depiction of NVS in narrow CSF space. Virtual endoscopy and volume rendering had the potential to provide additional information in the evaluation of the three-dimensional relationships of NVS. Combination of 3D TOF MRA with MRC was helpful in differentiating arteries, veins, and nerves. With the judicious use of various postprocessing techniques and combined MRA, the value of MRC in the evaluation of patients with various cranial nerve symptoms can be further strengthened. (author)

  2. Magnetic resonance cisternography using the fast spin echo method for the evaluation of vestibular schwannoma

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, Shigeru; Yokoyama, Tetsuo; Uemura, Kenichi [Hamamatsu Univ. School of Medicine, Shizuoka (Japan)

    1999-04-01

    Neuroimaging of vestibular schwannoma was performed with the fat-suppression spoiled gradient recalled acquisition in the steady state (SPGR) method and magnetic resonance (MR) cisternography, which is a fast spin echo method using a long echo train length, for the preoperative evaluation of the lateral extension of the tumor in the internal auditory canal, and the anatomical identification of the posterior semicircular canal and the nerves in the canal distal to the tumor. The SPGR method overestimated the lateral extension in eight cases, probably because of enhancement of the nerves adjacent to the tumor in the canal. The posterior semicircular canal could not be clearly identified, and the cranial nerves in the canal were shown only as a nerve bundle. In contrast, MR cisternography showed clear images of the lateral extension of the tumor and the facial and cochlear nerves adjacent to the tumor in the internal auditory canal. The anatomical location of the posterior semicircular canal was also clearly shown. These preoperative findings are very useful to plan the extent to which the internal auditory canal can be opened, and for intraoperative identification of the nerves in the canal. MR cisternography is less invasive since no contrast material or radiation is required, as with thin-slice high-resolution computed tomography (CT). MR cisternography should replace high-resolution CT for the preoperative neuroradiological evaluation of vestibular schwannoma. (author)

  3. MR cisternography with three-dimensional fast advanced spin-echo (FASE)

    Energy Technology Data Exchange (ETDEWEB)

    Ohgi, Kazuyuki; Yamamoto, Hidefumi; Yokote, Hiroyuki [Japanese Red-Cross Medical Center, Tokyo (Japan)] [and others

    2000-06-01

    To evaluate the usefulness of MR cisternography (MRC) combined with various postprocessing techniques and three-dimensional (3D) time-of-flight (TOF) MR angiography, MR cisternograms in 212 patients with various cranial nerve symptoms were retrospectively evaluated. MR examinations were performed with a 1.5 T MR imager using a 3D fast advanced spin-echo (FASE) sequence. Maximum intensity projection (MIP) had the advantage of demonstrating fluid-filled structures such as cerebrospinal fluid (CSF)-internal auditory canal (IAC) and Meckel's cave. Minimum intensity projection (Min IP) was especially useful in delineating neurovascular structures (NVS) in wide CSF space. Addition provided the most well-balanced images of NVS, and was superior to Min IP in the depiction of NVS in narrow CSF space. Virtual endoscopy and volume rendering had the potential to provide additional information in the evaluation of the three-dimensional relationships of NVS. Combination of 3D TOF MRA with MRC was helpful in differentiating arteries, veins, and nerves. With the judicious use of various postprocessing techniques and combined MRA, the value of MRC in the evaluation of patients with various cranial nerve symptoms can be further strengthened. (author)

  4. Fast spin-echo MR assessment of patients with poor outcome following spinal cervical surgery

    International Nuclear Information System (INIS)

    Wu, W.; Thuomas, K.AA.; Hedlund, R.; Leszniewski, W.; Vavruch, L.

    1996-01-01

    The aim of the investigation was to evaluate poor outcome following spinal cervical surgery. A total of 146 consecutive patients operated with anterior discectomy and fusion (ADF) with the Cloward technique were investigated. Clinical notes, plain radiography, CT, and fast spin-echo (FSE) images were retrospectively evaluated. Some 30% of the patients had unsatisfactory clinical results within 12 months after surgery; 13% had initial improvement followed by deterioration of the preoperative symptoms, while 14.4% were not improved or worsened. Disc herniation and bony stenosis above, below, or at the fused level were the most common findings. In 45% of patients, surgery failed to decompress the spinal canal. In only 4 patients was no cause of remaining myelopathy and/or radiculopathy found. FSE demonstrated a large variety of pathological findings in the patients with poor clinical outcome after ADF. Postoperatively, patients with good clinical outcome had a lower incidence of pathological changes. FSE is considered the primary imaging modality for the cervical spine. However, CT is a useful complement in the axial projection to visualize bone changes. (orig.)

  5. Fast fluid-attenuated inversion-recovery MR image in the intracranial tumors: comparison with fast spin-echo image

    International Nuclear Information System (INIS)

    Choi, Hye Young; Kwang, Hyoen Joo; Baek, Seoung Yeon; Lee, Sun Wha

    1997-01-01

    To evaluate the significance of fluid-attenuated inversion recovery(FLAIR) magnetic resonance(MR) images for the diagnosis of intracranial tumors. MR imaging was used to study 15 patients with various intracranial tumors and were compared the findings according to fast spin echo and fast FLAIR images. In 12 of 15 patients, tumor signal intensities on FLAIR images were consistent with those shown on T2-weighted(T2W) images. In seven of eight patients who had cystic or necrotic components within the mass, FLAIR images showed isosignal intensity and in the other patient, high signal intensity was seen. There was variation in the signal intensity from cerebrospinal fluid(CSF). In 12 of 13 patients in whom edema was associated with tumor, FLAIR images were clearer than T2W images as their signal intensity was brighter. In eight patients, however, FLAIR and T2W images provided a similar definition of the margin between edema and tumor. In six patients with intratumoral hemorrhage except the chronic cystic stage. We concluded that in the diagnosis of intracranial tumors, FLAIR images can supplement conventional spin-echo images

  6. The evaluation of fat saturation fast spin-echo T2WI for patients with acute spinal trauma

    International Nuclear Information System (INIS)

    Kim, Sung Gyu; Lee, Chang Jun; Lee, Myung Joon; Kang, Ik Won; Yoo, Jeong Hyun

    2002-01-01

    To determine the usefulness of fat saturation fast spin-echo T2WI for patients with mild acute trauma of the spine. Between July 1998 and June 2002, 36 patients with acute spinal trauma underwent MRI within four months of injury. One, whose clinal symptoms indicated neurological paralysis, was excluded form our study. A superconductive 1.0-T MRI scanner was used, and conventional T1W1, T2W1, and additional fat-saturation fast spin-echo T2W1 were performed. Two radiologists compared conventional T2-weighted sagittal imaging and fat-saturation T2-weighted sagittal imaging in terms of the extension of increased high signal intensities in soft tissue and vertebral bodies, bone marrow signal change, disk herniation, and signal change of the disk. The detection rate of focal high signal intensities in soft tissue and bone marrow was significantly higher at fat-saturation fast spin-echo T2W1 is useful the evaluation of patients with mild acute spinal trauma without neurological impairment

  7. Comparison of dynamic dual spin-echo and fast-gradient-echo techniques in the evaluation of cardiac diseases

    International Nuclear Information System (INIS)

    Pettigrew, R.I.; Eisner, R.L.; Groen, J.P.; Baron, M.G.

    1987-01-01

    To determine the relative roles of a dynamic spin-echo method and a fast acquisition with multiphase excitations (FAME) technique, ten patients with myocardial infarction (MI), five with myocardial masses, and five healthy patients were studied with both methods. The dynamic dual-spin-echo (DSE) technique allows acquisition of each of seven sections at 14 cardiac phases in 20 minutes. Wall motion abnormalities were seen equally well with both techniques, but FAME usually required a shorter study time (10 minutes). DSE, however, was superior for evaluating cardiac masses and provided superior wall blood contrast. Thus, these techniques are complementary, and both are now a routine part of the authors' study of cardiac patients

  8. Self-Calibrating Wave-Encoded Variable-Density Single-Shot Fast Spin Echo Imaging.

    Science.gov (United States)

    Chen, Feiyu; Taviani, Valentina; Tamir, Jonathan I; Cheng, Joseph Y; Zhang, Tao; Song, Qiong; Hargreaves, Brian A; Pauly, John M; Vasanawala, Shreyas S

    2018-04-01

    It is highly desirable in clinical abdominal MR scans to accelerate single-shot fast spin echo (SSFSE) imaging and reduce blurring due to T 2 decay and partial-Fourier acquisition. To develop and investigate the clinical feasibility of wave-encoded variable-density SSFSE imaging for improved image quality and scan time reduction. Prospective controlled clinical trial. With Institutional Review Board approval and informed consent, the proposed method was assessed on 20 consecutive adult patients (10 male, 10 female, range, 24-84 years). A wave-encoded variable-density SSFSE sequence was developed for clinical 3.0T abdominal scans to enable high acceleration (3.5×) with full-Fourier acquisitions by: 1) introducing wave encoding with self-refocusing gradient waveforms to improve acquisition efficiency; 2) developing self-calibrated estimation of wave-encoding point-spread function and coil sensitivity to improve motion robustness; and 3) incorporating a parallel imaging and compressed sensing reconstruction to reconstruct highly accelerated datasets. Image quality was compared pairwise with standard Cartesian acquisition independently and blindly by two radiologists on a scale from -2 to 2 for noise, contrast, confidence, sharpness, and artifacts. The average ratio of scan time between these two approaches was also compared. A Wilcoxon signed-rank tests with a P value under 0.05 considered statistically significant. Wave-encoded variable-density SSFSE significantly reduced the perceived noise level and improved the sharpness of the abdominal wall and the kidneys compared with standard acquisition (mean scores 0.8, 1.2, and 0.8, respectively, P variable-density sampling SSFSE achieves improved image quality with clinically relevant echo time and reduced scan time, thus providing a fast and robust approach for clinical SSFSE imaging. 1 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:954-966. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Evaluation of chondromalacia of the patella with axial inversion recovery-fast spin-echo imaging.

    Science.gov (United States)

    Lee, S H; Suh, J S; Cho, J; Kim, S J; Kim, S J

    2001-03-01

    The purpose of our study was to assess the accuracy of inversion recovery-fast spin-echo (IR-FSE) imaging for the evaluation of chondromalacia of the patella. Eighty-six patients were included, they underwent magnetic resonance (MR) examination and subsequent knee arthroscopy. Medial and lateral facets of the patella were evaluated separately. Axial images were obtained by using IR-FSE (TR/TE/TI = 3000/25/150 msec; echo train length, 8; 4-mm thickness; 12-cm field of view; 512 x 256 matrix; two, number of excitations) with a 1.5-T MR machine. MR interpretation of chondromalacia was made on the basis of the arthroscopic grading system. Of a total of 172 facets graded, arthroscopy revealed chondromalacia in 14 facets with various grades (G0, 158; G1, 1; G2, 3; G3, 6; G4, 4). Sensitivity, specificity, and accuracy in the chondromalacia grades were 57.1%, 93.0%, and 90.1%, respectively. There was one false-negative case (G4) and 11 false-positive cases (G1, eight; G2, two; G3, one). Sensitivity and specificity corrected by one grade difference were improved to 85.7% and 98.1%, respectively. When cartilage changes were grouped into early (corresponding to grade 1 and 2) and advanced (grade 3 and 4) diseases, sensitivity and specificity of the early and advanced diseases were 75% and 94% and 80% and 99%, respectively. IR-FSE imaging of the knee revealed high specificity but low sensitivity for the evaluation of chondromalacia of the patella.

  10. Evaluation of aqueductal patency in patients with hydrocephalus: Three-dimensional high-sampling efficiency technique(SPACE) versus two-dimensional turbo spin echo at 3 Tesla

    International Nuclear Information System (INIS)

    Ucar, Murat; Guryildirim, Melike; Tokgoz, Nil; Kilic, Koray; Borcek, Alp; Oner, Yusuf; Akkan, Koray; Tali, Turgut

    2014-01-01

    To compare the accuracy of diagnosing aqueductal patency and image quality between high spatial resolution three-dimensional (3D) high-sampling-efficiency technique (sampling perfection with application optimized contrast using different flip angle evolutions [SPACE]) and T2-weighted (T2W) two-dimensional (2D) turbo spin echo (TSE) at 3-T in patients with hydrocephalus. This retrospective study included 99 patients diagnosed with hydrocephalus. T2W 3D-SPACE was added to the routine sequences which consisted of T2W 2D-TSE, 3D-constructive interference steady state (CISS), and cine phase-contrast MRI (PC-MRI). Two radiologists evaluated independently the patency of cerebral aqueduct and image quality on the T2W 2D-TSE and T2W 3D-SPACE. PC-MRI and 3D-CISS were used as the reference for aqueductal patency and image quality, respectively. Inter-observer agreement was calculated using kappa statistics. The evaluation of the aqueductal patency by T2W 3D-SPACE and T2W 2D-TSE were in agreement with PC-MRI in 100% (99/99; sensitivity, 100% [83/83]; specificity, 100% [16/16]) and 83.8% (83/99; sensitivity, 100% [67/83]; specificity, 100% [16/16]), respectively (p < 0.001). No significant difference in image quality between T2W 2D-TSE and T2W 3D-SPACE (p = 0.056) occurred. The kappa values for inter-observer agreement were 0.714 for T2W 2D-TSE and 0.899 for T2W 3D-SPACE. Three-dimensional-SPACE is superior to 2D-TSE for the evaluation of aqueductal patency in hydrocephalus. T2W 3D-SPACE may hold promise as a highly accurate alternative treatment to PC-MRI for the physiological and morphological evaluation of aqueductal patency.

  11. Evaluation of aqueductal patency in patients with hydrocephalus: Three-dimensional high-sampling efficiency technique(SPACE) versus two-dimensional turbo spin echo at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Ucar, Murat; Guryildirim, Melike; Tokgoz, Nil; Kilic, Koray; Borcek, Alp; Oner, Yusuf; Akkan, Koray; Tali, Turgut [School of Medicine, Gazi University, Ankara (Turkey)

    2014-12-15

    To compare the accuracy of diagnosing aqueductal patency and image quality between high spatial resolution three-dimensional (3D) high-sampling-efficiency technique (sampling perfection with application optimized contrast using different flip angle evolutions [SPACE]) and T2-weighted (T2W) two-dimensional (2D) turbo spin echo (TSE) at 3-T in patients with hydrocephalus. This retrospective study included 99 patients diagnosed with hydrocephalus. T2W 3D-SPACE was added to the routine sequences which consisted of T2W 2D-TSE, 3D-constructive interference steady state (CISS), and cine phase-contrast MRI (PC-MRI). Two radiologists evaluated independently the patency of cerebral aqueduct and image quality on the T2W 2D-TSE and T2W 3D-SPACE. PC-MRI and 3D-CISS were used as the reference for aqueductal patency and image quality, respectively. Inter-observer agreement was calculated using kappa statistics. The evaluation of the aqueductal patency by T2W 3D-SPACE and T2W 2D-TSE were in agreement with PC-MRI in 100% (99/99; sensitivity, 100% [83/83]; specificity, 100% [16/16]) and 83.8% (83/99; sensitivity, 100% [67/83]; specificity, 100% [16/16]), respectively (p < 0.001). No significant difference in image quality between T2W 2D-TSE and T2W 3D-SPACE (p = 0.056) occurred. The kappa values for inter-observer agreement were 0.714 for T2W 2D-TSE and 0.899 for T2W 3D-SPACE. Three-dimensional-SPACE is superior to 2D-TSE for the evaluation of aqueductal patency in hydrocephalus. T2W 3D-SPACE may hold promise as a highly accurate alternative treatment to PC-MRI for the physiological and morphological evaluation of aqueductal patency.

  12. A fast random walk algorithm for computing the pulsed-gradient spin-echo signal in multiscale porous media.

    Science.gov (United States)

    Grebenkov, Denis S

    2011-02-01

    A new method for computing the signal attenuation due to restricted diffusion in a linear magnetic field gradient is proposed. A fast random walk (FRW) algorithm for simulating random trajectories of diffusing spin-bearing particles is combined with gradient encoding. As random moves of a FRW are continuously adapted to local geometrical length scales, the method is efficient for simulating pulsed-gradient spin-echo experiments in hierarchical or multiscale porous media such as concrete, sandstones, sedimentary rocks and, potentially, brain or lungs. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Cardiac T2-mapping using a fast gradient echo spin echo sequence - first in vitro and in vivo experience

    OpenAIRE

    Baessler, Bettina; Schaarschmidt, Frank; Stehning, Christian; Schnackenburg, Bernhard; Maintz, David; Bunck, Alexander C.

    2015-01-01

    Background: The aim of this study was the evaluation of a fast Gradient Spin Echo Technique (GraSE) for cardiac T2-mapping, combining a robust estimation of T2 relaxation times with short acquisition times. The sequence was compared against two previously introduced T2-mapping techniques in a phantom and in vivo. Methods: Phantom experiments were performed at 1.5 T using a commercially available cylindrical gel phantom. Three different T2-mapping techniques were compared: a Multi Echo Spin Ec...

  14. Comparison of 3D vs. 2D fast spin echo imaging for evaluation of articular cartilage in the knee on a 3 T system scientific research

    International Nuclear Information System (INIS)

    Milewski, Matthew D.; Smitaman, Edward; Moukaddam, Hicham; Katz, Lee D.; Essig, David A.; Medvecky, Michael J.; Haims, Andrew H.

    2012-01-01

    Highlights: ► Compared 3D to 2D MR sequences for articular cartilage in the knee. ► 3D imaging acquired in a single plane, 2D acquired in 3 separate planes. ► No significant difference in accuracy between 3D and 2D sequences. - Abstract: Purpose: We sought to retrospectively compare the accuracy of a three-dimensional fat-suppressed, fast spin-echo sequences acquired in the sagittal plane, with multiplanar reconstructions to that of two-dimensional fat-suppressed, fast spin echo sequences acquired in three planes on a 3 T MR system for the evaluation of articular cartilage in the knee. Materials and methods: Our study group consisted of all patients (N = 34) that underwent 3 T MR imaging of the knee at our institution with subsequent arthroscopy over an 18-month period. There were 21 males and 13 females with an average age of 36 years. MR images were reviewed by 3 musculoskeletal radiologists, blinded to operative results. 3D and 2D sequences were reviewed at different sittings separated by 4 weeks to prevent bias. Six cartilage surfaces were evaluated both with MR imaging and arthroscopically with a modified Noyes scoring system and arthroscopic results were used as the gold standard. Sensitivity, specificity, and accuracy were calculated for each reader along with Fleiss Kappa assessment agreement between the readers. Accuracies for each articular surface were compared using a difference in proportions test with a 95% confidence interval and statistical significance was calculated using a Fisher's Exact Test. Results: Two hundred and four articular surfaces were evaluated and 49 articular cartilage lesions were present at arthroscopy. For the patellofemoral surfaces, the sensitivity, specificity, and accuracy were 76.5%, 83%, and 78.2% for the 3D sequences and were 82.3%, 76%, and 82% respectively for the 2D sequences. For the medial compartment surfaces, the sensitivity, specificity, and accuracy were 81.1%, 65.1%, and 78.5% for the 3D sequences and were

  15. Lesion discrimination in optic neuritis using high-resolution fat-suppressed fast spin-echo MRI

    International Nuclear Information System (INIS)

    Gass, A.; Moseley, I.F.; Barker, G.J.; Jones, S.; MacManus, D.; McDonald, W.I.; Miller, D.H.

    1996-01-01

    Fast spin-echo (FSE) is a new sequence with acquisition times currently down to one-sixteenth of those obtained with conventional spin-echo sequences, which allows high-resolution (512 x 512 matrix) images to be acquired in an acceptable time. We compared the higher resolution of FSE with the medium resolution of a short inversion-time inversion-recovery (STIR) sequence in depicting the optic nerves of healthy controls and patients with optic neuritis. Optic nerve MRI examinations were performed in 18 patients with optic neuritis and 10 normal controls. Two sequences were obtained coronally: fat-suppressed FSE (FSE TR 3250 ms/TEef 68 ms, echo-train length 16, 4 excitations, 24 cm rectangular field of view, 3 mm interleaved contiguous slices, in-plane resolution 0.5 x 0.5 mm) and STIR (TR 2000 ms/TE 50 ms/TI 175 ms, in-plane resolution 0.8 x 0.8 mm, slice thickness 5 mm). FSE demonstrated much more anatomical detail than STIR, e. g. distinction of optic nerve and sheath. Lesions were seen in 20 of 21 symptomatic nerves using FSE and in 18 of 21 using STIR. Nerve swelling or partial cross-sectional lesions of the optic nerve were each seen only on FSE in 3 cases. Fat-suppressed FSE imaging of the optic nerve improves anatomical definition and increases lesion detection in optic neuritis. (orig.). With 5 figs

  16. MRI of acute cerebral infarction: a comparison of FLAIR and T2-weighted fast spin-echo imaging

    International Nuclear Information System (INIS)

    Noguchi, K.; Ogawa, T.; Inugami, A.; Fujita, H.; Hatazawa, J.; Shimosegawa, E.; Okudera, T.; Uemura, K.; Seto, H.

    1997-01-01

    Fluid-attenuated inversion-recovery (FLAIR) sequences have been reported to provide high sensitivity to a wide range of central nervous system diseases. To our knowledge, however, FLAIR sequences have not been used to study patients with acute cerebral infarcts. We evaluated the usefulness of FLAIR sequences in this context. FLAIR sequences were acquired on a 0.5 T superconducting unit within 8 h of the onset in 19 patients (aged 26-80 years) with a total of 23 ischaemic lesions. The images were reviewed retrospectively by three neuroradiologists, and the FLAIR images were compared with T2-weighted fast spin-echo images. All but one of the ischaemic lesions involving grey matter was clearly demonstrated on FLAIR images as increased signal intensity in cortical or central grey matter. FLAIR images were particularly useful for detecting the hyperacute cortical infarcts within 3 h of onset, which were not readily detected on the spin-echo images. In 9 of 11 patients with complete proximal occlusion, the distal portion of the cerebral artery was visible as an area of high signal intensity on FLAIR images. (orig.). With 4 figs., 1 tab

  17. 3D isotropic T2-weighted fast spin echo (VISTA) versus 2D T2-weighted fast spin echo in evaluation of the calcaneofibular ligament in the oblique coronal plane.

    Science.gov (United States)

    Park, H J; Lee, S Y; Choi, Y J; Hong, H P; Park, S J; Park, J H; Kim, E

    2017-02-01

    To investigate whether the image quality of three-dimensional (3D) volume isotropic fast spin echo acquisition (VISTA) magnetic resonance imaging (MRI) of the calcaneofibular ligament (CFL) view is comparable to that of 2D fast spin echo T2-weighted images (2D T2 FSE) for the evaluation of the CFL, and whether 3D VISTA can replace 2D T2 FSE for the evaluation of CFL injuries. This retrospective study included 76 patients who underwent ankle MRI with CFL views of both 2D T2 FSE MRI and 3D VISTA. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of both techniques were measured. The anatomical identification score and diagnostic performances were evaluated by two readers independently. The diagnostic performances of 3D VISTA and 2D T2 FSE were analysed by sensitivity, specificity, and accuracy for diagnosing CFL injury with reference standards of surgically or clinically confirmed diagnoses. Surgical correlation was performed in 29% of the patients, and clinical examination was used in those who did not have surgery (71%). The SNRs and CNRs of 3D VISTA were significantly higher than those of 2D T2 FSE. The anatomical identification scores on 3D VISTA were inferior to those on 2D T2 FSE, and the differences were statistically significant (pT2 FSE for the anatomical evaluation of CFL, 3D VISTA has a diagnostic performance comparable to that of 2D T2 FSE for the diagnosis of CFL injuries. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  18. Qualitative and quantitative assessment of wrist MRI at 3.0T - Comparison between isotropic 3D turbo spin echo and isotropic 3D fast field echo and 2D turbo spin echo

    International Nuclear Information System (INIS)

    Jung, Jee Young; Yoon, Young Cheol; Jung, Jin Young; Choe, Bong-Keun

    2013-01-01

    Background: Isotropic three-dimensional (3D) magnetic resonance imaging (MRI) has been applied to various joints. However, comparison for image quality between isotropic 3D MRI and two-dimensional (2D) turbo spin echo (TSE) sequence of the wrist at a 3T MR system has not been investigated. Purpose: To compare the image quality of isotropic 3D MRI including TSE intermediate-weighted (VISTA) sequence and fast field echo (FFE) sequence with 2D TSE intermediate-weighted sequence of the wrist joint at 3.0 T. Material and Methods: MRI was performed in 10 wrists of 10 healthy volunteers with isotropic 3D sequences (VISTA and FFE) and 2D TSE intermediate-weighted sequences at 3.0 T. The signal-to-noise ratio (SNR) was obtained by imaging phantom and noise-only image. Contrast ratios (CRs) were calculated between fluid and cartilage, triangular fibrocartilage complex (TFCC), and the scapholunate ligament. Two radiologists independently assessed the visibility of TFCC, carpal ligaments, cartilage, tendons and nerves with a four-point grading scale. Statistical analysis to compare CRs (one way ANOVA with a Tukey test) and grades of visibility (Kruskal-Wallis test) between three sequences and those for inter-observer agreement (kappa analysis) were performed. Results: The SNR of 2D TSE (46.26) was higher than those of VISTA (23.34) and 3D FFE (19.41). CRs were superior in 2D TSE than VISTA (P = 0.02) for fluid-cartilage and in 2D TSE than 3D FFE (P < 0.01) for fluid-TFCC. The visibility was best in 2D TSE (P < 0.01) for TFCC and in VISTA (P = 0.01) for scapholunate ligament. The visibility was better in 2D TSE and 3D FFE (P 0.04) for cartilage and in VISTA than 3D FFE (P < 0.01) for TFCC. The inter-observer agreement for the visibility of anatomic structures was moderate or substantial. Conclusion: Image quality of 2D TSE was superior to isotropic 3D MR imaging for cartilage, and TFCC. 3D FFE has better visibility for cartilage than VISTA and VISTA has superior visibility for

  19. Qualitative and quantitative assessment of wrist MRI at 3.0T - Comparison between isotropic 3D turbo spin echo and isotropic 3D fast field echo and 2D turbo spin echo

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jee Young [Dept. of Radiology, Chungang Univ. Hospital, School of Medicine, Chungang Univ. (Korea, Republic of); Yoon, Young Cheol [Dept. of Radiology, Samsung Medical Center, School of Medicine, Sungkyunkwan Univ. (Korea, Republic of)], e-mail: ycyoon@skku.edu; Jung, Jin Young [Dept. of Radiology, Saint Paul' s Hospital, The Catholic Univ. (Korea, Republic of); Choe, Bong-Keun [Dept. of Preventive Medicine, School of Medicine, Kyung Hee Univ., Seoul (Korea, Republic of)

    2013-04-15

    Background: Isotropic three-dimensional (3D) magnetic resonance imaging (MRI) has been applied to various joints. However, comparison for image quality between isotropic 3D MRI and two-dimensional (2D) turbo spin echo (TSE) sequence of the wrist at a 3T MR system has not been investigated. Purpose: To compare the image quality of isotropic 3D MRI including TSE intermediate-weighted (VISTA) sequence and fast field echo (FFE) sequence with 2D TSE intermediate-weighted sequence of the wrist joint at 3.0 T. Material and Methods: MRI was performed in 10 wrists of 10 healthy volunteers with isotropic 3D sequences (VISTA and FFE) and 2D TSE intermediate-weighted sequences at 3.0 T. The signal-to-noise ratio (SNR) was obtained by imaging phantom and noise-only image. Contrast ratios (CRs) were calculated between fluid and cartilage, triangular fibrocartilage complex (TFCC), and the scapholunate ligament. Two radiologists independently assessed the visibility of TFCC, carpal ligaments, cartilage, tendons and nerves with a four-point grading scale. Statistical analysis to compare CRs (one way ANOVA with a Tukey test) and grades of visibility (Kruskal-Wallis test) between three sequences and those for inter-observer agreement (kappa analysis) were performed. Results: The SNR of 2D TSE (46.26) was higher than those of VISTA (23.34) and 3D FFE (19.41). CRs were superior in 2D TSE than VISTA (P = 0.02) for fluid-cartilage and in 2D TSE than 3D FFE (P < 0.01) for fluid-TFCC. The visibility was best in 2D TSE (P < 0.01) for TFCC and in VISTA (P = 0.01) for scapholunate ligament. The visibility was better in 2D TSE and 3D FFE (P 0.04) for cartilage and in VISTA than 3D FFE (P < 0.01) for TFCC. The inter-observer agreement for the visibility of anatomic structures was moderate or substantial. Conclusion: Image quality of 2D TSE was superior to isotropic 3D MR imaging for cartilage, and TFCC. 3D FFE has better visibility for cartilage than VISTA and VISTA has superior visibility for

  20. Comparison of fast spin echo, fast multiplanner spoiled gradient recalled and conventional T1 and T2 weighted imaging for experimentally induced hepatic tumors in rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myeong Jin; Lee, Jong Tae; Suh, Jin Suk; Choi, Pil Sik; Lee, Yeon Hee; Yoo, Hyung Sik; Kim, Ki Whang [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1994-10-15

    To compare the ability of tumor detection and the lesion conspicuity between T1- and T2-weighted fast scanning sequence and T1- and T2-weighted conventional spin echo techniques in MR imaging of hepatic tumors. Hepatic tumors were induced on 13 male Sprague-Dawley rats by feeding 3'-methyl-dimethylethyl aminoazobenzene mixed with Miller's III formula for 12 weeks. MR images were obtained with 1.5 T magnet with dual TMJ coil(Sigma, GE Medical systems, Milwaukee, USA). Animals were anesthetized with 150 mg/kg of ketamine hydrochloride. T2 weighted fast spin echo(FSE), conventional spin echo(CSE) T2- and T1WI, fast multiplanner spoiled gradient recalled(FMPSPGR) imaging were obtained. Number of detected tumors and contrast-to-noise ratio of the tumors were compared for each sequence. Overall 110 tumors were developed. 75% of the tumors were detected on FSE. 65% on FMPSPGR, 41% on conventional T2WI, and 41% on T1WI images. For tumors more than 5 mm in diameter, sensitivity was 88% on FMPSPGR, 65% on conventional T2WI, and 81% on T1WI images respectively. CNR of the tumor was 28.94 {+-} 21.6 on FSE, 13.57 {+-} 8.64 on FMPSPGR, 12.62 {+-} 10.65 on CSE T2WI, and 9.47 {+-} 8.05 on CSE T1WI images, which was significantly high on FSE(p<0.05). Fast spin echo T2WI shows highest sensitivity and tumor-to-liver contrast. FMPSPGR imaging is also favorably comparable with conventional T1WI. Therefore, these two pulse sequences can be useful in clinical condition for hepatic MR imaging.

  1. The Usefulness of Fast-Spin-Echo T2-Weighted MR Imaging in Nutcracker Syndrome: a Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Heong Leng; Chen, Matt Chiung Yu; Wu, Cgek Siung; Fu, Kuo An; Lin, Cheng Hao [Yuan' s General Hospital, Kaohsiung (China); Weng, Mei Jui; Liang, Huei Lung; Pan, Huay Ben [National Yang-Ming University, Taipei (Korea, Republic of)

    2010-06-15

    Nutcracker syndrome occurs when the left renal vein (LRV) is compressed between the superior mesenteric artery and the aorta, and this syndrome is often characterized by venous hypertension and related pathologies. However, invasive studies such as phlebography and measuring the reno-caval pressure gradient should be performed to identify venous hypertension. Here we present a case of Nutcracker syndrome where the LRV and intra-renal varicosities appeared homogeneously hyperintense on magnetic resonance (MR) fast-spin-echo T2- weighted imaging, which suggested markedly stagnant intravenous blood flow and the presence of venous hypertension. The patient was diagnosed and treated without obtaining the reno-caval pressure gradient. The discomfort of the patient lessened after treatment. Furthermore, on follow-up evaluation, the LRV displayed a signal void, and this was suggestive of a restoration of the normal LRV flow and a decrease in LRV pressure.

  2. Comparative study between the Spin-echo and 3-D fast imaging techniques in the Knee evaluation with magnetic resonance

    International Nuclear Information System (INIS)

    Oleaga Zufiria, L.; Ibanez Zubiarrain, A.; Grande Icaran, J.; Vela Martin, A.C.; Cintora Leon, E.; Grau Garcia, M.; Grande Icaran, D.

    1993-01-01

    We have carried out a retrospective analysis of the results of magnetic resonance (MR) studies in 20 patients, comparing two different sequences. We compared a 2-D spin-echo (SE2D) sequence with a 3-D fast imaging with steady-state precession (FISP3D) sequence in the attempt to compare the reliability of each in the detection of knee injuries. Arthroscopy was employed as a control technique. Our study revealed no statistically significant difference between the two sequences, although the overall sensitivity for the detection of meniscal lesions was slightly greater with the FISP3D sequence; however, the reliability in the detection of ruptures of the posterior cruciate ligament is less with this sequence than with the SE2D sequence. Both sequences showed very low sensitivity in the detection of hyaline cartilage injuries. (Author) 14 refs

  3. 3D hybrid profile order technique in a single breath-hold 3D T2-weighted fast spin-echo sequence: Usefulness in diagnosis of small liver lesions.

    Science.gov (United States)

    Hirata, Kenichiro; Nakaura, Takeshi; Okuaki, Tomoyuki; Tsuda, Noriko; Taguchi, Narumi; Oda, Seitaro; Utsunomiya, Daisuke; Yamashita, Yasuyuki

    2018-01-01

    We compared the efficacy of three-dimensional (3D) isotropic T2-weighted fast spin-echo imaging using a 3D hybrid profile order technique with a single-breath-hold (3D-Hybrid BH) with a two-dimensional (2D) T2-weighted fast spin-echo conventional respiratory-gated (2D-Conventional RG) technique for visualising small liver lesions. This study was approved by our institutional review board. The requirement to obtain written informed consent was waived. Fifty patients with small (≤15mm) hepatocellular carcinomas (HCC) (n=26), or benign cysts (n=24), had undergone hepatic MRI including both 2D-Conventional RG and 3D-Hybrid BH. We calculated the signal-to-noise ratio (SNR) and tumour-to-liver contrast (TLC). The diagnostic performance of the two protocols was analysed. The image acquisition time was 89% shorter with the 3D-Hybrid BH than with 2D-Conventional RG. There was no significant difference in the SNR between the two protocols. The area under the curve (AUC) of the TLC was significantly higher on 3D-Hybrid BH than on 2D-Conventional RG. The 3D-Hybrid BH sequence significantly improved diagnostic performance for small liver lesions with a shorter image acquisition time without sacrificing accuracy. Copyright © 2017. Published by Elsevier B.V.

  4. MR imaging of the gastrointestinal tract with half-fourier single-shot fast spin echo (SSFSE)

    International Nuclear Information System (INIS)

    Boku, Houjun; Takehara, Yasuo; Isoda, Haruo; Isogai, Satoshi; Kaneko, Masao

    1999-01-01

    Our objective was to implement a non-invasive magnetic resonance imaging (MRI) technique combined with concentrated milk ingestion for depicting the gastrointestinal (GI) tract and detecting gastrointestinal motility and transit. The half-Fourier SSFSE (single-shot fast spin echo) sequence was optimized on the basis of a phantom study. In order to determine the feasibility of milk ingestion as a substitute for contrast medium, ten human volunteers were examined with SSFSE after two types of liquid ingestion (i.e., milk and water). The snapshot images provided subsecond data acquisition for each coronal plane, allowing visualization of peristalsis in the gastrointestinal tract in an almost real-time fashion, without motion-related image degradation, as would normally be seen using conventional MRI. There was no significant difference between concentrated milk and water in terms of depiction of the upper gastrointestinal tract; however, 10 min and 30 min after ingestion, concentrated milk showed better delineation of the intestine than that observed after water ingestion (p<0.01). MR gastrointestinal imaging is a non-invasive method that allows gastrointestinal depiction as well as analysis of motility and passage. Especially with concentrated milk ingestion, the distal intestines were well depicted with adequate contrast filling and distention. (author)

  5. Fast spin-echo T2-weighted MR imaging of tongue cancer; the value of fat-suppression

    International Nuclear Information System (INIS)

    Kim, Zu Byoung; Na, Dong Gyu; Ryoo, Jae Wook; Kim, Kyeong Ah; Byun, Hong Sik; Baek, Chung Whan; Son, Yong Ik

    2000-01-01

    To compare the diagnostic efficacy of fast spin-echo (FSE) T2-weighted MR imaging with and without fat suppression. Twelve patients (7 men and 5 women; mean age, 48 years) with pathologically proven cancer of the tongue were included in this study. In all of these, FSE T2-weighted MR images with and without fat suppression were obtained in the same imaging planes before surgery or biopsy. Two radiologists visually compared the images thus obtained in terms of detection, extent, and conspicuity of the tumor, and the contrast-to-noise ratio (CNR) of each tumor was also calculated. In all patients, both imaging modalities were equal in terms of tumor detection. In 4 of 12(33%), the extent of the tumor was greater with fat suppression, while in eight (67%), it was almost the same both with and without. In ten patients (83%), the tumor was more conspicuous with fat suppression, and percentage CNRs were significantly higher with fat suppression than without (180±70% and 113±61%, respectively; p=0.02). For the evaluation of patients with tongue cancer, fat-suppressed FSE T2-weighted MR imaging is superior to its conventional equivalent

  6. Evaluation with fat-suppression fast spin-echo T2-weighted images for bone and soft tissue disorders

    International Nuclear Information System (INIS)

    Kakitsubata, Yousuke; Watanabe, Katsushi; Kakitsubata, Sachiko; Shimizu, Tokiyoshi.

    1997-01-01

    One hundred and sixty-four magnetic resonance (MR) studies of bone or soft tissue disorders were evaluated with T2-weighted fast spin echo (FSE) imaging and T2-weighted fat-suppressed FSE (FS-FSE) imaging. Fifty-two patients with bone contusion of the knee were also evaluated with conventional T2-weighted SE imaging and T2-weighted FS-FSE imaging. In 50 of 71 patients (70.4%), areas of high signal intensity in bone marrow were more clearly demonstrated on T2-weighted FS-FSE images than on T2-weighted FSE image. Edema or inflammation of soft tissues were also clearly revealed on T2-weighted FS-FSE images. In 27 of 32 patients (84%), bone contusions were more apparently shown on T2-weighted FS-FSE images than on conventional T2-weighted SE image. T2-weighted FS-FSE imaging is a sensitive method of evaluating the long T2 lesions of bone or soft tissue disorders. (author)

  7. Moderately T2-weighted images obtained with the single-shot fast spin-echo technique. Differentiating between malignant and benign urinary obstructions

    International Nuclear Information System (INIS)

    Obuchi, Masao; Sugimoto, Hideharu; Kubota, Hayato; Yamamoto, Wakako; Kinebuchi, Yuko; Honda, Minoru; Takahara, Taro

    2002-01-01

    The purpose of this study was to determine whether a distinction could be made between benign and malignant urinary obstructions in moderately T 2 -weighted images obtained with the single-shot fast spin-echo technique. Forty-four lesions in 39 patients with urinary obstruction were evaluated with the single-shot fast spin-echo (SSFSE) technique with an effective TE of 90-100 ms and without fat saturation. Benign and malignant lesions were compared for the presence of ureteral wall thickening and a signal intensity relative to the proximal ureteral wall. Statistically significant differences were found between benign and malignant lesions in both morphologic change (P 2 -weighted SSFSE technique without fat saturation can accurately distinguish between benign and malignant urinary obstructions. (author)

  8. 3D Fast Spin Echo T2-weighted Contrast for Imaging the Female Cervix

    Science.gov (United States)

    Vargas Sanchez, Andrea Fernanda

    Magnetic Resonance Imaging (MRI) with T2-weighted contrast is the preferred modality for treatment planning and monitoring of cervical cancer. Current clinical protocols image the volume of interest multiple times with two dimensional (2D) T2-weighted MRI techniques. It is of interest to replace these multiple 2D acquisitions with a single three dimensional (3D) MRI acquisition to save time. However, at present the image contrast of standard 3D MRI does not distinguish cervical healthy tissue from cancerous tissue. The purpose of this thesis is to better understand the underlying factors that govern the contrast of 3D MRI and exploit this understanding via sequence modifications to improve the contrast. Numerical simulations are developed to predict observed contrast alterations and to propose an improvement. Improvements of image contrast are shown in simulation and with healthy volunteers. Reported results are only preliminary but a promising start to establish definitively 3D MRI for cervical cancer applications.

  9. Proton T2 Relaxation effect of superparamagnetic iron oxide on fast spin echo sequence. Influence of echo number (even or odd) of effective TE

    International Nuclear Information System (INIS)

    Tsuchihashi, Toshio; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Takeshi; Fujita, Isao

    1999-01-01

    The T 2 relaxation effect of the fast spin echo sequence (FSE) was investigated using superparamagnetic iron oxide (SPIO) particles. When even echoes were used as the effective TE of FSE, the signal intensity ratio [signal intensity of FSE/signal intensity of conventional spin echo sequence (CSE)] of FSE and CSE increased, whereas the T 2 relaxation effect of SPIO with FSE was reduced. However, when odd echoes were used, neither signal intensity changed, and weakening of the T 2 relaxation effect, considered a problem with FSE, was reduced. This phenomenon was not observed when the refocusing flip angle was changed to 30 and 60 degrees. However, it was observed when the refocusing flip angle was 120 and 150 degrees. Thus, this phenomenon can be considered to be related to oscillation in longitudinal magnetization when using the Carr-Purcell-Meiboom-Gill (CPMG) technique. (author)

  10. Hemodynamic analysis of bladder tumors using T1-dynamic contrast-enhanced fast spin-echo MRI

    International Nuclear Information System (INIS)

    Kanazawa, Yuki; Miyati, Tosiaki; Sato, Osamu

    2012-01-01

    Objectives: To evaluate the hemodynamics of bladder tumors, we developed a method to calculate change in R 1 value (ΔR 1 ) from T 1 -dynamic contrast-enhanced fast spin-echo magnetic resonance imaging (T 1 DCE-FSE-MRI). Materials and methods: On a 1.5-T MR system, T 1 DCE-FSE-MRI was performed. This study was applied to 12 patients with urinary bladder tumor, i.e. urothelial carcinoma. We compared ΔR 1 –time and ΔSI–time between a peak in the ΔR 1 –time and ΔSI–time curve occurred during the first pass within 60 s. Next, we assessed the slope of increase for 180 s after CA injection (Slope 0–180 ). Results: The mean slope of the first pass was significantly higher for bladder tumors on both the ΔR 1 –time and the ΔSI–time curve compared with normal bladder walls. Moreover, a significant difference was apparent between bladder tumors and normal bladder walls on the mean Slope 0–180 in the ΔR 1 -time curve. However, no significant difference in the mean Slope 0–180 was observed on the ΔSI-time curve between bladder tumors and normal bladder walls. Conclusion: T 1 DCE-FSE-MRI offers three advantages: quantitative analysis; high-quality (i.e., artifact-free) images; and high temporal resolution even for SE images. Use of ΔR 1 analysis with T 1 DCE-FSE-MRI allows more detailed information on the hemodynamics of bladder tumors to be obtained and assists in differentiation between bladder tumors and the normal bladder wall.

  11. Accelerated whole brain intracranial vessel wall imaging using black blood fast spin echo with compressed sensing (CS-SPACE).

    Science.gov (United States)

    Zhu, Chengcheng; Tian, Bing; Chen, Luguang; Eisenmenger, Laura; Raithel, Esther; Forman, Christoph; Ahn, Sinyeob; Laub, Gerhard; Liu, Qi; Lu, Jianping; Liu, Jing; Hess, Christopher; Saloner, David

    2018-06-01

    Develop and optimize an accelerated, high-resolution (0.5 mm isotropic) 3D black blood MRI technique to reduce scan time for whole-brain intracranial vessel wall imaging. A 3D accelerated T 1 -weighted fast-spin-echo prototype sequence using compressed sensing (CS-SPACE) was developed at 3T. Both the acquisition [echo train length (ETL), under-sampling factor] and reconstruction parameters (regularization parameter, number of iterations) were first optimized in 5 healthy volunteers. Ten patients with a variety of intracranial vascular disease presentations (aneurysm, atherosclerosis, dissection, vasculitis) were imaged with SPACE and optimized CS-SPACE, pre and post Gd contrast. Lumen/wall area, wall-to-lumen contrast ratio (CR), enhancement ratio (ER), sharpness, and qualitative scores (1-4) by two radiologists were recorded. The optimized CS-SPACE protocol has ETL 60, 20% k-space under-sampling, 0.002 regularization factor with 20 iterations. In patient studies, CS-SPACE and conventional SPACE had comparable image scores both pre- (3.35 ± 0.85 vs. 3.54 ± 0.65, p = 0.13) and post-contrast (3.72 ± 0.58 vs. 3.53 ± 0.57, p = 0.15), but the CS-SPACE acquisition was 37% faster (6:48 vs. 10:50). CS-SPACE agreed with SPACE for lumen/wall area, ER measurements and sharpness, but marginally reduced the CR. In the evaluation of intracranial vascular disease, CS-SPACE provides a substantial reduction in scan time compared to conventional T 1 -weighted SPACE while maintaining good image quality.

  12. Application of three-dimensional fast spin-echo T2-weighted image in lesions of the inner ear

    International Nuclear Information System (INIS)

    Xian Junfang; Wang Zhenchang; Yan Fei; Niu Yantao; Zhu Ye; Wang Yan; Tian Qichang; Lan Baosen

    1999-01-01

    Objective: To investigate the advantage of three-dimensional fast spin-echo T 2 -weighted image (3D FSE T 2 WI) in depicting normal structures and lesions of the inner ear. Methods: 3D FSE T 2 WI and 2D FSE T 2 WI were performed in 10 healthy volunteers and 20 cases with inner ear diseases. Advantages and disadvantages of the two techniques were compared. CT was performed in 6 cases with enlarged endo-lymphatic sac and 1 cases of Mondini malformation. Results: 3D FSE T 2 WI enabled visualization of detailed anatomic structures. Enlarged endo-lymphatic sacs were clearly revealed in 9 cases on 16 sides by 3D FSE T 2 WI, while only a part but not the whole of the enlarged endo-lymphatic sac could be shown on 2D FSE T 2 WI. In 6 cases, 3D FSE T 2 WI displayed enlarged endo-lymphatic sac on 11 sides and normal on 1 side; however, CT revealed enlarged vestibular aqueduct on all 12 sides. One case with small acoustic neuroma (only 4 mm in diameter) was clearly demonstrated on 3D FSE T 2 WI but not well shown on 2D FSE T 2 WI. One case with cochlear Mondini malformation associated with dysplasia of vestibule and semicircular canals was displayed more clearly on 3D FSE T 2 WI than on 2D FSE T 2 WI. Conclusions: 3D FSE T 2 WI can clearly display normal structures and lesions of the inner ear

  13. Detection of cerebrospinal fluid leakage: initial experience with three-dimensional fast spin-echo magnetic resonance myelography.

    Science.gov (United States)

    Tomoda, Y; Korogi, Y; Aoki, T; Morioka, T; Takahashi, H; Ohno, M; Takeshita, I

    2008-03-01

    The pathogenesis of cerebrospinal fluid (CSF) hypovolemia is supposed to be caused by CSF leakage through small dural defects. To compare source three-dimensional (3D) fast spin-echo (FSE) images of magnetic resonance (MR) myelography with radionuclide cisternography findings, and to evaluate the feasibility of MR myelography in the detection of CSF leakage. A total of 67 patients who were clinically suspected of CSF hypovolemia underwent indium-111 radionuclide cisternography, and 27 of those who had direct findings of CSF leakage were selected for evaluation. MR myelography with 3D FSE sequences (TR/TE 6000/203 ms) was performed at the lumbar spine for all patients. We evaluated source images and maximum intensity projection (MIP) images of MR myelography, and the findings were correlated with radionuclide cisternography findings. MR myelography of five healthy volunteers was used as a reference. The MR visibility of the CSF leakage was graded as definite (leakage clearly visible), possible (leakage poorly seen), or absent (not shown). CSF leakage was identified with source 3D FSE images in 22 (81.5%) of 27 patients. Of the 22 patients, 16 were graded as definite and six were graded as possible. For the definite cases, 3D FSE images clearly showed the extent of the leaked CSF in the paraspinal structures. In the remaining five patients with absent findings, radionuclide cisternography showed only slight radionuclide activity out of the arachnoid space. Source 3D FSE images of MR myelography seem useful in the detection of CSF leakage. Invasive radionuclide cisternography may be reserved for equivocal cases only.

  14. Utility of single shot fast spin echo technique in evaluating pancreaticobiliary diseases: T2-weighted image and magnetic resonance cholangiopancreatography

    International Nuclear Information System (INIS)

    Choi, Byoung Wook; Kim, Myeong Jin; Chung, Jae Bok; Ko, Heung Kyu; Kim, Dong Joon; Kim, Joo Hee; Chung, Jae Joon; Yoo, Hyung Sik; Lee, Jong Tae

    1999-01-01

    To evaluate the accuracy of T2-weighted imaging an MR cholangiopancreatography using the single shot fast spin-echo technique for evaluating pancreaticobiliary disease. Between March and July 1997, axial and coronal T2-weighted images(TE: 80-200 msec) and MR cholangiopancreatograms (TE: 800-1200 msec) were obtained in two ways [single slab (thickness: 30-50 mm) and multislice acquisition under chemical fat saturation] using SSFSE pulse sequencing in 131 cases of suspected pancreati-cobiliary disease. The accuracy of SSFSE MR imaging was assessed in 89 lesions of 74 patients [male, 48; female, 26; age range, 30-86 (mean, 59) years] confirmed surgicopathologically (50 lesions in 39 patients) and clinically (39 lesions in 35 patients). Two radiologists reviewed the MR images and diagnosis was determined by consensus. Correct diagnosis was confirmed in 84 of 89 lesions (94%). Seven lesions were falsely interpreted, false positive and false negative results accounting for two and five cases, respectively. Two pancreatic cancers were misdiagnosed as pancreatitis and a cancer of the proximal common bile duct(CBD) was interpreted as a distal CBD cancer. The sensitivity of SSFSE MR imaging for malignancy was 93 %. One CBD stone revealed by endoscopic retrograde cholangiopancreatography (ERCP) was not detected on MR images. In contrast, a stone in the CBD seen on MR images was not apparent on subsequent ERCP. Sensitivity and specificity for calculous disease were 96% and 99.7%, respectively. A benign stricture of the ampulla of Vater was falsely interpreted as normal, and correct diagnosis was possible in two falsely diagnosed cases when MR images were reviewed retrospectively. The combination of T2-weighted and cholangiographic images using SSFSE is an accurate method for diagnosing pancreatcobiliary diseases

  15. T2-weighted fast spin-echo MR imaging of the pelvis

    International Nuclear Information System (INIS)

    Francis, I.R.; Steiner, R.M.; Herfkens, R.J.; Jain, K.; Glover, G.H.

    1991-01-01

    A fast Se (FSE) sequence capable of acquiring SE images with a wide range of TRs and TEs in short imaging times has been recently introduced. I this paper, the authors evaluated the value of this technique compared with standard T2-weighted SE imaging. Twenty-five patients were evaluated with T2-weighted SE and FSE images on a 1.5-T GE Signa imager. Imaging times ranged from 3 to 5 minutes for the FSE acquisition and from 12 to 15 minutes for the SE images. Three observers performed a comparison by using a 10-point scale for organ definition and lesion conspicuity, with differences settled by consensus reading. Pelvic organ definition was superior and pelvic tumors and free fluid were also more conspicuous on FSE images. In 2/25 patients ringing artifacts were present

  16. Comparing an accelerated 3D fast spin-echo sequence (CS-SPACE) for knee 3-T magnetic resonance imaging with traditional 3D fast spin-echo (SPACE) and routine 2D sequences

    Energy Technology Data Exchange (ETDEWEB)

    Altahawi, Faysal F.; Blount, Kevin J.; Omar, Imran M. [Northwestern University Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Morley, Nicholas P. [Marshfield Clinic, Department of Radiology, Marshfield, WI (United States); Raithel, Esther [Siemens Healthcare GmbH, Erlangen (Germany)

    2017-01-15

    To compare a faster, new, high-resolution accelerated 3D-fast-spin-echo (3D-FSE) acquisition sequence (CS-SPACE) to traditional 2D and high-resolution 3D sequences for knee 3-T magnetic resonance imaging (MRI). Twenty patients received knee MRIs that included routine 2D (T1, PD ± FS, T2-FS; 0.5 x 0.5 x 3 mm{sup 3}; ∝10 min), traditional 3D FSE (SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝7.5 min), and accelerated 3D-FSE prototype (CS-SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝5 min) acquisitions on a 3-T MRI system (Siemens MAGNETOM Skyra). Three musculoskeletal radiologists (MSKRs) prospectively and independently reviewed the studies with graded surveys comparing image and diagnostic quality. Tissue-specific signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were also compared. MSKR-perceived diagnostic quality of cartilage was significantly higher for CS-SPACE than for SPACE and 2D sequences (p < 0.001). Assessment of diagnostic quality of menisci and synovial fluid was higher for CS-SPACE than for SPACE (p < 0.001). CS-SPACE was not significantly different from SPACE but had lower assessments than 2D sequences for evaluation of bones, ligaments, muscles, and fat (p ≤ 0.004). 3D sequences had higher spatial resolution, but lower overall assessed contrast (p < 0.001). Overall image quality from CS-SPACE was assessed as higher than SPACE (p = 0.007), but lower than 2D sequences (p < 0.001). Compared to SPACE, CS-SPACE had higher fluid SNR and CNR against all other tissues (all p < 0.001). The CS-SPACE prototype allows for faster isotropic acquisitions of knee MRIs over currently used protocols. High fluid-to-cartilage CNR and higher spatial resolution over routine 2D sequences may present a valuable role for CS-SPACE in the evaluation of cartilage and menisci. (orig.)

  17. Fat-suppressed fast spin-echo mid-TE (TE[effective]=34) MR images: comparison with fast spin-echo T2-weighted images for the diagnosis of tears and anatomic variants of the glenoid labrum

    Energy Technology Data Exchange (ETDEWEB)

    Tuite, M J [Dept. of Radiology, Univ. of Wisconsin School of Medicine, Madison (United States); University of Wisconsin Hospital and Clinics, Dept. of Radiology, Madison, WI (United States); Shinners, T J; Hollister, M C [Dept. of Radiology, Univ. of Wisconsin School of Medicine, Madison (United States); Orwin, J F [Dept. of Orthopedic Surgery, University of Wisconsin School of Medicine, Madison (United States)

    1999-12-01

    Objective. To compare the sensitivity, specificity, and accuracy of fat-suppressed fast spin-echo (FSE) mid-TE (TE[effective]=34) images with fat-suppressed FSE T2-weighted images for the diagnosis of labral abnormalities.Design and patients. The study included 27 consecutive patients who had axial fat-suppressed FSE T2-weighted and fat-suppressed FSE mid-TE MR images, and had labral abnormalities diagnosed at arthroscopy. The acquisition time was about 5 min for each sequence, but the mid-TE sequence allowed a higher spatial resolution than the T2-weighted images (256 x 256 versus 256 x 192). Twenty-eight age-matched patients with arthroscopically normal labra were included as a control group. The labrum was graded on the MR images as normal or abnormal separately by two musculoskeletal radiologists who were masked to the history and arthroscopic results. The surgical findings were used as the gold standard for calculating the sensitivity, specificity, and accuracy for interpreting the correct location of a labral abnormality. The sensitivity, specificity, and accuracy for the two sequences were compared with a McNemar test, and significance defined as P<0.05.Results. For observer 1, the sensitivity for labral abnormalities was 0.59 on the T2-weighted images, and 0.78 on the mid-TE images (P=0.12). The specificity was 0.54 for the T2-weighted, and 0.64 for the mid-TE images (P=0.51). The accuracy was 0.56 for the T2-weighted, and 0.71 for the mid-TE images (P=0.08). For observer 2, the sensitivity/specificity/accuracy was 0.67/0.93/0.80 for the T2-weighted, and 0.70/0.86/0.78 for the mid-TE images (all P>0.5).Conclusion. In this small study there is no statistically significant difference for demonstrating labral abnormalities between FSE T2-weighted images, and higher-resolution fat-suppressed FSE mid-TE (TE[effective]=34) images obtained with a similar acquisition time. Although there was a general trend toward higher sensitivity and accuracy with the mid

  18. SNR-optimized phase-sensitive dual-acquisition turbo spin echo imaging: a fast alternative to FLAIR.

    Science.gov (United States)

    Lee, Hyunyeol; Park, Jaeseok

    2013-07-01

    Phase-sensitive dual-acquisition single-slab three-dimensional turbo spin echo imaging was recently introduced, producing high-resolution isotropic cerebrospinal fluid attenuated brain images without long inversion recovery preparation. Despite the advantages, the weighted-averaging-based technique suffers from noise amplification resulting from different levels of cerebrospinal fluid signal modulations over the two acquisitions. The purpose of this work is to develop a signal-to-noise ratio-optimized version of the phase-sensitive dual-acquisition single-slab three-dimensional turbo spin echo. Variable refocusing flip angles in the first acquisition are calculated using a three-step prescribed signal evolution while those in the second acquisition are calculated using a two-step pseudo-steady state signal transition with a high flip-angle pseudo-steady state at a later portion of the echo train, balancing the levels of cerebrospinal fluid signals in both the acquisitions. Low spatial frequency signals are sampled during the high flip-angle pseudo-steady state to further suppress noise. Numerical simulations of the Bloch equations were performed to evaluate signal evolutions of brain tissues along the echo train and optimize imaging parameters. In vivo studies demonstrate that compared with conventional phase-sensitive dual-acquisition single-slab three-dimensional turbo spin echo, the proposed optimization yields 74% increase in apparent signal-to-noise ratio for gray matter and 32% decrease in imaging time. The proposed method can be a potential alternative to conventional fluid-attenuated imaging. Copyright © 2012 Wiley Periodicals, Inc.

  19. Comparison of a conventional cardiac-triggered dual spin-echo and a fast STIR sequence in detection of spinal cord lesions in multiple sclerosis

    International Nuclear Information System (INIS)

    Bot, J.C.J.; Barkhof, F.; Lycklama a Nijeholt, G.J.; Bergers, E.; Castelijns, J.A.; Polman, C.H.; Ader, H.J.

    2000-01-01

    The current optimal imaging protocol in spinal cord MR imaging in patients with multiple sclerosis includes a long TR conventional spin-echo (CSE) sequence, requiring long acquisition times. Using short tau inversion recovery fast spin-echo (fast STIR) sequences both acquisition time can be shortened and sensitivity in the detection of multiple sclerosis (MS) abnormalities can be increased. This study compares both sequences for the potential to detect both focal and diffuse spinal abnormalities. Spinal cords of 5 volunteers and 20 MS patients were studied at 1.0 T. Magnetic resonance imaging included cardiac-gated sagittal dual-echo CSE and a cardiac-gated fast STIR sequence. Images were scored regarding number, size, and location of focal lesions, diffuse abnormalities and presence/hindrance of artifacts by two experienced radiologists. Examinations were scored as being definitely normal, indeterminate, or definitely abnormal. Interobserver agreement regarding focal lesions was higher for CSE (κ=0.67) than for fast STIR (κ=0.57) but did not differ significantly. Of all focal lesions scored in consensus, 47 % were scored on both sequences, 31 % were only detected by fast STIR, and 22 % only by dual-echo CSE (n. s.). Interobserver agreement for diffuse abnormalities was lower with fast STIR (κ=0.48) than dual-echo CSE (κ=0.65; n. s.). After consensus, fast STIR showed in 10 patients diffuse abnormalities and dual-echo CSE in 3. After consensus, in 19 of 20 patients dual-echo CSE scans were considered as definitely abnormal compared with 17 for fast STIR. The fast STIR sequence is a useful adjunct to dual-echo CSE in detecting focal abnormalities and is helpful in detecting diffuse MS abnormalities in the spinal cord. Due to the frequent occurrence of artifacts and the lower observer concordance, fast STIR cannot be used alone. (orig.)

  20. MRI in multiple sclerosis of the spinal cord: evaluation of fast short-tan inversion-recovery and spin-echo sequences

    International Nuclear Information System (INIS)

    Dietemann, J.L.; Thibaut-Menard, A.; Neugroschl, C.; Gillis, C.; Abu Eid, M.; Bogorin, A.; Warter, J.M.; Tranchant, C.

    2000-01-01

    We compared the sensitivity of T2-weighted spin-echo (FSE) and fast short-tau inversion-recovery (fSTIR) sequences in detection of multiple sclerosis of the spinal cord in 100 consecutive patients with clinically confirmed multiple sclerosis (MS); 86 patients underwent also brain MRI. In all, 310 focal lesions were detected on fSTIR and 212 on T2-weighted FSE, spinal cord lesions were seen better on fSTIR images, with a higher contrast between the lesion and the normal spinal cord. In 24 patients in whom cord plaques were shown with both sequences, the cranial study was normal or inconclusive. Assessment of spinal plaques can be particularly important when MRI of the brain is inconclusive, and in there situations fSTIR can be helpful. (orig.)

  1. MR Imaging of the Spine at 3.0T with T2-Weighted IDEAL Fast Recovery Fast Spin-Echo Technique

    International Nuclear Information System (INIS)

    Ren, Ai Jun; Guo, Yong; Tian, Shu Ping; Shi, Li Jing; Huang, Min Hua

    2012-01-01

    To compare the iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method with a fat-saturated T2-weighted (T2W) fast recovery fast spin-echo (FRFSE) imaging of the spine. Images acquired at 3.0 Tesla (T) in 35 patients with different spine lesions using fat-saturated T2W FRFSE imaging were compared with T2W IDEAL FRFSE images. Signal-to-noise ratio (SNR)-efficiencies measurements were made in the vertebral bodies and spinal cord in the mid-sagittal plane or nearest to the mid-sagittal plane. Images were scored with the consensus of two experienced radiologists on a four-point grading scale for fat suppression and overall image quality. Statistical analysis of SNR-efficiency, fat suppression and image quality scores was performed with a paired Student's t test and Wilcoxon's signed rank test. Signal-to-noise ratio-efficiency for both vertebral body and spinal cord was higher with T2W IDEAL FRFSE imaging (p < 0.05) than with T2W FRFSE imaging. T2W IDEAL FRFSE demonstrated superior fat suppression (p < 0.01) and image quality (p < 0.01) compared to fat-saturated T2W FRFSE. As compared with fat-saturated T2W FRFSE, IDEAL can provide a higher image quality, higher SNR-efficiency, and consistent, robust and uniform fat suppression. T2W IDEAL FRFSE is a promising technique for MR imaging of the spine at 3.0T.

  2. MRI of the anterior talofibular ligament, talar cartilage and os subfibulare: Comparison of isotropic resolution 3D and conventional 2D T2-weighted fast spin-echo sequences at 3.0 T

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Jisook; Cha, Jang Gyu [Soonchunhyang University Bucheon Hospital, Department of Radiology, Wonmi-gu, Bucheon-si (Korea, Republic of); Lee, Young Koo [Soonchunhyang University Bucheon Hospital, Department of Orthopedics, Wonmi-gu, Bucheon-si (Korea, Republic of); Lee, Bo Ra [Soonchunhyang University Bucheon Hospital, Department of Biomedical Statistics, Wonmi-gu, Bucheon-si (Korea, Republic of); Jeon, Chan Hong [Soonchunhyang University Bucheon Hospital, Division of Rheumatology, Department of Internal Medicine, Wonmi-gu, Bucheon-si (Korea, Republic of)

    2016-07-15

    To determine the accuracy of a three-dimensional (3D) T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequence compared with two-dimensional (2D) sequence for diagnosing anterior talofibular ligament (ATFL) tears, chondral lesion of the talus (CLT) and os subfibulare/avulsion fracture of the distal fibula (OSF). Thirty-five patients were included, who had undergone ankle MRI with 3D T2-weighted FSE and 2D T2-weighted FSE sequences, as well as subsequent ankle arthroscopy, between November 2013 and July 2014. Each MR imaging sequence was independently scored by two readers retrospectively for the presence of ATFL tears, CLT and OSF. The area under the receiver operating curve (AUC) was compared to determine the discriminatory power of the two image sequences. Interobserver agreement was expressed as unweighted kappa value. Arthroscopic findings confirmed 21 complete tears of the ATFL, 14 partial tears of the ATFL, 17 CLTs and 7 OSFs. There were no significant differences in the diagnoses of ATFL tears (p = 0.074-0.501), CLT (p = 0.090-0.450) and OSF (p = 0.317) obtained from the 2D and 3D sequences by either reader. The interobserver agreement rates between two readers using the 3D T2-weighted FSE sequence versus those obtained with the 2D sequence were substantial (κ = 0.659) versus moderate (κ = 0.553) for ATFL tears, moderate (κ = 0.499) versus substantial (κ = 0.676) for CLT and substantial (κ = 0.621) versus substantial (κ = 0.689) for OSF. Three-dimensional isotropic T2-weighted FSE MRI of the ankle resulted in no statistically significant difference in diagnostic performance compared to two-dimensional T2-weighted FSE MRI in the evaluation of ATFL tears, CLTs and OSFs. (orig.)

  3. MRI of the anterior talofibular ligament, talar cartilage and os subfibulare: Comparison of isotropic resolution 3D and conventional 2D T2-weighted fast spin-echo sequences at 3.0 T

    International Nuclear Information System (INIS)

    Yi, Jisook; Cha, Jang Gyu; Lee, Young Koo; Lee, Bo Ra; Jeon, Chan Hong

    2016-01-01

    To determine the accuracy of a three-dimensional (3D) T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequence compared with two-dimensional (2D) sequence for diagnosing anterior talofibular ligament (ATFL) tears, chondral lesion of the talus (CLT) and os subfibulare/avulsion fracture of the distal fibula (OSF). Thirty-five patients were included, who had undergone ankle MRI with 3D T2-weighted FSE and 2D T2-weighted FSE sequences, as well as subsequent ankle arthroscopy, between November 2013 and July 2014. Each MR imaging sequence was independently scored by two readers retrospectively for the presence of ATFL tears, CLT and OSF. The area under the receiver operating curve (AUC) was compared to determine the discriminatory power of the two image sequences. Interobserver agreement was expressed as unweighted kappa value. Arthroscopic findings confirmed 21 complete tears of the ATFL, 14 partial tears of the ATFL, 17 CLTs and 7 OSFs. There were no significant differences in the diagnoses of ATFL tears (p = 0.074-0.501), CLT (p = 0.090-0.450) and OSF (p = 0.317) obtained from the 2D and 3D sequences by either reader. The interobserver agreement rates between two readers using the 3D T2-weighted FSE sequence versus those obtained with the 2D sequence were substantial (κ = 0.659) versus moderate (κ = 0.553) for ATFL tears, moderate (κ = 0.499) versus substantial (κ = 0.676) for CLT and substantial (κ = 0.621) versus substantial (κ = 0.689) for OSF. Three-dimensional isotropic T2-weighted FSE MRI of the ankle resulted in no statistically significant difference in diagnostic performance compared to two-dimensional T2-weighted FSE MRI in the evaluation of ATFL tears, CLTs and OSFs. (orig.)

  4. Rotary spin echoes

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, I. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes Nucleaires de Saclay, BP2, Gif-sur-Yvette (France)

    1959-07-01

    Torrey has observed the free precession of nuclear spins around an r-f field H{sub 1}, fixed in a frame rotating at the Larmor frequency ω{sub 0} = γH{sub 0} around a large d-c magnetic field H{sub 0}. He showed that for an H{sub 1}, much larger than inhomogeneity of H{sub 0}, the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H{sub 1}. We report here on a method of overcoming the inhomogeneity of H{sub 1}, by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H{sub 1}, is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302.

  5. Rotary spin echoes

    International Nuclear Information System (INIS)

    Solomon, I.

    1959-01-01

    Torrey has observed the free precession of nuclear spins around an r-f field H 1 , fixed in a frame rotating at the Larmor frequency ω 0 = γH 0 around a large d-c magnetic field H 0 . He showed that for an H 1 , much larger than inhomogeneity of H 0 , the latter has a negligible effect on the decay of the spin magnetization which is mainly due to the inhomogeneity of H 1 . We report here on a method of overcoming the inhomogeneity of H 1 , by production of echoes in the rotating frame ('rotary echoes'). These echoes are obtained by a 180 deg. phase shift at t = τ on the r-f field so that H 1 , is suddenly reversed, producing a re-focussing of the magnetization vectors at the time t = 2 τ. The rotary echoes so obtained are very similar to the usual spin-echoes with, however some specific features that make them particularly suitable for the measurement of long relaxation times. Reprint of a paper published in Physical Review Letters, vol. 2, no. 7, Apr 1959, p. 301-302

  6. Free-breathing black-blood CINE fast-spin echo imaging for measuring abdominal aortic wall distensibility: a feasibility study

    Science.gov (United States)

    Lin, Jyh-Miin; Patterson, Andrew J.; Chao, Tzu-Cheng; Zhu, Chengcheng; Chang, Hing-Chiu; Mendes, Jason; Chung, Hsiao-Wen; Gillard, Jonathan H.; Graves, Martin J.

    2017-05-01

    The paper reports a free-breathing black-blood CINE fast-spin echo (FSE) technique for measuring abdominal aortic wall motion. The free-breathing CINE FSE includes the following MR techniques: (1) variable-density sampling with fast iterative reconstruction; (2) inner-volume imaging; and (3) a blood-suppression preparation pulse. The proposed technique was evaluated in eight healthy subjects. The inner-volume imaging significantly reduced the intraluminal artifacts of respiratory motion (p  =  0.015). The quantitative measurements were a diameter of 16.3  ±  2.8 mm and wall distensibility of 2.0  ±  0.4 mm (12.5  ±  3.4%) and 0.7  ±  0.3 mm (4.1  ±  1.0%) for the anterior and posterior walls, respectively. The cyclic cross-sectional distensibility was 35  ±  15% greater in the systolic phase than in the diastolic phase. In conclusion, we developed a feasible CINE FSE method to measure the motion of the abdominal aortic wall, which will enable clinical scientists to study the elasticity of the abdominal aorta.

  7. Bilateral mesial temporal sclerosis: MRI with high-resolution fast spin-echo and fluid-attenuated inversion-recovery sequences

    Energy Technology Data Exchange (ETDEWEB)

    Oppenheim, C.; Dormont, D.; Lehericy, S.; Marsault, C. [Dept. of Neuroradiology, Groupe Hospitalier Pite-Salpetriere, Paris (France); Hasboun, D. [Dept. of Neuroradiology, Groupe Hospitalier Pite-Salpetriere, Paris (France)]|[Dept. of Neurology, Paris VI Univ. (France); Bazin, B.; Samson, S.; Baulac, M. [Dept. of Neurology, Paris VI Univ. (France)

    1999-07-01

    We report a retrospective analysis of MRI in 206 patients with intractable seizures and describe the findings in bilateral mesial temporal sclerosis (MTS) on fast spin-echo (FSE) and fast fluid-attenuated inversion-recovery (fFLAIR) sequences. Criteria for MTS were atrophy, signal change and loss of the digitations of the head of the hippocampus. In patients with bilateral MRI signs of MTS, correlation with clinical electro, volumetric MRI data and neuropsychological tests, when available, was performed. Bilateral MTS was observed in seven patients. Bilateral loss of the digitations and signal change of fFLAIR was seen in all seven. In three, bilateral atrophy was obvious. In two patients, mild bilateral atrophy was observed and in two others, the hippocampi were: asymmetrical, with obvious atrophy on only one side. Volumetric data confirmed bilateral symmetrical atrophy in five patients, and volumes were at the lowest of the normal range in other two. The EEG showed temporal abnormalities in all patients, unilateral in five and bilateral in two. All patients had memory impairment and neuropsychological data confirmed visual and verbal memory deficits; two patients failed the Wada test on both sides. High-resolution T2-weighted FSE and fFLAIR sequences allow diagnosis of bilateral MTS, which has important therapeutic and prognostic implications. (orig.)

  8. Bilateral mesial temporal sclerosis: MRI with high-resolution fast spin-echo and fluid-attenuated inversion-recovery sequences

    International Nuclear Information System (INIS)

    Oppenheim, C.; Dormont, D.; Lehericy, S.; Marsault, C.; Hasboun, D.; Bazin, B.; Samson, S.; Baulac, M.

    1999-01-01

    We report a retrospective analysis of MRI in 206 patients with intractable seizures and describe the findings in bilateral mesial temporal sclerosis (MTS) on fast spin-echo (FSE) and fast fluid-attenuated inversion-recovery (fFLAIR) sequences. Criteria for MTS were atrophy, signal change and loss of the digitations of the head of the hippocampus. In patients with bilateral MRI signs of MTS, correlation with clinical electro, volumetric MRI data and neuropsychological tests, when available, was performed. Bilateral MTS was observed in seven patients. Bilateral loss of the digitations and signal change of fFLAIR was seen in all seven. In three, bilateral atrophy was obvious. In two patients, mild bilateral atrophy was observed and in two others, the hippocampi were: asymmetrical, with obvious atrophy on only one side. Volumetric data confirmed bilateral symmetrical atrophy in five patients, and volumes were at the lowest of the normal range in other two. The EEG showed temporal abnormalities in all patients, unilateral in five and bilateral in two. All patients had memory impairment and neuropsychological data confirmed visual and verbal memory deficits; two patients failed the Wada test on both sides. High-resolution T2-weighted FSE and fFLAIR sequences allow diagnosis of bilateral MTS, which has important therapeutic and prognostic implications. (orig.)

  9. Magnetic resonance, especially spin echo, in spinor Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Yasunaga, Masashi; Tsubota, Makoto

    2009-01-01

    Magnetic resonance, especially NMR and ESR, has been studied in magnetic materials for a long time, having been used in various fields. Spin echo is typical phenomenon in magnetic resonance. The magnetic resonance should be applied to spinor Bose-Einstein condensates (BECs). We numerically study spin echo of a spinor BEC in a gradient magnetic field by calculating the spin-1 two-dimensional Gross-Pitaevskii equations, obtaining the recovery of the signal of the spins, which is called spin echo. We will discuss the relation between the spin echo and the Stern-Gelrach separation in the system.

  10. Visual discrimination among patients with depression and schizophrenia and healthy individuals using semiquantitative color-coded fast spin-echo T1-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Makoto; Kudo, Kohsuke; Narumi, Shinsuke [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Shibata, Eri; Ohtsuka, Kotaro; Endoh, Jin; Sakai, Akio [Iwate Medical University, Department of Neuropsychiatry, Morioka (Japan)

    2010-02-15

    Fast spin-echo (FSE) T1-weighted (T1W) magnetic resonance imaging (MRI) at 3T, which is sensitive to neuromelanin-related contrast, can quantitatively detect signal alterations in the locus ceruleus (LC) and the substantia nigra pars compacta (SNc) of depressive and schizophrenic patients; however, its qualitative diagnostic performance remains unknown. We investigated whether visual interpretation of semiquantitative color maps can be used for discriminating between depressive and schizophrenic patients and healthy individuals. We retrospectively examined 23 patients with major depression, 23 patients with schizophrenia, and 23 age-matched healthy controls by using a FSE-T1W MRI technique. Semiquantitative color maps of sections through the LC and SNc were visually interpreted by nine raters using a continuous confidence rating scale for receiver operating characteristic (ROC) analysis. The area under the ROC curve (Az), which reflects the performance in differentiating between depressive patients and controls, was 0.88, and the sensitivity and specificity at the maximum likelihood were 76% and 83%, respectively. In contrast, the Az value, sensitivity, and specificity values between schizophrenics and controls and between depressives and schizophrenics were 0.66 and 0.69, 42% and 48%, and 82% and 84%, respectively. Semiquantitative, color-coded FSE-T1W MRI at 3T can be used for visually differentiating depressive patients from healthy individuals with a substantially high likelihood, but this technique cannot be applied to distinguish schizophrenic patients from the other two groups. (orig.)

  11. Visual discrimination among patients with depression and schizophrenia and healthy individuals using semiquantitative color-coded fast spin-echo T1-weighted magnetic resonance imaging

    International Nuclear Information System (INIS)

    Sasaki, Makoto; Kudo, Kohsuke; Narumi, Shinsuke; Shibata, Eri; Ohtsuka, Kotaro; Endoh, Jin; Sakai, Akio

    2010-01-01

    Fast spin-echo (FSE) T1-weighted (T1W) magnetic resonance imaging (MRI) at 3T, which is sensitive to neuromelanin-related contrast, can quantitatively detect signal alterations in the locus ceruleus (LC) and the substantia nigra pars compacta (SNc) of depressive and schizophrenic patients; however, its qualitative diagnostic performance remains unknown. We investigated whether visual interpretation of semiquantitative color maps can be used for discriminating between depressive and schizophrenic patients and healthy individuals. We retrospectively examined 23 patients with major depression, 23 patients with schizophrenia, and 23 age-matched healthy controls by using a FSE-T1W MRI technique. Semiquantitative color maps of sections through the LC and SNc were visually interpreted by nine raters using a continuous confidence rating scale for receiver operating characteristic (ROC) analysis. The area under the ROC curve (Az), which reflects the performance in differentiating between depressive patients and controls, was 0.88, and the sensitivity and specificity at the maximum likelihood were 76% and 83%, respectively. In contrast, the Az value, sensitivity, and specificity values between schizophrenics and controls and between depressives and schizophrenics were 0.66 and 0.69, 42% and 48%, and 82% and 84%, respectively. Semiquantitative, color-coded FSE-T1W MRI at 3T can be used for visually differentiating depressive patients from healthy individuals with a substantially high likelihood, but this technique cannot be applied to distinguish schizophrenic patients from the other two groups. (orig.)

  12. Anteroinferior tears of the glenoid labrum: fat-suppressed fast spin-echo T2 versus gradient-recalled echo MR images

    Energy Technology Data Exchange (ETDEWEB)

    Tuite, M J [Department of Radiology, University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, WI 53792 (United States); De Smet, A A [Department of Radiology, University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, WI 53792 (United States); Norris, M A [Department of Radiology, University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, WI 53792 (United States); Orwin, J F [Department of Orthopedic Surgery, University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, WI 53792 (United States)

    1997-05-01

    Objective. To compare fat-suppressed fast spin-echo (FSE) T2-weighted images with gradient-recalled echo (GRE) T2*-weighted images in the evaluation of anteroinferior labral tears. Design. MR images were retrospectively reviewed by two radiologists masked to the history and arthroscopic findings. They separately interpreted the anteroinferior labrum as torn or intact, first on one pulse sequence and then, 4 weeks later, on the other sequence. The MR interpretations were correlated with the arthroscopic findings. Patients. Nine patients with anteroinferior labral tears, and nine similarly-aged patients with normal, labra were studied. Results and conclusions. Observer 1 had a sensitivity of 0.56 on the GRE images and 0.67 on the FSE images (P>0.5), with a specificity of 1.0 for both sequences. Observer 2 had a sensitivity of 0.78 and a specificity of 0.89 for both sequences. In this small study there is no significant difference between GRE and fat-suppressed FSE images in their ability to diagnose anteroinferior labral tears. When evaluating the labrum with conventional MRI, axial fat-suppressed FSE T2-weighted images can be used in place of GRE images without a loss of accuracy. (orig.). With 3 figs., 1 tab.

  13. Differential diagnosis of pituitary adenomas and Rathke's cleft cysts by diffusion-weighted MRI using single-shot fast spin echo technique

    International Nuclear Information System (INIS)

    Abe, Takumi; Izumiyama, Hitoshi; Fukuda, Ataru; Tanioka, Daisuke; Kunii, Norihiko; Komatsu, Daisuke; Fujita, Shogo; Ukisu, Ryutaro; Moritani, Toshio

    2002-01-01

    The purpose of the present study was to prospectively evaluate the diagnostic ability of diffusion-weighted magnetic resonance imaging (DWI) using single-shot fast spin echo (SSFSE) technique to discriminate pituitary adenomas from Rathke's cleft cysts. DWIs were obtained from 40 patients with pathologically proven pituitary macroadenomas and 15 patients with proven Rathke's cleft cysts. Pituitary adenomas were divided into 27 cases with solid components alone, five with non-hemorrhagic large cysts, and eight with intratumoral hemorrhage. On SSFSE DWI, solid components of pituitary adenomas revealed iso or slightly increased intensity and intratumoral hemorrhage showed higher intensity than normal brain parenchyma, whereas Rathke's cleft cysts and intratumoral cysts demonstrated very low intensity. SSFSE DWI did not display the susceptibility artifacts that are seen close to the skull base and sinonasal cavities on echo planar diffusion imaging. On the basis of our preliminary findings, DWI may enable us to differentiate pituitary adenomas with only solid components and hemorrhagic pituitary adenomas appearing hyperintense on T1-weighted images from Rathke's cleft cysts without administration of gadolinium-DTPA. SSFSE DWI appears to be a useful technique for characterizing pituitary diseases without the susceptibility artifacts. Our study is the first report to demonstrate the identification of pituitary disorders on SSFSE DWI. (author)

  14. Differential diagnosis of pituitary adenomas and Rathke's cleft cysts by diffusion-weighted MRI using single-shot fast spin echo technique

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Takumi; Izumiyama, Hitoshi; Fukuda, Ataru; Tanioka, Daisuke; Kunii, Norihiko; Komatsu, Daisuke; Fujita, Shogo; Ukisu, Ryutaro; Moritani, Toshio [Showa Univ., Tokyo (Japan). School of Medicine

    2002-09-01

    The purpose of the present study was to prospectively evaluate the diagnostic ability of diffusion-weighted magnetic resonance imaging (DWI) using single-shot fast spin echo (SSFSE) technique to discriminate pituitary adenomas from Rathke's cleft cysts. DWIs were obtained from 40 patients with pathologically proven pituitary macroadenomas and 15 patients with proven Rathke's cleft cysts. Pituitary adenomas were divided into 27 cases with solid components alone, five with non-hemorrhagic large cysts, and eight with intratumoral hemorrhage. On SSFSE DWI, solid components of pituitary adenomas revealed iso or slightly increased intensity and intratumoral hemorrhage showed higher intensity than normal brain parenchyma, whereas Rathke's cleft cysts and intratumoral cysts demonstrated very low intensity. SSFSE DWI did not display the susceptibility artifacts that are seen close to the skull base and sinonasal cavities on echo planar diffusion imaging. On the basis of our preliminary findings, DWI may enable us to differentiate pituitary adenomas with only solid components and hemorrhagic pituitary adenomas appearing hyperintense on T1-weighted images from Rathke's cleft cysts without administration of gadolinium-DTPA. SSFSE DWI appears to be a useful technique for characterizing pituitary diseases without the susceptibility artifacts. Our study is the first report to demonstrate the identification of pituitary disorders on SSFSE DWI. (author)

  15. Faster pediatric 3-T abdominal magnetic resonance imaging: comparison between conventional and variable refocusing flip-angle single-shot fast spin-echo sequences

    Energy Technology Data Exchange (ETDEWEB)

    Ruangwattanapaisarn, Nichanan [Mahidol University, Department of Diagnostic and Therapeutic Radiology, Ramathibodi Hospital, Bangkok (Thailand); Stanford University, LPCH Department of Radiology, Stanford, CA (United States); Loening, Andreas M.; Saranathan, Manojkumar; Vasanawala, Shreyas S. [Stanford University, LPCH Department of Radiology, Stanford, CA (United States); Litwiller, Daniel V. [GE Healthcare, Rochester, MN (United States)

    2015-06-15

    Single-shot fast spin echo (SSFSE) is particularly appealing in pediatric patients because of its motion robustness. However radiofrequency energy deposition at 3 tesla forces long pauses between slices, leading to longer scans, longer breath-holds and more between-slice motion. We sought to learn whether modulation of the SSFSE refocusing flip-angle train could reduce radiofrequency energy deposition without degrading image quality, thereby reducing inter-slice pauses and overall scan times. We modulated the refocusing flip-angle train for SSFSE to minimize energy deposition while minimizing blurring and motion-related signal loss. In a cohort of 50 consecutive patients (25 boys, mean age 5.5 years, range 1 month to 17 years) referred for abdominal MRI we obtained standard SSFSE and variable refocusing flip-angle (vrfSSFSE) images and recorded sequence scan times. Two readers independently scored the images in blinded, randomized order for noise, tissue contrast, sharpness, artifacts and left lobe hepatic signal uniformity on a four-point scale. The null hypothesis of no difference between SSFSE and vrfSSFSE image-quality was assessed with a Mann-Whitney U test, and the null hypothesis of no scan time difference was assessed with the paired t-test. SSFSE and vrfSSFSE mean acquisition times were 54.3 and 26.2 s, respectively (P-value <0.0001). For each reader, SSFSE and vrfSSFSE noise, tissue contrast, sharpness and artifacts were not significantly different (P-values 0.18-0.86). However, SSFSE had better left lobe hepatic signal uniformity (P < 0.01, both readers). vrfSSFSE is twice as fast as SSFSE, with equivalent image quality with the exception of left hepatic lobe signal heterogeneity. (orig.)

  16. Utility of two types of MR cisternography for patency evaluation of aqueduct and third ventriculostomy site: Three dimentsional sagittal fast spin echo sequence and steady-state coherent fast gradient echo sequence

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Hyun; Kim, Eun Hee; Park, Jong Bin; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheol Kyu; Bae, Yun Jung; Lee, Kyung Mi [Dept. of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2015-07-15

    We aimed to evaluate the utility of two types of MR cisternography [fast spin echo sequence and steady-state coherent gradient echo (GRE) sequence] in addition to phase contrast-cine imaging (PC-cine), for assessing patency at the aqueduct and third ventriculostomy site. 43 patients (35 patients with suspected aqueductal stenosis and 8 patients with third ventriculostomy) were retrospectively analyzed. PC-cine, 3 dimensional sagittal fast spin echo sequence [driven-equilibrium imaging (DRIVE) or volumetric isotrophic T2-weighted acquisition (T2 VISTA)] and steady-state coherent fast GRE sequence (balanced turbo field echo; bTFE) imaging were performed in all patients. The patency of the aqueduct or third ventriculostomy site was scored. Some pitfalls of each sequence were also analyzed in individual cases. 93% of all cases showed consistent scores in PC-cine, DRIVE/T2 VISTA, and bTFE imaging. DRIVE/T2 VISTA imaging provided functional information of cerebrospinal fluid flow with flow-related artifacts, while bTFE imaging allowed direct visualization of the aqueduct or ventriculostomy site. However, evaluation of anatomical structures was difficult in three cases with strong flow-related artifacts on DRIVE/T2 VISTA and in 2 cases with susceptibility artifacts on bTFE. Both DRIVE/T2 VISTA and bTFE imaging have complementary roles in evaluating the patency of the aqueduct and 3rd ventriculostomy site.

  17. Utility of two types of MR cisternography for patency evaluation of aqueduct and third ventriculostomy site: Three dimentsional sagittal fast spin echo sequence and steady-state coherent fast gradient echo sequence

    International Nuclear Information System (INIS)

    Park, Jung Hyun; Kim, Eun Hee; Park, Jong Bin; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheol Kyu; Bae, Yun Jung; Lee, Kyung Mi

    2015-01-01

    We aimed to evaluate the utility of two types of MR cisternography [fast spin echo sequence and steady-state coherent gradient echo (GRE) sequence] in addition to phase contrast-cine imaging (PC-cine), for assessing patency at the aqueduct and third ventriculostomy site. 43 patients (35 patients with suspected aqueductal stenosis and 8 patients with third ventriculostomy) were retrospectively analyzed. PC-cine, 3 dimensional sagittal fast spin echo sequence [driven-equilibrium imaging (DRIVE) or volumetric isotrophic T2-weighted acquisition (T2 VISTA)] and steady-state coherent fast GRE sequence (balanced turbo field echo; bTFE) imaging were performed in all patients. The patency of the aqueduct or third ventriculostomy site was scored. Some pitfalls of each sequence were also analyzed in individual cases. 93% of all cases showed consistent scores in PC-cine, DRIVE/T2 VISTA, and bTFE imaging. DRIVE/T2 VISTA imaging provided functional information of cerebrospinal fluid flow with flow-related artifacts, while bTFE imaging allowed direct visualization of the aqueduct or ventriculostomy site. However, evaluation of anatomical structures was difficult in three cases with strong flow-related artifacts on DRIVE/T2 VISTA and in 2 cases with susceptibility artifacts on bTFE. Both DRIVE/T2 VISTA and bTFE imaging have complementary roles in evaluating the patency of the aqueduct and 3rd ventriculostomy site

  18. Comparison of T1-weighted fast spin-echo and T1-weighted fluid-attenuated inversion recovery images of the lumbar spine at 3.0 Tesla

    International Nuclear Information System (INIS)

    Lavdas, Eleftherios; Vlychou, Marianna; Arikidis, Nikos; Kapsalaki, Eftychia; Roka, Violetta; Fezoulidis, Ioannis V.

    2010-01-01

    Background: T1-weighted fluid-attenuated inversion recovery (FLAIR) sequence has been reported to provide improved contrast between lesions and normal anatomical structures compared to T1-weighted fast spin-echo (FSE) imaging at 1.5T regarding imaging of the lumbar spine. Purpose: To compare T1-weighted FSE and fast T1-weighted FLAIR imaging in normal anatomic structures and degenerative and metastatic lesions of the lumbar spine at 3.0T. Material and Methods: Thirty-two consecutive patients (19 females, 13 males; mean age 44 years, range 30-67 years) with lesions of the lumbar spine were prospectively evaluated. Sagittal images of the lumbar spine were obtained using T1-weighted FSE and fast T1-weighted FLAIR sequences. Both qualitative and quantitative analyses measuring the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and relative contrast (ReCon) between degenerative and metastatic lesions and normal anatomic structures were conducted, comparing these sequences. Results: On quantitative evaluation, SNRs of cerebrospinal fluid (CSF), nerve root, and fat around the root of fast T1-weighted FLAIR imaging were significantly lower than those of T1-weighted FSE images (P<0.001). CNRs of normal spinal cord/CSF and disc herniation/ CSF for fast T1-weighted FLAIR images were significantly higher than those for T1-weighted FSE images (P<0.001). ReCon of normal spinal cord/CSF, disc herniation/CSF, and vertebral lesions/CSF for fast T1-weighted FLAIR images were significantly higher than those for T1-weighted FSE images (P<0.001). On qualitative evaluation, it was found that CSF nulling and contrast at the spinal cord (cauda equina)/CSF interface for T1-weighted FLAIR images were significantly superior compared to those for T1-weighted FSE images (P<0.001), and the disc/spinal cord (cauda equina) interface was better for T1-weighted FLAIR images (P<0.05). Conclusion: The T1-weighted FLAIR sequence may be considered as the preferred lumbar spine imaging

  19. T1-weighted fluid-attenuated inversion recovery and T1-weighted fast spin-echo contrast-enhanced imaging: a comparison in 20 patients with brain lesions

    International Nuclear Information System (INIS)

    Al-Saeed, O.; Athyal, R. P.; Ismail, M.; Rudwan, M.; Khafajee, S.

    2009-01-01

    Full text: Tl-weighted fluid-attenuated inversion recovery (FLAIR) sequence is a relatively new pulse sequence for intracranial MR imaging. This study was performed to compare the image quality of Tl-weighted FLAIR with the Tl-weighted FSE sequence. Twenty patients with brain lesions underwent Tl-weighted fast spin-echo (FSE) and Tl-weighted FLAIR during the same imaging session. Four quantitative and three qualitative criteria were used to compare the two sequences after contrast. Two of four quantitative criteria pertained to lesion characteristics: lesion to white matter (WM) contrast-to-noise ratio (CNR) and lesion to cerebrospinal fluid (CSF) CNR, and two related to signals from normal tissue: grey matter to WM CNR and WM to CSF CNR. The three qualitative criteria were conspicuousness of the lesion, the presence of image artefacts and the overall image contrast. Both Tl-weighted FSE and FLAIR images were effective in demonstrating lesions. Image contrast was superior in Tl-weighted FLAIR images with significantly improved grey matter-WM CNRs and CSF-WM CNRs. The overall image contrast was judged to be superior on Tl-weighted FLAIR images compared with Tl-weighted FSE images by all neuroradiologists. Two of three reviewers considered that the FLAIR images had slightly increased imaging artefacts that, however, did not interfere with image interpretation. Tl-weighted FLAIR imaging provides improved lesion-to-background and grey to WM contrast-to-noise ratios. Superior conspicuity of lesions and overall image contrast is obtained in comparable acquisition times. These indicate an important role for Tl-weighted FLAIR in intracranial imaging and highlight its advantage over the more widely practiced Tl-weighted FSE sequence

  20. Optimization image of magnetic resonance imaging (MRI) T2 fast spin echo (FSE) with variation echo train length (ETL) on the rupture tendon achilles case

    International Nuclear Information System (INIS)

    Muzamil, Akhmad; Firmansyah, Achmad Haries

    2017-01-01

    The research was done the optimization image of Magnetic Resonance Imaging (MRI) T2 Fast Spin Echo (FSE) with variation Echo Train Length (ETL) on the Rupture Tendon Achilles case. This study aims to find the variations Echo Train Length (ETL) from the results of ankle’s MRI image and find out how the value of Echo Train Length (ETL) works on the MRI ankle to produce optimal image. In this research, the used ETL variations were 12 and 20 with the interval 2 on weighting T2 FSE sagittal. The study obtained the influence of Echo Train Length (ETL) on the quality of ankle MRI image sagittal using T2 FSE weighting and analyzed in 25 images of five patients. The data analysis has done quantitatively with the Region of Interest (ROI) directly on computer MRI image planes which conducted statistical tests Signal to Noise Ratio (SNR) and Contras to Noise Ratio (CNR). The Signal to Noise Ratio (SNR) was the highest finding on fat tissue, while the Contras to Noise Ratio (CNR) on the Tendon-Fat tissue with ETL 12 found in two patients. The statistics test showed the significant SNR value of the 0.007 (p<0.05) of Tendon tissue, 0.364 (p>0.05) of the Fat, 0.912 (p>0.05) of the Fibula, and 0.436 (p>0.05) of the Heel Bone. For the contrast to noise ratio (CNR) of the Tendon-FAT tissue was about 0.041 (p>0.05). The results of the study showed that ETL variation with T2 FSE sagittal weighting had difference at Tendon tissue and Tendon-Fat tissue for MRI imaging quality. SNR and CNR were an important aspect on imaging optimization process to give the diagnose information. (paper)

  1. Evaluation of the menisci of the knee joint using three-dimensional isotropic resolution fast spin-echo imaging: diagnostic performance in 250 patients with surgical correlation

    Energy Technology Data Exchange (ETDEWEB)

    Kijowski, Richard; Davis, Kirkland W.; Blankenbaker, Donna G.; Woods, Michael A.; De Smet, Arthur A. [University of Wisconsin School of Medicine and Public Health, Department of Radiology, Madison, WI (United States); Munoz del Rio, Alejandro [University of Wisconsin School of Medicine and Public Health, Department of Radiology, Madison, WI (United States); University of Wisconsin School of Medicine and Public Health, Department of Statistics, Madison, WI (United States)

    2012-02-15

    To compare the diagnostic performance of FSE-Cube, a three-dimensional isotropic resolution intermediate-weighted fast spin-echo sequence, with a routine magnetic resonance (MR) protocol at 3.0 T for detecting surgically confirmed meniscal tears of the knee joint in a large patient population. FSE-Cube was added to a routine MR protocol performed at 3.0 T on 250 patients who underwent subsequent knee arthroscopy. Three radiologists independently used FSE-Cube during one review and the routine MR protocol during a second review to detect medial and lateral meniscal tears. Using arthroscopy as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR protocol for detecting meniscal tears were determined for all readers combined. McNemar's tests were used to compare diagnostic performance between FSE-Cube and the routine MR protocol. FSE-cube and the routine MR protocol had similar sensitivity (95.5%/95.3% respectively, P=0.94) and similar specificity (69.8%/74.0% respectively, P=0.10) for detecting 156 medial meniscal tears. FSE-Cube had significantly lower sensitivity than the routine MR protocol (79.4%/85.0% respectively, P < 0.05) but similar specificity (83.9%/82.2% respectively, P=0.37) for detecting 89 lateral mensical tears. For lateral meniscal tears, FSE-Cube had significantly lower sensitivity (P < 0.05) than the routine MR protocol for detecting 19 root tears but similar sensitivity (P=0.17-1.00) for detecting all other tear locations and types. FSE-Cube had diagnostic performance similar to a routine MR protocol for detecting meniscal tears except for a significantly lower sensitivity for detecting lateral meniscal tears, which was mainly attributed to decreased ability to identify lateral meniscus root tears. (orig.)

  2. SPAMM, cine phase contrast imaging and fast spin-echo T2-weighted imaging in the study of intracranial cerebrospinal fluid (CSF) flow

    International Nuclear Information System (INIS)

    Connor, S.E.J.; O'Gorman, R.; Summers, P.; Simmons, A.; Moore, E.M.; Chandler, C.; Jarosz, J.M.

    2001-01-01

    AIM: To compare the qualitative assessment of cerebrospinal fluid (CSF) flow using a SPAMM (spatial modulation of magnetization) technique with cine phase contrast images (cine PC) and fast spin echo (FSE) T2-weighted images. MATERIALS AND METHODS: SPAMM, PC and T2-weighted sequences were performed on 22 occasions in 19 patients. Eleven of the studies were performed following a neuroendoscopic third ventriculostomy (NTV), and in these cases, the success of the NTV was determined by clinical follow-up. Two observers used consensus to grade the presence of CSF flow at nine different sites for each study. RESULTS: At 14 of the 178 matched sites, which could be assessed by both SPAMM and cine PC, SPAMM CSF flow grade was higher than that of cine PC. At a further 14/178 matched sites, the cine PC grade was higher than that of SPAMM. There was definite CSF flow at 113/182 (62%) of all the cine PC sites assessed, and 110/181 (61%) of all SPAMM sites assessed whilst 108/198 (54%) of FSE T2-weighted image sites demonstrated flow voids. Cine PC grades were higher than SPAMM at the cerebral aqueduct (P < 0.05, Wilcoxon sign rank test). Definite CSF flow within the anterior third ventricle was present in 4/5 (SPAMM) and 3/5 (cine PC) successful NTVs, 0/2 (SPAMM and cine PC) unsuccessful NTVs and 1/10 (SPAMM and cine PC) patients without NTV. CONCLUSION: SPAMM provides a comparable assessment of intracranial CSF flow to that of cine phase contrast imaging at all CSF sites except the cerebral aqueduct. Connor, S.E.J. et al. (2001)

  3. Evaluation of the menisci of the knee joint using three-dimensional isotropic resolution fast spin-echo imaging: diagnostic performance in 250 patients with surgical correlation

    International Nuclear Information System (INIS)

    Kijowski, Richard; Davis, Kirkland W.; Blankenbaker, Donna G.; Woods, Michael A.; De Smet, Arthur A.; Munoz del Rio, Alejandro

    2012-01-01

    To compare the diagnostic performance of FSE-Cube, a three-dimensional isotropic resolution intermediate-weighted fast spin-echo sequence, with a routine magnetic resonance (MR) protocol at 3.0 T for detecting surgically confirmed meniscal tears of the knee joint in a large patient population. FSE-Cube was added to a routine MR protocol performed at 3.0 T on 250 patients who underwent subsequent knee arthroscopy. Three radiologists independently used FSE-Cube during one review and the routine MR protocol during a second review to detect medial and lateral meniscal tears. Using arthroscopy as the reference standard, the sensitivity and specificity of FSE-Cube and the routine MR protocol for detecting meniscal tears were determined for all readers combined. McNemar's tests were used to compare diagnostic performance between FSE-Cube and the routine MR protocol. FSE-cube and the routine MR protocol had similar sensitivity (95.5%/95.3% respectively, P=0.94) and similar specificity (69.8%/74.0% respectively, P=0.10) for detecting 156 medial meniscal tears. FSE-Cube had significantly lower sensitivity than the routine MR protocol (79.4%/85.0% respectively, P < 0.05) but similar specificity (83.9%/82.2% respectively, P=0.37) for detecting 89 lateral mensical tears. For lateral meniscal tears, FSE-Cube had significantly lower sensitivity (P < 0.05) than the routine MR protocol for detecting 19 root tears but similar sensitivity (P=0.17-1.00) for detecting all other tear locations and types. FSE-Cube had diagnostic performance similar to a routine MR protocol for detecting meniscal tears except for a significantly lower sensitivity for detecting lateral meniscal tears, which was mainly attributed to decreased ability to identify lateral meniscus root tears. (orig.)

  4. High-resolution T2-weighted MR imaging of the inner ear using a long echo-train-length 3D fast spin-echo sequence

    International Nuclear Information System (INIS)

    Naganawa, S.; Yamakawa, K.; Fukatsu, H.; Ishigaki, T.; Nakashima, T.; Sugimoto, H.; Aoki, I.; Miyazaki, M.; Takai, H.

    1996-01-01

    The purpose of this study was to assess the value of a long echo-train-length 3D fast spin-echo (3D-FSE) sequence in visualizing the inner ear structures. Ten normal ears and 50 patient ears were imaged on a 1.5T MR unit using a head coil. Axial high-resolution T2-weighted images of the inner ear and the internal auditory canal (IAC) were obtained in 15 min. In normal ears the reliability of the visualization for the inner ear structures was evaluated on original images and the targeted maximum intensity projection (MIP) images of the labyrinth. In ten normal ears, 3D surface display (3D) images were also created and compared with MIP images. On the original images the cochlear aqueduct, the vessels in the vicinity of the IAC, and more than three branches of the cranial nerves were visualized in the IAC in all the ears. The visibility of the endolympathic duct was 80%. On the MIP images the visibility of the three semicircular canals, anterior and posterior ampulla, and of more than two turns of the cochlea was 100%. The MIP images and 3D images were almost comparable. The visibility of the endolymphatic duct was 80% in normal ears and 0% in the affected ears of the patients with Meniere's disease (p<0.001). In one patient ear a small intracanalicular tumor was depicted clearly. In conclusion, the long echo train length T2-weighted 3D-FSE sequence enables the detailed visualization of the tiny structures of the inner ear and the IAC within a clinically acceptable scan time. Furthermore, obtaining a high contrast between the soft/bony tissue and the cerebrospinal/endolymph/perilymph fluid would be of significant value in the diagnosis of the pathologic conditions around the labyrinth and the IAC. (orig.)

  5. BLADE acquisition method improves T2-weighted MR images of the female pelvis compared with a standard fast spin-echo sequence

    International Nuclear Information System (INIS)

    Fujimoto, Koji; Koyama, Takashi; Tamai, Ken; Morisawa, Nobuko; Okada, Tomohisa; Togashi, Kaori

    2011-01-01

    Purpose: To investigate feasibility of the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER or BLADE) T2-weighted imaging (T2WI) of the female pelvis by comparing it with standard fast spin-echo T2WI (STD-T2WI). Materials and methods: Sagittal STD-T2WI and BLADE-T2WI of the female pelvis were performed with (36 patients) or without (15 patients) administration of butylscopolamine on a 1.5 T MR unit. Two radiologists independently rated depiction of the uterus, ovary, intestines, bladder, gynecological lesions, overall quality, and artifacts using a four-point scale. Results were compared between STD-T2WI vs. BLADE-T2WI either with (B+) or without (B−) administration of butylscopolamine, BLADE-T2WI (B−) vs. BLADE-T2WI (B+), and STD-T2WI (B+) vs. BLADE-T2WI (B−). Results: When butylscopolamine was administrated, depiction of the uterus, ovary, intestines, gynecological lesions, and overall image quality was rated higher and artifacts were rated fewer for BLADE-T2WI with significance compared with STD-T2WI. When the drug was not administrated, significant difference was observed in depiction of the lesion, overall quality, and artifacts. Depiction of the uterus, gynecological lesion, and overall quality was rated significantly higher and artifacts were fewer in BLADE-T2WI (B+) than in BLADE-T2WI (B−). Conclusion: BLADE method was feasible for female pelvic MRI, with best image quality in BLADE-T2WI (B+).

  6. A fundamental study of non-contrast enhanced MR angiography using ECG gated-3D fast spin echo at 3.0 T

    International Nuclear Information System (INIS)

    Nakato, Kengo; Hiai, Yasuhiro; Tomiguchi, Seiji

    2010-01-01

    Contrast-enhanced magnetic resonance angiography (CE-MRA) is frequently performed in body and extremity studies because of its superior ability to detect the vascular stenosis. However, nephrotoxicity of the contrast medium has been emphasized in recent years. Non-contrast MRA using the three-dimensional electrocardiogram-synchronized fast spin echo method (fresh blood imaging (FBI), non-contrast MRA of arteries and veins (NATIVE) and triggered acquisition non contrast enhancement MRA (TRANCE)) is recommended as a substitute for CE-MRA. There are a few reports in the literature that evaluate the detectability of vascular stenosis using non-contrast MRA on 3.0 T MRI. The purpose of this study was to evaluate the detectability of vascular stenosis using non-contrast MRA at 3.0 T with an original vascular phantom. The vascular phantom consisted of silicon tubes. 30% and 70% stenosis of luminal diameter were made. Each silicon tube connected a pump producing a pulsatile flow. A flowing material to was used in this study to show the similarity of the intensity to blood on MRI. MRA without a contrast medium (NATIVE sequence) were performed in the vascular phantom by changing the image matrix, static magnetic field strength and flow velocity. In addition, the NATIVE sequence was used with or without flow compensation. Vascular stenosis was quantitatively estimated by measurement of the signal intensities in non-contrast MRA images. MRA with NATIVE sequence demonstrated an accurate estimation of 30% vascular stenosis at slow flow velocity. However, 30% stenosis was overestimated in cases of high flow velocity. Estimation was improved by using a flow compensation sequence. 70% stenosis was overestimated on MRA with NATIVE sequence. Estimation of 70% stenosis was improved by using a flow compensation sequence. Accurate estimation of vascular stenosis in MRA with a NATIVE sequence is improved by using the flow compensation technique. MRA with NATIVE sequence is considered to

  7. Optimal Padding for the Two-Dimensional Fast Fourier Transform

    Science.gov (United States)

    Dean, Bruce H.; Aronstein, David L.; Smith, Jeffrey S.

    2011-01-01

    One-dimensional Fast Fourier Transform (FFT) operations work fastest on grids whose size is divisible by a power of two. Because of this, padding grids (that are not already sized to a power of two) so that their size is the next highest power of two can speed up operations. While this works well for one-dimensional grids, it does not work well for two-dimensional grids. For a two-dimensional grid, there are certain pad sizes that work better than others. Therefore, the need exists to generalize a strategy for determining optimal pad sizes. There are three steps in the FFT algorithm. The first is to perform a one-dimensional transform on each row in the grid. The second step is to transpose the resulting matrix. The third step is to perform a one-dimensional transform on each row in the resulting grid. Steps one and three both benefit from padding the row to the next highest power of two, but the second step needs a novel approach. An algorithm was developed that struck a balance between optimizing the grid pad size with prime factors that are small (which are optimal for one-dimensional operations), and with prime factors that are large (which are optimal for two-dimensional operations). This algorithm optimizes based on average run times, and is not fine-tuned for any specific application. It increases the amount of times that processor-requested data is found in the set-associative processor cache. Cache retrievals are 4-10 times faster than conventional memory retrievals. The tested implementation of the algorithm resulted in faster execution times on all platforms tested, but with varying sized grids. This is because various computer architectures process commands differently. The test grid was 512 512. Using a 540 540 grid on a Pentium V processor, the code ran 30 percent faster. On a PowerPC, a 256x256 grid worked best. A Core2Duo computer preferred either a 1040x1040 (15 percent faster) or a 1008x1008 (30 percent faster) grid. There are many industries that

  8. Value of MR cisternography using three-dimensional half-fourier single-shot fast spin-echo sequences in the diagnosis of diseases related to cranial nerves VII and VIII

    Energy Technology Data Exchange (ETDEWEB)

    Yamakami, Norio [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    1999-05-01

    The purpose of this study was to evaluate the value of MR cisternography using three-dimensional half-Fourier single-shot fast spin-echo sequences in the diagnosis of diseasea related to cranial nerves VII and VIII. With a 0.5-T imager, the most appropriate setting of echo time and section thickness was first assessed in five volunteers. This resulted in echo time of 250 msec and section thickness of 2 mm as the most effective parameters. Second, using echo time of 120 msec and section thickness of 1.5 mm that were available from the beginning of this study, the demonstration of four nerves within the audistory canal was assessed in seven volunteers. In all of the volunteers, the facial, cochlear, and vestibular nerves were determined with demonstration of each of superior and inferior vestibular nerves in four of them. Next, MR cisternography using the same echo time and section thickness was applied in 368 patients with suspicion of acoustic neurinoma and 14 with hemifacial spasm. In 28 of the 368 patients, MR cisternograms depicted an acoustic neurinoma that was confirmed on postcontrast T1-weighted images. Meanwhile, in five of the 14 patients with hemifacial spasm, MR cisternograms revealed a vessel compressing the root exit zone of the affected facial nerve. It is concluded that MR cisternography using three-dimensional half-Fourier single-shot fast spin-echo sequences can be a useful means for demonstrating nerves within the auditory nerve as well as for the screening of acoustic neurionoma. (author)

  9. Value of MR cisternography using three-dimensional half-fourier single-shot fast spin-echo sequences in the diagnosis of diseases related to cranial nerves VII and VIII

    International Nuclear Information System (INIS)

    Yamakami, Norio

    1999-01-01

    The purpose of this study was to evaluate the value of MR cisternography using three-dimensional half-Fourier single-shot fast spin-echo sequences in the diagnosis of diseasea related to cranial nerves VII and VIII. With a 0.5-T imager, the most appropriate setting of echo time and section thickness was first assessed in five volunteers. This resulted in echo time of 250 msec and section thickness of 2 mm as the most effective parameters. Second, using echo time of 120 msec and section thickness of 1.5 mm that were available from the beginning of this study, the demonstration of four nerves within the audistory canal was assessed in seven volunteers. In all of the volunteers, the facial, cochlear, and vestibular nerves were determined with demonstration of each of superior and inferior vestibular nerves in four of them. Next, MR cisternography using the same echo time and section thickness was applied in 368 patients with suspicion of acoustic neurinoma and 14 with hemifacial spasm. In 28 of the 368 patients, MR cisternograms depicted an acoustic neurinoma that was confirmed on postcontrast T1-weighted images. Meanwhile, in five of the 14 patients with hemifacial spasm, MR cisternograms revealed a vessel compressing the root exit zone of the affected facial nerve. It is concluded that MR cisternography using three-dimensional half-Fourier single-shot fast spin-echo sequences can be a useful means for demonstrating nerves within the auditory nerve as well as for the screening of acoustic neurionoma. (author)

  10. The time window of MRI of murine atherosclerotic plaques after administration of CB2 receptor targeted micelles: inter-scan variability and relation between plaque signal intensity increase and gadolinium content of inversion recovery prepared versus non-prepared fast spin echo

    NARCIS (Netherlands)

    te Boekhorst, B. C. M.; Bovens, S. M.; van de Kolk, C. W. A.; Cramer, M. J. M.; Doevendans, P. A. F. M.; ten Hove, M.; van der Weerd, L.; Poelmann, R.; Strijkers, G. J.; Pasterkamp, G.; van Echteld, C. J. A.

    2010-01-01

    Single fast spin echo scans covering limited time frames are mostly used for contrast-enhanced MRI of atherosclerotic plaque biomarkers. Knowledge on inter-scan variability of the normalized enhancement ratio of plaque (NER(plaque)) and relation between NER(plaque) and gadolinium content for

  11. Performance of a fast and high-resolution multi-echo spin-echo sequence for prostate T2 mapping across multiple systems.

    Science.gov (United States)

    van Houdt, Petra J; Agarwal, Harsh K; van Buuren, Laurens D; Heijmink, Stijn W T P J; Haack, Søren; van der Poel, Henk G; Ghobadi, Ghazaleh; Pos, Floris J; Peeters, Johannes M; Choyke, Peter L; van der Heide, Uulke A

    2018-03-01

    To evaluate the performance of a multi-echo spin-echo sequence with k-t undersampling scheme (k-t T 2 ) in prostate cancer. Phantom experiments were performed at five systems to estimate the bias, short-term repeatability, and reproducibility across all systems expressed with the within-subject coefficient of variation (wCV). Monthly measurements were performed on two systems for long-term repeatability estimation. To evaluate clinical repeatability, two T 2 maps (voxel size 0.8 × 0.8 × 3 mm 3 ; 5 min) were acquired at separate visits on one system for 13 prostate cancer patients. Repeatability was assessed per patient in relation to spatial resolution. T 2 values were compared for tumor, peripheral zone, and transition zone. Phantom measurements showed a small bias (median = -0.9 ms) and good short-term repeatability (median wCV = 0.5%). Long-term repeatability was 0.9 and 1.1% and reproducibility between systems was 1.7%. The median bias observed in patients was -1.1 ms. At voxel level, the median wCV was 15%, dropping to 4% for structures of 0.5 cm 3 . The median tumor T 2 values (79 ms) were significantly lower (P < 0.001) than in the peripheral zone (149 ms), but overlapped with the transition zone (91 ms). Reproducible T 2 mapping of the prostate is feasible with good spatial resolution in a clinically reasonable scan time, allowing reliable measurement of T 2 in structures as small as 0.5 cm 3 . Magn Reson Med 79:1586-1594, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  12. Degenerative disc disease of the lumbar spine: a prospective comparison of fast T1-weighted fluid-attenuated inversion recovery and T1-weighted turbo spin echo MR imaging

    International Nuclear Information System (INIS)

    Erdem, L. Oktay; Erdem, C. Zuhal; Acikgoz, Bektas; Gundogdu, Sadi

    2005-01-01

    Objective: To compare fast T1-weighted fluid-attenuated inversion recovery (FLAIR) and T1-weighted turbo spin-echo (TSE) imaging of the degenerative disc disease of the lumbar spine. Materials and methods: Thirty-five consecutive patients (19 females, 16 males; mean age 41 years, range 31-67 years) with suspected degenerative disc disease of the lumbar spine were prospectively evaluated. Sagittal images of the lumbar spine were obtained using T1-weighted TSE and fast T1-weighted FLAIR sequences. Two radiologists compared these sequences both qualitatively and quantitatively. Results: On qualitative evaluation, CSF nulling, contrast at the disc-CSF interface, the disc-spinal cord (cauda equina) interface, and the spinal cord (cauda equina)-CSF interface of fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.001). On quantitative evaluation of the first 15 patients, signal-to-noise ratios of cerebrospinal fluid of fast T1-weighted FLAIR imaging were significantly lower than those for T1-weighted TSE images (P < 0.05). Contrast-to-noise ratios of spinal cord/CSF and normal bone marrow/disc for fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.05). Conclusion: Results in our study have shown that fast T1-weighted FLAIR imaging may be a valuable imaging modality in the armamentarium of lumbar spinal T1-weighted MR imaging, because the former technique has definite superior advantages such as CSF nulling, conspicuousness of the normal anatomic structures and changes in the lumbar spinal discogenic disease and image contrast and also almost equally acquisition times

  13. Degenerative disc disease of the lumbar spine: a prospective comparison of fast T1-weighted fluid-attenuated inversion recovery and T1-weighted turbo spin echo MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Erdem, L. Oktay [Department of Radiology, Zonguldak Karaelmas University, School of Medicine, 6700 Kozlu, Zonguldak (Turkey)]. E-mail: sunarerdem@yahoo.com; Erdem, C. Zuhal [Department of Radiology, Zonguldak Karaelmas University, School of Medicine, 6700 Kozlu, Zonguldak (Turkey); Acikgoz, Bektas [Department of Neurosurgery, Zonguldak Karaelmas University, School of Medicine, Zonguldak (Turkey); Gundogdu, Sadi [Department of Radiology, Zonguldak Karaelmas University, School of Medicine, 6700 Kozlu, Zonguldak (Turkey)

    2005-08-01

    Objective: To compare fast T1-weighted fluid-attenuated inversion recovery (FLAIR) and T1-weighted turbo spin-echo (TSE) imaging of the degenerative disc disease of the lumbar spine. Materials and methods: Thirty-five consecutive patients (19 females, 16 males; mean age 41 years, range 31-67 years) with suspected degenerative disc disease of the lumbar spine were prospectively evaluated. Sagittal images of the lumbar spine were obtained using T1-weighted TSE and fast T1-weighted FLAIR sequences. Two radiologists compared these sequences both qualitatively and quantitatively. Results: On qualitative evaluation, CSF nulling, contrast at the disc-CSF interface, the disc-spinal cord (cauda equina) interface, and the spinal cord (cauda equina)-CSF interface of fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.001). On quantitative evaluation of the first 15 patients, signal-to-noise ratios of cerebrospinal fluid of fast T1-weighted FLAIR imaging were significantly lower than those for T1-weighted TSE images (P < 0.05). Contrast-to-noise ratios of spinal cord/CSF and normal bone marrow/disc for fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.05). Conclusion: Results in our study have shown that fast T1-weighted FLAIR imaging may be a valuable imaging modality in the armamentarium of lumbar spinal T1-weighted MR imaging, because the former technique has definite superior advantages such as CSF nulling, conspicuousness of the normal anatomic structures and changes in the lumbar spinal discogenic disease and image contrast and also almost equally acquisition times.

  14. J-NSE: Neutron spin echo spectrometer

    Directory of Open Access Journals (Sweden)

    Olaf Holderer

    2015-08-01

    Full Text Available Neutron Spin-Echo (NSE spectroscopy is well known as the only neutron scattering technique that achieves energy resolution of several neV. By using the spin precession of polarized neutrons in magnetic field one can measure tiny velocity changes of the individual neutron during the scattering process. Contrary to other inelastic neutron scattering techniques, NSE measures the intermediate scattering function S(Q,t in reciprocal space and time directly. The Neutron Spin-Echo spectrometer J-NSE, operated by JCNS, Forschungszentrum Jülich at the Heinz Maier-Leibnitz Zentrum (MLZ in Garching, covers a time range (2 ps to 200 ns on length scales accessible by small angle scattering technique. Along with conventional NSE spectroscopy that allows bulk measurements in transmission mode, J-NSE offers a new possibility - gracing incidence spin echo spectroscopy (GINSENS, developed to be used as "push-button" option in order to resolve the depth dependent near surface dynamics.

  15. A prospective comparison study of fast T1 weighted fluid attenuation inversion recovery and T1 weighted turbo spin echo sequence at 3 T in degenerative disease of the cervical spine.

    Science.gov (United States)

    Ganesan, K; Bydder, G M

    2014-09-01

    This study compared T1 fluid attenuation inversion recovery (FLAIR) and T1 turbo spin echo (TSE) sequences for evaluation of cervical spine degenerative disease at 3 T. 72 patients (44 males and 28 females; mean age of 39 years; age range, 27-75 years) with suspected cervical spine degenerative disease were prospectively evaluated. Sagittal images of the spine were obtained using T1 FLAIR and T1 TSE sequences. Two experienced neuroradiologists compared the sequences qualitatively and quantitatively. On qualitative evaluation, cerebrospinal fluid (CSF) nulling and contrast at cord-CSF, disc-CSF and disc-cord interfaces were significantly higher on fast T1 FLAIR images than on T1 TSE images (p degenerative disease, owing to higher cord-CSF, disc-cord and disc-CSF contrast. However, intrinsic cord contrast is low on T1 FLAIR images. T1 FLAIR is more promising and sensitive than T1 TSE for evaluation of degenerative spondyloarthropathy and may provide a foundation for development of MR protocols for early detection of degenerative and neoplastic diseases.

  16. Two-dimensional fast marching for geometrical optics.

    Science.gov (United States)

    Capozzoli, Amedeo; Curcio, Claudio; Liseno, Angelo; Savarese, Salvatore

    2014-11-03

    We develop an approach for the fast and accurate determination of geometrical optics solutions to Maxwell's equations in inhomogeneous 2D media and for TM polarized electric fields. The eikonal equation is solved by the fast marching method. Particular attention is paid to consistently discretizing the scatterers' boundaries and matching the discretization to that of the computational domain. The ray tracing is performed, in a direct and inverse way, by using a technique introduced in computer graphics for the fast and accurate generation of textured images from vector fields. The transport equation is solved by resorting only to its integral form, the transport of polarization being trivial for the considered geometry and polarization. Numerical results for the plane wave scattering of two perfectly conducting circular cylinders and for a Luneburg lens prove the accuracy of the algorithm. In particular, it is shown how the approach is capable of properly accounting for the multiple scattering occurring between the two metallic cylinders and how inverse ray tracing should be preferred to direct ray tracing in the case of the Luneburg lens.

  17. Inter- and intra-rater reliability of patellofemoral kinematic and contact area quantification by fast spin echo MRI and correlation with cartilage health by quantitative T1ρ MRI.

    Science.gov (United States)

    Lau, Brian C; Thuillier, Daniel U; Pedoia, Valentina; Chen, Ellison Y; Zhang, Zhihong; Feeley, Brian T; Souza, Richard B

    2016-01-01

    Patellar maltracking is a leading cause of patellofemoral pain syndrome (PFPS). The aim of this study was to determine the inter- and intra-rater reliability of a semi-automated program for magnetic resonance imaging (MRI) based patellofemoral kinematics. Sixteen subjects (10 with PFPS [mean age 32.3; SD 5.2; eight females] and six controls without PFPS 19 [mean age 28.6; SD 2.8; three females]) participated in the study. One set of T2-weighted, fat-saturated fast spin-echo (FSE) MRIs were acquired from each subject in full extension and 30° of knee flexion. MRI including axial T1ρ relaxation time mapping sequences was also performed on each knee. Following image acquisitions, regions of interest for kinematic MRI, and patellar and trochlear cartilage were segmented and quantified with in-house designed spline- based MATLAB semi-automated software. Intraclass Correlations Coefficients (ICC) of calculated kinematic parameters were good to excellent, ICC > 0.8 in patellar flexion, rotation, tilt, and translation (anterior -posterior, medial -lateral, and superior -inferior), and contact area translation. Only patellar tilt in the flexed position and motion from extended to flexed state was significantly different between PFPS and control patients (p=0.002 and p=0.006, respectively). No significant correlations were identified between patellofemoral kinematics and contact area with T1ρ relaxation times. A semi-automated, spline-based kinematic MRI technique for patellofemoral kinematic and contact area quantification is highly reproducible with the potential to help better understand the role of patellofemoral maltracking in PFPS and other knee disorders. Level IV. Published by Elsevier B.V.

  18. Inter- and intra-rater reliability of patellofemoral kinematic and contact area quantification by fast spin echo MRI and correlation with cartilage health by quantitative T1ρ MRI☆

    Science.gov (United States)

    Lau, Brian C.; Thuillier, Daniel U.; Pedoia, Valentina; Chen, Ellison Y.; Zhang, Zhihong; Feeley, Brian T.; Souza, Richard B.

    2016-01-01

    Background Patellar maltracking is a leading cause of patellofemoral pain syndrome (PFPS). The aim of this study was to determine the inter- and intra-rater reliability of a semi-automated program for magnetic resonance imaging (MRI) based patellofemoral kinematics. Methods Sixteen subjects (10 with PFPS [mean age 32.3; SD 5.2; eight females] and six controls without PFPS 19 [mean age 28.6; SD 2.8; three females]) participated in the study. One set of T2-weighted, fat-saturated fast spin-echo (FSE) MRIs were acquired from each subject in full extension and 30° of knee flexion. MRI including axial T1ρ relaxation time mapping sequences was also performed on each knee. Following image acquisitions, regions of interest for kinematic MRI, and patellar and trochlear cartilage were segmented and quantified with in-house designed spline- based MATLAB semi-automated software. Results Intraclass Correlations Coefficients (ICC) of calculated kinematic parameters were good to excellent, ICC > 0.8 in patellar flexion, rotation, tilt, and translation (anterior -posterior, medial -lateral, and superior -inferior), and contact area translation. Only patellar tilt in the flexed position and motion from extended to flexed state was significantly different between PFPS and control patients (p = 0.002 and p = 0.006, respectively). No significant correlations were identified between patellofemoral kinematics and contact area with T1ρ relaxation times. Conclusions A semi-automated, spline-based kinematic MRI technique for patellofemoral kinematic and contact area quantification is highly reproducible with the potential to help better understand the role of patellofemoral maltracking in PFPS and other knee disorders. PMID:26746045

  19. Workshop on neutron spin-echo

    Energy Technology Data Exchange (ETDEWEB)

    Aynajian, P.; Habicht, K.; Keller, Th.; Keimer, B.; Mezei, F.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Fetters, L.J.; Muller, K.; Kreiling, S.; Dehnicke, K.; Greiner, A.; Ehlers, G.; Arbe, A.; Colmenero, J.; Richter, D.; Farago, B.; Monkenbusch, M.; Ohl, M.; Butzek, M.; Kozielewski, T.; Monkenbusch, M.; Richter, D.; Pappas, C.; Hillier, A.; Manuel, P.; Cywinski, R.; Bentley, P.; Alba, M.; Mezei, F.; Campbell, I.A.; Zimmermann, U.; Ellis, J.; Jobic, H.; Pickup, R.M.; Pappas, C.; Farago, B.; Cywinski, R.; Haussler, W.; Holderer, O.; Frielinghaus, H.; Byelov, D.; Monkenbusch, M.; Allgaier, J.; Richter, D.; Egger, H.; Hellweg, Th.; Malikova, N.; Cadene, A.; Marry, V.; Dubois, E.; Turq, P.; Gardner, J.S.; Ehlers, G.; Bramwell, St.S.; Grigoriev, S.; Kraan, W.; Rekveldt, T.; Bouwman, W.; Van Dijk, N.; Falus, P.; Vorobiev, A.; Major, J.; Felcher, G.P.; Te-velthuis, S.; Dosch, H.; Vorobiev, A.; Dridi, M.H.; Major, J.; Dosch, H.; Falus, P.; Felcher, G.P.; Te Velthuis, S.G.E.; Bleuel, M.; Broell, M.; Lang, E.; Littrell, K.; Gahler, R.; Lal, J.; Lauter, H.; Toperverg, B.; Lauter, V.; Jernenkov, M.; Stueber, S.; Enderle, M.; Janoschek, M.; Keller, Th.; Klimko, S.; Boeni, P.; Nagao, M.; Yamada, N.; Kawabata, Y.; Seto, H.; Takeda, T.; Yoshizawa, H.; Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.C.; Longeville, St

    2005-07-01

    This document gathers the abstracts of most papers presented at the workshop. Neutron spin-echo (NSE) spectroscopy is a well established technique with a growing expert user community, the aim of the meeting was to discuss the latest achievements in neutron spin-echo science and instrumentation. One of the applications presented is the investigation on the microscopic scale of the dynamics of water in montmorillonite clays with Na{sup +} and Cs{sup +} ions in monolayer and bilayer states. The NSE technique has been used in the normal and resonance modes. NSE results show consistently slower dynamics (higher relaxation times) than both time-of-flight technique (TOF) and classical molecular dynamics simulations (MD). In the present TOF and NSE experiments, anisotropy of the water motion in the interlayer is almost impossible to detect, due to the use of powder samples and insufficient resolution. (A.C.)

  20. [The use of the T2-weighted turbo-spin-echo sequence in studying the neurocranium. A comparison with the conventional T2-weighted spin-echo sequence].

    Science.gov (United States)

    Siewert, C; Hosten, N; Felix, R

    1994-07-01

    T2-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neurocranium. We evaluated fast spin-echo T2-weighted imaging (TT2) of the neurocranium in comparison to conventional spin-echo T2-weighted imaging (T2). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher in TT2 than in T2 (with the exception of gray-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT2, Parkinson patients have to be examined by conventional T2. If these limitations are taken into account, fast spin-echo T2-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T2-weighting achieved in a short acquisition time.

  1. Advantages of T2 reversed fast spin-echo image and enhanced three-dimensional surface MR angiography for the diagnosis of cerebral arteriovenous malformations

    International Nuclear Information System (INIS)

    Tanabe, Sumiyoshi; Honmou, Osamu; Minamida, Yoshihiro; Hashi, Kazuo

    2001-01-01

    Although the anatomical investigation of cerebral arteriovenous malformation (AVM) with conventional neuro-imagings considerably supports the preoperative evaluation, it is still hard to dissect the detailed anatomical conformations of AVMs such as location of nidus, identification of feeding arteries or draining veins, and the three-dimensional configuration of nidus in sulci or gyri. In this study, we investigated the efficacy of enhanced three-dimensional surface MR angiography (surface MRA) and T2 reversed image (T2R image) in the diagnosis and surgical planning for cerebral AVMs. The diagnostic accuracy was studied in twelve AVMs: four AVMs closed to motor area, one to Broca area, one to Wernicke area, four in temporal lobe, and two in occipital lobe. Images were obtained with a SIGNA HORIZON LX 1.5T VER 8.2. To construct T2R, the brain is scanned by fast SE method with long TR and was displayed with the reversed gray scale, which seemed similar to T1WI. Surface MRA is a fusion image of MRA and surface image in the workstation. The original data was obtained by enhanced 3D-SPGR method. MRA image was reconstructed with MIP method, and surface image was manipulated with a volume rendering method. T2R images demonstrated seven sulcal AVMs, three gyral AVMs, and two sulco-gyral AVMs; five AVMs located on cortex, four extended to subcortex, and three to paraventricular brain. The images clearly showed six AVMs had hypervascular network such as modja-modja vascular formation. Surface MRA represented nidus adjacent to eloquent area. They were present in central sulcus, precentral sulcus, intraparietal sulcus, inferior frontal sulcus, sylvian fissure, superior temporal sulcus, inferior temporal sulcus, superior temporal gyrus, inferior temporal gyrus, medial temporal gyrus, premotor area and superior frontal sulcus, precuneus and parieto-occipital sulcus. It was easy to identify the point of feeding arteries going down into the sulcus and the junction-point of nidus

  2. Advantages of T2 reversed fast spin-echo image and enhanced three-dimensional surface MR angiography for the diagnosis of cerebral arteriovenous malformations

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, Sumiyoshi; Honmou, Osamu; Minamida, Yoshihiro; Hashi, Kazuo [Sapporo Medical Univ. (Japan). School of Medicine

    2001-09-01

    Although the anatomical investigation of cerebral arteriovenous malformation (AVM) with conventional neuro-imagings considerably supports the preoperative evaluation, it is still hard to dissect the detailed anatomical conformations of AVMs such as location of nidus, identification of feeding arteries or draining veins, and the three-dimensional configuration of nidus in sulci or gyri. In this study, we investigated the efficacy of enhanced three-dimensional surface MR angiography (surface MRA) and T2 reversed image (T2R image) in the diagnosis and surgical planning for cerebral AVMs. The diagnostic accuracy was studied in twelve AVMs: four AVMs closed to motor area, one to Broca area, one to Wernicke area, four in temporal lobe, and two in occipital lobe. Images were obtained with a SIGNA HORIZON LX 1.5T VER 8.2. To construct T2R, the brain is scanned by fast SE method with long TR and was displayed with the reversed gray scale, which seemed similar to T1WI. Surface MRA is a fusion image of MRA and surface image in the workstation. The original data was obtained by enhanced 3D-SPGR method. MRA image was reconstructed with MIP method, and surface image was manipulated with a volume rendering method. T2R images demonstrated seven sulcal AVMs, three gyral AVMs, and two sulco-gyral AVMs; five AVMs located on cortex, four extended to subcortex, and three to paraventricular brain. The images clearly showed six AVMs had hypervascular network such as modja-modja vascular formation. Surface MRA represented nidus adjacent to eloquent area. They were present in central sulcus, precentral sulcus, intraparietal sulcus, inferior frontal sulcus, sylvian fissure, superior temporal sulcus, inferior temporal sulcus, superior temporal gyrus, inferior temporal gyrus, medial temporal gyrus, premotor area and superior frontal sulcus, precuneus and parieto-occipital sulcus. It was easy to identify the point of feeding arteries going down into the sulcus and the junction-point of nidus

  3. Neutron spin echo scattering angle measurement (SESAME)

    International Nuclear Information System (INIS)

    Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

    2005-01-01

    We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-μm-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for

  4. Assessment of diagnosing metastatic bone tumor on T2*-weighted images. Comparison between turbo spin echo (TSE) method and gradient echo (GE) method

    International Nuclear Information System (INIS)

    Hayashi, Takahiko; Sugiyama, Akira; Katayama, Motoyuki

    1996-01-01

    We examined the usefulness of T2 * weighted gradient field echo images for diagnosis for metastatic bone tumors in comparison with T2 weighted turbo spin echo (fast spin echo) images. In T2 * weighted gradient field echo sequence to obtain maximum contrast-to-noise ratio (CNR), we experimentally manipulated flip angle (FA) (5deg-90deg), repetition time (TR) (400, 700 msec), and echo time (TE) (10-50 msec). The best CNR was 16.4 in fast low angle shot (FLASH) (TE: 24 msec, TR: 700 msec, FA: 40deg). Magnetic resonance imaging was carried out in 28 patients with metastatic bone tumors. In addition to conventional T1 weighted spin echo images, T2 weighted turbo spin echo (fast spin echo images) and T2 * weighted gradient field echo images were obtained. T2 * weighted gradient field echo images were superior to T2 weighted turbo spin echo (fast spin echo) images in delineating the tumors, adjacent fat tissues, and bone marrow. (author)

  5. Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-Dimensional Fast Fourier Transform Decomposition

    OpenAIRE

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S.; Puerari, Ivânio

    2012-01-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quanti...

  6. Challenges in neutron spin echo spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, C., E-mail: c.pappas@tudelft.n [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Lelievre-Berna, E.; Falus, P.; Farago, B. [Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Bentley, P. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Institut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Moskvin, E. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); PNPI, 188300 Gatchina, Leningrad District (Russian Federation); Krist, Th. [Helmholtz-Zentrum Berlin for Materials and Energy, Glienicker Str. 100, 14109 Berlin (Germany); Grigoriev, S. [PNPI, 188300 Gatchina, Leningrad District (Russian Federation)

    2009-09-01

    With the new brilliant neutron sources and the developments of novel optical elements, neutron spin echo (NSE) spectroscopy evolves to tackle new problems and scientific fields. The new developments pave the way to complex experimental set-ups such as the intensity modulated variant of NSE (IMNSE), a powerful technique which was introduced some 20 years ago but found limited use up to now. With the new compact supermirror or He{sup 3} polarizers IMNSE becomes attractive for a broad range of applications in magnetism, soft matter and biology. A novel development along this line is the polarimetric NSE technique, which combines IMNSE and the zero-field polarimeter Cryopad to access components of the scattered polarization that are transverse to the incoming polarization. Polarimetric NSE is the method of choice for studying chiral fluctuations, as illustrated by new results on the reference helimagnet MnSi.

  7. Theory of electron spin echoes in solids

    CERN Document Server

    Asadullina, N Y; Asadullin, Y Y

    2002-01-01

    We propose modified Bloch equations (MBEs) with specific power-dependent relaxation and dispersion parameters characteristic for two-pulse excitation and when the magnetic dipole-dipole interactions in the electron spin system control the dephasing. We discriminate between the 'active' (excited by both pulses) and 'passive' (excited by the second pulse only) spins: it is shown that the 'active' spins participate in a new effect, an active spin frequency modulation effect giving rise to the power-dependent dispersion and multiple electron spin echoes (ESEs); the 'passive' spins contribute to the power-dependent relaxation. The MBEs are solved and a general expression for the two-pulse ESEs is obtained. Detailed numerical analysis of this expression gives results in good quantitative agreement with the recent experiments on the two-pulse ESEs at conventional low applied fields. The developed theory is applied also to high field ESEs, which are promising for future investigations. On the basis of published resul...

  8. The basics of neutron spin echo

    International Nuclear Information System (INIS)

    Farago, B.

    1999-01-01

    Until 1974 inelastic neutron scattering consisted of producing by some means a neutron beam of known speed and measuring the final speed of the neutrons after the scattering event. The smaller the energy change was, the better the neutron speed had to be defined. As the neutrons come form a reactor with an approximately Maxwell distribution, an infinitely good energy resolution can be achieved only at the expense of infinitely low count rate. This introduces a practical resolution limit around 0.1 μeV on back-scattering instruments. In 1972 F. Mezei discovered the method of Neutron Spin Echo. This method decouples the energy resolution from intensity loss. The basics of this method is presented. (author)

  9. Application of synthesis methods to two-dimensional fast reactor transient study

    International Nuclear Information System (INIS)

    Izutsu, Sadayuki; Hirakawa, Naohiro

    1978-01-01

    Space time synthesis and time synthesis codes were developed and applied to the space-dependent kinetics benchmark problem of a two-dimensional fast reactor model, and it was found both methods are accurate and economical for the fast reactor kinetics study. Comparison between the space time synthesis and the time synthesis was made. Also, in space time synthesis, the influence of the number of trial functions on the error and on the computing time and the effect of degeneration of expansion coefficients are investigated. The matrix factorization method is applied to the inversion of the matrix equation derived from the synthesis equation, and it is indicated that by the use of this scheme space-dependent kinetics problem of a fast reactor can be solved efficiently by space time synthesis. (auth.)

  10. Fast Estimation Method of Space-Time Two-Dimensional Positioning Parameters Based on Hadamard Product

    Directory of Open Access Journals (Sweden)

    Haiwen Li

    2018-01-01

    Full Text Available The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA and direction of arrival (DOA parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM system, and the Cramer-Rao bound (CRB is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT algorithm and 2D matrix pencil (MP algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.

  11. Fast algorithm for two-dimensional data table use in hydrodynamic and radiative-transfer codes

    International Nuclear Information System (INIS)

    Slattery, W.L.; Spangenberg, W.H.

    1982-01-01

    A fast algorithm for finding interpolated atomic data in irregular two-dimensional tables with differing materials is described. The algorithm is tested in a hydrodynamic/radiative transfer code and shown to be of comparable speed to interpolation in regularly spaced tables, which require no table search. The concepts presented are expected to have application in any situation with irregular vector lengths. Also, the procedures that were rejected either because they were too slow or because they involved too much assembly coding are described

  12. Magnetic resonance findings in amyotrophic lateral sclerosis using a spin echo magnetization transfer sequence: preliminary report

    Directory of Open Access Journals (Sweden)

    ROCHA ANTÔNIO JOSÉ DA

    1999-01-01

    Full Text Available We present the magnetic resonance (MR findings of five patients with amyotrophic lateral sclerosis (ALS using a spin-echo sequence with an additional magnetization transfer (MT pulse on T1-weighted images (T1 SE/MT. These findings were absent in the control group and consisted of hyperintensity of the corticospinal tract. Moreover we discuss the principles and the use of this fast but simple MR technique in the diagnosis of ALS

  13. Comparative study between the Spin-echo and 3-D fast imaging techniques in the Knee evaluation with magnetic resonance. Estudio comparativo entre las tecnicas de Spin-Eco ecogradiente 3D, en la evaluacion de la rodilla con resonancia magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Oleaga Zufiria, L.; Ibaez Zubiarrain, A.; Grande Icaran, J.; Vela Martin, A.C.; Cintora Leon, E.; Grau Garcia, M.; Grande Icaran, D. (Hospital Civil de Bilbao. Servicio de Radiodiagnostico. Bilbao (Spain))

    1993-01-01

    We have carried out a retrospective analysis of the results of magnetic resonance (MR) studies in 20 patients, comparing two different sequences. We compared a 2-D spin-echo (SE2D) sequence with a 3-D fast imaging with steady-state precession (FISP3D) sequence in the attempt to compare the reliability of each in the detection of knee injuries. Arthroscopy was employed as a control technique. Our study revealed no statistically significant difference between the two sequences, although the overall sensitivity for the detection of meniscal lesions was slightly greater with the FISP3D sequence; however, the reliability in the detection of ruptures of the posterior cruciate ligament is less with this sequence than with the SE2D sequence. Both sequences showed very low sensitivity in the detection of hyaline cartilage injuries. (Author) 14 refs.

  14. Fast Transient And Spatially Non-Homogenous Accident Analysis Of Two-Dimensional Cylindrical Nuclear Reactor

    International Nuclear Information System (INIS)

    Yulianti, Yanti; Su'ud, Zaki; Waris, Abdul; Khotimah, S. N.; Shafii, M. Ali

    2010-01-01

    The research about fast transient and spatially non-homogenous nuclear reactor accident analysis of two-dimensional nuclear reactor has been done. This research is about prediction of reactor behavior is during accident. In the present study, space-time diffusion equation is solved by using direct methods which consider spatial factor in detail during nuclear reactor accident simulation. Set of equations that obtained from full implicit finite-difference discretization method is solved by using iterative methods ADI (Alternating Direct Implicit). The indication of accident is decreasing macroscopic absorption cross-section that results large external reactivity. The power reactor has a peak value before reactor has new balance condition. Changing of temperature reactor produce a negative Doppler feedback reactivity. The reactivity will reduce excess positive reactivity. Temperature reactor during accident is still in below fuel melting point which is in secure condition.

  15. Two dimensional code for modeling of high ione cyclotron harmonic fast wave heating and current drive

    International Nuclear Information System (INIS)

    Grekov, D.; Kasilov, S.; Kernbichler, W.

    2016-01-01

    A two dimensional numerical code for computation of the electromagnetic field of a fast magnetosonic wave in a tokamak at high harmonics of the ion cyclotron frequency has been developed. The code computes the finite difference solution of Maxwell equations for separate toroidal harmonics making use of the toroidal symmetry of tokamak plasmas. The proper boundary conditions are prescribed at the realistic tokamak vessel. The currents in the RF antenna are specified externally and then used in Ampere law. The main poloidal tokamak magnetic field and the ''kinetic'' part of the dielectric permeability tensor are treated iteratively. The code has been verified against known analytical solutions and first calculations of current drive in the spherical torus are presented.

  16. MEASUREMENT OF GALACTIC LOGARITHMIC SPIRAL ARM PITCH ANGLE USING TWO-DIMENSIONAL FAST FOURIER TRANSFORM DECOMPOSITION

    International Nuclear Information System (INIS)

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S.; Puerari, Ivânio

    2012-01-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  17. Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-dimensional Fast Fourier Transform Decomposition

    Science.gov (United States)

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S.; Puerari, Ivânio

    2012-04-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  18. MEASUREMENT OF GALACTIC LOGARITHMIC SPIRAL ARM PITCH ANGLE USING TWO-DIMENSIONAL FAST FOURIER TRANSFORM DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S. [Arkansas Center for Space and Planetary Sciences, 202 Field House, University of Arkansas, Fayetteville, AR 72701 (United States); Puerari, Ivanio [Instituto Nacional de Astrofisica, Optica y Electronica, Calle Luis Enrique Erro 1, 72840 Santa Maria Tonantzintla, Puebla (Mexico)

    2012-04-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  19. Development and validation of a two-dimensional fast-response flood estimation model

    Energy Technology Data Exchange (ETDEWEB)

    Judi, David R [Los Alamos National Laboratory; Mcpherson, Timothy N [Los Alamos National Laboratory; Burian, Steven J [UNIV OF UTAK

    2009-01-01

    A finite difference formulation of the shallow water equations using an upwind differencing method was developed maintaining computational efficiency and accuracy such that it can be used as a fast-response flood estimation tool. The model was validated using both laboratory controlled experiments and an actual dam breach. Through the laboratory experiments, the model was shown to give good estimations of depth and velocity when compared to the measured data, as well as when compared to a more complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies show that a relatively numerical scheme used to solve the complete shallow water equations can be used to accurately estimate flood inundation. Future work will focus on further reducing the computation time needed to provide flood inundation estimates for fast-response analyses. This will be accomplished through the efficient use of multi-core, multi-processor computers coupled with an efficient domain-tracking algorithm, as well as an understanding of the impacts of grid resolution on model results.

  20. Analysis of artefacts and detail resolution of lung MRI with breath-hold T1-weighted gradient-echo and T2-weighted fast spin-echo sequences with respiratory triggering

    International Nuclear Information System (INIS)

    Biederer, J.; Reuter, M.; Both, M.; Grimm, J.; Heller, M.; Muhle, C.; Graessner, J.

    2002-01-01

    The aim of this study was to evaluate feasibility and limitations of two MR sequences for imaging of the lung using a semi-quantitative rating scale. Ten healthy volunteers were assessed with a breath-hold T1-weighted gradient-recalled-echo (TR/TE=129/2.2 ms, matrix 173 x 256) and a T2-weighted turbo spin-echo (TSE) sequence with respiratory triggering (TR/TE=3000-5000/120 ms, matrix 270 x 512) in axial 6-mm slices. The T1-weighted GRE protocol included a pre-saturation pulse over the mediastinal structures. Artefacts and resolution of vessel/airway structures in each lung segment were evaluated by two observers (10 volunteers, 180 segments). Cardiac and vessel pulsation artefacts predominated on T1-weighted GRE, respiration artefacts on T2-weighted TSE (lingula and middle lobe). Pre-saturation of the mediastinum reduced pulsation artefacts on T1-weighted GRE. T1-weighted GRE images were improved by bright flow signal of vessels, whereas image quality of T2-weighted TSE was reduced by black-blood effects in central parts of the lung. Delineation of lung periphery and the mediastinum was superior with T2-weighted TSE. Segmental/sub-segmental vessels (up to fourth/fifth order) and bronchi (up to third order) were identified. All 180 lung segments were imaged in diagnostic quality with at least one of the two sequences (T1-weighted GRE not diagnostic in 9 of 180, T2-weighted TSE in 4 of 180). Both sequences were found to be complementary: superior identification of gross lung anatomy with T1-weighted GRE and higher detail resolution in the periphery and the mediastinum with T2-weighted TSE. (orig.)

  1. Characterization of trehalose aqueous solutions by neutron spin echo

    Energy Technology Data Exchange (ETDEWEB)

    Branca, C.; Faraone, A.; Magazu' , S.; Maisano, G.; Mangione, A. [Dipartimento di Fisica and INFM, Universita di Messina, PO Box 55, 98166 Messina (Italy); Pappas, C.; Triolo, A. [Hahn-Meitner-Institut, BENSC (NI), Glienicker Strasse, 14109 Berlin (Germany)

    2002-07-01

    The present work reports neutron spin-echo (NSE) results on aqueous mixtures of trehalose, a naturally occurring disaccharide of glucose, which shows an extraordinary bioprotective effectiveness against dehydration and freezing. The aim of the work is to furnish new results on the dynamics of the trehalose/water system on the nano- and picosecond scales. (orig.)

  2. Spin-Echo Small-Angle Neutron Scattering Development

    NARCIS (Netherlands)

    Uca, O.

    2003-01-01

    Spin-Echo Small-Angle Neutron Scattering (SESANS) instrument is a novel SANS technique which enables one to characterize distances from a few nanometers up to the micron range. The most striking difference between normal SANS and SESANS is that in SESANS one gets information in real space, whereas

  3. Characterization of trehalose aqueous solutions by neutron spin echo

    CERN Document Server

    Branca, C; Magazù, S; Maisano, G; Mangione, A; Pappas, C; Triolo, A

    2002-01-01

    The present work reports neutron spin-echo (NSE) results on aqueous mixtures of trehalose, a naturally occurring disaccharide of glucose, which shows an extraordinary bioprotective effectiveness against dehydration and freezing. The aim of the work is to furnish new results on the dynamics of the trehalose/water system on the nano- and picosecond scales. (orig.)

  4. Fast chemical reaction in two-dimensional Navier-Stokes flow: initial regime.

    Science.gov (United States)

    Ait-Chaalal, Farid; Bourqui, Michel S; Bartello, Peter

    2012-04-01

    This paper studies an infinitely fast bimolecular chemical reaction in a two-dimensional biperiodic Navier-Stokes flow. The reactants in stoichiometric quantities are initially segregated by infinite gradients. The focus is placed on the initial stage of the reaction characterized by a well-defined one-dimensional material contact line between the reactants. Particular attention is given to the effect of the diffusion κ of the reactants. This study is an idealized framework for isentropic mixing in the lower stratosphere and is motivated by the need to better understand the effect of resolution on stratospheric chemistry in climate-chemistry models. Adopting a Lagrangian straining theory approach, we relate theoretically the ensemble mean of the length of the contact line, of the gradients along it, and of the modulus of the time derivative of the space-average reactant concentrations (here called the chemical speed) to the joint probability density function of the finite-time Lyapunov exponent λ with two times τ and τ[over ̃]. The time 1/λ measures the stretching time scale of a Lagrangian parcel on a chaotic orbit up to a finite time t, while τ measures it in the recent past before t, and τ[over ̃] in the early part of the trajectory. We show that the chemical speed scales like κ(1/2) and that its time evolution is determined by rare large events in the finite-time Lyapunov exponent distribution. The case of smooth initial gradients is also discussed. The theoretical results are tested with an ensemble of direct numerical simulations (DNSs) using a pseudospectral model.

  5. Oxygen speciation in upgraded fast pyrolysis bio-oils by comprehensive two-dimensional gas chromatography.

    Science.gov (United States)

    Omais, Badaoui; Crepier, Julien; Charon, Nadège; Courtiade, Marion; Quignard, Alain; Thiébaut, Didier

    2013-04-21

    Biomass fast pyrolysis is considered as a promising route to produce liquid for the transportation field from a renewable resource. However, the derived bio-oils are mainly oxygenated (45-50%w/w O on a wet basis) and contain almost no hydrocarbons. Therefore, upgrading is necessary to obtain a liquid with lower oxygen content and characterization of oxygenated compounds in these products is essential to assist conversion reactions. For this purpose, comprehensive two-dimensional gas chromatography (GC × GC) can be investigated. Oxygen speciation in such matrices is hampered by the large diversity of oxygenated families and the complexity of the hydrocarbon matrix. Moreover, response factors must be taken into account for oxygenate quantification as the Flame Ionisation Detector (FID) response varies when a molecule contains heteroatoms. To conclude, no distillation cuts were accessible and the analysis had to cover a large range of boiling points (30-630 °C). To take up this analytical challenge, a thorough optimization approach was developed. In fact, four GC × GC column sets were investigated to separate oxygenated compounds from the hydrocarbon matrix. Both model mixtures and the upgraded biomass flash pyrolysis oil were injected using GC × GC-FID to reach a suitable chromatographic separation. The advantages and drawbacks of each column combination for oxygen speciation in upgraded bio-oils are highlighted in this study. Among the four sets, an original polar × semi-polar column combination was selected and enabled the identification by GC × GC-ToF/MS of more than 40 compounds belonging to eight chemical families: ketones, furans, alcohols, phenols, carboxylic acids, guaiacols, anisols, and esters. For quantification purpose, the GC × GC-FID chromatogram was divided into more than 60 blobs corresponding to the previously identified analyte and hydrocarbon zones. A database associating each blob to a molecule and its specific response factor (determined

  6. Nanosecond time-resolved EPR in pulse radiolysis via the spin echo method

    International Nuclear Information System (INIS)

    Trifunac, A.D.; Norris, J.R.; Lawler, R.G.

    1979-01-01

    The design and operation of a time-resolved electron spin echo spectrometer suitable for detecting transient radicals produced by 3 MeV electron radiolysis is described. Two modes of operation are available: Field swept mode which generates a normal EPR spectrum and kinetic mode in which the time dependence of a single EPR line is monitored. Techniques which may be used to minimize the effects of nonideal microwave pulses and overlapping sample tube signals are described. The principal advantages of the spin echo method over other time-resolved EPR methods are: (1) Improved time resolution (presently approx.30--50 nsec) allows monitoring of fast changes in EPR signals of transient radicals, (2) Lower susceptibility to interference between the EPR signal and the electron beam pulse at short times, and (3) Lack of dependence of transient signals on microwave field amplitude or static field inhomogeneity at short times. The performance of the instrument is illustrated using CIDEP from acetate radical formed in pulsed radiolysis of aqueous solutions of potassium acetate. The relaxation time and CIDEP enhancement factor obtained for this radical using the spin echo method compare favorably with previous determinations using direct detection EPR. Radical decay rates yield estimates of initial radical concentrations of 10 -4 10 -3 M per electron pulse. The Bloch equations are solved to give an expression for the echo signal for samples exhibiting CIDEP using arbitrary microwave pulse widths and distributions of Larmor frequencies. Conditions are discussed under which the time-dependent signal would be distorted by deviations from an ideal nonselective 90 0 --tau--180 0 pulse sequence

  7. Variable-flip-angle spin-echo imaging (VFSE)

    International Nuclear Information System (INIS)

    Kasai, Toshifumi; Sugimura, Kazuro; Kawamitsu, Hideaki; Yasui, Kiyoshi; Ishida, Tetsuya; Tsukamoto, Tetsuji.

    1990-01-01

    T 2 weighted imaging provides images with high object contrast for pathologic conditions in which the water content of tissues is increased. The authors predicted theoretical analysis of the effects of changing flip angle, and analyzed the effects in MR imaging of both phantoms and humans. Variable flip angle spin echo MR imaging (VFSE) with a 1,000/80 (repetition time msec/echo time msec) can obtain T 2 weighted image when flip angle is smaller than 80 degrees. VFSE with 40 to 60 degrees flip angle have higher contrast than other flip angle images. Signal to noise ratio (S/N) of VFSE are 55% at a 30 degree, 76% at a 45 degree, 92% at a 60 degree respectively as compared with conventional spin echo image (2000/80, flip angle 90 degree). VFSE is applicable to obtain T 2 weighted image reduced imaging time. (author)

  8. Stimulated nuclear spin echos and spectral diffusion in glasses

    International Nuclear Information System (INIS)

    Borges, N.M.; Engelsberg, M.

    1984-01-01

    Experimental results of stimulated nuclear spin echos decay in glasses are presented. The measurements were performed in B 2 O 3 glasses, at the 23Na and 11 B resonance lines. The data analysis allows the study of Spectral diffusion at an inhomogeneous nuclear magnetic (NMR) resonance line, broadened for a desordered system of nuclear spins. A model is proposed to explain the time constants, and the particular form of the decay. (A.C.A.S.) [pt

  9. Polarimetric neutron spin echo: Feasibility and first results

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, C. [Hahn-Meitner Institut Berlin, Glienickerstr. 100, 14109 Berlin (Germany)], E-mail: pappas@hmi.de; Lelievre-Berna, E. [Institut Laue-Langevin, 6, Rue Jules Horowitz, 38042 Grenoble (France); Bentley, P. [Hahn-Meitner Institut Berlin, Glienickerstr. 100, 14109 Berlin (Germany); Bourgeat-Lami, E. [Institut Laue-Langevin, 6, Rue Jules Horowitz, 38042 Grenoble (France); Moskvin, E. [Hahn-Meitner Institut Berlin, Glienickerstr. 100, 14109 Berlin (Germany); PNPI, 188300 Gatchina, Leningrad District (Russian Federation); Thomas, M. [Institut Laue-Langevin, 6, Rue Jules Horowitz, 38042 Grenoble (France); Grigoriev, S.; Dyadkin, V. [PNPI, 188300 Gatchina, Leningrad District (Russian Federation)

    2008-07-21

    Neutron Spin Echo (NSE) spectroscopy uses polarized neutrons and accordingly polarization analysis is an intrinsic feature of NSE. However, the multifaceted dynamics of antiferromagnets and helimagnets require more than the classical NSE set-up. Here we present the feasibility test and first results of a new and powerful technique: Polarimetric NSE, obtained by combining the wide angle NSE spectrometer SPAN, developed at HMI with the zero-field polarimeter Cryopad developed at ILL.

  10. Polarimetric neutron spin echo: Feasibility and first results

    International Nuclear Information System (INIS)

    Pappas, C.; Lelievre-Berna, E.; Bentley, P.; Bourgeat-Lami, E.; Moskvin, E.; Thomas, M.; Grigoriev, S.; Dyadkin, V.

    2008-01-01

    Neutron Spin Echo (NSE) spectroscopy uses polarized neutrons and accordingly polarization analysis is an intrinsic feature of NSE. However, the multifaceted dynamics of antiferromagnets and helimagnets require more than the classical NSE set-up. Here we present the feasibility test and first results of a new and powerful technique: Polarimetric NSE, obtained by combining the wide angle NSE spectrometer SPAN, developed at HMI with the zero-field polarimeter Cryopad developed at ILL

  11. Comprehensive two-dimensional gas chromatography for fast characterization of oil contamination

    International Nuclear Information System (INIS)

    Van De Weghe, H.; Vanermen, G.; Gemoets, J.; Lookman, R.; Bertels, D.

    2005-01-01

    Most analytical methods for the characterization of oil contamination rely on gas chromatography. Capillary GC offers a high separation power (peak capacity typically 100 - 500), and by using a boiling point column a volatility based distribution is obtained. However, petrochemical mixtures like mineral oil easily contain more then 5000 compounds, and capillary GC does not succeed in separating such mixtures up to the level of individual components. Analytical results are therefore limited to a classification into boiling point (or equivalent-carbon) fractions. Recent methods refined the classification by fractionation in aromatic and aliphatic hydrocarbons prior to GC-analysis (TPH method, Weisman 1998), and by incorporating water solubility (TTE and OK method, for a detailed description we refer to the Consoil 2005 lecture by R. Lookman 'Oil characterization: assessment of composition, degradation and remediation potential of total petroleum hydrocarbons in soil'). However, besides analytical difficulties and time consuming protocols related with these methods, the resulting classification still remains coarse and the various groups are not univocally chemically identified. Recently, comprehensive two-dimensional GC (GCXGC) was introduced. This technique combines two GC-columns with different separation mechanisms. The two columns are connected by a modulator, a device that traps, focuses and re-injects the peaks that elute from the first column into the second column. Each peak from the first column (representing a number of overlapping peaks) is further separated on the second column. The very high separation power of GCXGC (peak capacity 2000 - 10000) is ideal for the analysis of complex mixtures like mineral oil. Another important feature is the generation of structured chromatograms. Isomers appear as distinct groups in the chromatogram as a result of their similar interaction with the 2D-column phase. For chemical identification comprehensive GC can be

  12. Comprehensive two-dimensional gas chromatography for fast characterization of oil contamination

    Energy Technology Data Exchange (ETDEWEB)

    Van De Weghe, H.; Vanermen, G.; Gemoets, J.; Lookman, R.; Bertels, D. [VITO, Mol (Belgium)

    2005-07-01

    Most analytical methods for the characterization of oil contamination rely on gas chromatography. Capillary GC offers a high separation power (peak capacity typically 100 - 500), and by using a boiling point column a volatility based distribution is obtained. However, petrochemical mixtures like mineral oil easily contain more then 5000 compounds, and capillary GC does not succeed in separating such mixtures up to the level of individual components. Analytical results are therefore limited to a classification into boiling point (or equivalent-carbon) fractions. Recent methods refined the classification by fractionation in aromatic and aliphatic hydrocarbons prior to GC-analysis (TPH method, Weisman 1998), and by incorporating water solubility (TTE and OK method, for a detailed description we refer to the Consoil 2005 lecture by R. Lookman 'Oil characterization: assessment of composition, degradation and remediation potential of total petroleum hydrocarbons in soil'). However, besides analytical difficulties and time consuming protocols related with these methods, the resulting classification still remains coarse and the various groups are not univocally chemically identified. Recently, comprehensive two-dimensional GC (GCXGC) was introduced. This technique combines two GC-columns with different separation mechanisms. The two columns are connected by a modulator, a device that traps, focuses and re-injects the peaks that elute from the first column into the second column. Each peak from the first column (representing a number of overlapping peaks) is further separated on the second column. The very high separation power of GCXGC (peak capacity 2000 - 10000) is ideal for the analysis of complex mixtures like mineral oil. Another important feature is the generation of structured chromatograms. Isomers appear as distinct groups in the chromatogram as a result of their similar interaction with the 2D-column phase. For chemical identification comprehensive GC

  13. IDEAL 3D spoiled gradient echo of the articular cartilage of the knee on 3.0 T MRI: a comparison with conventional 3.0 T fast spin-echo T2 fat saturation image.

    Science.gov (United States)

    Han, Chul Hee; Park, Hee Jin; Lee, So Yeon; Chung, Eun Chul; Choi, Seon Hyeong; Yun, Ji Sup; Rho, Myung Ho

    2015-12-01

    Many two-dimensional (2D) morphologic cartilage imaging sequences have disadvantages such as long acquisition time, inadequate spatial resolution, suboptimal tissue contrast, and image degradation secondary to artifacts. IDEAL imaging can overcome these disadvantages. To compare sound-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and quality of two different methods of imaging that include IDEAL 3D SPGR and 3.0-T FSE T2 fat saturation (FS) imaging and to evaluate the utility of IDEAL 3D SPGR for knee joint imaging. SNR and CNR of the patellar and femoral cartilages were measured and calculated. Two radiologists performed subjective scoring of all images for three measures: general image quality, FS, and cartilage evaluation. SNR and CNR values were compared by paired Student's t-tests. Mean SNRs of patellar and femoral cartilages were 90% and 66% higher, respectively, for IDEAL 3D SPGR. CNRs of patellar cartilages and joint fluids were 2.4 times higher for FSE T2 FS, and CNR between the femoral cartilage and joint fluid was 2.2 times higher for FSE T2 FS. General image quality and FS were superior using FSE T2 FS compared to those of IDEAL 3D SPGR imaging according to both readers, while cartilage evaluation was superior using IDEAL 3D SPGR. Additionally, cartilage injuries were more prominent in IDEAL 3D SPGR than in FSE T2FS according to both readers. IDEAL 3D SPGR images show excellent visualization of patellar and femoral cartilages in 3.0 T and can compensate for the weaknesses of FSE T2 FS in the evaluation of cartilage injuries. © The Foundation Acta Radiologica 2014.

  14. A fast semi-discrete Kansa method to solve the two-dimensional spatiotemporal fractional diffusion equation

    Science.gov (United States)

    Sun, HongGuang; Liu, Xiaoting; Zhang, Yong; Pang, Guofei; Garrard, Rhiannon

    2017-09-01

    Fractional-order diffusion equations (FDEs) extend classical diffusion equations by quantifying anomalous diffusion frequently observed in heterogeneous media. Real-world diffusion can be multi-dimensional, requiring efficient numerical solvers that can handle long-term memory embedded in mass transport. To address this challenge, a semi-discrete Kansa method is developed to approximate the two-dimensional spatiotemporal FDE, where the Kansa approach first discretizes the FDE, then the Gauss-Jacobi quadrature rule solves the corresponding matrix, and finally the Mittag-Leffler function provides an analytical solution for the resultant time-fractional ordinary differential equation. Numerical experiments are then conducted to check how the accuracy and convergence rate of the numerical solution are affected by the distribution mode and number of spatial discretization nodes. Applications further show that the numerical method can efficiently solve two-dimensional spatiotemporal FDE models with either a continuous or discrete mixing measure. Hence this study provides an efficient and fast computational method for modeling super-diffusive, sub-diffusive, and mixed diffusive processes in large, two-dimensional domains with irregular shapes.

  15. Neutron optics using transverse field neutron spin echo method

    International Nuclear Information System (INIS)

    Achiwa, Norio; Hino, Masahiro; Yamauchi, Yoshihiro; Takakura, Hiroyuki; Tasaki, Seiji; Akiyoshi, Tsunekazu; Ebisawa, Toru.

    1993-01-01

    A neutron spin echo (NSE) spectrometer with perpendicular magnetic field to the neutron scattering plane, using an iron yoke type electro-magnet has been developed. A combination of cold neutron guider, supermirror neutron polarizer of double reflection type and supermirror neutron analyser was adopted for the spectrometer. The first application of the NSE spectrometer to neutron optics by passing Larmor precessing neutrons through gas, solid and liquid materials of several different lengths which are inserted in one of the precession field have been examined. Preliminary NSE spectra of this sample geometry are discussed. (author)

  16. A conception of a new neutron spin echo reflectometer

    International Nuclear Information System (INIS)

    Kali, Gy.

    1999-01-01

    Complete text of publication follows. The tilted field technique in the neutron spin echo (NSE) spectroscopy came into the centre of attention in the recent few years. The method was first proposed by F. Mezei and R. Pynn in 1980. A real measurement for high resolution small angle scattering (SANS) on their resonance spin-echo spectrometer was published by Keller et al. [1]. A conception of a new instrument was proposed by M.T. Rekveldt [2] for SANS and reflectometry, using dc field perpendicular to the neutron beam. By further developing these ideas, the setup of a multitask instrument using the traditional way (dc field parallel to the beam) is discussed. This spectrometer may be best applicable in liquid surface reflectometry combining NSE by separating specular and nonspecular reflection. This instrument setup uses wide wavelength band and/or non-collimated neutron beam. (author) [1] T. Keller et al, Neutron News 6, no 3 (1995) 16.; [2] M.T. Rekveldt, Nuc. Inst. and Meth. in Physics Res. B 114 (1996) 366

  17. Experimental separation of a frequency spin echo signal

    International Nuclear Information System (INIS)

    Bun'kov, Yu.M.; Dmitriev, V.V.

    1981-01-01

    To study systems with bound nuclear-electron precession CsMnF 2 antiferromagnetic light-plane monocrystal was investigated. Crystal orientation was carried out by roentgenoscopy. Measurements were performed at helium temperatures in the 500-700 MHz frequency range. A NMR pulsed spectrometer with generators of both resonance and doubled frequency was used to produce an echo signal (to study by the parametric echo method). It was shown that the theory of the formation of a frequency modulated echo (FM echo) did not fully describe the properties of the echo signals in systems with dynamic frequency shift (DFS). An intense spin echo signal, which formation was apparently connected with other nonlinear properties of the systems with nuclear-electron precession, was observed. The spin echo signal in magnetics with DFS, which properties correspond to notions of the frequency mechanism of echo formation, was experimentally separated. As a result of the investigations it had been possible to settle contradictions between the theory of FM echo formation and the experimental results for the last 9 years. It turned out that the mechanism of FM echo formation in the magnetics with bound nuclear-electron precession was effective only at large delay times between the pulses. In the range of small delays the FM echo is ''jammed'' by a gigantic echo signal of a nature different from that of the traditional FM signal. The constant of gigantic echo intensity drop at increasing delay between the pulses weakly depends on spin-spin relaxation time [ru

  18. A two-dimensional simulator of the neutronic behaviour of low power fast reactors

    International Nuclear Information System (INIS)

    Penha, M.A.V.R. da.

    1984-01-01

    A model to simulate the temporal neutronic behaviour of fast breeder reactors was developed. The effective cross-sections are corrected, whenever the reactor state change; by using linear correlations and interpolation schemes with data contained in a library previously compiled. This methodology was coupled with a simplified spatial neutronic calculation to investigate the temporal behaviour of neutronic parameters such as breeding gain, flux and power. (Author) [pt

  19. Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT

    International Nuclear Information System (INIS)

    Krombach, G.A.; Schmitz-Rode, T.; Haage, P.; Guenther, R.W.; DiMartino, E.; Prescher, A.; Kinzel, S.

    2004-01-01

    We assessed the value of MRI for delineation of dehiscence of the superior or posterior semicircular canal, as compared with CT, the current standard study for this entity. We reviewed heavily T2-weighted fast spin-echo images and high-resolution CT of the temporal bones of 185 patients independently semicircular canal dehiscence and its extent. In 30 patients (19 men, 11 women) we identified dehiscence of the bone over the superior and/or posterior semicircular canal on MRI. In 27 of these cases CT also showed circumscribed bone defects. In one patient dehiscence of the superior semicircular canal was initially overlooked on MRI, but seen on CT. MRI imaging thus had a sensitivity of 96% and specificity of 98%. Knowledge of the appearances of this entity on MRI may contribute to early diagnosis in patients with vertigo due to semicircular canal dehiscence. (orig.)

  20. Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT

    Energy Technology Data Exchange (ETDEWEB)

    Krombach, G.A.; Schmitz-Rode, T.; Haage, P.; Guenther, R.W. [Department of Diagnostic Radiology, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); DiMartino, E. [Department of Otorhinolaryngology, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); Prescher, A. [Department of Anatomy, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); Kinzel, S. [Department of Experimental Veterinary Medicine, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany)

    2004-04-01

    We assessed the value of MRI for delineation of dehiscence of the superior or posterior semicircular canal, as compared with CT, the current standard study for this entity. We reviewed heavily T2-weighted fast spin-echo images and high-resolution CT of the temporal bones of 185 patients independently semicircular canal dehiscence and its extent. In 30 patients (19 men, 11 women) we identified dehiscence of the bone over the superior and/or posterior semicircular canal on MRI. In 27 of these cases CT also showed circumscribed bone defects. In one patient dehiscence of the superior semicircular canal was initially overlooked on MRI, but seen on CT. MRI imaging thus had a sensitivity of 96% and specificity of 98%. Knowledge of the appearances of this entity on MRI may contribute to early diagnosis in patients with vertigo due to semicircular canal dehiscence. (orig.)

  1. Two-dimensional Fast ESPRIT Algorithm for Linear Array SAR Imaging

    Directory of Open Access Journals (Sweden)

    Zhao Yi-chao

    2015-10-01

    Full Text Available The linear array Synthetic Aperture Radar (SAR system is a popular research tool, because it can realize three-dimensional imaging. However, owning to limitations of the aircraft platform and actual conditions, resolution improvement is difficult in cross-track and along-track directions. In this study, a twodimensional fast Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT algorithm for linear array SAR imaging is proposed to overcome these limitations. This approach combines the Gerschgorin disks method and the ESPRIT algorithm to estimate the positions of scatterers in cross and along-rack directions. Moreover, the reflectivity of scatterers is obtained by a modified pairing method based on “region growing”, replacing the least-squares method. The simulation results demonstrate the applicability of the algorithm with high resolution, quick calculation, and good real-time response.

  2. Two-dimensional multigroup finite element calculation of fast reactor in diffusion approximation

    International Nuclear Information System (INIS)

    Schmid, J.

    1986-06-01

    When a linear element of triangular shape is used the actual finite element calculation is relatively simple. Extensive programs for mesh generation were written for easy inputting the configuration of reactors. A number of other programs were written for plotting neutron flux fields in individual groups, the power distribution, spatial plotting of fields, etc. The operation of selected programs, data preparation and operating instructions are described and examples given of data and results. All programs are written in GIER ALGOL. The used method and the developed programs have demonstrated that they are a useful instrument for the calculation of criticality and the distribution of neutron flux and power of both fast and thermal reactors. (J.B.)

  3. Investigations on resolution enhancement in EPR by means of electron spin echoes

    International Nuclear Information System (INIS)

    Merks, R.P.J.

    1979-01-01

    The electron spin echo technique has been applied in four types of experiments: the measurement of electric field induced shifts of the EPR line; the detection of electron spin echo ENDOR; a relaxation measurement and the measurement of hyperfine interactions via the nuclear modulation effect. (Auth.)

  4. Depolarization of neutron spin echo by magnetic fluid

    International Nuclear Information System (INIS)

    Achiwa, N.; Sirozu, G.; Nishioka, T.; Ebisawa, T.; Hino, M.; Tasaki, S.; Kawai, T.; Yamazaki, D.

    2001-01-01

    A new method to study the fluctuations of magnetization in magnetic fluids by measuring relations between the phase shift of Larmor precession and the visibility of the neutron spin echo caused by the change of flight path length is studied. Magnetic fluid in which fine particles of magnetite of about 10 nm diameters coated with oleic acid and suspended in water was used. Thickness of the sample was 2 mm. In the dynamics of magnetic fluids, Brownian motions of colloids and the thermal fluctuations of magnetization known as the superparamagnetism are dominant. Isolated ferromagnetic particles of the present size are superparamagnetic but they aggregate to form clusters in a weak magnetic field in the sample of 40% weight density. When neutrons pass the sample, spins process in the magnetic flux density of the clusters fluctuating in time and space. Consequently the Larmor precession phases become distributed and the quantization axes are fluctuated. The result is observed as a decrease of the visibility of the spin echo signals. The change of magnetic flux density in the magnetic fluid is measured from the change of echo visibility of the neutrons, vice versa. In the present experiment, echo was measured at q=0. It is observed that the phase shift changes as a quadratic function of the sample angle reflecting the change of the path length through the sample. Since the number of Larmor precession is proportional to the product of the magnetic field and the length of the flight path, mean flux density in the magnetic fluid is calculated from the phase shift. On the other hand, the decrease of the spin echo amplitude as the function of the sample angle reflects the time and space fluctuations of the flux density in the sample. If the direction of the magnetic flux density vector (quantization axis) changes slowly enough compared to the Larmor precession period while a neutron passes one magnetic domain, the neutron spin rotation in the domain is given by the spin

  5. Four-wave neutron-resonance spin echo

    International Nuclear Information System (INIS)

    Grigoriev, S.V.; Kraan, W.H.; Rekveldt, M.Th.

    2004-01-01

    We develop a technique of scattering from many-body systems. It is based on the principle of the neutron spin echo (SE), where a neutron wave in the magnetic field splits into two waves, which are separated in space or in time after propagation in this field. The neutron thus prepared as a probe passes through the sample to test its properties on a space R or time t scale. This separation in space or in time can be measured using coherence of these two waves as a phase shift φ between them. These two waves are collected or focused and compensated by the SE technique in order to compare their phases after interaction with the sample. In this way one studies interference between these waves and thus can directly measure the pair-correlation function in space or in time. Instead of two-wave SE we propose to realize the four-wave neutron-resonance spin-echo (NRSE). In our experiments, spin precession produced by a couple of the neutron-resonance coils in one arm is compensated by an identical couple of other NR coils in a second arm of a spin-echo machine. The neutron spin-flip probability ρ in the resonance coils is a key parameter of the NRSE arm. The limiting cases, ρ=0 and ρ=1, provide, in quantum terms, a two-level-two-wave k splitting of the neutron and result in the separation of the split waves into two different lengths in space (R 1 ,R 2 ) or in time (t 1 ,t 2 ). These two cases correspond to Larmor precession with phase φ 1 in the static magnetic fields of the NR flippers or to NRSE precession with φ 2 , respectively. The intermediate case, 0 1 ,R 2 ,R 3 ) or in time (t 1 ,t 2 ,t 3 ). The interference of each pair of waves after compensation results in three different echos with phases φ 1 , φ 2 , and φ 3 =(φ 1 +φ 2 )/2. Focusing or compensating all four waves into a single point of the phase-of-waves diagram produces quantum interference of all newly created waves. This task of focusing is experimentally performed. Different options for the

  6. Analysis of effects of laser profiles on fast electron generation by two-dimensional Particle-In-Cell simulations

    International Nuclear Information System (INIS)

    Hata, M.

    2010-01-01

    Complete text of publication follows. A cone-guided target is used in the Fast Ignition Realization Experiment project phase-I (FIREX-I) and optimization of its design is performed. However a laser profile is not optimized much, because the laser profile that is the best for core heating is not known well. To find that, it is useful to investigate characteristics of generated fast electrons in each condition of different laser profiles. In this research, effects of laser profiles on fast electron generation are investigated on somewhat simple conditions by two-dimensional Particle-In-Cell simulations. In these simulations, a target is made up of Au pre-plasma and Au plasma. The Au pre-plasma has the exponential profile in the x direction with the scale length L = 4.0 μm and the density from 0.10 n cr to 20 n cr . The Au plasma has the flat profile in the x direction with 10 μm width and 20 n cr . Plasma profiles are uniform in the y direction. The ionization degree and the mass number of plasmas are 40 and 197, where the ionization degree is determined by PINOCO simulations. PINOCO is a two-dimensional radiation hydrodynamics simulation code, which simulates formation of the high-density plasma during the compression phase in the fast ignition. A laser is assumed to propagate as plane wave from the negative x direction to the positive x direction. Laser profiles are supposed to be uniform in the y direction. Three different laser profiles, namely flat one with t flat = 100 fs, Gaussian one with t rise/fall = 47.0 fs and flat + Gaussian one with t rise/fall = 23.5 fs and t flat = 50 fs are used. The energy and the peak intensity are constant with E = 10 7 J/cm 2 and I L = 10 20 W/cm 2 in all cases of different laser profiles. We compare results in each condition of three different laser profiles and investigate effects of laser profiles on fast electron generation. Time-integrated energy spectra are similar in all cases of three different laser profiles. In the

  7. A spin echo study of A15 intermetallic compounds

    International Nuclear Information System (INIS)

    Schoep, G.K.

    1976-01-01

    This thesis mainly concerns the measurement of spin-lattice relaxation times in intermetallic compounds of the bcc lattice structure, having the formula V 3 X (C = Pt, Ir, Os, Pd, Rh, Ni, Co, Au). When, in a spin echo experiment, a two-pulse sequence was applied, several quadrupolar echoes were observed. Special attention is given to the 'forbidden' echoes (absol.(Δm')GT1) in V 3 Au and V 3 Co. In relation to the V 3 X compounds, several characteristics are discussed including temperature dependence and concentration dependence of spin relaxation times, superconductivity and the importance of d-state electrons in determination of the spin relaxation times. Finally, the above characteristics were determined for 6 different samples of the vanadium-gold alloy, V 3 Au, specifically

  8. Neutron spin echo and high resolution inelastic spectroscopy

    International Nuclear Information System (INIS)

    Mezei, F.; Hungarian Academy of Sciences, Budapest. Central Research Inst. for Physics)

    1982-01-01

    The principles of neutrons spin echo (NSE) technique are considered. It is shown that the basis of NSE principle is a single step measurement of the change of the neutron velocity in the scattering process. The backscattering soectroscopy and the NSE techniques are compared. The NSF spectrometer is described. It is shown that 0.5 MeV energy resolution achieved in the NSE experiment is about 40 times superior to those achieved by the other techniques. The NSE technique has the unique feature that provides high resolution in neutron energy change independently of the monochromatization of the beam. The NSE instrument not only covers a wider dynamic range on a pulsed source that on a continuous one, but also collects data more efficiently

  9. Neutron spin-echo spectroscopy for diffusion in crystalline solids

    International Nuclear Information System (INIS)

    Kaisermayr, M.; Rennhofer, M.; Vogl, G.; Pappas, C.; Longeville, S.

    2002-01-01

    Neutron spin-echo spectroscopy (NSE) offers unprecedented opportunities in the investigation of diffusion in crystalline systems due to its outstanding energy resolution. NSE not only enables measurements at lower diffusivities than the established techniques of neutron spectroscopy, but it also gives a very immediate access to the different time scales involved in the diffusion process. This is demonstrated in detail on the example of the binary alloy NiGa where the Ni atoms hop between regular sites on the Ni sublattice and anti-sites on the Ga sublattice. Experiments on two different NSE instruments are compared to measurements using neutron backscattering spectroscopy. The potential of NSE for the investigation of jump diffusion and experimental requirements are discussed

  10. Neutron spin echo spectrometer at JRR-3M

    International Nuclear Information System (INIS)

    Takeda, Takayoshi; Komura, Shigehiro; Seto, Hideki; Nagai, Michihiro; Kobayashi, Hideki; Yokoi, Eiji; Ebisawa, Tooru; Tasaki, Seiji.

    1993-01-01

    We have designed and have been constructing at C 2-2 cold neutron guide port of JRR-3M, JAERI, a neutron spin echo spectrometer (NSE) which is equipped with two optimized magnets for neutron spin precession, a position sensitive detector (PSD), a converging polarizer and a wide area analyzer. The dynamic range of scattering vector Q covers from 0.01 A -1 to 0.3 A -1 and that of energy E from 30neV to 0.1meV. This spectrometer makes it possible to study a mesoscopic spatial structure of the order of 1-100nm combined with a nanosecond temporal structure of the order of 0.1-100ns corresponding to dynamical behavior of large molecules such as polymer. A test experiment shows that the homogeneity condition of the precession magnet is loosened by means of PSD. (author)

  11. MRI of the lumbar spine: comparison of 3D isotropic turbo spin-echo SPACE sequence versus conventional 2D sequences at 3.0 T.

    Science.gov (United States)

    Lee, Sungwon; Jee, Won-Hee; Jung, Joon-Yong; Lee, So-Yeon; Ryu, Kyeung-Sik; Ha, Kee-Yong

    2015-02-01

    Three-dimensional (3D) fast spin-echo sequence with variable flip-angle refocusing pulse allows retrospective alignments of magnetic resonance imaging (MRI) in any desired plane. To compare isotropic 3D T2-weighted (T2W) turbo spin-echo sequence (TSE-SPACE) with standard two-dimensional (2D) T2W TSE imaging for evaluating lumbar spine pathology at 3.0 T MRI. Forty-two patients who had spine surgery for disk herniation and had 3.0 T spine MRI were included in this study. In addition to standard 2D T2W TSE imaging, sagittal 3D T2W TSE-SPACE was obtained to produce multiplanar (MPR) images. Each set of MR images from 3D T2W TSE and 2D TSE-SPACE were independently scored for the degree of lumbar neural foraminal stenosis, central spinal stenosis, and nerve compression by two reviewers. These scores were compared with operative findings and the sensitivities were evaluated by McNemar test. Inter-observer agreements and the correlation with symptoms laterality were assessed with kappa statistics. The 3D T2W TSE and 2D TSE-SPACE had similar sensitivity in detecting foraminal stenosis (78.9% versus 78.9% in 32 foramen levels), spinal stenosis (100% versus 100% in 42 spinal levels), and nerve compression (92.9% versus 81.8% in 59 spinal nerves). The inter-observer agreements (κ = 0.849 vs. 0.451 for foraminal stenosis, κ = 0.809 vs. 0.503 for spinal stenosis, and κ = 0.681 vs. 0.429 for nerve compression) and symptoms correlation (κ = 0.449 vs. κ = 0.242) were better in 3D TSE-SPACE compared to 2D TSE. 3D TSE-SPACE with oblique coronal MPR images demonstrated better inter-observer agreements compared to 3D TSE-SPACE without oblique coronal MPR images (κ = 0.930 vs. κ = 0.681). Isotropic 3D T2W TSE-SPACE at 3.0 T was comparable to 2D T2W TSE for detecting foraminal stenosis, central spinal stenosis, and nerve compression with better inter-observer agreements and symptom correlation. © The Foundation Acta Radiologica 2014 Reprints and

  12. Two-dimensional CsPbBr3/PCBM heterojunctions for sensitive, fast and flexible photodetectors boosted by charge transfer

    Science.gov (United States)

    Shen, Yalong; Yu, Dejian; Wang, Xiong; Huo, Chengxue; Wu, Ye; Zhu, Zhengfeng; Zeng, Haibo

    2018-02-01

    Inorganic halide perovskites exhibited promising potentials for high-performance wide-band photodetectors (PDs) due to their high light absorption coefficients, long carrier diffusion length and wide light absorption ranges. Here, we report two-dimensional (2D) CsPbBr3/PCBM heterojunctions for sensitive, fast and flexible PDs, whose performances can be greatly boosted by the charge transfer through the energy-aligned interface. The 2D CsPbBr3 nanosheets with high crystallinity were fabricated via a simple solution-process at room temperature, and then assembled into flexible heterojunctions films with polymerphenyl-C61-butyric acid methyl ester (PCBM). Significantly, the efficient and fast charge transfer at the heterojunctions interface was evidenced by the obvious photoluminescence quenching and variation of recombination dynamics. Subsequently, such heterojunctions PD exhibited an enhanced responsivity of 10.85 A W-1 and an ultrahigh detectivity of 3.06 × 1013 Jones. In addition, the PD shows a broad linear dynamic range of 73 dB, a fast response speed with rise time of 44 μs and decay time of 390 μs, respectively. Moreover, the PD lying on polyethylene terephthalate substrates exhibited an outstanding mechanical flexibility and a robust electrical stability. These results could provide a new avenue for integration of 2D perovskites and organic functional materials and for high-performance flexible PDs.

  13. Spin-echo based diagonal peak suppression in solid-state MAS NMR homonuclear chemical shift correlation spectra

    Science.gov (United States)

    Wang, Kaiyu; Zhang, Zhiyong; Ding, Xiaoyan; Tian, Fang; Huang, Yuqing; Chen, Zhong; Fu, Riqiang

    2018-02-01

    The feasibility of using the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed in such a way that in the indirect dimension only the spin diffused signals are evolved, while all signals not involved in polarization transfer are refocused for cancellation. A data processing procedure is further introduced to reconstruct this acquired spectrum into a conventional two-dimensional homonuclear chemical shift correlation spectrum. A uniformly 13C, 15N labeled Fmoc-valine sample and the transmembrane domain of a human protein, LR11 (sorLA), in native Escherichia coli membranes have been used to illustrate the capability of the proposed method in comparison with standard 13C-13C chemical shift correlation experiments.

  14. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuqing; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin, E-mail: linyq@xmu.edu.cn, E-mail: chenz@xmu.edu.cn; Chen, Zhong, E-mail: linyq@xmu.edu.cn, E-mail: chenz@xmu.edu.cn [Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005 (China); Lin, Yung-Ya [Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095 (United States)

    2016-03-14

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

  15. Spin echo SPI methods for quantitative analysis of fluids in porous media.

    Science.gov (United States)

    Li, Linqing; Han, Hui; Balcom, Bruce J

    2009-06-01

    Fluid density imaging is highly desirable in a wide variety of porous media measurements. The SPRITE class of MRI methods has proven to be robust and general in their ability to generate density images in porous media, however the short encoding times required, with correspondingly high magnetic field gradient strengths and filter widths, and low flip angle RF pulses, yield sub-optimal S/N images, especially at low static field strength. This paper explores two implementations of pure phase encode spin echo 1D imaging, with application to a proposed new petroleum reservoir core analysis measurement. In the first implementation of the pulse sequence, we modify the spin echo single point imaging (SE-SPI) technique to acquire the k-space origin data point, with a near zero evolution time, from the free induction decay (FID) following a 90 degrees excitation pulse. Subsequent k-space data points are acquired by separately phase encoding individual echoes in a multi-echo acquisition. T(2) attenuation of the echo train yields an image convolution which causes blurring. The T(2) blur effect is moderate for porous media with T(2) lifetime distributions longer than 5 ms. As a robust, high S/N, and fast 1D imaging method, this method will be highly complementary to SPRITE techniques for the quantitative analysis of fluid content in porous media. In the second implementation of the SE-SPI pulse sequence, modification of the basic measurement permits fast determination of spatially resolved T(2) distributions in porous media through separately phase encoding each echo in a multi-echo CPMG pulse train. An individual T(2) weighted image may be acquired from each echo. The echo time (TE) of each T(2) weighted image may be reduced to 500 micros or less. These profiles can be fit to extract a T(2) distribution from each pixel employing a variety of standard inverse Laplace transform methods. Fluid content 1D images are produced as an essential by product of determining the

  16. Usefulness of dual echo volumetric isotropic turbo spin echo acquisition (VISTA) in MR imaging of the temporomandibular joint

    International Nuclear Information System (INIS)

    Sugimori, Yuko; Tanaka, Shigeko; Naito, Yukari; Nishimura, Tetsuya; Yamamoto, Akira; Miki, Yukio; Ohfuji, Satoko; Katsumata, Yasutomo

    2013-01-01

    We investigated the ability to detect the articular disk and joint effusion of the temporomandibular joint (TMJ) of a method of dual echo volumetric isotropic turbo spin echo acquisition (DE-VISTA) additional fusion images (AFI). DE-VISTA was performed in the 26 TMJ of 13 volunteers and 26 TMJ of 13 patients. Two-dimensional (2D) dual echo turbo spin echo was performed in the 26 TMJ of 13 volunteers. On a workstation, we added proton density-weighted images (PDWI) and T 2 weighted images (T 2 WI) of the DE-VISTA per voxel to reconstruct DE-VISTA-AFI. Two radiologists reviewed these images visually and quantitatively. Visual evaluation of the articular disk was equivalent between DE-VISTA-AFI and 2D-PDWI. The sliding thin-slab multiplanar reformation (MPR) method of DE-VISTA-AFI could detect all articular disks. The ratio of contrast (CR) of adipose tissue by the articular disk to that of the articular disk itself was significantly higher in DE-VISTA-AFI than DE-VISTA-PDWI (P 2 WI but in only 3 of those joints in 2D-T 2 WI. The CR of joint effusion to adipose tissue on DE-VISTA-AFI did not differ significantly from that on DE-VISTA-PDWI. However, using DE-VISTA-T 2 WI in addition to DE-VISTA-PDWI, we could visually identify joint effusion on DE-VISTA-AFI that could not be identified on DE-VISTA-PDWI alone. DE-VISTA-AFI can depict the articular disk and a small amount of joint effusion by the required plane of MPR using the sliding thin-slab MPR method. (author)

  17. Spin-Echo Small Angle Neutron Scattering analysis of liposomes and bacteria

    Science.gov (United States)

    van Heijkamp, Léon F.; Sevcenco, Ana-Maria; Abou, Diane; van Luik, Remko; Krijger, Gerard C.; Hagedoorn, Peter-Leon; de Schepper, Ignatz M.; Wolterbeek, Bert; Koning, Gerben A.; Bouwman, Wim G.

    2010-10-01

    Two types of liposomes, commonly used in drug delivery studies, and E. coli bacteria, all prepared in H2O, were resuspended in D2O and measured with Small Angle Spin-Echo Neutron Scattering (SESANS). Modeling was performed using correlation functions for solid spheres and hollow spheres. The signal strength and curve shape were more indicative of hollow particles, indicating that the H2O-D2O exchange occurred too fast to be observed with the available time resolution. Fitting the particle diameter and membrane thickness of the hollow sphere model to the data, gave results which were in good agreement with Dynamic Light Scattering (DLS) data and literature, showing as a proof-of-principle that SESANS is able to investigate such systems. SESANS may become a good alternative to conventional tritium studies or a tool with which to study intracellular vesicle transport phenomena, with possible in vivo applications. Calculations show that a substantial change in numbers of a mixed system of small and large biological particles should be observable. A possible application is the destruction by external means of great numbers of liposomes in the presence of tumor cells for triggered drug release in cancer treatment. Since SESANS is both non-invasive and non-destructive and can handle relatively thick samples, it could be a useful addition to more conventional techniques.

  18. CISS MR imaging findings of epidermoid tumor : comparison with spin-echo images

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Woo; Kim, Hak Jin; Choi, Sang Yoel; Heo, Jin Sam; Jung, Hoon Sik; Lee, Suck Hong; Kim, Byung Soo [Pusan National Univ. College of Medicine, Pusan (Korea, Republic of); Lee, Jong Wha [Ulsan Univ. Hospital, Ulsan (Korea, Republic of)

    1999-03-01

    To evaluate CISS MR imaging findings of epidermoid tumor in comparison with conventional spin-echo images. We studied 6 cases of epidermoid tumor in the subarachnoid space. We used a 1.5T MR unit to obtain CISS images(TR/TE/FA ; 12.3msec/5.9 msec/700) and T1- and T2- weighted spin-echo images. CISS MR imaging findings were evaluated with respect to tumor's signal intensity , contour, and relation with adjacent structures. Conspicuity of the tumor was compared between CISS and spin-echo images. A quantitative analysis was performed by measuring tumor to CSF contrast. In qualitative analysis, three radiologists independently compared CISS image and conventional spin-echo images for visibility of the tumor and graded them into three categories( poor, good, and excellent). Epidermoid tumors were located in the cerebellopontine angle in 4 cases, the prepontine cisstern in 1 case, and the cerebellopontine angle-prepontine cistern in 1 case. The tumors were hyperintense relative to brain parenchyma and hypointense relative to CSF on CISS images, were lobulated, encased adjacent cranial nerve and vessels, and invaginated into brain parenchyma. In qualitative analysis, CISS images showed clear demarcation between tumor and CSF, exact tumor extension, and tumor's relation with cranial nerves and vessels better than conventional spin-echo images. In quantitative analysis, the mean contrast values of tumor to CSF on T1-, T2-weighted images, and CISS images were 0.12, 0.06, and 0.52, respectively. The contrast value for CISS images was significantly higher than that for T1-and T2-weighted images(p<0.05). Epidermoid tumors in the subarachnoid space are better demonstrated on CISS images than on conventional spin-echo images. This special MR sequence can be added as a routine protocol in the diagnosis of subarachnoid epidermoid tumor.

  19. Development of Instrumentation for Spin-Echo Induced Spatial Beam Modulations

    DEFF Research Database (Denmark)

    Sales, Morten

    Spin-Echo Modulated Small Angle Neutron Scattering in Time-of-Flight mode (ToF SEMSANS) is an emerging technique extending the measurable phase space covered by neutron scattering. Using inclined magnetic field surfaces, (very) small angle scattering from a sample can be mapped into the spin...... orientation of the neutron as it has been shown in Spin-Echo Small Angle Neutron Scattering (SESANS). Taking this technique further we have shown that it is possible to perform quantitative Dark-Field Imaging, where the small angle scattering signal of individual areas in a neutron image can be obtained...

  20. Design and experimental tests of a novel neutron spin analyzer for wide angle spin echo spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Fouquet, Peter; Farago, Bela; Andersen, Ken H.; Bentley, Phillip M.; Pastrello, Gilles; Sutton, Iain; Thaveron, Eric; Thomas, Frederic [Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9 (France); Moskvin, Evgeny [Helmholtzzentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany); Pappas, Catherine [Helmholtzzentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany); Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

    2009-09-15

    This paper describes the design and experimental tests of a novel neutron spin analyzer optimized for wide angle spin echo spectrometers. The new design is based on nonremanent magnetic supermirrors, which are magnetized by vertical magnetic fields created by NdFeB high field permanent magnets. The solution presented here gives stable performance at moderate costs in contrast to designs invoking remanent supermirrors. In the experimental part of this paper we demonstrate that the new design performs well in terms of polarization, transmission, and that high quality neutron spin echo spectra can be measured.

  1. Application of MSS-neutron spin echo spectrometer to pulsed neutron sources

    International Nuclear Information System (INIS)

    Tasaki, S.; Ebisawa, T.; Hino, M.; Kawai, T.

    2001-01-01

    A multilayer spin splitter (MSS) is a neutron device that gives phase difference between field-parallel and -antiparallel spin component of a superposing state. Since the phase difference is equivalent to the Larmor precession angle, MSS enables us to construct a new type of neutron spin echo (NSE) spectrometer. The new NSE spectrometer has its properties that 1. since the phase shift is neutron flight path length, the spectrometer can be drastically small, 2. the neutron spin echo time is proportional to the neutron wavelength. (author)

  2. Electron spin echo studies of the internal motion of radicals in crystals: Phase memory vs correlation time

    International Nuclear Information System (INIS)

    Kispert, L.D.; Bowman, M.K.; Norris, J.R.; Brown, M.S.

    1982-01-01

    An electron spin echo (ESE) study of the internal motion of the CH 2 protons in irradiated zinc acetate dihydrate crystals shows that quantitative measurements of the motional correlation time can be obtained quite directly from pulsed measurements. In the slow motional limit, the motional correlation time is equal to the phase memory time determined by ESE. In the fast motional limit, the motional correlation time is proportional to the no motion spectral second moment divided by the ESE phase memory time. ESE offers a convenient method of studying motion, electron transfer, conductivity, etc. in a variety of systems too complicated for study by ordinary EPR. New systems for study by ESE include biological samples, organic polymers, liquid solutions of radicals with unresolved hyperfine, etc. When motion modulates large anisotropic hyperfine couplings, ESE measurements of the phase memory time are sensitive to modulation of pseudosecular hyperfine interactions

  3. Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

    International Nuclear Information System (INIS)

    Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeda, T.

    2005-01-01

    We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does include only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed

  4. Fast fringe-field switching of a liquid crystal cell by two-dimensional confinement with virtual walls

    OpenAIRE

    Choi, Tae-Hoon; Oh, Seung-Won; Park, Young-Jin; Choi, Yeongyu; Yoon, Tae-Hoon

    2016-01-01

    We report a simple method for reducing the response time of a fringe-field switching liquid crystal cell by using two-dimensional confinement of the liquid crystals. Through both numerical calculations and experiments, we show that the switching speed can be increased by several fold in a fringe-field switching cell by simply using a rubbing angle of zero, which causes virtual walls to be built when an electric field is applied between the interdigitated electrodes and the common electrode, w...

  5. Design and implementation in VHDL code of the two-dimensional fast Fourier transform for frequency filtering, convolution and correlation operations

    Science.gov (United States)

    Vilardy, Juan M.; Giacometto, F.; Torres, C. O.; Mattos, L.

    2011-01-01

    The two-dimensional Fast Fourier Transform (FFT 2D) is an essential tool in the two-dimensional discrete signals analysis and processing, which allows developing a large number of applications. This article shows the description and synthesis in VHDL code of the FFT 2D with fixed point binary representation using the programming tool Simulink HDL Coder of Matlab; showing a quick and easy way to handle overflow, underflow and the creation registers, adders and multipliers of complex data in VHDL and as well as the generation of test bench for verification of the codes generated in the ModelSim tool. The main objective of development of the hardware architecture of the FFT 2D focuses on the subsequent completion of the following operations applied to images: frequency filtering, convolution and correlation. The description and synthesis of the hardware architecture uses the XC3S1200E family Spartan 3E FPGA from Xilinx Manufacturer.

  6. TOF-SEMSANS—Time-of-flight spin-echo modulated small-angle neutron scattering

    NARCIS (Netherlands)

    Strobl, M.; Tremsin, A.S.; Hilger, A.; Wieder, F.; Kardjilov, N.; Manke, I.; Bouwman, W.G.; Plomp, J.

    2012-01-01

    We report on measurements of spatial beam modulation of a polarized neutron beam induced by triangular precession regions in time-of-flight mode and the application of this novel technique spin-echo modulated small-angle neutron scattering (SEMSANS) to small-angle neutron scattering in the very

  7. IN15 ultra-high-resolution spin-echo project. First experiment

    Energy Technology Data Exchange (ETDEWEB)

    Schleger, P; Hayes, C [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Kollmar, A [Forschungszentrum Juelich GmbH (Germany)

    1997-04-01

    The IN15 project is a collaboration between the ILL, HMI (Berlin), and FZ (Juelich) to construct a spin-echo spectrometer with a fourier time-range surpassing half a microsecond. Three different operational modes are possible: normal, with neutron focusing, and time-of-flight. Present status of the project is described. (author). 3 refs.

  8. Magnetic field mapping around metal implants using an asymmetric spin-echo sequence

    Czech Academy of Sciences Publication Activity Database

    Bartušek, Karel; Dokoupil, Zdeněk; Gescheidtová, E.

    2006-01-01

    Roč. 17, č. 12 (2006), s. 3293-3300 ISSN 0957-0233 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : nuclear magnetic resonance * spin echo * MRI * B0 mapping * dental material Subject RIV: FS - Medical Facilities ; Equipment Impact factor: 1.228, year: 2006

  9. The neutron spin-echo spectrometer: a new high resolution technique in neutron scattering

    International Nuclear Information System (INIS)

    Nicholson, L.K.

    1981-01-01

    The neutron spin-echo (NSE) spectrometer provides the highest energy resolution available in neutron scattering experiments. The article describes the principles behind the first NSE spectrometer (at the Institute Laue-Langevin, Grenoble, France) and, as an example of one of its applications, some recent results on polymer chain dynamics are presented. (author)

  10. Optimal control design of turbo spin-echo sequences with applications to parallel-transmit systems

    NARCIS (Netherlands)

    Sbrizzi, Alessandro; Hoogduin, Hans; Hajnal, Joseph V; van den Berg, CAT; Luijten, Peter R; Malik, Shaihan J

    PURPOSE: The design of turbo spin-echo sequences is modeled as a dynamic optimization problem which includes the case of inhomogeneous transmit radiofrequency fields. This problem is efficiently solved by optimal control techniques making it possible to design patient-specific sequences online.

  11. Relativistic effects in the energy loss of a fast charged particle moving parallel to a two-dimensional electron gas

    Science.gov (United States)

    Mišković, Zoran L.; Akbari, Kamran; Segui, Silvina; Gervasoni, Juana L.; Arista, Néstor R.

    2018-05-01

    We present a fully relativistic formulation for the energy loss rate of a charged particle moving parallel to a sheet containing two-dimensional electron gas, allowing that its in-plane polarization may be described by different longitudinal and transverse conductivities. We apply our formulation to the case of a doped graphene layer in the terahertz range of frequencies, where excitation of the Dirac plasmon polariton (DPP) in graphene plays a major role. By using the Drude model with zero damping we evaluate the energy loss rate due to excitation of the DPP, and show that the retardation effects are important when the incident particle speed and its distance from graphene both increase. Interestingly, the retarded energy loss rate obtained in this manner may be both larger and smaller than its non-retarded counterpart for different combinations of the particle speed and distance.

  12. Application of fast Fourier transforms to the direct solution of a class of two-dimensional separable elliptic equations on the sphere

    Science.gov (United States)

    Moorthi, Shrinivas; Higgins, R. W.

    1993-01-01

    An efficient, direct, second-order solver for the discrete solution of a class of two-dimensional separable elliptic equations on the sphere (which generally arise in implicit and semi-implicit atmospheric models) is presented. The method involves a Fourier transformation in longitude and a direct solution of the resulting coupled second-order finite-difference equations in latitude. The solver is made efficient by vectorizing over longitudinal wave-number and by using a vectorized fast Fourier transform routine. It is evaluated using a prescribed solution method and compared with a multigrid solver and the standard direct solver from FISHPAK.

  13. The evolution of two-dimensional effects in fast electron transport from high intensity laser plasma interactions

    International Nuclear Information System (INIS)

    Amiranoff, F.; Eidmann, K.; Sigel, R.; Fedosejevs, R.; Maaswinkel, A.; Teng, Y.L.; Kilkenny, J.D.; Hares, J.D.; Bradley, D.K.; MacGowan, B.J.

    1982-04-01

    Measurements of local and remote energy deposition by fast electrons have been made in 1.3 μm and 1.05 μm laser irradiation experiments with plane targets and various pulse lengths. From optical and X-ray streak photography and spatially resolved Kα yield measurements it is found that up to 30% of the absorbed laser energy spreads laterally to distances of several millimeters from the focal spot with a spreading velocity in excess of 10 8 cm sec -1 . (orig.)

  14. New spoiled spin-echo technique for three-dimensional MR imaging

    International Nuclear Information System (INIS)

    Darrasse, L.; Mao, L.; Saint-Jalmes, H.

    1989-01-01

    For 3D MR imaging within a convenient scanning time, the authors propose an improved spin-echo technique that permits the use of TRs shorter than 100 msec. They use a two-pulse RF sequence (α-π echo). The echo is read with conventional 3DFT encoding. To avoid steady-state signal refocusing before either α or (imperfect) π pulses, we apply randomized gradient spoilers both before each α pulse and on each side of the π pulse. So the sequence works like standard spin- echo sequences, with the z-magnetization recovery being adjusted by means of α rather than TR. The authors have investigated the method on a new 0.1-T Magnetom system dedicated for 3D MR imaging

  15. Neutron spin quantum precession using multilayer spin splitters and a phase-spin echo interferometer

    International Nuclear Information System (INIS)

    Ebisawa, Toru; Tasaki, Seiji; Kawai, Takeshi; Hino, Masahiro; Akiyoshi, Tsunekazu; Achiwa, Norio; Otake, Yoshie; Funahashi, Haruhiko.

    1996-01-01

    Neutron spin quantum precession by multilayer spin splitter has been demonstrated using a new spin interferometer. The multilayer spin splitter consists of a magnetic multilayer mirror on top, followed by a gap layer and a non magnetic multilayer mirror which are evaporated on a silicon substrate. Using the multilayer spin splitter, a polarized neutron wave in a magnetic field perpendicular to the polarization is split into two spin eigenstates with a phase shift in the direction of the magnetic field. The spin quantum precession is equal to the phase shift, which depends on the effective thickness of the gap layer. The demonstration experiments verify the multilayer spin splitter as a neutron spin precession device as well as the coherent superposition principle of the two spin eigenstates. We have developed a new phase-spin echo interferometer using the multilayer spin splitters. We present successful performance tests of the multilayer spin splitter and the phase-spin echo interferometer. (author)

  16. A quasi-elastic neutron scattering and neutron spin-echo study of hydrogen bonded system

    Energy Technology Data Exchange (ETDEWEB)

    Branca, C.; Faraone, A.; Magazu, S.; Maisano, G.; Mangione, A

    2004-07-15

    This work reports neutron spin echo results on aqueous solutions of trehalose, a naturally occurring disaccharide of glucose, showing an extraordinary bioprotective effectiveness against dehydration and freezing. We collected data using the SPAN spectrometer (BENSC, Berlin) on trehalose aqueous solutions at different temperature values. The obtained findings are compared with quasi-elastic neutron scattering results in order to furnish new results on the dynamics of the trehalose/water system on the nano and picoseconds scale.

  17. Dynamical scaling in polymer solutions investigated by the neutron spin echo technique

    International Nuclear Information System (INIS)

    Richter, D.; Ewen, B.

    1979-01-01

    Chain dynamics in polymer solutions was investigated by means of the recently developed neutron spin echo spectroscopy. - By this technique, it was possible for the first time to verify unambiguously the scaling predictions of the Zimm model in the case of single chain behaviour and to observe the cross over to many chain behaviour. The segmental diffusion of single chains exhibits deviations from a simple exponential law, indicating the importance of memory effects. (orig.) [de

  18. Spin echo dynamics under an applied drift field in graphene nanoribbon superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Sanjay, E-mail: sprabhakar@wlu.ca [M 2NeT Laboratory, Wilfrid Laurier University, 75 University Avenue West, Waterloo, Ontario N2L 3C5 (Canada); Melnik, Roderick [M 2NeT Laboratory, Wilfrid Laurier University, 75 University Avenue West, Waterloo, Ontario N2L 3C5 (Canada); Gregorio Millan Institute, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Bonilla, Luis L. [Gregorio Millan Institute, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Raynolds, James E. [Drinker Biddle and Reath LLP, Washington, DC 20005 (United States)

    2013-12-02

    We investigate the evolution of spin dynamics in graphene nanoribbon superlattices (GNSLs) with armchair and zigzag edges in the presence of a drift field. We determine the exact evolution operator and show that it exhibits spin echo phenomena due to rapid oscillations of the quantum states along the ribbon. The evolution of the spin polarization is accompanied by strong beating patterns. We also provide detailed analysis of the band structure of GNSLs with armchair and zigzag edges.

  19. Spin echo dynamics under an applied drift field in graphene nanoribbon superlattices

    International Nuclear Information System (INIS)

    Prabhakar, Sanjay; Melnik, Roderick; Bonilla, Luis L.; Raynolds, James E.

    2013-01-01

    We investigate the evolution of spin dynamics in graphene nanoribbon superlattices (GNSLs) with armchair and zigzag edges in the presence of a drift field. We determine the exact evolution operator and show that it exhibits spin echo phenomena due to rapid oscillations of the quantum states along the ribbon. The evolution of the spin polarization is accompanied by strong beating patterns. We also provide detailed analysis of the band structure of GNSLs with armchair and zigzag edges

  20. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  1. Determination of the amounts of C, CH, CH/sub 2/, and CH fragments by the spin echo method

    Energy Technology Data Exchange (ETDEWEB)

    Polonov, V.M.; Kalabin, G.A.; Kushnarev, D.F.; Latyshev, V.P.

    1984-01-01

    A new method has been developed for the quantitative determination of the amounts of primary, secondary, tertiary, and quaternary carbon atoms in soluble products of coal origin which is based on pulsed sequence of /sup 13/C NMR spin echo.

  2. Slow flow and mural thrombus in aortic diseases: Spin-echo MR findings and their differentiation

    International Nuclear Information System (INIS)

    Chung, Jin Wook; Park, Jae Hyung; Han, Man Chung

    1993-01-01

    In order to evaluate the ability of spin-echo MR imaging to differentiate slow flow from mural thrombus in aortic diseases, we reviewed the spin-echo MR images of 13 patients with intraaortic thrombus documented by CT (N=11) or aortography (N=2). Six patients had aortic aneurysms and seven had aortic dissections. Intraaortic mural thrombi were accompanied by flow-related intraluminal signal of various pattern and extents in all 13 patients. On 10 gated MR studies, slow flow regions showed ever-echo rephasing phenomenon (N=8), interslice variation of signal intensities of the intraluminal signal (N=7) and flow-related ghost artifact (N=2). However, these MR flow phenomena were obscured on two of three non-gated studies. Seven of 13 intraaortic thrombi remained hyperintense on T2-weighted second-echo images. In these circumstance, a hypointense boundary layer between slow flow and mural thrombus, which was caused by either ' boundary layer dephasing phenomenon' of slow flow or 'paramagnetic T2 shortening' of fresh clot at the edge of mural thrombus, was very useful in discriminating the area of slow flow from that of mural thrombus. Proper interpretation of spin-echo MR images may obviate the need for phase display imaging or gradient-echo imaging in differentiating slow flow and mural thrombus

  3. T2-weighted MR imaging of liver lesions: a prospective evaluation comparing turbo spin-echo, breath-hold turbo spin-echo and half-Fourier turbo spin-echo (HASTE) sequences

    International Nuclear Information System (INIS)

    Martin, J.; Villajos, M.; Oses, M. J.; Veintemillas, M.; Rue, M.; Puig, J.; Sentis, M.

    2000-01-01

    To compare turbo spin-echo (TSE), breath-hold TSE and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences quantitatively and qualitatively in T2-weighted images of liver lesions. The authors evaluated prospectively 89 liver lesions in 73 patients using a 1.0-T magnetic resonance system to compare TSE, breath-hold TSE and HASTE sequences. The quantitative parameters were: lesion-to-liver contrast and lesion-to-liver contrast-to-noise ratio. The qualitative analysis was performed by two observers in consensus who examined four parameters: respiratory artifacts, lesion edge definition, intrahepatic vessel definition and image quality. Repeated measures analysis of variance was utilized to compare the quantitative variables and Friedman's nonparametric test for the qualitative parameters. In quantitative terms, the lesion-to-liver contrast was similar in TSE and breath-hold TSE sequences (2.45±1.44 versus 2.60±1.66), both of which were significantly better than the HASTE sequence (1.12±0.72; p<0.001). The lesion-to-liver contrast-to-noise ratio was significantly higher in the TSE sequence (62.60±46.40 versus 40.22±25.35 versus 50.90±32.10 for TSE, breath-hold TSE and HASTE sequences, respectively; p<0.001). In the qualitative comparisons, the HASTE sequence was significantly better than the TSE and breath-hold TSE sequences (p<0.001) in terms of artifacts and definition of lesion edge and intrahepatic vessels. Image quality was also significantly greater in the HASTE sequence (p<0.001). In quantitative terms, the TSE sequence is better than the breath-hold TSE and HASTE sequences, but there are no movement artifacts in the HASTE sequence, which is also significantly superior to TSE and breath-hold TSE sequences in qualitative terms and, thus, can be employed for T2-weighted images in liver studies. (Author) 17 refs

  4. Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo sequence: improvement of the image quality of oxygen-enhanced MRI

    International Nuclear Information System (INIS)

    Ohno, Yoshiharu; Hatabu, Hiroto; Higashino, Takanori; Kawamitsu, Hideaki; Watanabe, Hirokazu; Takenaka, Daisuke; Cauteren, Marc van; Sugimura, Kazuro

    2004-01-01

    Purpose: The purpose of the study presented here was to determine the improvement in image quality of oxygen-enhanced magnetic resonance (MR) subtraction imaging obtained with a centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence compared with that obtained with a conventional sequentially reordered inversion recovery single-shot HASTE (s-IR-HASTE) sequence for pulmonary imaging. Materials and methods: Oxygen-enhanced MR imaging using a 1.5 T whole body scanner was performed on 12 healthy, non-smoking volunteers. Oxygen-enhanced MR images were obtained with the coronal two-dimensional (2D) c-IR-HASTE sequence and 2D s-IR-HASTE sequence combined with respiratory triggering. For a 256x256 matrix, 132 phase-encoding steps were acquired including four steps for phase correction. Inter-echo spacing for each sequence was 4.0 ms. The effective echo time (TE) for c-IR-HASTE was 4.0 ms, and 16 ms for s-IR-HASTE. The inversion time (TI) was 900 ms. To determine the improvement in oxygen-enhanced MR subtraction imaging by c-IR-HASTE, CNRs of subtraction image, overall image quality, and image degradation of the c-IR-HASTE and s-IR-HASTE techniques were statistically compared. Results: CNR, overall image quality, and image degradation of c-IR-HASTE images showed significant improvement compared to those s-IR-HASTE images (P<0.05). Conclusion: Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence enhanced the signal from the lung and improved the image quality of oxygen-enhanced MR subtraction imaging

  5. Development of new neutron spin echo spectrometer using multi-layer film spin splitter

    International Nuclear Information System (INIS)

    Tasaki, Seiji; Ebisawa, Toru; Hino, Masahiro; Achiwa, Norio

    2001-01-01

    Neutron spin echo spectrometry is a method using neutron Larmor precession motion in magnetic field, for the measurement of velocity change before and after quasi-elastic scattering of neutron by a sample, such as macromolecules, with high accuracy. The neutron spin echo spectrometer is an interferometer in quantum mechanics, which a neutron is arranged with a parallel or an antiparallel state against magnetic field direction. Intensities of neutron interaction with matters are measured by the superposition of the both spin state components. The contrast losses of interference fringes caused from velocity diversion of incident neutrons are protected by spin echo method, in which a phase shift between the parallel and anti-parallel state neutrons is reduced by reversion of the spin state on the way of neutron path. Neutron beam of high intensity can be measured with a high energy resolution. Strong magnetic field is usually needed to introduce the phase shift between the both spin state components. A multi-layer film spin splitter (MSS) is developed for introducing the phase shift instead of the strong magnetic fields. The MSS consists of three layers, non-magnetic mirror of Ni/Ti, gap layer of Ti (∼1 μm), and magnetic mirror of Permalloy/Ge. Surface roughness of the gap layer leads to diversions of the phase shift, because that the fluctuation of thickness of gap layer is proportional to the phase shift. Characteristics of the MSS are tested as follow: (1) reflectivity of polarized neutron, (2) function check of the MSS, (3) uniformity check of the gap layer, (4) evaluation of the gap layer-thickness. (Suetake, M.)

  6. Neutron spin echo: A new concept in polarized thermal neutron techniques

    International Nuclear Information System (INIS)

    Mezei, F.

    1980-01-01

    A simple method to change and keep track of neutron beam polarization non-parallel to the magnetic field is described. It makes possible the establishment of a new focusing effect we call neutron spin echo. The technique developed and tested experimentally can be applied in several novel ways, e.g. for neutron spin flipper of superior characteristics, for a very high resolution spectrometer for direct determination of the Fourier transform of the scattering function, for generalised polarization analysis and for the measurement of neutron particle properties with significantly improved precision. (orig.)

  7. Neutron spin echo studies of the effects of temperature and pressure in a ternary microemulsion

    CERN Document Server

    Kawabata, Y; Seto, H; Takeda, T; Komura, S; Schwahn, D

    2002-01-01

    In order to clarify the self-assembling mechanisms in complex fluids involving amphiphiles, we have investigated dynamic features of amphiphilic membranes and droplets at high temperature and at high pressure in a ternary microemulsion, consisting of AOT, water, and n-decane. A high-pressure cell for neutron spin echo (NSE) experiments has been improved, and the static and dynamic features of droplets are observed in detail by means of small angle neutron scattering and NSE. It is found that the size fluctuation and the diffusion of droplets are enhanced by increasing temperature, while they are suppressed by increasing pressure. (orig.)

  8. Observation of undulation motion of lipid bilayers by neutron spin echo

    International Nuclear Information System (INIS)

    Yamada, Norifumi L.; Seto, Hideki; Hishida, Mafumi

    2010-01-01

    Aqueous solutions of synthesized phospholipids have been well investigated as model biomembranes. These lipids usually self-assemble into regular stacks of bilayers with a characteristic repeat distance on the order of nm, whereas real biomembrane exist as single bilayers. The key phenomenon in understanding the formation of single isolated bilayers in 'unbinding' of lipid bilayers, in which the inter-bilayer distance of lipid bilayers diverges by the steric interaction due to the membrane undulation. In this paper, we show some results of neutron spin-echo (NSE) experiments to investigate the effect of the steric interaction on unbinding and related phenomena. (author)

  9. Fullerene-containing polymeric stars in bulk and solution by neutron spin-echo

    CERN Document Server

    Lebedev, V T; Toeroek, G; Cser, L; Bershtein, V A; Zgonnik, V N; Melenevskaya, E Y; Vinogradova, L V

    2002-01-01

    Stars with C sub 6 sub 0 fullerene core and poly (styrene) (PS) arms have been studied in benzene and in the bulk by neutron spin echo (NSE). Behaviours of stars (six arms, each with a mass M=5.10 sup 3) at momentum transfer q=0.2-0.6 nm sup - sup 1 in the time range t=0.01-20 ns at temperatures T=20-60 C were compared with dynamics of free PS chains. Displaying depressed molecular mobility, the stars did not obey the usual dynamic Zimm or Rouse model. The fullerene polymer interaction at a specific molecular architecture results in oscillating dynamics. (orig.)

  10. MR STIR imaging versus spin-echo imaging of the breast

    International Nuclear Information System (INIS)

    Zobel, B.B.; Tella, S.; Patrizio, G.; Confalone, D.; D'Archivio, C.; Passariello, R.

    1989-01-01

    A valid tissue characterization of human breast diseases with conventional spin-echo (SE) sequences has not been achieved yet. In spite of experimental works showing that fibroadenomas have a small but significant difference in T1 relaxation time, T1- and T2-weighted SE sequences are not always able to differentiate them. We tried to solve the problem employing two different short T1 inversion-recovery (STIR) sequences with T1 values adequate to nullify the signal of glandular and fatty tissues. This paper reports on twenty-five nodules, including cysts, fibroadenomas, phylloids, and adenocarcinomas, examined with both STIR sequences performed on a superconductive 0.5-T unit

  11. Dynamics of polymers in elongational flow studied by the neutron spin-echo technique

    International Nuclear Information System (INIS)

    Rheinstaedter, Maikel C.; Sattler, Rainer; Haeussler, Wolfgang; Wagner, Christian

    2010-01-01

    The nanoscale fluctuation dynamics of semidilute high molecular weight polymer solutions of polyethylenoxide (PEO) in D 2 O under non-equilibrium flow conditions were studied by the neutron spin-echo technique. The sample cell was in contraction flow geometry and provided a pressure driven flow with a high elongational component that stretched the polymers most efficiently. Neutron scattering experiments in dilute polymer solutions are challenging because of the low polymer concentration and corresponding small quasi-elastic signals. A relaxation process with relaxation times of about 10 ps was observed, which shows anisotropic dynamics with applied flow.

  12. Low flip angle spin-echo MR imaging to obtain better Gd-DTPA enhanced imaging with ECG gating

    International Nuclear Information System (INIS)

    Sugimura, Kazuro; Kawamitsu, Hideaki; Yoshikawa, Kazuaki; Kasai, Toshifumi; Yuasa, Koji; Ishida, Tetsuya

    1992-01-01

    ECG-gated spin-echo imaging (ECG-SE) can reduce physiological motion artifact. However, ECG-SE does not provide strong T1-weighted images because repetition time (TR) depends on heart rate (HR). We investigated the usefulness of low flip angle spin-echo imaging (LFSE) in obtaining more T1-dependent contrast with ECG gating. In computer simulation, the predicted image contrast and single-to-noise ratio (SNR) obtained for each flip angle (0-180deg) and each TR (300 msec-1200 msec) were compared with those obtained by conventional T1-weighted spin-echo imaging (CSE: TR=500 msec, TE=20 msec). In clinical evaluation, tissue contrast [contrast index (CI): (SI of lesion-SI of muslce) 2* 100/SI of muscle] obtained by CSE and LFSE were compared in 17 patients. At a TR of 1,000 msec, T1-dependent contrast increased with decreasing flip angle and that at 38deg was identical to that with T1-weighted spin-echo. SNR increased with the flip angle until 100deg, and that at 53deg was identical to that with T1-weighted spin-echo. CI on LFSE (74.0±52.0) was significantly higher than CI on CSE (40.9±35.9). ECG-gated LFSE imaging provides better T1-dependent contrast than conventional ECG-SE. This method was especially useful for Gd-DTPA enhanced MR imaging. (author)

  13. Two-dimensional errors

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    This chapter addresses the extension of previous work in one-dimensional (linear) error theory to two-dimensional error analysis. The topics of the chapter include the definition of two-dimensional error, the probability ellipse, the probability circle, elliptical (circular) error evaluation, the application to position accuracy, and the use of control systems (points) in measurements

  14. Characterization technique for detection of atom-size crystalline defects and strains using two-dimensional fast-Fourier-transform sampling Moiré method

    Science.gov (United States)

    Kodera, Masako; Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi; Yoshioka, Akira; Sugiyama, Toru; Hamamoto, Takeshi; Miyashita, Naoto

    2018-04-01

    Recently, we have developed a two-dimensional (2D) fast-Fourier-transform (FFT) sampling Moiré technique to visually and quantitatively determine the locations of minute defects in a transmission electron microscopy (TEM) image. We applied this technique for defect detection with GaN high electron mobility transistor (HEMT) devices, and successfully and clearly visualized atom-size defects in AlGaN/GaN crystalline structures. The defect density obtained in the AlGaN/GaN structures is ∼1013 counts/cm2. In addition, we have successfully confirmed that the distribution and number of defects closely depend on the process conditions. Thus, this technique is quite useful for a device development. Moreover, the strain fields in an AlGaN/GaN crystal were effectively calculated with nm-scale resolution using this method. We also demonstrated that this sampling Moiré technique is applicable to silicon devices, which have principal directions different from those of AlGaN/GaN crystals. As a result, we believe that the 2D FFT sampling Moiré method has great potential applications to the discovery of new as yet unknown phenomena occurring between the characteristics of a crystalline material and device performance.

  15. Neutron spin echo spectroscopy. Its application to the study of the dynamics of polymers in solution

    International Nuclear Information System (INIS)

    Papoular, Robert

    1992-06-01

    This work focuses on Neutron Spin Echo (NSE) spectroscopy and on the NSE spectrometer MESS, which we have built at the L.L.B. (CE Saclay). After analyzing in detail the classical and quantum principles of this type of instrument, and illustrated them with optical analogies, we expound a simple formalism for the interpretation of polarized neutron experiments of the most general type. In a second part, we describe the MESS spectrometer extensively; its characteristics and performances as well as the first results obtained with this instrument. In particular, we include two papers showing how the neutron depolarization, spin rotation and echoes can be used to investigate high-Tc superconductors. The last part deals with the dynamics of Polymer-Polymer-Solvent ternary solutions and demonstrates how the Neutron Spin Echo technique becomes a privileged tool for such physico-chemical studies thanks to the joint use of NSE and contrast variation methods, coupled with the adequate ranges of time and scattering vectors accessible. Finally, we describe the specific case of partially deuterated polydimethyl-siloxane (PDMS) in semi-dilute solution in Toluene. We have experimentally and separately evidenced the cooperative and inter-diffusive diffusion modes predicted by the theory of Akcasu, Benoit, Benmouna et al. These results, obtained at the L.L.B. (CE Saclay) are the subject matter of the last paper included in this work. (author) [fr

  16. STIR imaging of lymphadenopathy: Advantages over conventional spin-echo techniques

    International Nuclear Information System (INIS)

    Porter, B.A.; Neumann, E.B.; Olson, D.O.; Nyberg, D.A.; Teefy, S.A.; Shields, A.F.

    1987-01-01

    Spin-echo (SE) imaging of lymphadenopathy has been limited by the high signal of surrounding fat. With short TI Inversion Recovery (STIR), fat is cancelled (black), T1 and T2 contrast are additive, and pathologic nodes are white. STIR images (repetition time, 1,400 - 2,400; echo time, 36 or 40; inversion time, 100 or 125) of 69 patients with malignant adenopathy were compared with T1-weighted spin-echo (T1 SE) or intermediate SE and some T2 SE sequences at 0.15 T. Signal-intensity measurements of nodes versus adjacent tissues were used as a measure of contrast. Ratios of these values ranged from 2.5- to more than 17-fold greater for STIR versus T1 or intermediate SE sequences and to more than 40:1 for STIR versus T2 SE images. Some nodes detected on STIR were only identifiable in retrospection CT or T1 SE. In two cases, STIR detected minimally enlarged nodes not detected on CT; biopsy confirmed malignancy. Normal nodes have lower signal than malignant nodes; inflammatory nodes may mimic neoplasm. The authors replaced T2 SE with a combination of T1 SE and STIR, shortening imaging time and enhancing detection of lymphadenopathy

  17. Diagnosis of partial and complete rotator cuff tears using combined gradient echo and spin echo imaging

    International Nuclear Information System (INIS)

    Tuite, M.J.; Yandow, D.R.; DeSmet, A.A.; Orwin, J.F.; Quintana, F.A.

    1994-01-01

    Most magnetic resonance (MR) studies evaluating the rotator cuff for tears have used T2-weighted imaging in the coronal oblique and sagittal oblique planes. T2 * -weighted gradient echo imaging, however, has advantages over spin echo imaging, including contiguous slices without cross-talk, high contrast around the cuff, and intrinsically shorter imaging times which can be used to increase the number of signals averaged and thus improve the signal-to-noise ratio. We reviewed the shoulder MR scans of 87 consecutive patients who underwent both a MR scan and a shoulder arthroscopy during which the size of tears, if present, was graded. The reviewers were blinded as to the history and arthroscopic results. The MR scans included oblique coronal T2 * -weighted gradient echo and oblique sagittal T2-weighted spin echo images. MR cuff grades were correlated with arthroscopic findings. For complete tears, the sensitivity of MR was 0.91 and the specificity 0.95. For partial tears, the sensitivity was 0.74 and the specificity 0.87. This accuracy is similar to two-plane T2-weighted imaging as previously reported in the literature. There was a statistically significant correlation (p < 0.0005) between the cuff grade as determined by MR and the arthroscopic findings. (orig.)

  18. Diagnosis of partial and complete rotator cuff tears using combined gradient echo and spin echo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tuite, M J [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); Yandow, D R [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); DeSmet, A A [Dept. of Radiology, Univ. of Wisconsin, Madison, WI (United States); Orwin, J F [Div. of Orthopedic Surgery, Univ. of Wisconsin, Madison, WI (United States); Quintana, F A [Dept. of Biostatistics, Univ. of Wisconsin, Madison, WI (United States)

    1994-10-01

    Most magnetic resonance (MR) studies evaluating the rotator cuff for tears have used T2-weighted imaging in the coronal oblique and sagittal oblique planes. T2{sup *}-weighted gradient echo imaging, however, has advantages over spin echo imaging, including contiguous slices without cross-talk, high contrast around the cuff, and intrinsically shorter imaging times which can be used to increase the number of signals averaged and thus improve the signal-to-noise ratio. We reviewed the shoulder MR scans of 87 consecutive patients who underwent both a MR scan and a shoulder arthroscopy during which the size of tears, if present, was graded. The reviewers were blinded as to the history and arthroscopic results. The MR scans included oblique coronal T2{sup *}-weighted gradient echo and oblique sagittal T2-weighted spin echo images. MR cuff grades were correlated with arthroscopic findings. For complete tears, the sensitivity of MR was 0.91 and the specificity 0.95. For partial tears, the sensitivity was 0.74 and the specificity 0.87. This accuracy is similar to two-plane T2-weighted imaging as previously reported in the literature. There was a statistically significant correlation (p < 0.0005) between the cuff grade as determined by MR and the arthroscopic findings. (orig.)

  19. On the dynamics of polymers in dense systems - Results of neutron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Richter, D.

    1997-01-01

    One of the basic problems in the dynamics of polymers concerns the importance of geometrical or topological interactions which are directly related to the large scale molecular structures. In the famous reptation model these constraints are pictured in terms of a tube of localization following the average chain profile and confining the chain motion to the curve-linear tube. Recently studying the dynamic structure factor of a single labeled chain in a polymer melt by means of neutron spin echo spectroscopy (NSE) led to a direct observation of these tube constraints. Here I shall summarize these neutron spin echo experiments. I shall address the NSE technique, present results on the entropy driven segmental chain dynamics, discuss the dynamics of single chains in the melt where the chain length is increased through the transition to 'reptation' dynamics and display NSE measurements on long chain systems which revealed the molecular existence of the entanglement distance. Their magnitudes agree very well with tube diameters derived from dynamical mechanical measurements on the basis of the reptation model proving thereby the basic assumption of this Nobel Price winning concept

  20. Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

    Science.gov (United States)

    Afach, S; Ayres, N J; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Griffith, W C; Grujić, Z D; Harris, P G; Heil, W; Hélaine, V; Kasprzak, M; Kermaidic, Y; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Plonka-Spehr, C; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severijns, N; Thorne, J A; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

    2015-10-16

    We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1  μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1  pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

  1. Spin-echo observation of radio frequency induced flux lattice annealing (RIFLA) in a type-II superconductor

    International Nuclear Information System (INIS)

    Clark, W.G.; Hanson, M.E.; Wong, W.H.

    1999-01-01

    We report the annealing of a strained flux line lattice (FLL) in 10 μm diameter type-II superconducting NbTi filaments by an RF magnetic field at 4.2 K in a magnetic field of 1 T. The strained FLL is prepared by slowly changing the direction of the applied magnetic field. When the RF magnetic field used to generate a 93 Nb NMR spin echo anneals the FLL, there is a corresponding reduction in the amplitude of the spin echo. Starting from an annealed condition, a rotation threshold of 3 mr is needed to produce enough FLL strain to be observed in these measurements. (orig.)

  2. Optimal MR pulse sequences for hepatic hemangiomas : comparison of T2-weighted turbo-spin-echo, T2-weighted breath-hold turbo-spin-echo, and T1-weighted FLASH dynamic imaging

    International Nuclear Information System (INIS)

    Wang, Wen Chao; Choi, Byung Ihn; Han, Joon Koo; Kim, Tae Kyoung; Cho, Soon Gu

    1997-01-01

    To optimize MR imaging pulse sequences in the imaging of hepatic hemangioma and to evaluate on dynamic MR imaging the enhancing characteristics of the lesions. Twenty patients with 35 hemangiomas were studied by using Turbo-spin-echo (TSE) sequence (T2-weighted, T2- and heavily T2-weighted breath-hold) and T1-weighted FLASH imaging acquired before, immediately on, and 1, 3 and 5 minutes after injection of a bolus of Gd-DTPA (0.1mmol/kg). Phased-array multicoil was employed. Images were quantitatively analyzed for lesion-to-liver signal difference to noise ratios (SD/Ns), and lesion-to-liver signal ratios (H/Ls), and qualitatively analyzed for lesion conspicuity. The enhancing characteristics of the hemangiomas were described by measuring the change of signal intensity as a curve in T1-weighted FLASH dynamic imaging. For T2-weighted images, breath-hold T2-weighted TSE had a slightly higher SD/N than other pulse sequences, but there was no statistical difference in three fast pulse sequences (p=0.211). For lesion conspicuity, heavily T2-weighted breath-hold TSE images was superior to T2-weighted breath-hold or non-breath-hold TSE (H/L, 5.75, 3.81, 2.87, respectively, p<0.05). T2-weighted breath-hold TSE imaging was more effective than T2-weighted TSE imaging in removing lesion blurring or lack of sharpness, and there was a 12-fold decrease in acquisition time (20sec versus 245 sec). T1-weighted FLASH dynamic images of normal liver showed peak enhancement at less than 1 minute, and of hemangioma at more than 3 minutes;the degree of enhancement for hemangioma decreased after a 3 minute delay. T2-weighed breath-hold TSE imaging and Gd-DTPA enhanced FLASH dynamic imaging with 5 minutes delay are sufficient for imaging hepatic hemangiomas

  3. Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

    CERN Document Server

    Mihailescu, M; Endo, H; Allgaier, J; Gompper, G; Stellbrink, J; Richter, D; Jakobs, B; Sottmann, T; Faragó, B

    2002-01-01

    Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C sub 1 sub 0 E sub 4) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is mo...

  4. Differential diagnosis of extra-axial intracranial tumours by dynamic spin-echo MRI

    International Nuclear Information System (INIS)

    Joo, Y.G.; Korogi, Y.; Hirai, T.; Sakamoto, Y.; Sumi, M.; Takahashi, M.; Ushio, Y.

    1995-01-01

    Dynamic MRI was performed on 22 patients with extra-axial intracranial tumours. Serial images were obtained every 30 s for 3 min using a spin-echo sequence (TR 200, TE 15 ms) after rapid injection of Gd-DTPA, 0.1 mmol/kg body weight. The contrast medium enhancement ratio (CER) was correlated with the histology of the tumours. Meningiomas and extra-axial metastases showed a sharp rise, then a gradual decline. Although both had a definite early peak of CER, metastases showed a more rapid decline. Neuromas and extra-axial lymphoma showed a slow, steady increase with no peak within 180 s. This study indicates that the CER is helpful in the differentiation of extra-axial tumours. (orig.)

  5. Numerical calculation of spin echo amplitude in pulsed NMR: effects of quadrupole interaction

    International Nuclear Information System (INIS)

    Sobral, R.R.

    1986-01-01

    The spin echo obtained by nuclear magnetic resonance, in systems which atomic nuclei interact with magnetic fields and electric field gradients, present oscillations in function of the time interval between two excitations pulses. Using the density matrix formalism, the amplitudes of these echo is calculated, analytically. In this work, echo amplitudes obtained under different excitation conditions for nuclei of different nuclear spin values are calculated. The numerical results are compared with disposable analytical solutions. Applications of this method to the case of electric field gradient without axial symmetry were studied. Within the used approximation limits, an expression for attnuation of oscillatory behaviour of echo amplitude in function of the time interval between experimentally observed pulses was obtained. (M.C.K.) [pt

  6. MRI in neuro-Behcet's syndrome: comparison of conventional spin-echo and FLAIR pulse sequences

    International Nuclear Information System (INIS)

    Jaeger, H.R.; Albrecht, T.; Curati-Alasonatti, W.L.; Williams, E.J.; Haskard, D.O.

    1999-01-01

    We compared the sensitivity of a fluid-attenuated inversion-recovery (FLAIR) sequence with that of a conventional dual-echo spin-echo (SE) sequence to brain lesions in 20 patients with Behcet's syndrome. They underwent 25 MRI examinations. The images were independently analysed for the number, type and anatomical location of lesions shown. There were 18 abnormal studies (13 initial and 5 follow-up). The FLAIR sequence detected significantly more lesions than the SE TE 80 (P < 0.05) and SE TE 20 (P < 0.01) sequences. It was particularly useful for demonstrating lesions in the juxtacortical white matter, which accounted for over half the lesions detected on the FLAIR images. Of patients presenting with nonspecific symptoms such as headache, seven had normal and five had abnormal studies. All patients presenting with focal neurological signs had abnormal imaging. We found supratentorial and, in particular, juxtacortical lesions to be more frequent than previously described. (orig.)

  7. Optimal Configuration for Relaxation Times Estimation in Complex Spin Echo Imaging

    Directory of Open Access Journals (Sweden)

    Fabio Baselice

    2014-01-01

    Full Text Available Many pathologies can be identified by evaluating differences raised in the physical parameters of involved tissues. In a Magnetic Resonance Imaging (MRI framework, spin-lattice T1 and spin-spin T2 relaxation time parameters play a major role in such an identification. In this manuscript, a theoretical study related to the evaluation of the achievable performances in the estimation of relaxation times in MRI is proposed. After a discussion about the considered acquisition model, an analysis on the ideal imaging acquisition parameters in the case of spin echo sequences, i.e., echo and repetition times, is conducted. In particular, the aim of the manuscript consists in providing an empirical rule for optimal imaging parameter identification with respect to the tissues under investigation. Theoretical results are validated on different datasets in order to show the effectiveness of the presented study and of the proposed methodology.

  8. Spin-echo small-angle neutron scattering study of the structure organization of the chromatin in biological cell

    NARCIS (Netherlands)

    Iashina, E.G.; Bouwman, W.G.; Duif, C.P.; Filatov, M.V.; Grigoriev, S. V.

    2017-01-01

    Spin-echo small-angle scattering (SESANS) technique is a method to measure the structure of materials from nano- to micrmeter length scales. This method could be important for studying the packaging of DNA in the eukaryotic cell. We measured the SESANS function from chicken erythrocyte nuclei

  9. Whole brain, high resolution spin-echo resting state fMRI using PINS multiplexing at 7 T

    NARCIS (Netherlands)

    Koopmans, P.J.; Boyacioglu, R.; Barth, M.; Norris, David Gordon

    2012-01-01

    This article demonstrates the application of spin-echo EPI for resting state fMRI at 7 T. A short repetition time of 1860 ms was made possible by the use of slice multiplexing which permitted whole brain coverage at high spatial resolution (84 slices of 1.6 mm thickness). Radiofrequency power

  10. High-field spin-echo MR imaging of superficial and subependymal siderosis secondary to neonatal intraventricular hemorrhage

    International Nuclear Information System (INIS)

    Gomori, J.M.; Grossman, R.I.; Goldberg, H.I.; Zimmerman, R.A.; Bilaniuk, L.T.

    1987-01-01

    Two cases of superficial siderosis with subependymal siderosis, secondary to neonatal intraventricular hemorrhage, are presented. High-field spin-echo MR imaging (1.5 Tesla) showed marginal hypointensity of the ventricular walls as well as of the subpial regions. These findings were most evident on T 2 weighted images, characteristic of hemosiderotic deposits. (orig.)

  11. Ultrafast bold fMRI using single-shot spin-echo echo planar imaging

    Directory of Open Access Journals (Sweden)

    Boujraf Said

    2009-01-01

    Full Text Available The choice of imaging parameters for functional MRI can have an impact on the accuracy of functional localization by affecting the image quality and the degree of blood oxygenation-dependent (BOLD contrast achieved. By improving sampling efficiency, parallel acquisition techniques such as sensitivity encoding (SENSE have been used to shorten readout trains in single-shot (SS echo planar imaging (EPI. This has been applied to susceptibility artifact reduction and improving spatial resolution. SENSE together with single-shot spin-echo (SS-SE imaging may also reduce off-resonance artifacts. The goal of this work was to investigate the BOLD response of a SENSE-adapted SE-EPI on a three Tesla scanner. Whole-brain fMRI studies of seven healthy right hand-dominant volunteers were carried out in a three Tesla scanner. fMRI was performed using an SS-SE EPI sequence with SENSE. The data was processed using statistical parametric mapping. Both, group and individual subject data analyses were performed. Individual average percentage and maximal percentage signal changes attributed to the BOLD effect in M1 were calculated for all the subjects as a function of echo time. Corresponding activation maps and the sizes of the activated clusters were also calculated. Our results show that susceptibility artifacts were reduced with the use of SENSE; and the acquired BOLD images were free of the typical quadrature artifacts of SS-EPI. Such measures are crucial at high field strengths. SS SE-EPI with SENSE offers further benefits in this regard and is more specific for oxygenation changes in the microvasculature bed. Functional brain activity can be investigated with the help of single-shot spin echo EPI using SENSE at high magnetic fields.

  12. Two-dimensional calculus

    CERN Document Server

    Osserman, Robert

    2011-01-01

    The basic component of several-variable calculus, two-dimensional calculus is vital to mastery of the broader field. This extensive treatment of the subject offers the advantage of a thorough integration of linear algebra and materials, which aids readers in the development of geometric intuition. An introductory chapter presents background information on vectors in the plane, plane curves, and functions of two variables. Subsequent chapters address differentiation, transformations, and integration. Each chapter concludes with problem sets, and answers to selected exercises appear at the end o

  13. Two-dimensional models

    International Nuclear Information System (INIS)

    Schroer, Bert; Freie Universitaet, Berlin

    2005-02-01

    It is not possible to compactly review the overwhelming literature on two-dimensional models in a meaningful way without a specific viewpoint; I have therefore tacitly added to the above title the words 'as theoretical laboratories for general quantum field theory'. I dedicate this contribution to the memory of J. A. Swieca with whom I have shared the passion of exploring 2-dimensional models for almost one decade. A shortened version of this article is intended as a contribution to the project 'Encyclopedia of mathematical physics' and comments, suggestions and critical remarks are welcome. (author)

  14. Diagnostic accuracy of dynamic contrast-enhanced MR imaging of renal masses with rapid-acquisition spin-echo technique

    International Nuclear Information System (INIS)

    Eilenberg, S.S.; Lee, J.K.T.; Brown, J.J.; Heiken, J.P.; Mirowitz, S.A.

    1990-01-01

    This paper compares the diagnostic accuracy of Gd-DTPA-enhanced rapid-acquisition spin-echo (RASE) imaging with standard spin-echo techniques for detecting renal cysts and solid renal neoplasms. RASE imaging combines a short TR (275 msec)/short TE (10 msec), single excitation pulse sequence with half-Fourier data sampling. Eighteen patients with CT evidence of renal masses were first evaluated with standard T1-and T2-weighted SE sequences. Pre- and serial postcontrast (Cd-DTPA, 0.1 mmol./kg) RASE sequences were then performed during suspended respiration. A final set of postcontrast images was obtained with the standard T1-weighted SE sequence. Each set of MR images was first reviewed separately (ie, T1, T2, pre- and post-contrast RASE, etc)

  15. On the analysis of time-of-flight spin-echo modulated dark-field imaging data

    DEFF Research Database (Denmark)

    Sales, Morten; Plomp, Jeroen; Bouwman, Wim G.

    2017-01-01

    Spin-Echo Modulated Small Angle Neutron Scattering with spatial resolution, i.e. quantitative Spin-Echo Dark Field Imaging, is an emerging technique coupling neutron imaging with spatially resolved quantitative small angle scattering information. However, the currently achieved relatively large...... modulation periods of the order of millimeters are superimposed to the images of the samples. So far this required an independent reduction and analyses of the image and scattering information encoded in the measured data and is involving extensive curve fitting routines. Apart from requiring a priori...... decisions potentially limiting the information content that is extractable also a straightforward judgment of the data quality and information content is hindered. In contrast we propose a significantly simplified routine directly applied to the measured data, which does not only allow an immediate first...

  16. Two-dimensional ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Blinov, L M; Fridkin, Vladimir M; Palto, Sergei P [A.V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russian Federaion (Russian Federation); Bune, A V; Dowben, P A; Ducharme, Stephen [Department of Physics and Astronomy, Behlen Laboratory of Physics, Center for Materials Research and Analysis, University of Nebraska-Linkoln, Linkoln, NE (United States)

    2000-03-31

    The investigation of the finite-size effect in ferroelectric crystals and films has been limited by the experimental conditions. The smallest demonstrated ferroelectric crystals had a diameter of {approx}200 A and the thinnest ferroelectric films were {approx}200 A thick, macroscopic sizes on an atomic scale. Langmuir-Blodgett deposition of films one monolayer at a time has produced high quality ferroelectric films as thin as 10 A, made from polyvinylidene fluoride and its copolymers. These ultrathin films permitted the ultimate investigation of finite-size effects on the atomic thickness scale. Langmuir-Blodgett films also revealed the fundamental two-dimensional character of ferroelectricity in these materials by demonstrating that there is no so-called critical thickness; films as thin as two monolayers (1 nm) are ferroelectric, with a transition temperature near that of the bulk material. The films exhibit all the main properties of ferroelectricity with a first-order ferroelectric-paraelectric phase transition: polarization hysteresis (switching); the jump in spontaneous polarization at the phase transition temperature; thermal hysteresis in the polarization; the increase in the transition temperature with applied field; double hysteresis above the phase transition temperature; and the existence of the ferroelectric critical point. The films also exhibit a new phase transition associated with the two-dimensional layers. (reviews of topical problems)

  17. Neutron spin echo investigation of elementary excitations in superfluid 4He

    International Nuclear Information System (INIS)

    Mezei, F.

    1980-01-01

    The present work represents the first experimental evidence for the application of Neutron Spin Echo (NSE) in high resolution study of both optical-like (non dispersive) and dispersive elementary excitations. The results obtained proved to be relevant contributions concerning the temperature dependence of the energy and linewidth of the roton excitation between 0.96 and 1.4 K; the temperature dependence of the linewidth of the 1.1 A -1 and 1.72 A -1 phonons and the suggested onset of three-phonon decay between 2.1 A -1 and 2.4 A -1 . The energy transfer resolution achieved in this work was 10-40 times superiour to those in previous similar neutron scattering experiments. In this paper most of the attention will be paid to the experimental aspects. In the first section the details of the NSE experiment are described, with particular emphasis on the first demonstration of the general scheme of NSE focussing, which involves the tuning of both the ratio of the precession fields H 0 /H 1 and their geometrical assymetry ('tilt angle'). The second section gives the experimental results without, however, a detailed discussion of their significance for the understanding of superfluid 4 He, which will be published elsewhere. (orig.)

  18. Gaussian-approximation formalism for evaluating decay of NMR spin echoes

    International Nuclear Information System (INIS)

    Recchia, C.H.; Gorny, K.; Pennington, C.H.

    1996-01-01

    We present a formalism for evaluating the amplitude of the NMR spin echo and stimulated echo as a function of pulse spacings, for situations in which the nuclear spins experience an effective longitudinal magnetic field h z (t) resulting from an arbitrary number of independent sources, each characterized by its own arbitrary time correlation function. The distribution of accumulated phase angles for the ensemble of nuclear spins at the time of the echo is approximated as a Gaussian. The development of the formalism is motivated by the need to understand the transverse relaxation of 89 Y in YBa 2 Cu 3 O 7 , in which the 89 Y experiences 63,65 Cu dipolar fields which fluctuate due to 63,65 Cu T 1 processes. The formalism is applied successfully to this example, and to the case of nuclei diffusing in a spatially varying magnetic field. Then we examine a situation in which the approximation fails emdash the classic problem of chemical exchange in dimethylformamide, where the methyl protons experience a chemical shift which fluctuates between two discrete values. In this case the Gaussian approximation yields a monotonic decay of the echo amplitude with increasing pulse spacing, while the exact solution yields distinct open-quote open-quote beats close-quote close-quote in the echo height, which we confirm experimentally. In light of this final example the limits of validity of the approximation are discussed. copyright 1996 The American Physical Society

  19. Evaluation of crosstalk effect on spin-echo images at 1.5 and 3 T

    International Nuclear Information System (INIS)

    Kajisako, Masaaki; Taniguchi, Masahiro; Koizumi, Koji; Hiraga, Akira; Miyati, Tosiaki; Syakudo, Yuko; Miki, Yukio

    2011-01-01

    The purpose of this study is to evaluate the crosstalk effect on spin-echo (SE) images at 1.5 and 3 T MRI. We examined the influence of crosstalk by comparing the full width at half-maximum (FWHM) and slice profile of images of a wedge-shaped phantom for various slice gaps. We also assessed crosstalk effect in the brain by comparing image contrast among healthy volunteers (n=8). Among the subjects, the shapes of the slice profiles at 1.5 T were similar to those at 3 T for long repetition times (TRs); however, at shorter TRs, differences in slice profiles were observed among the subjects and were more apparent at 3 than at 1.5 T. The relative contrast between white matter and gray matter on T 1 -weighted images was lower at 3 than at 1.5 T. The crosstalk effect was strongest when the TR of the excitation pulse was short. The influence of the adjacent excitation pulse is important in the process of T 1 relaxation because T 1 values are greater at 3 T. In conclusion, the influence of crosstalk on SE T 1 -weighted images is greater at 3 than at 1.5 T. (author)

  20. Elucidation of spin echo small angle neutron scattering correlation functions through model studies.

    Science.gov (United States)

    Shew, Chwen-Yang; Chen, Wei-Ren

    2012-02-14

    Several single-modal Debye correlation functions to approximate part of the overall Debey correlation function of liquids are closely examined for elucidating their behavior in the corresponding spin echo small angle neutron scattering (SESANS) correlation functions. We find that the maximum length scale of a Debye correlation function is identical to that of its SESANS correlation function. For discrete Debye correlation functions, the peak of SESANS correlation function emerges at their first discrete point, whereas for continuous Debye correlation functions with greater width, the peak position shifts to a greater value. In both cases, the intensity and shape of the peak of the SESANS correlation function are determined by the width of the Debye correlation functions. Furthermore, we mimic the intramolecular and intermolecular Debye correlation functions of liquids composed of interacting particles based on a simple model to elucidate their competition in the SESANS correlation function. Our calculations show that the first local minimum of a SESANS correlation function can be negative and positive. By adjusting the spatial distribution of the intermolecular Debye function in the model, the calculated SESANS spectra exhibit the profile consistent with that of hard-sphere and sticky-hard-sphere liquids predicted by more sophisticated liquid state theory and computer simulation. © 2012 American Institute of Physics

  1. Size Distribution Imaging by Non-Uniform Oscillating-Gradient Spin Echo (NOGSE MRI.

    Directory of Open Access Journals (Sweden)

    Noam Shemesh

    Full Text Available Objects making up complex porous systems in Nature usually span a range of sizes. These size distributions play fundamental roles in defining the physicochemical, biophysical and physiological properties of a wide variety of systems - ranging from advanced catalytic materials to Central Nervous System diseases. Accurate and noninvasive measurements of size distributions in opaque, three-dimensional objects, have thus remained long-standing and important challenges. Herein we describe how a recently introduced diffusion-based magnetic resonance methodology, Non-Uniform-Oscillating-Gradient-Spin-Echo (NOGSE, can determine such distributions noninvasively. The method relies on its ability to probe confining lengths with a (length6 parametric sensitivity, in a constant-time, constant-number-of-gradients fashion; combined, these attributes provide sufficient sensitivity for characterizing the underlying distributions in μm-scaled cellular systems. Theoretical derivations and simulations are presented to verify NOGSE's ability to faithfully reconstruct size distributions through suitable modeling of their distribution parameters. Experiments in yeast cell suspensions - where the ground truth can be determined from ancillary microscopy - corroborate these trends experimentally. Finally, by appending to the NOGSE protocol an imaging acquisition, novel MRI maps of cellular size distributions were collected from a mouse brain. The ensuing micro-architectural contrasts successfully delineated distinctive hallmark anatomical sub-structures, in both white matter and gray matter tissues, in a non-invasive manner. Such findings highlight NOGSE's potential for characterizing aberrations in cellular size distributions upon disease, or during normal processes such as development.

  2. A neutron spin echo spectrometer with two optimal field shape coils for neutron spin precession

    International Nuclear Information System (INIS)

    Takeda, T.; Ebisawa, T.; Tasaki, S.; Ito, Y.; Takahashi, S.; Yoshizawa, H.

    1995-01-01

    We have designed and have been constructing at the C 2-2 cold neutron guide port of JRR-3M, JAERI, a neutron spin echo spectrometer (NSE) which is equipped with two optimal field shape (OFS) coils for neutron spin precession with the maximum field integral of 0.22 T m, an assembly of position sensitive detectors (PSD), a converging polarizer and a wide area analyzer. The dynamic range of scattering vector Q covers from 0.005 A -1 to 0.2 A -1 and that of energy hω from 10 neV to 30 μeV. Performance tests of the OFS coils show that the inhomogeneity of the magnetic field integral in the OFS coils with the spiral coils is so small that the NSE signal amplitude decreases little even for the neutron cross section of 30 mm diameter as the Fourier time t increases up to 25 ns, though the precession coils are close to iron covers of the neighboring neutron guide. This verifies that the OFS precession coils are appropriate for this NSE spectrometer. Another test experiment shows that the homogeneity condition of the precession magnet is loosened by use of PSD. (orig.)

  3. Spherical neutron polarimetry applied to spin-echo and time-of-flight spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lelievre-Berna, E., E-mail: lelievre@ill.e [Institut Laue Langevin (ILL), 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Bentley, P.; Bourgeat-Lami, E.; Thomas, M. [Institut Laue Langevin (ILL), 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Pappas, C. [Helmholtz Centre Berlin for Materials and Energy (HCB), Glienickerstr. 100, 14109 Berlin (Germany); Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Kischnik, R.; Moskvin, E. [Helmholtz Centre Berlin for Materials and Energy (HCB), Glienickerstr. 100, 14109 Berlin (Germany)

    2009-09-01

    The changes in direction of the neutron spin that take place on scattering by a magnetic interaction vector are highly dependent on their relative directions. In some circumstances, without zero-field polarimeter, it is impossible to distinguish between a simple depolarisation and a rotation of the polarisation vector. Motivated by the investigation of chiral magnetic fluctuations, we have implemented the third-generation zero-field polarimeter Cryopad on the neutron spin-echo spectrometer SPAN at the Helmholtz Centre Berlin (HCB). We present the method and the limitations of this novel technique that is now available on IN15 at the ILL. The huge progress accomplished with {sup 3}He neutron spin filters/flippers are going to facilitate the exploitation of polarised beams at spallation sources. Zero-field polarimeters like Cryopad are used routinely at several steady-state sources but their design would be inefficient at a pulse source. We have investigated the possibility to implement a zero-field polarimeter on a time-of-flight spectrometer. We propose a design that would lead to a better efficiency and present the finite element calculations.

  4. Acoustic noise reduction in T 1- and proton-density-weighted turbo spin-echo imaging.

    Science.gov (United States)

    Ott, Martin; Blaimer, Martin; Breuer, Felix; Grodzki, David; Heismann, Björn; Jakob, Peter

    2016-02-01

    To reduce acoustic noise levels in T 1-weighted and proton-density-weighted turbo spin-echo (TSE) sequences, which typically reach acoustic noise levels up to 100 dB(A) in clinical practice. Five acoustic noise reduction strategies were combined: (1) gradient ramps and shapes were changed from trapezoidal to triangular, (2) variable-encoding-time imaging was implemented to relax the phase-encoding gradient timing, (3) RF pulses were adapted to avoid the need for reversing the polarity of the slice-rewinding gradient, (4) readout bandwidth was increased to provide more time for gradient activity on other axes, (5) the number of slices per TR was reduced to limit the total gradient activity per unit time. We evaluated the influence of each measure on the acoustic noise level, and conducted in vivo measurements on a healthy volunteer. Sound recordings were taken for comparison. An overall acoustic noise reduction of up to 16.8 dB(A) was obtained by the proposed strategies (1-4) and the acquisition of half the number of slices per TR only. Image quality in terms of SNR and CNR was found to be preserved. The proposed measures in this study allowed a threefold reduction in the acoustic perception of T 1-weighted and proton-density-weighted TSE sequences compared to a standard TSE-acquisition. This could be achieved without visible degradation of image quality, showing the potential to improve patient comfort and scan acceptability.

  5. Neutron spin echo measurements of monolayer and capillary condensed water in MCM-41 at low temperatures

    International Nuclear Information System (INIS)

    Yoshida, K; Yamaguchi, T; Kittaka, S; Bellissent-Funel, M-C; Fouquet, P

    2012-01-01

    Neutron spin echo measurements of monolayer and capillary condensed heavy water (D 2 O) confined in MCM-41 C10 (pore diameter 2.10 nm) were performed in a temperature range of 190-298 K. The intermediate scattering functions were analyzed by the Kohlrausch-Williams-Watts stretched exponential function. The relaxation times of confined D 2 O in the capillary condensed state follow remarkably well the Vogel-Fulcher-Tammann equation between 298 and 220 K, whereas below 220 K they show an Arrhenius type behavior. That is, the fragile-to-strong (FTS) dynamic crossover occurs, which has never been seen in experiments on bulk water. On the other hand, for monolayer D 2 O, the FTS dynamic crossover was not observed in the temperature range measured. The FTS dynamic crossover observed in capillary condensed water would take place in the central region of the pore, not near the pore surface. Because the tetrahedral-like water structure in the central region of the pore is more preserved than that near the pore surface, the FTS dynamic crossover would be concerned with the tetrahedral-like water structure. (paper)

  6. Self-diffusion imaging by spin echo in Earth's magnetic field.

    Science.gov (United States)

    Mohoric, A; Stepisnik, J; Kos, M; Planinsi

    1999-01-01

    The NMR of the Earth's magnetic field is used for diffusion-weighted imaging of phantoms. Due to a weak Larmor field, care needs to be taken regarding the use of the usual high field assumption in calculating the effect of the applied inhomogeneous magnetic field. The usual definition of the magnetic field gradient must be replaced by a generalized formula valid when the strength of a nonuniform magnetic field and a Larmor field are comparable (J. Stepisnik, Z. Phys. Chem. 190, 51-62 (1995)). It turns out that the expression for spin echo attenuation is identical to the well-known Torrey formula only when the applied nonuniform field has a proper symmetry. This kind of problem may occur in a strong Larmor field as well as when the slow diffusion rate of particles needs an extremely strong gradient to be applied. The measurements of the geomagnetic field NMR demonstrate the usefulness of the method for diffusion and flow-weighted imaging. Copyright 1999 Academic Press.

  7. Liver iron content determined by MRI. Spin-echo vs. gradient-echo

    Energy Technology Data Exchange (ETDEWEB)

    Juchems, M.S.; Wunderlich, A.P. [Universitaetskliniken Ulm (Germany). Klinik fuer Diagnostische und Interventionelle Radiologie; Cario, H. [Universitaetskliniken Ulm (Germany). Klinik fuer Kinder- und Jugendmedizin; Schmid, M. [Stadtspital Triemli, Zuerich (Switzerland). Medizinische Onkologie und Haematologie

    2012-05-15

    Purpose: Liver iron content (LIC) measurement plays a central role in the management of patients with transfusional iron overload. Calculating the LIC with data obtained from standardized MRI sequences represents an attractive alternative diagnostic possibility. The purpose of this study was to compare the LIC measurement obtained with gradient-echo (GRE) sequences to the mean liver proton transverse relaxation (R2) acquired with SE sequences. Materials and Methods: 68 patients with iron overload (median age: 24, range: 3 - 88) underwent 1.5 T MRI for liver iron content measurement. All patients received spin-echo (SE) and gradient-echo (GRE) sequences. Results: The two MRI methods revealed different liver iron content results although a significant correlation was found (r = 0.85, p < 0.001). Values evaluated using GRE sequences (median: 260 {mu}mol/g dry weight [d.w.], range: 6 - 732) were generally higher than those obtained by SE examinations (median: 161 {mu}mol /g d.w., range: 5 - 830). Conclusion: In conclusion, our study revealed different results for both MRI measurements, which could lead to different decisions concerning the management of chelation therapy in individual patients. (orig.)

  8. Clustering Effects on Dynamics in Ionomer Solutions: A Neutron Spin Echo Insight

    Science.gov (United States)

    Perahia, Dvora; Wijesinghe, Sidath; Senanayake, Manjula; Wickramasinghe, Anuradhi; Mohottalalage, Supun S.; Ohl, Michael

    Ionizable blocks in ionomers associate into aggregates serving as physical cross-links and concurrently form transport pathways. The dynamics of ionomers underline their functionality. Incorporating small numbers of ionic groups into polymers significantly constraint their dynamics. Recent computational studies demonstrated a direct correlation between ionic cluster morphology and polymer dynamics. Here using neutron spin echo, we probe the segmental dynamics of polystyrene sulfonate (PSS) as the degree of sulfonation of the PSS and the solution dielectrics are varied. Specifically, 20Wt% PSS of 11,000 g/mol with polydispersity of 1.02 with 3% and 9% sulfonation were studies in toluene (dielectric constant ɛ = 2.8), a good solvent for polystyrene, and with 5Wt% of ethanol (ɛ = 24.3l) added. The dynamic structure factor S(q,t) was analyzed with a single exponential except for a limited q range where two time constants associated with constraint and mobile segments were detected. S(q,t) exhibits several distinctive time and length scales for the dynamics with a crossover appearing at the length scale of the ionic clusters. NSF DMR 1611136.

  9. Usefulness of turbo spin-echo MR imaging in meniscal tears of the knee

    International Nuclear Information System (INIS)

    Jeong, Gun Young; Choi, Chang Lak; Chung, Jin Young; Han, Tae Il; Jang, Hong Im; Kim, Ji Min; Han, Hyun Young; Song, Mun Kab; Yang, Chang Kyu

    1998-01-01

    To evaluate the usefulness and diagnostic accuracy of turbo spin-echo(TSE) proton-density and T2-weighted images of meniscal tears of the knee. We retrospectively evaluated the sensitivity, specificity, and accuracy of TSE proton density and T2-weighted images of meniscal tears confirmed arthroscopically or surgically in 47 patients(98 menisci). The routine TSE parameters used in all patients were the dual echo sequence with sagittal proton density and T2-weighed images(4000/16, 90/5/2 [TR/effectiveTE/ETL/NEX]), and fat-suppressed coronal proton density and T2-weighted images. The chi-square test was used for statistical analysis. The sensitivity, specificity, and accuracy of TSE proton density images for the detection of meniscal tears were 93.9%, 93.8%, and 93.9%, respectively, in the medial meniscus, and 92.9%, 91.4%, and 91.8% in the lateral. On T2-weighted images the corresponding figures were 87.9%, 8%, and 89.8%, respectively, in the medial meniscus, and 64.3%, 91.4%, and 83.7% in the lateral. With regard to sensitivity and accuracy, TSE proton density images of meniscal tears were superior to TSE T2-weighted images.=20

  10. Electron spin echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel

    OpenAIRE

    Cieslak, John A.; Focia, Pamela J.; Gross, Adrian

    2010-01-01

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential ...

  11. Determination of the amounts of C, CH, CH/sub 2/ and CH/sub 3/ fragments by the spin echo method

    Energy Technology Data Exchange (ETDEWEB)

    Polonov, V.M.; Kalabin, G.A.; Kushnarev, D.F.; Latyshev, V.P.

    1984-01-01

    A new method is presented for the quantitative determination of primary, secondary, tertiary and quarternary carbon atoms in soluble coal products. The method is based on pulsed spin echo of /sup 13/C nuclear magnetic resonance.

  12. On the analysis of time-of-flight spin-echo modulated dark-field imaging data

    Science.gov (United States)

    Sales, Morten; Plomp, Jeroen; Bouwman, Wim G.; Tremsin, Anton S.; Habicht, Klaus; Strobl, Markus

    2017-06-01

    Spin-Echo Modulated Small Angle Neutron Scattering with spatial resolution, i.e. quantitative Spin-Echo Dark Field Imaging, is an emerging technique coupling neutron imaging with spatially resolved quantitative small angle scattering information. However, the currently achieved relatively large modulation periods of the order of millimeters are superimposed to the images of the samples. So far this required an independent reduction and analyses of the image and scattering information encoded in the measured data and is involving extensive curve fitting routines. Apart from requiring a priori decisions potentially limiting the information content that is extractable also a straightforward judgment of the data quality and information content is hindered. In contrast we propose a significantly simplified routine directly applied to the measured data, which does not only allow an immediate first assessment of data quality and delaying decisions on potentially information content limiting further reduction steps to a later and better informed state, but also, as results suggest, generally better analyses. In addition the method enables to drop the spatial resolution detector requirement for non-spatially resolved Spin-Echo Modulated Small Angle Neutron Scattering.

  13. On the analysis of time-of-flight spin-echo modulated dark-field imaging data

    International Nuclear Information System (INIS)

    Sales, Morten; Strobl, Markus; Plomp, Jeroen; Bouwman, Wim G.; Tremsin, Anton S.; Habicht, Klaus

    2017-01-01

    Spin-Echo Modulated Small Angle Neutron Scattering with spatial resolution, i.e. quantitative Spin-Echo Dark Field Imaging, is an emerging technique coupling neutron imaging with spatially resolved quantitative small angle scattering information. However, the currently achieved relatively large modulation periods of the order of millimeters are superimposed to the images of the samples. So far this required an independent reduction and analyses of the image and scattering information encoded in the measured data and is involving extensive curve fitting routines. Apart from requiring a priori decisions potentially limiting the information content that is extractable also a straightforward judgment of the data quality and information content is hindered. In contrast we propose a significantly simplified routine directly applied to the measured data, which does not only allow an immediate first assessment of data quality and delaying decisions on potentially information content limiting further reduction steps to a later and better informed state, but also, as results suggest, generally better analyses. In addition the method enables to drop the spatial resolution detector requirement for non-spatially resolved Spin-Echo Modulated Small Angle Neutron Scattering. (paper)

  14. Non magnetic neutron spin quantum precession using multilayer spin splitter and a phase-spin echo interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Ebisawa, T.; Tasaki, S.; Kawai, T.; Akiyoshi, T. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Achiwa, N.; Hino, M.; Otake, Y.; Funahashi, H.

    1996-08-01

    The authors have developed cold neutron optics and interferometry using multilayer mirrors. The advantages of the multilayer mirrors are their applicability to long wavelength neutrons and a great variety of the mirror performance. The idea of the present spin interferometry is based on nonmagnetic neutron spin quantum precession using multilayer spin splitters. The equation for polarized neutrons means that the polarized neutrons are equivalent to the coherent superposition of two parallel spin eigenstates. The structure and principle of a multilayer spin splitter are explained, and the nonmagnetic gap layer of the multilayer spin splitter gives rise to neutron spin quantum precession. The performance test of the multilayer spin splitter were made with a new spin interferometer, which is analogous optically to a spin echo system with vertical precession field. The spin interferometers were installed at Kyoto University research reactor and the JRR-3. The testing method and the results are reported. The performance tests on a new phase-spin echo interferometer are described, and its applications to the development of a high resolution spin echo system and a Jamin type cold neutron interferometer are proposed. (K.I.)

  15. Fat-saturated, contrast-enhanced spin echo sequences in magnetic resonance tomographic diagnosis of peritoneal carcinosis

    International Nuclear Information System (INIS)

    Ricke, J.; Hosten, N.; Stroszczynski, C.; Amthauer, H.; Felix, R.; Sehouli, J.; Buchmann, E.; Rieger, J.

    1999-01-01

    Purpose: To evaluate contrast-enhanced, fat-saturated spin echo sequences for the detection of peritoneal carcinosis with MRI. Material and Methods: 61 patients, 35 with and 26 without peritoneal carcinosis, were examined with abdominal MRI. Fat-saturated, T 1 -weighted spin echo sequences were performed before and after administration of Gd-DTPA. In addition, 22 patients with peritoneal carcinosis were examined with contrast-enhanced abdominal CT. Results: 32 of 35 patients with peritoneal carcinosis demonstrated contrast enhancement of the visceral and 30 to 35 enhancement of the parietal peritoneum (91 and 86%, respectively). Wall thickening of the intestine or parietal peritoneum were noted in 21 and 20 of 35 patients (60 and 57%, respectively), ascites in 18 of 35 patients (51%). False positive contrast enhancement of the peritoneum was noted in 4 of 26 patients (15%). In the direct comparison of MRI and CT, 22 of 22 patients versus 7 of 22 patients showed contrast enhancement of the visceral peritoneum (100 and 32%, respectively). For other signs of peritoneal carcinosis (e.g., ascites, peritoneal seedings), no differences in diagnostic reliability were demonstrated. Conclusions: The use of fat-saturated, spin echo sequences facilitates the diagnosis of peritoneal carcinosis by artifact reduction and improved detection of peritoneal contrast enhancement. MRI with fat-saturated sequences was superior to CT. (orig.) [de

  16. Usefulness of fluid attenuated inversion recovery(FLAIR) image in mesial temporal sclerosis : comparison with turbo spin-echo T2-weighted image

    Energy Technology Data Exchange (ETDEWEB)

    Son, Seok Hyun; Chang, Seung Kuk; Eun, Choong Ki [Pusan Paik Hospital, Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

    1999-12-01

    To determine the usefulness of fluid attenuated inversion recovery(FLAIR) imaging for the in detection of high signal intensity of hippocampus or amygdala in mesial temporal sclerosis (MTS), compared with that of turbo spin-echo T2-weighted imaging. Two neuroradiologists independently analyzed randomly mixed MR images of 20 lesions of 17 patients in whom MTS had been diagnosed, and ten normal controls. All subjects underwent both who performed both FLAIR and turbo spin-echo T2-weighted imaging, in a blind fashion. In order to determine hippocampal morphology, oblique coronal images perpendicular to the long axis of the hippocampus were obtained. The detection rate of high signal intensity in hippocampus or amygdala, the radiologists' preferred imaging sequence, and intersubject consistency of detection were evaluated. Signal intensity in hippocampus or amygdala was considered high if substantially higher than signal intensity in the cortex of adjacent temporo-parietal lobe. In all normal controls, FLAIR and spin-echo T2-weighted images showed normal signal intensity in hippocampus or amygdala. In MTS, the mean detection rate of high signal intensity in hippocampus or amygdala, as seen on FLAIR images was 93%, compared with 43% on spin-echo T2-weighted images. In all cases in which signal intensity on FLAIR images was normal, signal intensity on spin-echo T2-weighted images was also normal. The radiologists preferred the contrast properties of FLAIR to those of spin-echo T2-weighted images. In the diagnosis of MTS using MRI, FLAIR images are more useful for the detection of high signal intensity of hippocampus or amygdala than are spin-echo T2-weighted images. In the diagnosis of MTS, FLAIR imaging is therefore a suitable alternative to spin-echo T2-weighted imaging.

  17. Usefulness of fluid attenuated inversion recovery(FLAIR) image in mesial temporal sclerosis : comparison with turbo spin-echo T2-weighted image

    International Nuclear Information System (INIS)

    Son, Seok Hyun; Chang, Seung Kuk; Eun, Choong Ki

    1999-01-01

    To determine the usefulness of fluid attenuated inversion recovery(FLAIR) imaging for the in detection of high signal intensity of hippocampus or amygdala in mesial temporal sclerosis (MTS), compared with that of turbo spin-echo T2-weighted imaging. Two neuroradiologists independently analyzed randomly mixed MR images of 20 lesions of 17 patients in whom MTS had been diagnosed, and ten normal controls. All subjects underwent both who performed both FLAIR and turbo spin-echo T2-weighted imaging, in a blind fashion. In order to determine hippocampal morphology, oblique coronal images perpendicular to the long axis of the hippocampus were obtained. The detection rate of high signal intensity in hippocampus or amygdala, the radiologists' preferred imaging sequence, and intersubject consistency of detection were evaluated. Signal intensity in hippocampus or amygdala was considered high if substantially higher than signal intensity in the cortex of adjacent temporo-parietal lobe. In all normal controls, FLAIR and spin-echo T2-weighted images showed normal signal intensity in hippocampus or amygdala. In MTS, the mean detection rate of high signal intensity in hippocampus or amygdala, as seen on FLAIR images was 93%, compared with 43% on spin-echo T2-weighted images. In all cases in which signal intensity on FLAIR images was normal, signal intensity on spin-echo T2-weighted images was also normal. The radiologists preferred the contrast properties of FLAIR to those of spin-echo T2-weighted images. In the diagnosis of MTS using MRI, FLAIR images are more useful for the detection of high signal intensity of hippocampus or amygdala than are spin-echo T2-weighted images. In the diagnosis of MTS, FLAIR imaging is therefore a suitable alternative to spin-echo T2-weighted imaging

  18. Optimized set of two-dimensional experiments for fast sequential assignment, secondary structure determination, and backbone fold validation of 13C/15N-labelled proteins

    International Nuclear Information System (INIS)

    Bersch, Beate; Rossy, Emmanuel; Coves, Jacques; Brutscher, Bernhard

    2003-01-01

    NMR experiments are presented which allow backbone resonance assignment, secondary structure identification, and in favorable cases also molecular fold topology determination from a series of two-dimensional 1 H- 15 N HSQC-like spectra. The 1 H- 15 N correlation peaks are frequency shifted by an amount ± ω X along the 15 N dimension, where ω X is the C α , C β , or H α frequency of the same or the preceding residue. Because of the low dimensionality (2D) of the experiments, high-resolution spectra are obtained in a short overall experimental time. The whole series of seven experiments can be performed in typically less than one day. This approach significantly reduces experimental time when compared to the standard 3D-based methods. The here presented methodology is thus especially appealing in the context of high-throughput NMR studies of protein structure, dynamics or molecular interfaces

  19. FINEDAN - an explicit finite-element calculation code for two-dimensional analyses of fast dynamic transients in nuclear reactor technology

    International Nuclear Information System (INIS)

    Adamik, V.; Matejovic, P.

    1989-01-01

    The problems are discussed of nonstationary, nonlinear dynamics of the continuum. A survey is presented of calculation methods in the given area with emphasis on the area of impact problems. A description is presented of the explicit finite elements method and its application to two-dimensional Cartesian and cylindrical configurations. Using the method the explicit calculation code FINEDAN was written which was tested in a series of verification calculations for different configurations and different types of continuum. The main characteristics are presented of the code and of some, of its practical applications. Envisaged trends of the development of the code and its possible applications in the technology of nuclear reactors are given. (author). 9 figs., 4 tabs., 10 refs

  20. T2-Weighted Dixon Turbo Spin Echo for Accelerated Simultaneous Grading of Whole-Body Skeletal Muscle Fat Infiltration and Edema in Patients With Neuromuscular Diseases.

    Science.gov (United States)

    Schlaeger, Sarah; Klupp, Elisabeth; Weidlich, Dominik; Cervantes, Barbara; Foreman, Sarah C; Deschauer, Marcus; Schoser, Benedikt; Katemann, Christoph; Kooijman, Hendrik; Rummeny, Ernst J; Zimmer, Claus; Kirschke, Jan S; Karampinos, Dimitrios C

    2018-04-02

    The assessment of fatty infiltration and edema in the musculature of patients with neuromuscular diseases (NMDs) typically requires the separate performance of T1-weighted and fat-suppressed T2-weighted sequences. T2-weighted Dixon turbo spin echo (TSE) enables the generation of T2-weighted fat- and water-separated images, which can be used to assess both pathologies simultaneously. The present study examines the diagnostic performance of T2-weighted Dixon TSE compared with the standard sequences in 10 patients with NMDs and 10 healthy subjects. Whole-body magnetic resonance imaging was performed including T1-weighted Dixon fast field echo, T2-weighted short-tau inversion recovery, and T2-weighted Dixon TSE. Fatty infiltration and intramuscular edema were rated by 2 radiologists using visual semiquantitative rating scales. To assess intermethod and interrater agreement, weighted Cohen's κ coefficients were calculated. The ratings of fatty infiltration showed high intermethod and high interrater agreement (T1-weighted Dixon fast field echo vs T2-weighted Dixon TSE fat image). The evaluation of edematous changes showed high intermethod and good interrater agreement (T2-weighted short-tau inversion recovery vs T2-weighted Dixon TSE water image). T2-weighted Dixon TSE imaging is an alternative for accelerated simultaneous grading of whole-body skeletal muscle fat infiltration and edema in patients with NMDs.

  1. Clinical utility of partial flip angle T2-weighted spin-echo imaging of the brain

    International Nuclear Information System (INIS)

    Chang, K.H.; Yi, J.G.; Han, M.H.; Han, M.C.; Kim, C.W.; Cho, M.H.; Cho, Z.H.

    1990-01-01

    To assess the clinical usefulness of partial flip angle (PFA) spin-echo (SE) brain imaging, a total of eighty patients were examined with both conventional double echo T2-weighted SE (2500/30, 80/90deg/one excitation) and PFA double echo SE (1200/30, 70/45deg/two excitations) on 2.0T system. Two comparative studies were performed: (1) In 65 patients PFA SE technique was compared with conventional SE without flow compensating gradients, and (2) in 15 patients the former was compared with the latter with flow compensating gradients. Imaging time was nearly identical in each sequence. In both studies we found that PFA T2-weighted SE images were almost identical to those obtained with the conventional SE technique in the contrast characteristics and the detection rate of the abnormalities (100%, 85/85 lesions), and more importantly, PFA SE revealed few flow artifacts in the brain stem, temporal lobes and basal ganglia which were frequently seen on conventional SE without flow compensating gradients. Additionally, PFA SE images demonstrated no suppression of CSF flow void in the aqueduct which was commonly seen on conventional SE with flow compensating gradients. In overall image quality, the PFA SE images, particularly the second echo images, were almost comparable with those of conventional SE with flow compensating gradients. A flip angle of 45deg seems to be close to Ernst angle, the angle at which maximum signal occurs, for a given TR of 1200 msec for CSF and most of the abnormalities containing higher water content. In conclusion, PFA SE sequence (i.e. 1200/30, 70/45deg/2) appears to be useful as a primary or an adjunctive technique in certain clinical circumstances, particularly in imaging of hydrocephalic patients for assessing aqueductal patency. (orig.)

  2. Magnetic resonance urography in pediatrics: utilization of ultrafast single-shot spin echo sequences

    International Nuclear Information System (INIS)

    Martin, C.; Martin, J.; Duran, C.; Rigol, S.; Rojo, J. C.

    1999-01-01

    To determine the value of magnetic resonance urography (MRU) using ultrafast single-shot (SS) rapid acquisition with relaxation enhancement (RARE) and half-Fourier (HF) SS-RARE (SS-HF-RARE or HASTE) in the evaluation of congenital urinary tract anomalies in pediatric patients, and their possible application as alternatives to intravenous urography (IVU). Eighteen children (11 boys and 7 girls) aged 2 months to 15 years (mean: 5 years) with a total of 19 congenital urinary tract anomalies were studies by MU using SS-RARE and HASTE sequences in a 1 Tesla scanner. All the patients had previously been studies by ultrasound (US) and IVU. Twelve patients required anesthesia. The images were acquired by means of a HASTE sequence with multisection technique (TR, infinite; TE e f, 87 msec; echo train, 128; interval between echoes, 10.9 msec; total acquisition time, 13 sections/12 seconds), and SS-RARE (TR, infinite; TE e f, 1.100 msec; echo train, 240, and acquisition time, 7 seconds). Four radiologists evaluated the images independently; two who reviewed the IV images in consensus and two who reviewed the MRU images in consensus. The images were evaluated to assess the dilatation of the urinary tract and their utility in detecting the level and cause of the obstruction. MRU images revealed the urinary tract dilation, the level of the obstruction and the type of anomaly in 18 patients (100%), while IVU provided this information in only 10 [ sensitivity, 53%, 95% confidence interval (29%, 76%)]. The mean time required for MRU was 20 minutes (range: 7 to 30 minutes), while that of IVU was 1,242 minutes (range: 45 to 1,440 minutes). MRU using ultrafast single-short spin echo sequences is a rapid and effective technique that permits and excellent evaluation of congenital urinary tract anomalies in pediatric patients and does not require the administration of contrast media or ionizing radiation. (Author) 10 refs

  3. Partial flip angle spin-echo imaging to obtain T1 weighted images with electrocardiographic gating

    International Nuclear Information System (INIS)

    Kawamitsu, Hideaki; Sugimura, Kazuro; Kasai, Toshifumi; Kimino, Katsuji

    1993-01-01

    ECG-gated spin-echo (SE) imaging can reduce physiologic motion artifact. However, it does not provide strong T 1 -weighted images, because the repetition time (TR) depends on heart rate (HR). For odd-echo SE imaging, T 1 contrast can be maximized by using a smaller flip angle (FA) of initial excitation RF pulses. We investigated the usefulness of partial FA SE imaging in order to obtain more T 1 -dependent contrast with ECG gating and determined the optimal FA at each heart rate. In computer simulation and phantom study, the predicted image contrast and signal-to-noise ratio (SNR) obtained for each FA (0∼180deg) and each HR (55∼90 beats per minute (bpm)) were compared with those obtained with conventional T 1 -weighted SE imaging (TR=500 ms, TE=20 ms, FA=90deg). The optimal FA was decreased by reducing HR. The FA needed to obtain T 1 -dependent contrast identical to that with T 1 -weighted SE imaging was 43deg at a HR of 65 bpm, 53deg at 70 bpm, 60deg at 75 bpm. This predicted FA were in excellent agreement with that obtained with clinical evaluation. The predicted SNR was decreased by reducing FA. The SNR of partial FA SE imaging at HR of 65 bpm (FA=43deg) was 80% of that with conventional T 1 -weighted SE imaging. However, this imaging method presented no marked clinical problem. ECG-gated partial FA SE imaging provides better T 1 -dependent contrast than conventional ECG-gated SE imaging, especially for Gd-DTPA enhanced imaging. (author)

  4. Two-dimensional calculation by finite element method of velocity field and temperature field development in fast reactor fuel assembly. II

    International Nuclear Information System (INIS)

    Schmid, J.

    1985-11-01

    A package of updated computer codes for velocity and temperature field calculations for a fast reactor fuel subassembly (or its part) by the finite element method is described. Isoparametric triangular elements of the second degree are used. (author)

  5. TU-EF-BRA-03: Free Induction Decay (without the Decay) and Spin-Echo Imaging

    International Nuclear Information System (INIS)

    Price, R.

    2015-01-01

    NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm. MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common

  6. TU-EF-BRA-03: Free Induction Decay (without the Decay) and Spin-Echo Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Price, R. [Vanderbilt Medical Center (United States)

    2015-06-15

    NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm. MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common

  7. SLAP tears: diagnosis using 3-T shoulder MR arthrography with the 3D isotropic turbo spin-echo space sequence versus conventional 2D sequences

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joon-Yong; Jee, Won-Hee; Park, Michael Yong [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of); Lee, So-Yeon [Sungkyunkwan University School of Medicine, Department of Radiology, Kangbuk Samsung Hospital, Seoul (Korea, Republic of); Kim, Yang-Soo [The Catholic University of Korea, Department of Orthopaedic Surgery, Seoul St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of)

    2013-02-15

    The aim of this study was to determine the accuracy and reliability of shoulder magnetic resonance (MR) arthrography with three-dimensional (3D) isotropic intermediate-weighted turbo spin-echo (TSE) sampling perfection with application-optimised contrasts using different flip angle evolution (SPACE) in the diagnosis of superior labrum anterior-to-posterior (SLAP) lesions compared with two-dimensional (2D) TSE at 3.0 T. MR arthrograms, including 2D TSE and 3D TSE-SPACE, in 87 patients who underwent arthroscopy were retrospectively analysed by two reviewers for the presence and type of SLAP lesions. Sensitivity and specificity were compared using McNemar's test, and inter-observer agreement was calculated using Cohen's kappa. Receiver operating characteristic (ROC) curve analyses were performed. The mean sensitivity, specificity and accuracy were 90%, 85% and 86% for 2D TSE, and 81%, 86% and 85% for 3D TSE-SPACE respectively, with no statistically significant differences. Inter-observer agreements were substantial in 2D TSE ({kappa} = 0.76) and 3D TSE-SPACE ({kappa} = 0.68). The areas under the ROC curves were 0.92 for 2D TSE and 0.90 for 3D TSE-SPACE, which were not significantly different. MR arthrography with 3D TSE-SPACE showed comparable accuracy and substantial inter-observer agreement for the diagnosis of SLAP lesions circle MR arthrography is regarded as the definitive method of shoulder imaging circle Different MR sequences are evolving for SLAP lesions circle 3D TSE-SPACE demonstrated comparable overall accuracy to 2D TSE for SLAP lesions. (orig.)

  8. MR imaging of articular cartilage : comparison of magnetization transfer contrast and fat-suppression in multiplanar and 3D gradient-echo, spin-echo, turbo spin-echo techniques

    International Nuclear Information System (INIS)

    Lee, Young Joon; Joo, Eun Young; Eun, Choong Ki

    1999-01-01

    The purpose of this study was to evaluate the effects of magnetization transfer contrast(MTC) and fat-suppression(FS) in variable spin-echo and gradient-echo sequences for articular cartilage imaging and to determine the optimal pulse sequences. Using variable 7-pulse sequences, the knees of 15 pigs were imaged Axial images were obtained using proton density and T2-weighted spin-echo (PDWSE and T2WSE), turbo spin-echo (TSE), multiplanar gradient-echo (MPGR), and 3D steady-state gradient-echo (3DGRE) sequences, and the same pulse sequences were then repeated using MTC. Also T1-weighted spin-echo(T1WSE) and 3D spoiled gradient-echo(3DSPGR) images of knees were also acquired, and the procedure was repeated using FS. For each knee, a total of 14 axial images were acquired, and using a 6-band scoring system, the visibility of and the visibilities of the the articular cartilage was analyzed. The visual effect of MTC and FS was scored using a 4-band scale. For each image, the signal intensities of articular cartilage, subchondral bone, muscles, and saline were measured, and signal-to-noise ratios(SNR) and contrast-to-noise ratios(CNR) were also calculated. Visibility of the cartilage was best when 3DSPGR and T1WSE sequences were used. MTC imaging increased the negative contrast between cartilage and saline, but FS imaging provided more positive contrast. CNR between cartilage and saline was highest when using TSE with FS(-351.1±15.3), though CNR between cartilage and bone then fell to -14.7±10.8. In MTC imaging using MPGR showed the greatest increase of negative contrast between cartilage and saline(CNR change=-74.7); the next highest was when 3DGRE was used(CNR change=-34.3). CNR between cartilage and bone was highest with MPGR(161.9±17.7), but with MTC, the greatest CNR decrease(-81.8) was observed. The greatest CNR increase between cartilage and bone was noted in T1WSE with FS. In all scans, FS provided a cartilage-only positive contrast image, though the absolute

  9. Endometrial cancer: preoperative staging using three-dimensional T2-weighted turbo spin-echo and diffusion-weighted MR imaging at 3.0 T: a prospective comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Masatoshi; Kim, Tonsok; Onishi, Hiromitsu; Nakamoto, Atsushi; Tomiyama, Noriyuki [Osaka University Graduate School of Medicine, Department of Radiology, Suita, Osaka (Japan); Imaoka, Izumi; Kagawa, Yuki; Murakami, Takamichi [Kinki University School of Medicine, Department of Radiology, Osaka (Japan); Ueguchi, Takashi; Tatsumi, Mitsuaki [Osaka University Hospital, Department of Radiology, Osaka (Japan); Enomoto, Takayuki [Osaka University Graduate School of Medicine, Department of Obstetrics and Gynecology, Osaka (Japan); Niigata University School of Medicine, Department of Obstetrics and Gynecology, Niigata (Japan); Kimura, Tadashi [Osaka University Graduate School of Medicine, Department of Obstetrics and Gynecology, Osaka (Japan)

    2013-08-15

    To prospectively assess the efficacy of 3-T magnetic resonance (MR) imaging using the three-dimensional turbo spin-echo T2-weighted and diffusion-weighted technique (3D-TSE/DW) compared with that of conventional imaging using the two-dimensional turbo spin-echo T2-weighted and dynamic contrast-enhanced technique (2D-TSE/DCE) for the preoperative staging of endometrial cancer, with pathological analysis as the reference standard. Seventy-one women with endometrial cancer underwent MR imaging using 3D-TSE/DW (b = 1,000 s/mm{sup 2}) and 2D-TSE/DCE. Two radiologists independently assessed the two imaging sets. Accuracy, sensitivity, and specificity for staging were analysed with the McNemar test; the areas under the receiver operating characteristic curve (Az) were compared with a univariate z-score test. The results for assessing deep myometrial invasion, accuracy, sensitivity, specificity and Az, respectively, were as follows: 3D-TSE/DW - observer 1, 87 %, 95 %, 85 % and 0.96; observer 2, 92 %, 84 %, 94 % and 0.95; 2D-TSE/DCE - observer 1, 80 %, 79 %, 81 % and 0.89; observer 2, 86 %, 84 %, 87 % and 0.86. Most of the values were higher with 3D-TSE/DW without significant differences (P > 0.12). For assessing cervical stromal invasion, there were no significant differences in those values for both observers (P > 0.6). Accuracy of 3D-TSE/DW was at least equivalent to that of the conventional technique for the preoperative assessment of endometrial cancer. (orig.)

  10. Diffusional behavior of n-paraffins with various chain lengths in urea adduct channels by pulsed field-gradient spin-echo NMR spectroscopy

    International Nuclear Information System (INIS)

    Kim, Sunmi; Kuroki, Shigeki; Ando, Isao

    2006-01-01

    The diffusion coefficients (D) of n-paraffin molecules (n-C n H 2n+2 ) with various chain-lengths (n = 8, 12, 21, 26, 28 and 32) in the long channels of a deuterated urea-d 4 adduct have been measured at 25 deg. C by means of pulsed field-gradient spin-echo 1 H NMR method. The aim is to clarify diffusional behavior of the n-paraffin molecules in the urea adduct channels. From the experimental results, it is found that n-paraffin molecules are diffusing in the long channels and have two kinds of diffusion components, namely a fast (D ∼ 10 -10 m 2 /s) and a slow diffusion component (D ∼ 10 -11 m 2 /s). The diffusing-time (Δ) dependence of the diffusion coefficients of the n-paraffins shows some likely evidence of restricted diffusion since the n-paraffin molecules are confined in the urea channel. The diffusion coefficients (D) decrease as the carbon number increases from 8 to 28, and very slowly decreases as the carbon number increases from 28 to 32

  11. Fast comprehensive two-dimensional gas chromatography method for fatty acid methyl ester separation and quantification using dual ionic liquid columns.

    Science.gov (United States)

    Nosheen, Asia; Mitrevski, Blagoj; Bano, Asghari; Marriott, Philip J

    2013-10-18

    Safflower oil is a complex mixture of C18 saturated and unsaturated fatty acids amongst other fatty acids, and achieving separation between these similar structure components using one dimensional gas chromatography (GC) may be difficult. This investigation aims to obtain improved separation of fatty acid methyl esters in safflower oil, and their quantification using comprehensive two-dimensional GC (GC×GC). Here, GC×GC separation is accomplished by the coupling of two ionic liquid (IL) column phases: the combination of SLB-IL111 with IL59 column phases was finally selected since it provided excellent separation of a FAME standard mixture, as well as fatty acids in safflower and linseed oil, compared to other tested column sets. Safflower oil FAME were well separated in a short run of 16min. FAME validation was demonstrated by method reproducibility, linearity over a range up to 500mgL(-1), and limits of detection which ranged from 1.9mgL(-1) to 5.2mgL(-1) at a split ratio of 20:1. Quantification was carried out using two dilution levels of 200-fold for major components and 20-fold for trace components. The fatty acids C15:0 and C17:0 were not reported previously in safflower oil. The SLB-IL111/IL59 column set proved to be an effective and novel configuration for separation and quantification of vegetable and animal oil fatty acids. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Measurement of vortex motion in a type-II superconductor: A novel use of the neutron spin-echo technique

    Science.gov (United States)

    Forgan; Kealey; Johnson; Pautrat; Simon; Lee; Aegerter; Cubitt; Farago; Schleger

    2000-10-16

    We have used the neutron spin-echo technique to measure the small energy change of neutrons which are diffracted by a moving vortex lattice in a low-pinning Nb-Ta superconducting sample. A transport current was passed in the mixed state to cause flux line movement. In the case of uniform motion, the flux velocity v(L) was given as expected by the values of electric and magnetic fields, via E = -v(L)wedgeB. We show that with a nonuniformly moving vortex lattice, one can measure the dispersion of the velocities, opening up new possibilities for investigating moving vortex lines.

  13. Rabi oscillation and electron-spin-echo envelope modulation of the photoexcited triplet spin system in silicon

    Science.gov (United States)

    Akhtar, Waseem; Sekiguchi, Takeharu; Itahashi, Tatsumasa; Filidou, Vasileia; Morton, John J. L.; Vlasenko, Leonid; Itoh, Kohei M.

    2012-09-01

    We report on a pulsed electron paramagnetic resonance (EPR) study of the photoexcited triplet state (S=1) of oxygen-vacancy centers in silicon. Rabi oscillations between the triplet sublevels are observed using coherent manipulation with a resonant microwave pulse. The Hahn echo and stimulated echo decay profiles are superimposed with strong modulations known as electron-spin-echo envelope modulation (ESEEM). The ESEEM spectra reveal a weak but anisotropic hyperfine coupling between the triplet electron spin and a 29Si nuclear spin (I=1/2) residing at a nearby lattice site, that cannot be resolved in conventional field-swept EPR spectra.

  14. Electron spin echo study of the E'-center phase relaxation in γ-irradiated quartz glass

    International Nuclear Information System (INIS)

    Dudkin, V.I.; Petrun'kin, V.Yu.; Rubinov, S.V.; Uspenskij, L.I.

    1986-01-01

    Experimental studies of phase relaxation of E'-centres in γ-irradiated quartz glass are conducted by the method of electron spin echo (ESE) for different concentrations of paramagnetic centres. Contribution of mechanisms of spectral and prompt diffusion to kinetics of amplitude drop of echo signal is proved to reduce with growth of delay time between exciting microwave pulse that results in increase of phase memory time at large delays. The mentioned property can be used in electric controlled delay lines on the base of ESE

  15. A case of Marchiafava-Bignami disease: MRI findings on spin-echo and fluid attenuated inversion recovery (FLAIR) images

    International Nuclear Information System (INIS)

    Yamamoto, Takashi; Ashikaga, Ryuichiro; Araki, Yutaka; Nishimura, Yasumasa

    2000-01-01

    Marchiafava-Bignami disease (MBD) was diagnosed in a 56-year-old man. Spin-echo (SE) magnetic resonance imaging (MRI) at the acute phase showed normal signal areas in the central layer of the corpus callosum (CC), although the intensity of these areas revealed abnormal hyperintensity on fluid attenuated inversion recovery (FLAIR). On follow-up SE MRI at the late phase, the central layer of the CC showed fluid-like intensity. On FLAIR MRI, the lesions of the CC turned into hypointense cores surrounded by hyperintense rims indicating central necrosis and peripheral demyelination. Degenerative changes of the CC in MBD were clearly demonstrated by FLAIR MRI

  16. Whole heart cine MR imaging of pulmonary veins in patients with congenital heart disease. Comparison with Spin Echo MR imaging

    International Nuclear Information System (INIS)

    Mitsui, Hideaki; Saito, Haruo; Ishibashi, Tadashi; Takahashi, Shoki; Zuguchi, Masayuki; Yamada, Shogo

    2002-01-01

    We evaluated the accuracy of Whole Heart Cine (WHC) magnetic resonance (MR) imaging in the depiction of pulmonary veins (PVs) in patients with congenital heart disease (CHD) compared to that of spin echo (SE) MR imaging. Among our 35 patients, 4 patients had anomalous PV return. Detectability of four PVs on each MR examination images were evaluated. MR imaging is an effective modality for the clarification of PVs, and WHC MR imaging is more useful in delineating PV anomalies than SE MR imaging. (author)

  17. Comparison of three dimensional isotropic and two dimensional conventional indirect MR arthrography for the diagnosis of rotator cuff tears

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Hyun; Yoon, Young Cheol; Kwon, Jong Won; Yoo, Jae Chul [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Cha, Jang Kyu [Dept. of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon (Korea, Republic of); Jee, Suk Kyoung [Joeun Madi Hospital, Seoul (Korea, Republic of)

    2014-12-15

    To compare the accuracy between a three-dimensional (3D) indirect isotropic T1-weighted fast spin-echo (FSE) magnetic resonance (MR) arthrography and a conventional two-dimensional (2D) T1-weighted sequences of indirect MR arthrography for diagnosing rotator cuff tears. The study was approved by our Institutional Review Board. In total, 205 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery for 206 shoulders were included in this study. Both conventional 2D T1-weighted FSE sequences and 3D isotropic T1-weighted FSE sequence were performed in all patients. Two radiologists evaluated the images for the presence of full- or partial-thickness tears in the supraspinatus-infraspinatus (SSP-ISP) tendons and tears in the subscapularis (SSC) tendons. Using the arthroscopic findings as the reference standard, the diagnostic performances of both methods were analyzed by the area under the receiver operating characteristic curve (AUC). Arthroscopy confirmed 165 SSP-ISP tendon tears and 103 SSC tendon tears. For diagnosing SSP-ISP tendon tears, the AUC values were 0.964 and 0.989 for the 2D sequences and 3D T1-weighted FSE sequence, respectively, in reader I and 0.947 and 0.963, respectively, in reader II. The AUC values for diagnosing SSC tendon tears were 0.921 and 0.925, respectively, for reader I and 0.856 and 0.860, respectively, for reader II. There was no significant difference between the AUC values of the 2D and 3D sequences in either reader for either type of tear. 3D indirect isotropic MR arthrography with FSE sequence and the conventional 2D arthrography are not significantly different in terms of accuracy for diagnosing rotator cuff tears.

  18. Comparison of three dimensional isotropic and two dimensional conventional indirect MR arthrography for the diagnosis of rotator cuff tears

    International Nuclear Information System (INIS)

    Lee, Ji Hyun; Yoon, Young Cheol; Kwon, Jong Won; Yoo, Jae Chul; Cha, Jang Kyu; Jee, Suk Kyoung

    2014-01-01

    To compare the accuracy between a three-dimensional (3D) indirect isotropic T1-weighted fast spin-echo (FSE) magnetic resonance (MR) arthrography and a conventional two-dimensional (2D) T1-weighted sequences of indirect MR arthrography for diagnosing rotator cuff tears. The study was approved by our Institutional Review Board. In total, 205 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery for 206 shoulders were included in this study. Both conventional 2D T1-weighted FSE sequences and 3D isotropic T1-weighted FSE sequence were performed in all patients. Two radiologists evaluated the images for the presence of full- or partial-thickness tears in the supraspinatus-infraspinatus (SSP-ISP) tendons and tears in the subscapularis (SSC) tendons. Using the arthroscopic findings as the reference standard, the diagnostic performances of both methods were analyzed by the area under the receiver operating characteristic curve (AUC). Arthroscopy confirmed 165 SSP-ISP tendon tears and 103 SSC tendon tears. For diagnosing SSP-ISP tendon tears, the AUC values were 0.964 and 0.989 for the 2D sequences and 3D T1-weighted FSE sequence, respectively, in reader I and 0.947 and 0.963, respectively, in reader II. The AUC values for diagnosing SSC tendon tears were 0.921 and 0.925, respectively, for reader I and 0.856 and 0.860, respectively, for reader II. There was no significant difference between the AUC values of the 2D and 3D sequences in either reader for either type of tear. 3D indirect isotropic MR arthrography with FSE sequence and the conventional 2D arthrography are not significantly different in terms of accuracy for diagnosing rotator cuff tears.

  19. A combined finite element-boundary integral formulation for solution of two-dimensional scattering problems via CGFFT. [Conjugate Gradient Fast Fourier Transformation

    Science.gov (United States)

    Collins, Jeffery D.; Volakis, John L.; Jin, Jian-Ming

    1990-01-01

    A new technique is presented for computing the scattering by 2-D structures of arbitrary composition. The proposed solution approach combines the usual finite element method with the boundary-integral equation to formulate a discrete system. This is subsequently solved via the conjugate gradient (CG) algorithm. A particular characteristic of the method is the use of rectangular boundaries to enclose the scatterer. Several of the resulting boundary integrals are therefore convolutions and may be evaluated via the fast Fourier transform (FFT) in the implementation of the CG algorithm. The solution approach offers the principal advantage of having O(N) memory demand and employs a 1-D FFT versus a 2-D FFT as required with a traditional implementation of the CGFFT algorithm. The speed of the proposed solution method is compared with that of the traditional CGFFT algorithm, and results for rectangular bodies are given and shown to be in excellent agreement with the moment method.

  20. Spectral narrowing and spin echo for localized carriers with heavy-tailed L evy distribution of hopping times

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Z. [Univ. of Utah, Salt Lake City, UT (United States); Mkhitaryan, Vagharsh [Ames Lab. and Iowa State Univ., Ames, IA (United States); Raikh, M. E. [Univ. of Utah, Salt Lake City, UT (United States)

    2016-02-02

    We study analytically the free induction decay and the spin echo decay originating from the localized carriers moving between the sites which host random magnetic fields. Due to disorder in the site positions and energies, the on-site residence times, , are widely spread according to the L evy distribution. The power-law tail ∝ τ-1-∝ in the distribution of does not affect the conventional spectral narrowing for α > 2, but leads to a dramatic acceleration of the free induction decay in the domain 2 > α > 1. The next abrupt acceleration of the decay takes place as becomes smaller than 1. In the latter domain the decay does not follow a simple-exponent law. To capture the behavior of the average spin in this domain, we solve the evolution equation for the average spin using the approach different from the conventional approach based on the Laplace transform. Unlike the free induction decay, the tail in the distribution of the residence times leads to the slow decay of the spin echo. The echo is dominated by realizations of the carrier motion for which the number of sites, visited by the carrier, is minimal.

  1. One and two-dimensional electrophoresis of fast axonally-transported proteins in rat nerves following acrylamide and 2,5-hexanedione exposure

    International Nuclear Information System (INIS)

    Sickles, D.W.

    1990-01-01

    Transient and repeated deficiencies in protein delivery to the axon are observed following injections of acrylamide (ACR) and 2,5-hexanedione (2,5-HD) (Sickles DW, Neurotoxicology 10: 91;103, 1989; Neurosci Abstr 14:1219, 1988). We have furthered these studies by measuring the effects of single 50 mg/kg ACR and 4 nmole/kg 2,5-HD injections on the quantity of select fast-transported proteins. Proteins were radiolabelled with 3H-leucine injections of the DRG; 1 and 2 dimensional gels were used for separation of the sciatic nerve (9-45mm distal to the ganglion) homogenates. Scintillation counting demonstrated that transport of all proteins studied were affected by both toxicants. Some variation in effect was observed; a direct correlation between molecular weight (r=0.71) and original quantity of radiolabel (r=0.80) with the percent reduction in transport was observed. Some apparent increases in transport of certain proteins were observed on the 2D gels; but this may indicate a change in the isoelectric points of these transported proteins

  2. Coherent Two-Dimensional Terahertz Magnetic Resonance Spectroscopy of Collective Spin Waves.

    Science.gov (United States)

    Lu, Jian; Li, Xian; Hwang, Harold Y; Ofori-Okai, Benjamin K; Kurihara, Takayuki; Suemoto, Tohru; Nelson, Keith A

    2017-05-19

    We report a demonstration of two-dimensional (2D) terahertz (THz) magnetic resonance spectroscopy using the magnetic fields of two time-delayed THz pulses. We apply the methodology to directly reveal the nonlinear responses of collective spin waves (magnons) in a canted antiferromagnetic crystal. The 2D THz spectra show all of the third-order nonlinear magnon signals including magnon spin echoes, and 2-quantum signals that reveal pairwise correlations between magnons at the Brillouin zone center. We also observe second-order nonlinear magnon signals showing resonance-enhanced second-harmonic and difference-frequency generation. Numerical simulations of the spin dynamics reproduce all of the spectral features in excellent agreement with the experimental 2D THz spectra.

  3. Assessment of the characteristics of MRI coils in terms of RF non-homogeneity using routine spin echo sequences

    International Nuclear Information System (INIS)

    Oghabian, M. A.; Mehdipour, Sh.; RiahicAlam, N.; Rafie, B.; Ghanaati, H.

    2005-01-01

    One of the major causes of image non-uniformity in MRI is due to the existence of non-homogeneity in RF receive and transmit. This can be the most effective source of error in quantitative studies in MRI imaging. Part of this non-homogeneity demonstrates the characteristics of RF coil and part of it is due to the interaction of RF field with the material being imaged. In this study, RF field non-homogeneity of surface and volume coils is measured using an oil phantom. The method employed in this work is based on a routine Spin Echo based sequence as proposed by this group previously. Materials and Methods: For the determination of RF non-uniformity, a method based on Spin Echo sequence (8θ-180) was used as reported previously by the same author. In this method, several images were obtained from one slice using different flip angles while keeping all other imaging parameters constant. Then, signal intensity at a ROI from all of these images were measured and fitted to the MRI defined mathematical model. Since this mathematical model describes the relation between signal intensity and flip angle in a (8θ-180) Spin Echo sequence, it is possible to obtain the variation in receive and transmit sensitivity in terms of the variation of signal intensity from the actual expected values. Since surface coils are functioning as only receiver (RF transmission is done by Body coil), first the results of receive coil homogeneity is measured, then characteristic of transmit coil (for the body coil) is evaluated Results: The coefficient of variation (C.V.) found for T(r) value obtained from images using head coils was in the order of 0.6%. Since the head coil is functioning as both transmitter and receiver, any non-uniformity in either transmit or receive stage can lead to non-homogeneity in RF field. A part from the surface coils, the amount of non-homogeneity due to receive coil was less than that of the transmit coil. In the case of the surface coils the variation in receive

  4. Fast spine echo and fast fluid attenuated inversion recovery sequences in multiple sclerosis

    International Nuclear Information System (INIS)

    Paolillo, Andrea; Giugni, Elisabetta; Bozzao, Alessandro; Bastianello, Stefano

    1997-01-01

    Fast spin echo (FSE) and fast fluid attenuated inversion recovery (fast-FLAIR) sequences, were compared with conventional spin echo (CSE) in quantitating multiple sclerosis (MS) lesion burden. For each sequence, the total number and volume of MS lesions were calculated in 38 remitting multiple sclerosis patients using a semiautomated lesion detection program. Conventional spin echo, fast spin echo, and fast fluid attenuated inversion recovery image were reported on randomly and at different times by two expert observers. Interobserver differences, the time needed to quantitative multiple sclerosis lesions and lesion signal intensity (contrast-to-noise ratio and overall contrast) were considered. The lesions were classified by site into infratentorial, white matter and cortical/subcortical. A total of 2970 lesions with a volume of 961.7 cm 3 was calculated on conventional spin echo images. Fast spin echo images depicted fewer (16.6%; p < .005) and smaller (24.9%; p < .0001) lesions and the differences were statistically significant. Despite an overall nonsignificant reduction for fast-FLAIR images (-5% and 4.8% for lesion number and volume, respectively), significantly lower values (lesion number: p < 0.1; volume: p < .04)were observed for infratentorial lesions, while significantly higher values were seen for cortical/subcortical lesions (lesion number: p < .01; volume: p < .02). A higher lesion/white matter contrast (p < .002), a significant time saving for lesion burden quantitation (p < .05) and very low interobserver variability were found in favor of fast-FLAIR. Our data suggest that, despite the limitations regarding infratentorial lesions, fast-FLAIR sequences are indicated in R studies because of their good identification of cortical/subcortical lesions, almost complete interobserver agreement, higher contrast-to-noise ratio and limited time needed for semiautomated quantitation

  5. Spin-echo small-angle neutron scattering study of the structure organization of the chromatin in biological cell

    International Nuclear Information System (INIS)

    Iashina, E G; Grigoriev, S V; Bouwman, W G; Duif, C P; Filatov, M V

    2017-01-01

    Spin-echo small-angle scattering (SESANS) technique is a method to measure the structure of materials from nano- to micrometer length scales. This method could be important for studying the packaging of DNA in the eukaryotic cell. We measured the SESANS function from chicken erythrocyte nuclei which is well fitted by the exponential function G ( z ) = exp(− z / ξ ), where ξ is the correlation length of a nucleus (in experimental data ξ = 3, 3 μ m). The exponential decay of G ( z ) corresponds to the logarithmic pair correlation function γ ( r ) = ln( ξ / r ). As the sensitivity of the SESANS signal depends on the neutron wavelength, we propose the SESANS setup with the changeable wavelength in the range from 2 to 12 Å. Such option allows one to study in great detail the internal structure of the biological cell in the length scale from 10 −2 μ m to 10 μ m. (paper)

  6. Spin-echo small-angle neutron scattering study of the structure organization of the chromatin in biological cell

    Science.gov (United States)

    Iashina, E. G.; Bouwman, W. G.; Duif, C. P.; Filatov, M. V.; Grigoriev, S. V.

    2017-06-01

    Spin-echo small-angle scattering (SESANS) technique is a method to measure the structure of materials from nano- to micrmeter length scales. This method could be important for studying the packaging of DNA in the eukaryotic cell. We measured the SESANS function from chicken erythrocyte nuclei which is well fitted by the exponential function G(z) = exp(-z/ξ), where ξ is the correlation length of a nucleus (in experimental data ξ = 3, 3 μm). The exponential decay of G(z) corresponds to the logarithmic pair correlation function γ(r) = ln(ξ/r). As the sensitivity of the SESANS signal depends on the neutron wavelength, we propose the SESANS setup with the changeable wavelength in the range from 2 to 12 Å. Such option allows one to study in great detail the internal structure of the biological cell in the length scale from 10-2 μm to 10 μm.

  7. Propagation of error from parameter constraints in quantitative MRI: Example application of multiple spin echo T2 mapping.

    Science.gov (United States)

    Lankford, Christopher L; Does, Mark D

    2018-02-01

    Quantitative MRI may require correcting for nuisance parameters which can or must be constrained to independently measured or assumed values. The noise and/or bias in these constraints propagate to fitted parameters. For example, the case of refocusing pulse flip angle constraint in multiple spin echo T 2 mapping is explored. An analytical expression for the mean-squared error of a parameter of interest was derived as a function of the accuracy and precision of an independent estimate of a nuisance parameter. The expression was validated by simulations and then used to evaluate the effects of flip angle (θ) constraint on the accuracy and precision of T⁁2 for a variety of multi-echo T 2 mapping protocols. Constraining θ improved T⁁2 precision when the θ-map signal-to-noise ratio was greater than approximately one-half that of the first spin echo image. For many practical scenarios, constrained fitting was calculated to reduce not just the variance but the full mean-squared error of T⁁2, for bias in θ⁁≲6%. The analytical expression derived in this work can be applied to inform experimental design in quantitative MRI. The example application to T 2 mapping provided specific cases, depending on θ⁁ accuracy and precision, in which θ⁁ measurement and constraint would be beneficial to T⁁2 variance or mean-squared error. Magn Reson Med 79:673-682, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  8. Qualitative characteristics and comparison of volatile fraction of vodkas made from different botanical materials by comprehensive two-dimensional gas chromatography and the electronic nose based on the technology of ultra-fast gas chromatography.

    Science.gov (United States)

    Wiśniewska, Paulina; Śliwińska, Magdalena; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek

    2017-03-01

    Vodka is a spirit-based beverage made from ethyl alcohol of agricultural origin. At present, increasingly more vodka brands have labels that specify the botanical origin of the product. Until now, the techniques for distinguishing between vodkas of different botanical origin have been costly, time-consuming and insufficient for making a distinction between vodka produced from similar raw materials. Therefore, it is of utmost importance to find a fast and relatively inexpensive technique for conducting such tests. In the present study, we employed comprehensive two-dimensional gas chromatography (GC×GC) and an electronic nose based on the technology of ultra-fast GC with chemometric methods such as partial least square discriminant analysis, discriminant function analysis and soft independent modeling of class analogy. Both techniques allow a distinction between the vodkas produced from different raw materials. In the case of GC×GC, the differences between vodkas were more noticeable than in the analysis by electronic nose; however, the electronic nose allowed the significantly faster analysis of vodkas. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  9. Fast Computation Methods Research for Two Dimensional MUSIC Spectrum Based on Circular Array%圆阵二维 MUSIC 谱快速计算方法研究

    Institute of Scientific and Technical Information of China (English)

    杜政东; 魏平; 赵菲; 尹文禄

    2015-01-01

    针对二维波达方向估计时 MUSIC 谱的快速计算问题,研究了均匀圆阵变换到虚拟线阵的 MUSIC 算法(UCA-ULA-MUSIC)、流形分离 MUSIC 算法(MS-MUSIC)、傅立叶域线性求根 MUSIC 算法(FD-Line-Search-MU-SIC)、基于 FFT 的2n 元均匀圆阵 MUSIC 算法(2n-UCA-FFT-MUSIC)与基于 FFT 的任意圆阵 MUSIC 算法(ACA-FFT-MUSIC)。对各种算法快速计算二维 MUSIC 谱的实现步骤进行了总结。在此基础上,给出了各算法计算二维MUSIC 谱的计算复杂度表达式,并以传统方法为参考,对比了各种快速算法相对于传统方法的计算复杂度比值;同时,针对不同的阵列形式,对适用的快速算法的测向性能进行了仿真对比。根据分析和对比的结果,指出 MS-MUSIC 算法与 ACA-FFT-MUSIC 算法具有更高的工程应用价值,由具体的情况单独或分频段联合使用 MS-MUSIC算法与 ACA-FFT-MUSIC 算法,可以使测向系统较好的兼顾测向性能与时效性。%According to the fast computation problem of MUSIC spectrum in two dimensional direction of arrival estimation, the fast algorithms by manifold transformation or spectrum function transformation are studied.The implementation steps of computation method for two dimensional MUSIC spectrum by these algorithms are summarized.Furthermore,expressions for computational complexity of discussed algorithms in computing two dimensional MUSIC spectrum are presented.With refer-ence to the conventional method,the ratio of computational complexity of discussed algorithms is compared.Meanwhile,for different circular arrays,the direction finding performance of applicable algorithms is compared by simulation.It is proved that the MUSIC algorithm based on Manifold Separation (MS-MUSIC)and Fast Fourier Transformation (FFT)which suits to arbitrary circular array (ACA-FFT-MUSIC)have higher engineering value according to the results of analysis and com-parison.The performance and

  10. Two-dimensional NMR spectrometry

    International Nuclear Information System (INIS)

    Farrar, T.C.

    1987-01-01

    This article is the second in a two-part series. In part one (ANALYTICAL CHEMISTRY, May 15) the authors discussed one-dimensional nuclear magnetic resonance (NMR) spectra and some relatively advanced nuclear spin gymnastics experiments that provide a capability for selective sensitivity enhancements. In this article and overview and some applications of two-dimensional NMR experiments are presented. These powerful experiments are important complements to the one-dimensional experiments. As in the more sophisticated one-dimensional experiments, the two-dimensional experiments involve three distinct time periods: a preparation period, t 0 ; an evolution period, t 1 ; and a detection period, t 2

  11. Quasi-two-dimensional holography

    International Nuclear Information System (INIS)

    Kutzner, J.; Erhard, A.; Wuestenberg, H.; Zimpfer, J.

    1980-01-01

    The acoustical holography with numerical reconstruction by area scanning is memory- and time-intensive. With the experiences by the linear holography we tried to derive a scanning for the evaluating of the two-dimensional flaw-sizes. In most practical cases it is sufficient to determine the exact depth extension of a flaw, whereas the accuracy of the length extension is less critical. For this reason the applicability of the so-called quasi-two-dimensional holography is appropriate. The used sound field given by special probes is divergent in the inclined plane and light focussed in the perpendicular plane using cylindrical lenses. (orig.) [de

  12. Two-dimensional metamaterial optics

    International Nuclear Information System (INIS)

    Smolyaninov, I I

    2010-01-01

    While three-dimensional photonic metamaterials are difficult to fabricate, many new concepts and ideas in the metamaterial optics can be realized in two spatial dimensions using planar optics of surface plasmon polaritons. In this paper we review recent progress in this direction. Two-dimensional photonic crystals, hyperbolic metamaterials, and plasmonic focusing devices are demonstrated and used in novel microscopy and waveguiding schemes

  13. Can a single-shot black-blood T2-weighted spin-echo echo-planar imaging sequence with sensitivity encoding replace the respiratory-triggered turbo spin-echo sequence for the liver? An optimization and feasibility study.

    Science.gov (United States)

    Hussain, Shahid M; De Becker, Jan; Hop, Wim C J; Dwarkasing, Soendersing; Wielopolski, Piotr A

    2005-03-01

    To optimize and assess the feasibility of a single-shot black-blood T2-weighted spin-echo echo-planar imaging (SSBB-EPI) sequence for MRI of the liver using sensitivity encoding (SENSE), and compare the results with those obtained with a T2-weighted turbo spin-echo (TSE) sequence. Six volunteers and 16 patients were scanned at 1.5T (Philips Intera). In the volunteer study, we optimized the SSBB-EPI sequence by interactively changing the parameters (i.e., the resolution, echo time (TE), diffusion weighting with low b-values, and polarity of the phase-encoding gradient) with regard to distortion, suppression of the blood signal, and sensitivity to motion. The influence of each change was assessed. The optimized SSBB-EPI sequence was applied in patients (N = 16). A number of items, including the overall image quality (on a scale of 1-5), were used for graded evaluation. In addition, the signal-to-noise ratio (SNR) of the liver was calculated. Statistical analysis was carried out with the use of Wilcoxon's signed rank test for comparison of the SSBB-EPI and TSE sequences, with P = 0.05 considered the limit for significance. The SSBB-EPI sequence was improved by the following steps: 1) less frequency points than phase-encoding steps, 2) a b-factor of 20, and 3) a reversed polarity of the phase-encoding gradient. In patients, the mean overall image quality score for the optimized SSBB-EPI (3.5 (range: 1-4)) and TSE (3.6 (range: 3-4)), and the SNR of the liver on SSBB-EPI (mean +/- SD = 7.6 +/- 4.0) and TSE (8.9 +/- 4.6) were not significantly different (P > .05). Optimized SSBB-EPI with SENSE proved to be feasible in patients, and the overall image quality and SNR of the liver were comparable to those achieved with the standard respiratory-triggered T2-weighted TSE sequence. (c) 2005 Wiley-Liss, Inc.

  14. Optimized two-dimensional Sn transport (BISTRO)

    International Nuclear Information System (INIS)

    Palmiotti, G.; Salvatores, M.; Gho, C.

    1990-01-01

    This paper reports on an S n two-dimensional transport module developed for the French fast reactor code system CCRR to optimize algorithms in order to obtain the best performance in terms of computational time. A form of diffusion synthetic acceleration was adopted, and a special effort was made to solve the associated diffusion equation efficiently. The improvements in the algorithms, along with the use of an efficient programming language, led to a significant gain in computational time with respect to the DOT code

  15. Anomalous diffusion measured by a twice-refocused spin echo pulse sequence: analysis using fractional order calculus.

    Science.gov (United States)

    Gao, Qing; Srinivasan, Girish; Magin, Richard L; Zhou, Xiaohong Joe

    2011-05-01

    To theoretically develop and experimentally validate a formulism based on a fractional order calculus (FC) diffusion model to characterize anomalous diffusion in brain tissues measured with a twice-refocused spin-echo (TRSE) pulse sequence. The FC diffusion model is the fractional order generalization of the Bloch-Torrey equation. Using this model, an analytical expression was derived to describe the diffusion-induced signal attenuation in a TRSE pulse sequence. To experimentally validate this expression, a set of diffusion-weighted (DW) images was acquired at 3 Tesla from healthy human brains using a TRSE sequence with twelve b-values ranging from 0 to 2600 s/mm(2). For comparison, DW images were also acquired using a Stejskal-Tanner diffusion gradient in a single-shot spin-echo echo planar sequence. For both datasets, a Levenberg-Marquardt fitting algorithm was used to extract three parameters: diffusion coefficient D, fractional order derivative in space β, and a spatial parameter μ (in units of μm). Using adjusted R-squared values and standard deviations, D, β, and μ values and the goodness-of-fit in three specific regions of interest (ROIs) in white matter, gray matter, and cerebrospinal fluid, respectively, were evaluated for each of the two datasets. In addition, spatially resolved parametric maps were assessed qualitatively. The analytical expression for the TRSE sequence, derived from the FC diffusion model, accurately characterized the diffusion-induced signal loss in brain tissues at high b-values. In the selected ROIs, the goodness-of-fit and standard deviations for the TRSE dataset were comparable with the results obtained from the Stejskal-Tanner dataset, demonstrating the robustness of the FC model across multiple data acquisition strategies. Qualitatively, the D, β, and μ maps from the TRSE dataset exhibited fewer artifacts, reflecting the improved immunity to eddy currents. The diffusion-induced signal attenuation in a TRSE pulse sequence

  16. Softening of phospholipid membranes by the adhesion of silica nanoparticles - as seen by neutron spin-echo (NSE)

    Science.gov (United States)

    Hoffmann, Ingo; Michel, Raphael; Sharp, Melissa; Holderer, Olaf; Appavou, Marie-Sousai; Polzer, Frank; Farago, Bela; Gradzielski, Michael

    2014-05-01

    The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon

  17. Evaluation of turbo spin echo sequences for MRI of focal liver lesions at 0.5 T

    International Nuclear Information System (INIS)

    Kreft, B.; Layer, G.; Steudel, A.; Spiller, L.; Heuck, A.; Mueller, A.; Gieseke, J.; Reiser, M.F.

    1994-01-01

    To determine whether turbo spin echo (TSE) sequences can replace conventional T2-weighted spin echo (SE) sequences in MRI of the liver, 40 patients with focal liver lesions were imaged at 0.5 T. A T2-weighted SE sequence (TR/TE 1800/90 ms, number of signals averaged [NEX] = 2, scan time 7:16 min), a TSE sequence (TR/TE 1800/90 ms, NEX = 4, number of echos per excitation = 13, echo spacing = 12.9 ms, scan time = 4:16 min) and a T1-weighted SE sequence (TR/TE 350/15 ms, NEX = 2, scan time = 4:21 min) were obtained and image quality, lesion detectability and lesion differentiation were evaluated qualitatively by subjective assessment using scores and quantitatively by lesion-liver contrast-to-noise (CNR) and tumour/liver signal intensity (SI) ratios. The image quality of the TSE sequence was substantially better compared with the T2-weighted SE sequence due to a reduction in motion artefacts and better delineation of anatomical details. Of a total of 158 visible lesions the T1-weighted SE, TSE and T2-weighted SE sequences showed 91 %, 81 % and 65 % of the lesions, respectively. Thus the TSE sequence depicted 24 % (P < 0.001) more lesions than the T2-weighted SE sequence. In all types of pathology the lesion-liver CNR of the TSE sequence was significantly (P < 0.001) higher compared to the CNR of the T2-weighted SE sequence ( +55-65 %), indicating superior lesion conspicuity. Lesion characterization was equally good on the two T2-weighted sequences with no difference in the tumour/liver SI ratio. Using a criterion of tumour/liver SI ratio equal to or higher than 2, haemangiomas larger than 1 cm in diameter could be differentiated from other lesions with a sensitivity and specificity of 95 % and 96 %, respectively. Our results indicate that the TSE sequence is suitable for replacing the conventional T2-weighted SE sequence in MRI of focal liver lesions. (orig.)

  18. Two-dimensional flexible nanoelectronics

    Science.gov (United States)

    Akinwande, Deji; Petrone, Nicholas; Hone, James

    2014-12-01

    2014/2015 represents the tenth anniversary of modern graphene research. Over this decade, graphene has proven to be attractive for thin-film transistors owing to its remarkable electronic, optical, mechanical and thermal properties. Even its major drawback--zero bandgap--has resulted in something positive: a resurgence of interest in two-dimensional semiconductors, such as dichalcogenides and buckled nanomaterials with sizeable bandgaps. With the discovery of hexagonal boron nitride as an ideal dielectric, the materials are now in place to advance integrated flexible nanoelectronics, which uniquely take advantage of the unmatched portfolio of properties of two-dimensional crystals, beyond the capability of conventional thin films for ubiquitous flexible systems.

  19. Two-dimensional topological photonics

    Science.gov (United States)

    Khanikaev, Alexander B.; Shvets, Gennady

    2017-12-01

    Originating from the studies of two-dimensional condensed-matter states, the concept of topological order has recently been expanded to other fields of physics and engineering, particularly optics and photonics. Topological photonic structures have already overturned some of the traditional views on wave propagation and manipulation. The application of topological concepts to guided wave propagation has enabled novel photonic devices, such as reflection-free sharply bent waveguides, robust delay lines, spin-polarized switches and non-reciprocal devices. Discrete degrees of freedom, widely used in condensed-matter physics, such as spin and valley, are now entering the realm of photonics. In this Review, we summarize the latest advances in this highly dynamic field, with special emphasis on the experimental work on two-dimensional photonic topological structures.

  20. Two-dimensional thermofield bosonization

    International Nuclear Information System (INIS)

    Amaral, R.L.P.G.; Belvedere, L.V.; Rothe, K.D.

    2005-01-01

    The main objective of this paper was to obtain an operator realization for the bosonization of fermions in 1 + 1 dimensions, at finite, non-zero temperature T. This is achieved in the framework of the real-time formalism of Thermofield Dynamics. Formally, the results parallel those of the T = 0 case. The well-known two-dimensional Fermion-Boson correspondences at zero temperature are shown to hold also at finite temperature. To emphasize the usefulness of the operator realization for handling a large class of two-dimensional quantum field-theoretic problems, we contrast this global approach with the cumbersome calculation of the fermion-current two-point function in the imaginary-time formalism and real-time formalisms. The calculations also illustrate the very different ways in which the transmutation from Fermi-Dirac to Bose-Einstein statistics is realized

  1. Two-dimensional critical phenomena

    International Nuclear Information System (INIS)

    Saleur, H.

    1987-09-01

    Two dimensional critical systems are studied using transformation to free fields and conformal invariance methods. The relations between the two approaches are also studied. The analytical results obtained generally depend on universality hypotheses or on renormalization group trajectories which are not established rigorously, so numerical verifications, mainly using the transfer matrix approach, are presented. The exact determination of critical exponents; the partition functions of critical models on toruses; and results as the critical point is approached are discussed [fr

  2. Two dimensional unstable scar statistics.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Kotulski, Joseph Daniel; Lee, Kelvin S. H. (ITT Industries/AES Los Angeles, CA)

    2006-12-01

    This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.

  3. Finding two-dimensional peaks

    International Nuclear Information System (INIS)

    Silagadze, Z.K.

    2007-01-01

    Two-dimensional generalization of the original peak finding algorithm suggested earlier is given. The ideology of the algorithm emerged from the well-known quantum mechanical tunneling property which enables small bodies to penetrate through narrow potential barriers. We merge this 'quantum' ideology with the philosophy of Particle Swarm Optimization to get the global optimization algorithm which can be called Quantum Swarm Optimization. The functionality of the newborn algorithm is tested on some benchmark optimization problems

  4. Correction of inhomogeneous RF field using multiple SPGR signals for high-field spin-echo MRI

    International Nuclear Information System (INIS)

    Ishimori, Yoshiyuki; Monma, Masahiko; Yamada, Kazuhiro; Kimura, Hirohiko; Uematsu, Hidemasa; Fujiwara, Yasuhiro; Yamaguchi, Isao

    2007-01-01

    The purpose of this study was to propose a simple and useful method for correcting nonuniformity of high-field (3 Tesla) T 1 -weighted spin-echo (SE) images based on a B1 field map estimated from gradient recalled echo (GRE) signals. The method of this study was to estimate B1 inhomogeneity, spoiled gradient recalled echo (SPGR) images were collected using a fixed repetition time of 70 ms, flip angles of 45 and 90 degrees, and echo times of 4.8 and 10.4 ms. Selection of flip angles was based on the observation that the relative intensity changes in SPGR signals were very similar among different tissues at larger flip angles than the Ernst angle. Accordingly, spatial irregularity that was observed on a signal ratio map of the SPGR images acquired with these 2 flip angles was ascribed to inhomogeneity of the B1 field. Dual echo time was used to eliminate T 2 * effects. The ratio map that was acquired was scaled to provide an intensity correction map for SE images. Both phantom and volunteer studies were performed using a 3T magnetic resonance scanner to validate the method. In the phantom study, the uniformity of the T 1 -weighted SE image improved by 23%. Images of human heads also showed practically sufficient improvement in the image uniformity. The present method improves the image uniformity of high-field T 1 -weighted SE images. (author)

  5. Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications

    Science.gov (United States)

    Epel, Boris; Sundramoorthy, Subramanian V.; Barth, Eugene D.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above∼100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors. PMID:21626937

  6. Zeeman perturbed nuclear quadrupole spin echo envelope modulations for spin 3/2 nuclei in polycrystalline specimens

    Science.gov (United States)

    Ramachandran, R.; Narasimhan, P. T.

    The results of theoretical and experimental studies of Zeeman-perturbed nuclear quadrupole spin echo envelope modulations (ZSEEM) for spin 3/2 nuclei in polycrystalline specimens are presented. The response of the Zeeman-perturbed spin ensemble to resonant two pulse excitations has been calculated using the density matrix formalism. The theoretical calculation assumes a parallel orientation of the external r.f. and static Zeeman fields and an arbitrary orientation of these fields to the principal axes system of the electric field gradient. A numerical powder averaging procedure has been adopted to simulate the response of the polycrystalline specimens. Using a coherent pulsed nuclear quadrupole resonance spectrometer the ZSEEM patterns of the 35Cl nuclei have been recorded in polycrystalline specimens of potassium chlorate, barium chlorate, mercuric chloride (two sites) and antimony trichloride (two sites) using the π/2-τ-π/2 sequence. The theoretical and experimental ZSEEM patterns have been compared. In the case of mercuric chloride, the experimental 35Cl ZSEEM patterns are found to be nearly identical for the two sites and correspond to a near-zero value of the asymmetry parameter, η, of the electric field gradient tensor. The difference in the η values for the two 35Cl sites (η ˜0·06 and η˜0·16) in antimony trichloride is clearly reflected in the experimental and theoretical ZSEEM patterns. The present study indicates the feasibility of evaluating η for spin 3/2 nuclei in polycrystalline specimens from ZSEEM investigations.

  7. Electron spin-echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel.

    Science.gov (United States)

    Cieslak, John A; Focia, Pamela J; Gross, Adrian

    2010-02-23

    Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential as a structural tool to describe the native environment of membrane proteins. Using the KcsA potassium channel as a model system, we demonstrate that deuterium ESEEM can detect water permeation along the lipid-exposed surface of the KcsA outer helix. We further demonstrate that (31)P ESEEM is able to identify channel residues that interact with the phosphate headgroup of the lipid bilayer. In combination with X-ray crystallography, the (31)P data may be used to define the phosphate interaction surface of the protein. The results presented here establish ESEEM as a highly informative technique for SDSL studies of membrane proteins.

  8. DrSPINE - New approach to data reduction and analysis for neutron spin echo experiments from pulsed and reactor sources

    International Nuclear Information System (INIS)

    Zolnierczuk, P.A.; Ohl, M.; Holderer, O.; Monkenbusch, M.

    2015-01-01

    Neutron spin echo (NSE) method at a pulsed neutron source presents new challenges to the data reduction and analysis as compared to the instruments installed at reactor sources. The main advantage of the pulsed source NSE is the ability to resolve the neutron wavelength and collect neutrons over a wider bandwidth. This allows us to more precisely determine the symmetry phase and measure the data for several Q-values at the same time. Based on the experience gained at the SNS NSE - the first, and to date the only one, NSE instrument installed at a pulsed spallation source, we propose a novel and unified approach to the NSE data processing called DrSPINE. The goals of the DrSPINE project are: -) exploit better symmetry phase determination due to the broader bandwidth at a pulsed source; -) take advantage of larger Q coverage for TOF instruments; -) use objective statistical criteria to get the echo fits right; -) provide robust reduction with report generation; -) incorporate absolute instrument calibration; and -) allow for background subtraction. The software must be able to read the data from various instruments, perform data integrity, consistency and compatibility checks and combine the data from compatible sets, partial scans, etc. We chose to provide a console-based interface with the ability to process macros (scripts) for batch evaluation. And last and not the least, a good software package has to provide adequate documentation. DrSPINE software is currently under development

  9. Spin echoes of nuclear magnetization diffusing in a constant magnetic field gradient and in a restricted geometry

    International Nuclear Information System (INIS)

    Sen, P.N.; Andre, A.; Axelrod, S.

    1999-01-01

    We study the influence of restriction on Carr - Purcell - Meiboom - Gill spin echoes response of magnetization of spins diffusing in a bounded region in the presence of a constant magnetic field gradient. Depending on three main length scales: L S pore size, L G dephasing length and L D diffusion length during half-echo time, three main regimes of decay have been identified: free, localization and motionally averaging regime. In localization regime, the decay exponent depends on a fractional power (2/3) of the gradient, denoting a strong breakdown of the second cumulant or the Gaussian phase approximation (GPA). In the other two regimes, the exponent depends on the gradient squared, and the GPA holds. We find that the transition from the localization to the motionally averaging regime happens when the magnetic field gradients approach special values, corresponding to branch points of the eigenvalues. Transition from one regime to another as a function of echo number for a certain range of parameters is discussed. In this transition region, the signal shows large oscillations with echo number. For large n, asymptotic behavior sets in as a function of n for the decay exponent per echo. This is true for all values of the parameters L S , L G , and L D . copyright 1999 American Institute of Physics

  10. Bone marrow lesions: evaluation with fat-suppression turbo spin echo MR imaging at 0.5T

    International Nuclear Information System (INIS)

    Chrysikopoulos, H.; Papazoglou, A.; Roussakis, A.; Andreou, J.

    1996-01-01

    The purpose of this study was the assessment of the diagnostic value of fat-suppression T2-weighted images for a variety of bone marrow lesions. We performed 40 studies of the axial or appendicular skeleton in 33 patients (age range 4-80 years) with neoplastic, inflammatory or traumatic lesions with a 0.5 T system (Gyroscan T5, Philips Medical Systems, Best, The Netherlands). Fat-suppression T2-weighted images [turbo spin echo (TSE) with spectral presaturation with inversion recovery (SPIR)] were obtained in addition to the routine T1-weighted SE and T2-weighted TSE sequences. Fat-suppression TSE T2-weighted images were better than standard TSE T2-weighted images in 25 studies. In 11 of them demonstration and characterization of the lesions (known from T1-weighted images) was possible only after fat suppression. In the other 14 patients demonstration of the full extent of the lesion especially to the nearby soft tissues was possible only after fat suppression. In 13 studies no advantage was conferred by SPIR, whereas in two instances T2-weighted images were better. Fat-suppression T2-weighted images are diagnostically useful in a variety of lesions of the musculoskeletal system, but their limitations should be known. (orig.)

  11. Frozen concentration fluctuations in a poly(N-isopropyl acrylamide) gel studied by neutron spin echo and small-angle neutron scattering

    CERN Document Server

    Koizumi, S; Richter, D; Schwahn, D; Faragó, B; Annaka, M

    2002-01-01

    By employing neutron spin echo and small-angle neutron scattering, we determined the structure factor of the frozen concentration fluctuations on nano-length scales in a swollen poly(N-isopropyl acrylamide) gel. The frozen contribution, showing a plateau at the low scattering wavenumber q (0.02 A sup - sup 1), is intimately related to the abnormal butterfly scattering pattern appearing at low q under deformation. (orig.)

  12. Detection and assignment of phosphoserine and phosphothreonine residues by {sup 13}C-{sup 31}P spin-echo difference NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    McIntosh, Lawrence P., E-mail: mcintosh@chem.ubc.ca; Kang, Hyun-Seo; Okon, Mark [University of British Columbia, Department of Biochemistry (Canada); Nelson, Mary L.; Graves, Barbara J. [University of Utah, Department of Oncological Sciences, Huntsman Cancer Institute (United States); Brutscher, Bernhard [CNRS, CEA, UJF, Institut de Biologie Structurale Jean-Pierre Ebel (France)], E-mail: bernhard.brutscher@ibs.fr

    2009-01-15

    A simple NMR method is presented for the identification and assignment of phosphorylated serine and threonine residues in {sup 13}C- or {sup 13}C/{sup 15}N-labeled proteins. By exploiting modest ({approx}5 Hz) 2- and 3-bond {sup 13}C-{sup 31}P scalar couplings, the aliphatic {sup 1}H-{sup 13}C signals from phosphoserines and phosphothreonines can be detected selectively in a {sup 31}P spin-echo difference constant time {sup 1}H-{sup 13}C HSQC spectrum. Inclusion of the same {sup 31}P spin-echo element within the {sup 13}C frequency editing period of an intraHNCA or HN(CO)CA experiment allows identification of the amide {sup 1}H{sup N} and {sup 15}N signals of residues (i) for which {sup 13}C{sup {alpha}}(i) or {sup 13}C{sup {alpha}}(i - 1), respectively, are coupled to a phosphate. Furthermore, {sup 31}P resonance assignments can be obtained by applying selective low power cw {sup 31}P decoupling during the spin-echo period. The approach is demonstrated using a PNT domain containing fragment of the transcription factor Ets-1, phosphorylated in vitro at Thr38 and Ser41 with the MAP kinase ERK2.

  13. Comparison between two.magnetic resonance sequences (spin-echo and gradient-echo) in the analysis of lesions of the knee joint meniscus

    International Nuclear Information System (INIS)

    Marti-Bonati, L.; Casillas, C.

    1999-01-01

    To compare the diagnostic reliability, the proportion of common diagnoses and the degree of agreement between the results of two magnetic resonance (MR) sequences in the diagnosis of lesions of the meniscus of the knee. One hundred consecutive patients were studied prospectively by MR (1,5 Teslas). All of them underwent T1-weighted spin-echo and T1 and T2-weighted gradient-echo sequences. The final diagnosis was based on the combined results of four imaging sequences. The sensitivity, specificity, positive predictive value (PPV) and negative predictive (NPV) in terms of the final diagnosis were calculated for each meniscus and MR technique. The chi.squared test and kappa test were employed for the statistical analysis. There were discrepancies between the final diagnosis and the spin-echo sequence in 4 cases and between the final diagnosis and the gradient-echo sequences in 5 Both spin-echo and gradient-echo sequences showed the same diagnostic reliabilities: sensitivity of 0.98, specificity of 0.99, PPV of 0.98 and NPV of 0.99. The correlation between the two sequences was highly significant (chi-squared, p < 0.001) with a very high rate of agreement (kappa=0.84). The two sequences can be considered equally reliable in the study of meniscal lesions. (Author) 7 refs

  14. Improved visualization of collateral ligaments of the ankle: multiplanar reconstructions based on standard 2D turbo spin-echo MR images

    International Nuclear Information System (INIS)

    Duc, Sylvain R.; Mengiardi, Bernard; Pfirrmann, Christian W.A.; Hodler, Juerg; Zanetti, Marco

    2007-01-01

    The purpose of the study was to evaluate the visualization of the collateral ankle ligaments on multiplanar reconstructions (MPR) based on standard 2D turbo spin-echo images. Coronal and axial T2-weighted turbo spin-echo and MPR angled parallel to the course of the ligaments of 15 asymptomatic and 15 symptomatic ankles were separately analyzed by two musculoskeletal radiologists. Image quality was assessed in the asymptomatic ankles qualitatively. In the symptomatic ankles interobserver agreement and reader confidence was determined for each ligament. On MPR the tibionavicular and calcaneofibular ligaments were more commonly demonstrated on a single image than on standard MR images (reader 1: 13 versus 0, P=0.002; reader 2: 14 versus 1, P=0.001 and reader 1: 13 versus 2, P=0.001; reader 2: 14 versus 0, P<0.001). The tibionavicular ligament was considered to be better delineated on MPR by reader 1 (12 versus 3, P=0.031). In the symptomatic ankles, reader confidence was greater with MPR for all ligaments except for the tibiocalcanear ligament (both readers) and the anterior and posterior talofibular ligaments (for reader 2). Interobserver agreement was increased with MPR for the tibionavicular ligament. Multiplanar reconstructions of 2D turbo spin-echo images improve the visualization of the tibionavicular and calcaneofibular ligaments and strengthen diagnostic confidence for these ligaments. (orig.)

  15. Two dimensional infinite conformal symmetry

    International Nuclear Information System (INIS)

    Mohanta, N.N.; Tripathy, K.C.

    1993-01-01

    The invariant discontinuous (discrete) conformal transformation groups, namely the Kleinian and Fuchsian groups Gamma (with an arbitrary signature) of H (the Poincare upper half-plane l) and the unit disc Delta are explicitly constructed from the fundamental domain D. The Riemann surface with signatures of Gamma and conformally invariant automorphic forms (functions) with Peterson scalar product are discussed. The functor, where the category of complex Hilbert spaces spanned by the space of cusp forms constitutes the two dimensional conformal field theory. (Author) 7 refs

  16. Two-dimensional liquid chromatography

    DEFF Research Database (Denmark)

    Græsbøll, Rune

    -dimensional separation space. Optimization of gradients in online RP×RP is more difficult than in normal HPLC as a result of the increased number of parameters and their influence on each other. Modeling the coverage of the compounds across the two-dimensional chromatogram as a result of a change in gradients could...... be used for optimization purposes, and reduce the time spend on optimization. In this thesis (chapter 6), and manuscript B, a measure of the coverage of the compounds in the twodimensional separation space is defined. It is then shown that this measure can be modeled for changes in the gradient in both...

  17. Two-dimensional capillary origami

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, N.D., E-mail: nbrubaker@math.arizona.edu; Lega, J., E-mail: lega@math.arizona.edu

    2016-01-08

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.

  18. Two-dimensional capillary origami

    International Nuclear Information System (INIS)

    Brubaker, N.D.; Lega, J.

    2016-01-01

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid. - Highlights: • Full solution set of the two-dimensional capillary origami problem. • Fluid does not necessarily wet the entire plate. • Global energy approach provides exact differential equations satisfied by minimizers. • Bifurcation diagrams highlight three different regimes. • Conditions for spontaneous encapsulation are identified.

  19. Two dimensional solid state NMR

    International Nuclear Information System (INIS)

    Kentgens, A.P.M.

    1987-01-01

    This thesis illustrates, by discussing some existing and newly developed 2D solid state experiments, that two-dimensional NMR of solids is a useful and important extension of NMR techniques. Chapter 1 gives an overview of spin interactions and averaging techniques important in solid state NMR. As 2D NMR is already an established technique in solutions, only the basics of two dimensional NMR are presented in chapter 2, with an emphasis on the aspects important for solid spectra. The following chapters discuss the theoretical background and applications of specific 2D solid state experiments. An application of 2D-J resolved NMR, analogous to J-resolved spectroscopy in solutions, to natural rubber is given in chapter 3. In chapter 4 the anisotropic chemical shift is mapped out against the heteronuclear dipolar interaction to obtain information about the orientation of the shielding tensor in poly-(oxymethylene). Chapter 5 concentrates on the study of super-slow molecular motions in polymers using a variant of the 2D exchange experiment developed by us. Finally chapter 6 discusses a new experiment, 2D nutation NMR, which makes it possible to study the quadrupole interaction of half-integer spins. 230 refs.; 48 figs.; 8 tabs

  20. Two-dimensional turbulent convection

    Science.gov (United States)

    Mazzino, Andrea

    2017-11-01

    We present an overview of the most relevant, and sometimes contrasting, theoretical approaches to Rayleigh-Taylor and mean-gradient-forced Rayleigh-Bénard two-dimensional turbulence together with numerical and experimental evidences for their support. The main aim of this overview is to emphasize that, despite the different character of these two systems, especially in relation to their steadiness/unsteadiness, turbulent fluctuations are well described by the same scaling relationships originated from the Bolgiano balance. The latter states that inertial terms and buoyancy terms balance at small scales giving rise to an inverse kinetic energy cascade. The main difference with respect to the inverse energy cascade in hydrodynamic turbulence [R. H. Kraichnan, "Inertial ranges in two-dimensional turbulence," Phys. Fluids 10, 1417 (1967)] is that the rate of cascade of kinetic energy here is not constant along the inertial range of scales. Thanks to the absence of physical boundaries, the two systems here investigated turned out to be a natural physical realization of the Kraichnan scaling regime hitherto associated with the elusive "ultimate state of thermal convection" [R. H. Kraichnan, "Turbulent thermal convection at arbitrary Prandtl number," Phys. Fluids 5, 1374-1389 (1962)].

  1. Comparison between FLAIR images and T2-weighted fast spin-echo images of cerebral territory and lacunar infarction

    International Nuclear Information System (INIS)

    Paeng, Mi Hye; Choi, Hye-Young; Lim, Soo Mee; Lee, Jung Sik

    2003-01-01

    To assess the significance of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in the diagnosis of intracranial infarctions and to find out differential points between central lacunar infarctions and perivascular spaces. We consecutively selected 25 cases of territorial infarction in 20 patients, 37 cases of central infarction in 40 patients, and 30 patients with perivascular space. Signal intensity and lesion conspicuity were analyzed and compared between FLAIR and FSE T2-weighted images, and differences in signal intensity between central infarction and perivascular spaces were determined. Lesion conspicuity for FLAIR was better than for T2-weighted images in 12 and 15, worse in 4 and 24, and similar in 9 and 16 of territorial and central infarctions, respectively. In nine cases of territorial and one case of central infarction, there was associated hemorrhage. At FLAIR imaging, perivascular spaces showed a fine round low signal without a peripheral high signal rim in 17 patients but no demonstrable signals in 15. Differential diagnosis of perivascular spaces and central infarction was thus not difficult. FLAIR MRI was useful in the diagnosis of infarctions and in differentiating between central small lacular infarctions and perivascular spaces

  2. Two-dimensional quantum repeaters

    Science.gov (United States)

    Wallnöfer, J.; Zwerger, M.; Muschik, C.; Sangouard, N.; Dür, W.

    2016-11-01

    The endeavor to develop quantum networks gave rise to a rapidly developing field with far-reaching applications such as secure communication and the realization of distributed computing tasks. This ultimately calls for the creation of flexible multiuser structures that allow for quantum communication between arbitrary pairs of parties in the network and facilitate also multiuser applications. To address this challenge, we propose a two-dimensional quantum repeater architecture to establish long-distance entanglement shared between multiple communication partners in the presence of channel noise and imperfect local control operations. The scheme is based on the creation of self-similar multiqubit entanglement structures at growing scale, where variants of entanglement swapping and multiparty entanglement purification are combined to create high-fidelity entangled states. We show how such networks can be implemented using trapped ions in cavities.

  3. Clinical application of Half Fourier Acquisition Single Shot Turbo Spin Echo (HASTE) imaging accelerated by simultaneous multi-slice acquisition.

    Science.gov (United States)

    Schulz, Jenni; P Marques, José; Ter Telgte, Annemieke; van Dorst, Anouk; de Leeuw, Frank-Erik; Meijer, Frederick J A; Norris, David G

    2018-01-01

    As a single-shot sequence with a long train of refocusing pulses, Half-Fourier Acquisition Single-Shot Turbo-Spin-Echo (HASTE) suffers from high power deposition limiting use at high resolutions and high field strengths, particularly if combined with acceleration techniques such as simultaneous multi-slice (SMS) imaging. Using a combination of multiband (MB)-excitation and PINS-refocusing pulses will effectively accelerate the acquisition time while staying within the SAR limitations. In particular, uncooperative and young patients will profit from the speed of the MB-PINS HASTE sequence, as clinical diagnosis can be possible without sedation. Materials and MethodsMB-excitation and PINS-refocusing pulses were incorporated into a HASTE-sequence with blipped CAIPIRINHA and TRAPS including an internal FLASH reference scan for online reconstruction. Whole brain MB-PINS HASTE data were acquired on a Siemens 3T-Prisma system from 10 individuals and compared to a clinical HASTE protocol. ResultsThe proposed MB-PINS HASTE protocol accelerates the acquisition by about a factor 2 compared to the clinical HASTE. The diagnostic image quality proved to be comparable for both sequences for the evaluation of the overall aspect of the brain, the detection of white matter changes and areas of tissue loss, and for the evaluation of the CSF spaces although artifacts were more frequently encountered with MB-PINS HASTE. ConclusionsMB-PINS HASTE enables acquisition of slice accelerated highly T2-weighted images and provides good diagnostic image quality while reducing acquisition time. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Magnetic resonance imaging of lumbar spine. Comparison of multiple spin echo and low flip angle gradient echo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Takamichi; Fujita, Norihiko; Harada, Koushi; Kozuka, Takahiro (Osaka Univ. (Japan). Faculty of Medicine)

    1989-07-01

    Sixteen patients including 13 cases with disk herniation and 3 cases with spondylosis of lumbar spine were examined on a resistive MRI system operating at 0.1 T. All lesions were studied with both multiple spin echo (MSE) and low flip angle gradient echo (LF) techniques to evaluate which technique is more effective in detecting the disk degeneration and the indentation on subarachnoid space. MSE images were obtained with repetition time (TR) of 1100-1500 ms or cardiac gating, an echo time (TE) of 30, 60, 90, 120, 150, and 180 ms symmetrical 6 echoes, and total acquisition time of more than 281 sec. LF images were obtained with TR of 500, 250, and 100 ms, TE of 18 ms, a flip angle of 30 degree, and total acquisition time of 128 sec. Eleven lesions of spinal disk degeneration and 12 of indentation on subarachnoid space were detected with LF. On the other hand, 26 lesions of spinal disk degeneration and 38 of indentation on subarachnoid space were detected with MSE. Although the parameters of LF employed in this study were relatively effective to emphasize T2{sup *}-based contrast, the ability of LF in detection of spinal disk degeneration and indentation on subarachnoid space is less than that of MSE. Signal contrast to noise ratios for normal disk and degenerative disk, epidural-fat and disk herniated material, CSF and disk herniated material, and epidural-fat and CSF were less than 4 with LF, but more than 4 with MSE. This difference of contrast to noise ratio between MSE and LF was one of the main causes of the difference of the detection rate of spinal disk degeneration and indentation on subarachnoid space. (author).

  5. Predictive value of PWI for blood supply and T1-spin echo MRI for consistency of pituitary adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zengyi; He, Wenqiang; Zhao, Yao; Zhang, Qilin; Li, Shiqi; Wang, Yongfei [Fudan University, Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Shanghai (China); Shanghai Pituitary Tumor Center, Shanghai (China); Yuan, Jie; Wu, Yue; Yao, Zhenwei [Fudan University, Department of Radiology, Huashan Hospital, Shanghai Medical College, Shanghai (China); Chen, Hong [Fudan University, Department of Neuropathology, Huashan Hospital, Shanghai Medical College, Shanghai (China)

    2016-01-15

    It is a common view that consistency and blood supply of pituitary adenoma (PA) can influence the surgical effect. The aim of this study was to determine whether MRI signal intensity (SI) was correlated to the consistency or blood supply of pituitary macroadenoma. Forty eight pituitary macroadenoma patients were underwent preoperative MRI, including precontrast and contrast-enhanced (CE) T1-spin echo (T1-SE) imaging, CE-sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE) imaging, and perfusion-weighted imaging (PWI). The tumor consistency and blood supply were determined by neurosurgeons. The expression of collagen IV and MIB-1 was detected with immunohistology. The correlation of the relative SI (rSI) values (tumor to normal frontal white matter SI) and PWI data to the tumor consistency, blood supply, and the expression level of collagen IV and MIB-1 was statistically studied by Kruskal-Wallis rank test (K-W test). A significant correlation was observed between the tumor consistency and the rSI on precontrast T1-SE imaging (P = 0.004) but not on CE T1-SE and CE SPACE imaging. The expression of collagen IV was also significantly associated with rSI on T1-SE imaging (P = 0.010). The blood supply was correlated with the relative CBV (rCBV) (P = 0.030). In addition, the expression of MIB-1 was correlated with rSI of CE T1-SE imaging (P = 0.007). Our results suggest that T1-SE imaging may be a simple and useful method for predicting consistency of PA. CBV value can provide helpful information for assessing the blood supply of pituitary macroadenoma. (orig.)

  6. Contrast-enhanced turbo spin-echo(TSE) T1-weighted imaging: improved contrast of enhancing lesions

    International Nuclear Information System (INIS)

    Choi, Sung Wook; Lee, Ghi Jai; Shim, Jae Chan; Lee, Young Ju; Jeong, Se Hyung; Kim, Ho kyun

    1997-01-01

    The purpose of this study was to evaluate the effect of contrast improvement of enhancing brain lesions by inherent magnetization transfer effect in turbo spin-echo(TSE)T1-weighted MR imaging. Twenty-six enhancing lesions of 19 patients were included in this study. Using a 1.0T superconductive MR unit, contrast-enhanced SE T1-weighted images(TR=3D600 msec, TE=3D12 msec, NEX=3D2, acquistition time=3D4min 27sec) and contrast-enhanced TSE T1-weighted images(TR=3D600 msec, TE=3D12, acquistition time=3D1min 44sec) were obtained. Signal intensities at enhancing lesions and adjacent white matter were measured in the same regions of both images. Signal-to-noise ratio(SNR) of enhancing lesions and adjacent white matter, and con-trast-to-noise ratio(CNR) and lesion-to-background contrast (LBC) of enhancing lesions were calculated and statistically analysed using the paired t-test. On contrast-enhanced TSE T1-weighted images, SNR of enhancing lesions and adjacent white matter decreased by 18%(p<0.01) and 32%(p<0.01), respectively, compared to contrast-enhanced SE T1-weighted images. CNR and LBC of enhancing lesions increased by 16%(p<0.05) and 66%(p<0.01), respectively. Due to the proposed inherent magnetization transfer effects in TSE imaging, con-trast-enhanced T1-weighted TSE images demonstrated a statistically significant improvement in CNR and LBC, compared to conventional contrast-enhanced T1-weighted SE images, and scan time was much shorter

  7. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg, E-mail: hansjoerg.graf@med.uni-tuebingen.de, E-mail: drGraf@t-online.de [Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany); Clasen, Stephan [Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany)

    2014-06-15

    Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

  8. Two-dimensional heterostructures for energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States); Pomerantseva, Ekaterina [Drexel Univ., Philadelphia, PA (United States)

    2017-06-12

    Two-dimensional (2D) materials provide slit-shaped ion diffusion channels that enable fast movement of lithium and other ions. However, electronic conductivity, the number of intercalation sites, and stability during extended cycling are also crucial for building high-performance energy storage devices. While individual 2D materials, such as graphene, show some of the required properties, none of them can offer all properties needed to maximize energy density, power density, and cycle life. Here we argue that stacking different 2D materials into heterostructured architectures opens an opportunity to construct electrodes that would combine the advantages of the individual building blocks while eliminating the associated shortcomings. We discuss characteristics of common 2D materials and provide examples of 2D heterostructured electrodes that showed new phenomena leading to superior electrochemical performance. As a result, we also consider electrode fabrication approaches and finally outline future steps to create 2D heterostructured electrodes that could greatly expand current energy storage technologies.

  9. Uterine cervical carcinoma: a comparison of two- and three-dimensional T2-weighted turbo spin-echo MR imaging at 3.0 T for image quality and local-regional staging

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Y.R. [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, 222, Banpo-daero, Seocho-gu, Seoul (Korea, Republic of); The Catholic University of Korea, Department of Radiology, Incheon St. Mary' s Hospital, College of Medicine, Bupyeong 6-dong, Bupyeong-gu, Incheon (Korea, Republic of); Rha, S.E.; Choi, B.G.; Oh, S.N.; Park, M.Y.; Byun, J.Y. [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, 222, Banpo-daero, Seocho-gu, Seoul (Korea, Republic of)

    2013-04-15

    To compare three-dimensional (3D) T2-weighted turbo spin-echo (TSE) with multiplanar two-dimensional (2D) T2-weighted TSE for the evaluation of invasive cervical carcinoma. Seventy-five patients with cervical carcinoma underwent MRI of the pelvis at 3.0 T, using both 5-mm-thick multiplanar 2D (total acquisition time = 12 min 25 s) and 1-mm-thick coronal 3D T2-weighted TSE sequences (7 min 20 s). Quantitative analysis of signal-to-noise ratio (SNR) and qualitative analysis of image quality were performed. Local-regional staging was performed in 45 patients who underwent radical hysterectomy. The estimated SNR of cervical carcinoma and the relative tumour contrast were significantly higher on 3D imaging (P < 0.0001). Tumour conspicuity was better with the 3D sequence, but the sharpness of tumour margin was better with the 2D sequence. No significant difference in overall image quality was noted between the two sequences (P = 0.38). There were no significant differences in terms of the diagnostic accuracy, sensitivity, and specificity of parametrial invasion, vaginal invasion, and lymph node metastases. Multiplanar reconstruction 3D T2-weighted imaging is largely equivalent to 2D T2-weighted imaging for overall image quality and staging accuracy of cervical carcinoma with a shorter MR data acquisition, but has limitations with regard to the sharpness of the tumour margin. circle 3D T2-weighted MR sequence is equivalent to 2D for cervical carcinoma staging. (orig.)

  10. Gadolinium-Enhanced Three-Dimensional Magnetization - Prepared Rapid Gradient-Echo (3D MP-RAGE) Imaging is Superior to Spin-Echo Imaging in Delineating Brain Metastases

    International Nuclear Information System (INIS)

    Takeda, T.; Takeda, A.; Nagaoka, T.; Kunieda, E.; Takemasa, K.; Watanabe, M.; Hatou, T.; Oguro, S.; Katayama, M.

    2008-01-01

    Background: Precisely defining the number and location of brain metastases is very important for establishing a treatment strategy for malignancies. Although magnetic resonance imaging (MRI) is now considered the best modality, various improvements in sequences are still being made. Purpose: To prospectively compare the diagnostic ability of three-dimensional, magnetization-prepared rapid gradient-echo (3D MP-RAGE) imaging in detecting metastatic brain tumors, with that of two-dimensional spin-echo (2D SE) T1-weighted imaging. Material and Methods: A total of 123 examinations were included in this study, and 119 examinations from 88 patients with known malignancies were analyzed. All patients underwent T1- and T2-weighted 2D SE transverse imaging, followed by gadolinium-enhanced T1-weighted transverse and coronal 2D SE imaging and 3D MP-RAGE transverse imaging. Four radiologists interpreted the images to compare the accuracy and the time required for interpretation for each imaging. Results: 3D MP-RAGE imaging was significantly better than 2D SE imaging for detecting metastatic brain lesions, regardless of the readers' experience. The sensitivities of the 3D MP-RAGE and 2D SE imaging for all observers were 0.81 vs. 0.80 (P>0.05), specificities were 0.93 vs. 0.87 (P 0.05), and accuracies were 0.84 vs. 0.78 (P<0.05), respectively. There was no significant difference in the time required for image interpretation between the two modalities (15.6±4.0 vs. 15.4±4.1 min). Conclusion: 3D MP-RAGE imaging proved superior to 2D SE imaging in the detection of brain metastases

  11. Spin-echo Echo-planar Imaging MR Elastography versus Gradient-echo MR Elastography for Assessment of Liver Stiffness in Children and Young Adults Suspected of Having Liver Disease.

    Science.gov (United States)

    Serai, Suraj D; Dillman, Jonathan R; Trout, Andrew T

    2017-03-01

    Purpose To compare two-dimensional (2D) gradient-recalled echo (GRE) and 2D spin-echo (SE) echo-planar imaging (EPI) magnetic resonance (MR) elastography for measurement of hepatic stiffness in pediatric and young adult patients suspected of having liver disease. Materials and Methods In this institutional review board-approved, HIPAA-compliant study, 58 patients underwent both 2D GRE and 2D SE-EPI MR elastography at 1.5 T during separate breath holds. Liver stiffness (mean of means; in kilopascals) was measured by five blinded reviewers. Pooled mean liver stiffness and region-of-interest (ROI) size were compared by using paired t tests. Intraclass correlation coefficients (ICCs) were used to assess agreement between techniques. Respiratory motion artifacts were compared across sequences by using the Fisher exact test. Results Mean patient age was 14.7 years ± 5.2 (standard deviation; age range, 0.7-20.5 years), and 55.2% (32 of 58) of patients were male. Mean liver stiffness was 2.92 kPa ± 1.29 measured at GRE MR elastography and 2.76 kPa ± 1.39 at SE-EPI MR elastography (n = 290; P = .15). Mean ROI sizes were 8495 mm 2 ± 4482 for 2D GRE MR elastography and 15 176 mm 2 ± 7609 for 2D SE-EPI MR elastography (n = 290; P range, 0.91-0.95). Moderate or severe breathing artifacts were observed on 27.5% (16 of 58) of 2D GRE images versus 0% 2D SE-EPI images (P < .001). Conclusion There is excellent agreement on measured hepatic stiffness between 2D GRE and 2D SE-EPI MR elastography across multiple reviewers. SE-EPI MR elastography allowed for stiffness measurement across larger areas of the liver and can be performed in a single breath hold. © RSNA, 2016.

  12. Equilibrium: two-dimensional configurations

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    In Chapter 6, the problem of toroidal force balance is addressed in the simplest, nontrivial two-dimensional geometry, that of an axisymmetric torus. A derivation is presented of the Grad-Shafranov equation, the basic equation describing axisymmetric toroidal equilibrium. The solutions to equations provide a complete description of ideal MHD equilibria: radial pressure balance, toroidal force balance, equilibrium Beta limits, rotational transform, shear, magnetic wall, etc. A wide number of configurations are accurately modeled by the Grad-Shafranov equation. Among them are all types of tokamaks, the spheromak, the reversed field pinch, and toroidal multipoles. An important aspect of the analysis is the use of asymptotic expansions, with an inverse aspect ratio serving as the expansion parameter. In addition, an equation similar to the Grad-Shafranov equation, but for helically symmetric equilibria, is presented. This equation represents the leading-order description low-Beta and high-Beta stellarators, heliacs, and the Elmo bumpy torus. The solutions all correspond to infinitely long straight helices. Bending such a configuration into a torus requires a full three-dimensional calculation and is discussed in Chapter 7

  13. A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

    Energy Technology Data Exchange (ETDEWEB)

    Juras, Vladimir; Szomolanyi, Pavol [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Institute of Measurement Science, Department of Imaging Methods, Bratislava (Slovakia); Bohndorf, Klaus; Kronnerwetter, Claudia; Hager, Benedikt; Zbyn, Stefan [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Heule, Rahel; Bieri, Oliver [University of Basel Hospital, Division of Radiological Physics, Department of Radiology, Basel (Switzerland); Trattnig, Siegfried [Medical University of Vienna, High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Vienna (Austria); Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna (Austria); Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Austrian Cluster for Tissue Regeneration, Vienna (Austria)

    2016-06-15

    To assess the clinical relevance of T{sub 2} relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T{sub 2}-mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T{sub 2} mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T{sub 2} values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T{sub 2} values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B{sub 1} and B{sub 0} changes. (orig.)

  14. Improved imaging of cochlear nerve hypoplasia using a 3-Tesla variable flip-angle turbo spin-echo sequence and a 7-cm surface coil.

    Science.gov (United States)

    Giesemann, Anja M; Raab, Peter; Lyutenski, Stefan; Dettmer, Sabine; Bültmann, Eva; Frömke, Cornelia; Lenarz, Thomas; Lanfermann, Heinrich; Goetz, Friedrich

    2014-03-01

    Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high-resolution T2-weighted sequence with a surface coil in a 3-Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia. Prospective study. Seven patients with cochlear nerve hypoplasia or aplasia were prospectively examined using a high-resolution three-dimensional variable flip-angle turbo spin-echo sequence using a surface coil, and the images were compared with the same sequence in standard resolution using a standard head coil. Three neuroradiologists evaluated the magnetic resonance images independently, rating the visibility of the nerves in diagnosing hypoplasia or aplasia. Eight ears in seven patients with hypoplasia or aplasia of the cochlear nerve were examined. The average age was 2.7 years (range, 9 months-5 years). Seven ears had accompanying malformations. The inter-rater reliability in diagnosing hypoplasia or aplasia was greater using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence (fixed-marginal kappa: 0.64) than with the same sequence in lower resolution (fixed-marginal kappa: 0.06). Examining cases of suspected cochlear nerve aplasia using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence in combination with a surface coil shows significant improvement over standard methods. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

  15. A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage.

    Science.gov (United States)

    Juras, Vladimir; Bohndorf, Klaus; Heule, Rahel; Kronnerwetter, Claudia; Szomolanyi, Pavol; Hager, Benedikt; Bieri, Oliver; Zbyn, Stefan; Trattnig, Siegfried

    2016-06-01

    To assess the clinical relevance of T2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T2-mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B1 and B0 changes. • 3D-TESS T 2 mapping provides clinically comparable results to CPMG in shorter scan-time. • Clinical and investigational studies may benefit from high temporal resolution of 3D-TESS. • 3D-TESS T 2 values are able to differentiate between healthy and damaged cartilage.

  16. A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

    International Nuclear Information System (INIS)

    Juras, Vladimir; Szomolanyi, Pavol; Bohndorf, Klaus; Kronnerwetter, Claudia; Hager, Benedikt; Zbyn, Stefan; Heule, Rahel; Bieri, Oliver; Trattnig, Siegfried

    2016-01-01

    To assess the clinical relevance of T 2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T 2 -mapping. Thirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T 2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T 2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent. The mean quantitative T 2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839). 3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B 1 and B 0 changes. (orig.)

  17. MRI detection of hypointense brain lesions in patients with multiple sclerosis: T1 spin-echo vs. gradient-echo

    Energy Technology Data Exchange (ETDEWEB)

    Dupuy, Sheena L.; Tauhid, Shahamat; Kim, Gloria; Chu, Renxin; Tummala, Subhash [Departments of Neurology, Brigham and Women' s Hospital, Laboratory for Neuroimaging Research, Partners MS Center, Harvard Medical School, Boston, MA (United States); Hurwitz, Shelley [Departments of Medicine, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States); Bakshi, Rohit, E-mail: rbakshi@bwh.harvard.edu [Departments of Neurology, Brigham and Women' s Hospital, Laboratory for Neuroimaging Research, Partners MS Center, Harvard Medical School, Boston, MA (United States); Departments of Radiology, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States)

    2015-08-15

    Highlights: • Compared T1SE and T1GE in detecting hypointense brain lesions in MS patients. • T1GE detected a higher cerebral lesion volume and number than T1SE. • T1SE correlated significantly with disability, while T1GE did not. • Hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. - Abstract: Objective: Compare T1 spin-echo (T1SE) and T1 gradient-echo (T1GE) sequences in detecting hypointense brain lesions in multiple sclerosis (MS). Background: Chronic hypointense lesions on T1SE MRI scans are a surrogate of severe demyelination and axonal loss in MS. The role of T1GE images in the detection of such lesions has not been clarified. Design/methods: In 45 patients with MS [Expanded Disability Status Scale (EDSS) score (mean ± SD) 3.5 ± 2.0; 37 relapsing-remitting (RR); 8 secondary progressive (SP)], cerebral T1SE, T1GE, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images were acquired on a 1.5 T MRI scanner. Images were re-sampled to axial 5 mm slices before directly comparing lesion detectability using Jim (v.7, Xinapse Systems). Statistical methods included Wilcoxon signed rank tests to compare sequences and Spearman correlations to test associations. Results: Considering the entire cohort, T1GE detected a higher lesion volume (5.90 ± 6.21 vs. 4.17 ± 4.84 ml, p < 0.0001) and higher lesion number (27.82 ± 20.66 vs. 25.20 ± 20.43, p < 0.05) than T1SE. Lesion volume differences persisted when considering RR and SP patients separately (both p < 0.01). A higher lesion number by T1GE was seen only in the RR group (p < 0.05). When comparing correlations between lesion volume and overall neurologic disability (EDSS score), T1SE correlated with EDSS (Spearman r = 0.29, p < 0.05) while T1GE (r = 0.23, p = 0.13) and FLAIR (r = 0.24, p = 0.12) did not. Conclusion: Our data suggest that hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. Based on these results, we hypothesize that T1GE

  18. MRI detection of hypointense brain lesions in patients with multiple sclerosis: T1 spin-echo vs. gradient-echo

    International Nuclear Information System (INIS)

    Dupuy, Sheena L.; Tauhid, Shahamat; Kim, Gloria; Chu, Renxin; Tummala, Subhash; Hurwitz, Shelley; Bakshi, Rohit

    2015-01-01

    Highlights: • Compared T1SE and T1GE in detecting hypointense brain lesions in MS patients. • T1GE detected a higher cerebral lesion volume and number than T1SE. • T1SE correlated significantly with disability, while T1GE did not. • Hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. - Abstract: Objective: Compare T1 spin-echo (T1SE) and T1 gradient-echo (T1GE) sequences in detecting hypointense brain lesions in multiple sclerosis (MS). Background: Chronic hypointense lesions on T1SE MRI scans are a surrogate of severe demyelination and axonal loss in MS. The role of T1GE images in the detection of such lesions has not been clarified. Design/methods: In 45 patients with MS [Expanded Disability Status Scale (EDSS) score (mean ± SD) 3.5 ± 2.0; 37 relapsing-remitting (RR); 8 secondary progressive (SP)], cerebral T1SE, T1GE, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images were acquired on a 1.5 T MRI scanner. Images were re-sampled to axial 5 mm slices before directly comparing lesion detectability using Jim (v.7, Xinapse Systems). Statistical methods included Wilcoxon signed rank tests to compare sequences and Spearman correlations to test associations. Results: Considering the entire cohort, T1GE detected a higher lesion volume (5.90 ± 6.21 vs. 4.17 ± 4.84 ml, p < 0.0001) and higher lesion number (27.82 ± 20.66 vs. 25.20 ± 20.43, p < 0.05) than T1SE. Lesion volume differences persisted when considering RR and SP patients separately (both p < 0.01). A higher lesion number by T1GE was seen only in the RR group (p < 0.05). When comparing correlations between lesion volume and overall neurologic disability (EDSS score), T1SE correlated with EDSS (Spearman r = 0.29, p < 0.05) while T1GE (r = 0.23, p = 0.13) and FLAIR (r = 0.24, p = 0.12) did not. Conclusion: Our data suggest that hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. Based on these results, we hypothesize that T1GE

  19. Electron spin resonance and electron spin echo modulation spectroscopic studies on the structure and reactivity of Pd(I) species in SAPO-11 molecular sieves

    International Nuclear Information System (INIS)

    Chul Wee Lee; Jong-Sung Yu; Kevan, L.

    1992-01-01

    This paper explores the possibility of using Pd ions in SAPO-11 by adding [Pd(NH 3 ) 4 ] 2+ during the synthesis of SAPO-11 to form PdSAPO-11, which is compared with solid-state ion exchange PdSAPO-11 and impregnation PdH-SAPO-11 in which palladium is in an extraframework position. Electron spin resonance and electron spin echo modulation spectroscopies are used to determine if the palladium position in PdSAPO-11 is located in a framework or extraframework

  20. Two-dimensional magnetism in the triangular antiferromagnet NiGa2S4

    International Nuclear Information System (INIS)

    Nambu, Yusuke

    2013-01-01

    At sufficiently low temperatures, electron spins in normal magnets generally order into some fashion, for instance, ferromagnetic and antiferromagnetic. Geometrical frustration and/or reduced dimensionality can suppress such conventional orders, and occasionally induce unknown states of matter. This is the case for the two-dimensional (2D) triangular antiferromagnet Ni(Ga 2 S 4 , in which S=1 nickel spins do not order, instead show an exotic magnetism. We found (1) a resonant critical slowing down toward T*=8.5 K followed by a viscous spin liquid behavior, and (2) a spin-size dependent ground state. To elucidate (1), spin dynamics ranging from 10 -13 to 10 0 seconds were quantitatively explored through the experimental techniques such as inelastic neutron scattering, backscattering, neutron spin echo, ac and nonlinear susceptibilities. The finding of (2) is evidenced by impurity effects. Integer spins substituted systems such as zinc and iron ions retain a quadratic temperature dependence of the magnetic specific heat as for the parent compound. However, substitutions of half-odd integer spins, cobalt and manganese ions, eventually induce a distinct behavior, indicating an importance of integer size of spins to stabilize the 2D magnetism realized in NiGa 2 S 4 . The article gives our experimental findings and as well as some relevant theoretical scenarios. (author)

  1. Comparison of axial T1 spin-echo and T1 fat-saturation magnetic resonance imaging techniques in the diagnosis of chondromalacia patellae.

    Science.gov (United States)

    Vanarthos, W J; Pope, T L; Monu, J U

    1994-12-01

    To test the diagnostic value of T1 spin-echo and T1 fat-saturated magnetic resonance images (MRIs), we reviewed axial T1-weighted images with and without fat saturation in 20 patients with clinically suspected chondromalacia of the patella. All scans were obtained on 1.5-MR units. The scans were randomly ordered and reviewed independently at different times by two radiologists without knowledge of the arthroscopy results. The sensitivity of the individual techniques for detecting grade 3 or 4 chondromalacia patellae was 92% for fat-saturated axial T1-weighted images alone, and 67% for axial T1-weighted images without fat saturation. The sensitivity of the combined techniques was 100% for grades 3 and 4 and 90% for all grades (0 to 4). Chondromalacia patellae is diagnosed more accurately by using T1 fat saturation than by using T1 spin-echo images. With a combination of the two techniques, accuracy is 90% to 100%.

  2. Frequency bandwidth extension by use of multiple Zeeman field offsets for electron spin-echo EPR oxygen imaging of large objects

    Science.gov (United States)

    Seifi, Payam; Epel, Boris; Sundramoorthy, Subramanian V.; Mailer, Colin; Halpern, Howard J.

    2011-01-01

    Purpose: Electron spin-echo (ESE) oxygen imaging is a new and evolving electron paramagnetic resonance (EPR) imaging (EPRI) modality that is useful for physiological in vivo applications, such as EPR oxygen imaging (EPROI), with potential application to imaging of multicentimeter objects as large as human tumors. A present limitation on the size of the object to be imaged at a given resolution is the frequency bandwidth of the system, since the location is encoded as a frequency offset in ESE imaging. The authors’ aim in this study was to demonstrate the object size advantage of the multioffset bandwidth extension technique.Methods: The multiple-stepped Zeeman field offset (or simply multi-B) technique was used for imaging of an 8.5-cm-long phantom containing a narrow single line triaryl methyl compound (trityl) solution at the 250 MHz imaging frequency. The image is compared to a standard single-field ESE image of the same phantom.Results: For the phantom used in this study, transverse relaxation (T2e) electron spin-echo (ESE) images from multi-B acquisition are more uniform, contain less prominent artifacts, and have a better signal to noise ratio (SNR) compared to single-field T2e images.Conclusions: The multi-B method is suitable for imaging of samples whose physical size restricts the applicability of the conventional single-field ESE imaging technique. PMID:21815379

  3. Reducing contrast contamination in radial turbo-spin-echo acquisitions by combining a narrow-band KWIC filter with parallel imaging.

    Science.gov (United States)

    Neumann, Daniel; Breuer, Felix A; Völker, Michael; Brandt, Tobias; Griswold, Mark A; Jakob, Peter M; Blaimer, Martin

    2014-12-01

    Cartesian turbo spin-echo (TSE) and radial TSE images are usually reconstructed by assembling data containing different contrast information into a single k-space. This approach results in mixed contrast contributions in the images, which may reduce their diagnostic value. The goal of this work is to improve the image contrast from radial TSE acquisitions by reducing the contribution of signals with undesired contrast information. Radial TSE acquisitions allow the reconstruction of multiple images with different T2 contrasts using the k-space weighted image contrast (KWIC) filter. In this work, the image contrast is improved by reducing the band-width of the KWIC filter. Data for the reconstruction of a single image are selected from within a small temporal range around the desired echo time. The resulting dataset is undersampled and, therefore, an iterative parallel imaging algorithm is applied to remove aliasing artifacts. Radial TSE images of the human brain reconstructed with the proposed method show an improved contrast when compared with Cartesian TSE images or radial TSE images with conventional KWIC reconstructions. The proposed method provides multi-contrast images from radial TSE data with contrasts similar to multi spin-echo images. Contaminations from unwanted contrast weightings are strongly reduced. © 2014 Wiley Periodicals, Inc.

  4. Theory of longitudinal atomic beam spin echo and parity violating Berry-phases in atoms; Theorie des longitudinalen Atomstrahl-Spinechos und paritaetsverletzende Berry-Phasen in Atomen

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, T.F.

    2006-07-19

    We present a nonrelativistic theory for the quantum mechanical description of longitudinal atomic beam spin echo experiments, where a beam of neutral atoms is subjected to static electric and magnetic fields. The atomic wave function is the solution of a matrix-valued Schroedinger equation and can be written as superposition of local (atomic) eigenstates of the potential matrix. The position- and time-dependent amplitude function of each eigenstate represents an atomic wave packet and can be calculated in a series expansion with a master formula that we derive. The zeroth order of this series expansion describes the adiabatic limit, whereas the higher order contributions contain the mixing of the eigenstates and the corresponding amplitude functions. We give a tutorial for the theoretical description of longitudinal atomic beam spin echo experiments and for the so-called Fahrplan model, which is a visualisation tool for the propagation of wave packets of different atomic eigenstates. As an example for the application of our theory, we study parity violating geometric (Berry-)phases. In this context, we define geometric flux densities, which for certain field configurations can be used to illustrate geometric phases in a vector diagram. Considering an example with a specific field configuration, we prove the existence of a parity violating geometric phase. (orig.)

  5. In vitro and in vivo spin echo diffusion imaging characteristics of synovial fluid: potential non-invasive differentiation of inflammatory and degenerative arthritis

    International Nuclear Information System (INIS)

    Eustace, S.; DiMasi, M.; Adams, J.; Ward, R.; Caruthers, S.; McAlindon, T.

    2000-01-01

    Objective. This study was undertaken to analyse the diffusion characteristics of synovial fluid in degenerative and inflammatory arthropathies.Design and patients. Ten in vitro specimens of synovial fluid from patients with both degenerative and inflammatory arthropathy were studied at body temperature with a navigator-corrected spin echo diffusion sequence (B values 0-512 s/mm 2 ), on a Philips 1.5-T Gyroscan. Subsequently synovial fluid from knee joint effusions of 25 patients (10 patients with osteoarthritis, 10 patients with effusions following trauma and 5 patients with effusions secondary to inflammatory arthritis) was evaluated with the same navigator-corrected spin echo diffusion sequence.Results. Both in vitro and in vivo study demonstrated decreased diffusion in patients with effusions secondary to degenerative joint disease (less than 2.40 x 10 -5 cm 2 /s) relative to patients with effusions accompanying knee trauma (greater than 2.75 x 10 -5 cm 2 /s) and inflammatory arthritis (in vitro and in vivo greater than 3.00 x 10 -5 cm 2 /s).Conclusion. Synovial fluid in degenerative arthritis shows less diffusion or free water movement than synovial fluid in inflammatory arthritis. Diffusion characteristics of synovial fluid may be used to predict the nature of the underlying form of arthritis in patients presenting with knee joint effusions. (orig.)

  6. Electronic Transport in Two-Dimensional Materials

    Science.gov (United States)

    Sangwan, Vinod K.; Hersam, Mark C.

    2018-04-01

    Two-dimensional (2D) materials have captured the attention of the scientific community due to the wide range of unique properties at nanometer-scale thicknesses. While significant exploratory research in 2D materials has been achieved, the understanding of 2D electronic transport and carrier dynamics remains in a nascent stage. Furthermore, because prior review articles have provided general overviews of 2D materials or specifically focused on charge transport in graphene, here we instead highlight charge transport mechanisms in post-graphene 2D materials, with particular emphasis on transition metal dichalcogenides and black phosphorus. For these systems, we delineate the intricacies of electronic transport, including band structure control with thickness and external fields, valley polarization, scattering mechanisms, electrical contacts, and doping. In addition, electronic interactions between 2D materials are considered in the form of van der Waals heterojunctions and composite films. This review concludes with a perspective on the most promising future directions in this fast-evolving field.

  7. Topology optimization of two-dimensional waveguides

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2003-01-01

    In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss.......In this work we use the method of topology optimization to design two-dimensional waveguides with low transmission loss....

  8. Feasibility and applications of the spin-echo modulation option for a small angle neutron scattering instrument at the European Spallation Source

    Science.gov (United States)

    Kusmin, A.; Bouwman, W. G.; van Well, A. A.; Pappas, C.

    2017-06-01

    We describe theoretical and practical aspects of spin-echo modulated small-angle neutron scattering (SEMSANS) as well as the potential combination with SANS. Based on the preliminary technical designs of SKADI (a SANS instrument proposed for the European Spallation Source) and a SEMSANS add-on, we assess the practicability, feasibility and scientific merit of a combined SANS and SEMSANS setup by calculating tentative SANS and SEMSANS results for soft matter, geology and advanced material samples that have been previously studied by scattering methods. We conclude that lengths from 1 nm up to 0.01 mm can be observed simultaneously in a single measurement. Thus, the combination of SANS and SEMSANS instrument is suited for the simultaneous observation of a wide range of length scales, e.g. for time-resolved studies of kinetic processes in complex multiscale systems.

  9. Whole brain, high resolution multiband spin-echo EPI fMRI at 7 T: A comparison with gradient-echo EPI using a color-word Stroop task

    NARCIS (Netherlands)

    Boyacioglu, R.; Schulz, J.; Müller, N.C.J.; Koopmans, P.J.; Barth, M.; Norris, David Gordon

    2014-01-01

    A whole brain, multiband spin-echo (SE) echo planar imaging (EPI) sequence employing a high spatial (1.5 mm isotropic) and temporal (TR of 2 s) resolution was implemented at 7 T. Its overall performance (tSNR, sensitivity and CNR) was assessed and compared to a geometrically matched gradient-echo

  10. Diagnosis of nerve root compromise of the lumbar spine: Evaluation of the performance of three-dimensional isotropic T2-weighted turbo spin-echo SPACE sequence at 3T

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Jin Kyeong; Jee, Won Hee; Jung, Joon Yong; Jang, Jin Hee; Kim, Jin Sung; Kim, Young Hoon; Ha, Kee Yong [Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)

    2017-01-15

    To explore the performance of three-dimensional (3D) isotropic T2-weighted turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip angle evolution (SPACE) sequence on a 3T system, for the evaluation of nerve root compromise by disc herniation or stenosis from central to extraforaminal location of the lumbar spine, when used alone or in combination with conventional two-dimensional (2D) TSE sequence. Thirty-seven patients who had undergone 3T spine MRI including 2D and 3D sequences, and had subsequent spine surgery for nerve root compromise at a total of 39 nerve levels, were analyzed. A total of 78 nerve roots (48 symptomatic and 30 asymptomatic sites) were graded (0 to 3) using different MRI sets of 2D, 3D (axial plus sagittal), 3D (all planes), and combination of 2D and 3D sequences, with respect to the nerve root compromise caused by posterior disc herniations, lateral recess stenoses, neural foraminal stenoses, or extraforaminal disc herniations; grading was done independently by two readers. Diagnostic performance was compared between different imaging sets using the receiver operating characteristics (ROC) curve analysis. There were no statistically significant differences (p = 0.203 to > 0.999) in the ROC curve area between the imaging sets for both readers 1 and 2, except for combined 2D and 3D (0.843) vs. 2D (0.802) for reader 1 (p = 0.035), and combined 2D and 3D (0.820) vs. 3D including all planes (0.765) for reader 2 (p = 0.049). The performance of 3D isotropic T2-weighted TSE sequence of the lumbar spine, whether axial plus sagittal images, or all planes of images, was not significantly different from that of 2D TSE sequences, for the evaluation of nerve root compromise of the lumbar spine. Combining 2D and 3D might possibly improve the diagnostic accuracy compared with either one.

  11. MR imaging findings of diffuse axonal injury: comparison of T2-weighted gradient images and T1- and T2-weighted spin-echo images

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seo Young; Lee, Ghi Jai; Kim, Jeong Seok; Shim, Jae Chan; Kim, Ho Kyun [Inje Univ. College of Medicine, Seoul (Korea, Republic of)

    1998-10-01

    To compare T2-weighted images with spin-echo T1- and turbo spin-echo (TSE) T2-weighted images in patients with diffuse axonal injury(DAI). Using a 1.0T MR unit, SE T1-, TSE T2-, and and FLASH T2-weighted images were obtained from 69 patients with a history of head trauma. In 18MR images of 17 patients with imaging findings of DAI, T2-weighted images were retrospectively compared with SE T1- and TSE T2-weighted images. The interval between trauma and MR scan varied from 5 days to 24(mean, 11) months. Focusing on the number of lesions, and their location and signal intensity, as weel as associated findings, three images were simultaueously evaluated. In 18 MR images of 17 patients with MR imaging findings of DAI, 21 lesions were detected on T1-weighted images, 28 on TSE T2-weighted images, and 70 on T2-weighted images;the last of these revealed all lesions detected on the other two. Most lesions were hypointense on T1-weighted images(17/21), hyperintense on TSE T2-weighted (21/28), and hypointense on T2-weighted (63/70). Common locations for DAI were the frontal lobe (n=3D35) and corpus callosum (n=3D22). Associated brain injuries were cortical contusion (n=3D5), brainstem injury (n=3D3), deep gray matter injury (n=3D2), and subdural hematoma(n=3D1). In patients with DAI. T2-weighted images can detect more lesions and associated petechial hemorrhage than can TSE T2-weighted images. This modality is thus useful for the evaluation of patients with head trauma.=20.

  12. T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Dohan, Anthony, E-mail: anthony.dohan@lrb.aphp.fr [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); UMR INSERM 965, Hôpital Lariboisière, 2 Rue Amboise Paré, 75010 Paris (France); Gavini, Jean-Philippe, E-mail: jpgavini@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); Placé, Vinciane, E-mail: vinciane.place@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Sebbag, Delphine, E-mail: delphinesebbag@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); Vignaud, Alexandre, E-mail: alexandre.vignaud@cea.fr [LRMN, Neurospin, CEA-SACLAY, Bâtiment 145, 91 191 Gif-sur-Yvette Cedex (France); and others

    2013-11-01

    Objective: To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver. Materials and methods: Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences. Results: SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001). Conclusion: SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.

  13. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao; Zhang, Hua

    2015-01-01

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards

  14. Construction of two-dimensional quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Klimek, S.; Kondracki, W.

    1987-12-01

    We present a sketch of the construction of the functional measure for the SU(2) quantum chromodynamics with one generation of fermions in two-dimensional space-time. The method is based on a detailed analysis of Wilson loops.

  15. Development of Two-Dimensional NMR

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 11. Development of Two-Dimensional NMR: Strucure Determination of Biomolecules in Solution. Anil Kumar. General Article Volume 20 Issue 11 November 2015 pp 995-1002 ...

  16. Fast FLAIR MR images of intracranial hemorrhage

    International Nuclear Information System (INIS)

    Chun, Eun Ju; Choi, Hye Young; Cho, Young A; Kim, Wha Young

    1998-01-01

    The purpose of this study is to evaluate the signal characteristics of intracranial hemorrhage, as seen on fluid attenuated inversion recovery (FLAIR) MR imaging according to various stages, and to compare FLAIR imaging with spin-echo T1- and T2-weighted MR imaging. We retrospectively evaluated fast FLAIR images along with spin-echo T1- and T2 weighted MR images of 32 lesions in 25 patients (12 males and 14 females, aged 3 - 84 yrs) with intracranial hemorrhagic lesions. For imaging, 1.5 T unit was used, and the nature of the lesions was found to be as follows : intracranial hemorrhage (n=15); tumor (n=9); infarction (n=4); arteriovenous malformation (n=3); and arachnoid cyst with hemorrhage (n=1). On the basis of spin-echo MR imaging, lesions were classified as acute, early subacute, late subacute, early chronic, or late chronic stage. The signal characteristics of intracranial hemorrhage were analysed in accordance with each staging, as seen on MR FLAIR imaging, and compared to the staging seen on spin-echo T1- and T-2 weighted MR imaging. The signal intensity of intracranial hemorrhage, as seen on FLAIR imaging, was not characteristic; it was similar to that of T2WI during the acute and subacute stages, and similiar to that of T1WI during the chronic stage. When used together with spin-echo T1- and T2-weighted MR imaging, however, FLAIR imaging may be useful for the classification of chronic intracranial hemorrhage as either early or late stage. (author). 20 refs., 2 tabs., 6 figs

  17. Phase transitions in two-dimensional systems

    International Nuclear Information System (INIS)

    Salinas, S.R.A.

    1983-01-01

    Some experiences are related using synchrotron radiation beams, to characterize solid-liquid (fusion) and commensurate solid-uncommensurate solid transitions in two-dimensional systems. Some ideas involved in the modern theories of two-dimensional fusion are shortly exposed. The systems treated consist of noble gases (Kr,Ar,Xe) adsorbed in the basal plane of graphite and thin films formed by some liquid crystal shells. (L.C.) [pt

  18. Two-dimensional nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Bax, A.; Lerner, L.

    1986-01-01

    Great spectral simplification can be obtained by spreading the conventional one-dimensional nuclear magnetic resonance (NMR) spectrum in two independent frequency dimensions. This so-called two-dimensional NMR spectroscopy removes spectral overlap, facilitates spectral assignment, and provides a wealth of additional information. For example, conformational information related to interproton distances is available from resonance intensities in certain types of two-dimensional experiments. Another method generates 1 H NMR spectra of a preselected fragment of the molecule, suppressing resonances from other regions and greatly simplifying spectral appearance. Two-dimensional NMR spectroscopy can also be applied to the study of 13 C and 15 N, not only providing valuable connectivity information but also improving sensitivity of 13 C and 15 N detection by up to two orders of magnitude. 45 references, 10 figures

  19. T2-weighted MR imaging of liver lesions: a prospective evaluation comparing turbo spin-echo, breath-hold turbo spin-echo and half-Fourier turbo spin-echo (HASTE) sequences; Estudio de lesiones hepaticas con imagenes de resonancia magnetica potenciadas en T2: evaluacion prospectiva comparando secuencias turbo eco del espin, turbo eco del espin con respiracion sostenida y half-Fourier turbo eco del espin (HASTE)

    Energy Technology Data Exchange (ETDEWEB)

    Martin, J.; Villajos, M.; Oses, M. J.; Veintemillas, M.; Rue, M.; Puig, J.; Sentis, M. [Fundacion Parc Tauli. Sabadell (Spain)

    2000-07-01

    To compare turbo spin-echo (TSE), breath-hold TSE and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences quantitatively and qualitatively in T2-weighted images of liver lesions. The authors evaluated prospectively 89 liver lesions in 73 patients using a 1.0-T magnetic resonance system to compare TSE, breath-hold TSE and HASTE sequences. The quantitative parameters were: lesion-to-liver contrast and lesion-to-liver contrast-to-noise ratio. The qualitative analysis was performed by two observers in consensus who examined four parameters: respiratory artifacts, lesion edge definition, intrahepatic vessel definition and image quality. Repeated measures analysis of variance was utilized to compare the quantitative variables and Friedman's nonparametric test for the qualitative parameters. In quantitative terms, the lesion-to-liver contrast was similar in TSE and breath-hold TSE sequences (2.45{+-}1.44 versus 2.60{+-}1.66), both of which were significantly better than the HASTE sequence (1.12{+-}0.72; p<0.001). The lesion-to-liver contrast-to-noise ratio was significantly higher in the TSE sequence (62.60{+-}46.40 versus 40.22{+-}25.35 versus 50.90{+-}32.10 for TSE, breath-hold TSE and HASTE sequences, respectively; p<0.001). In the qualitative comparisons, the HASTE sequence was significantly better than the TSE and breath-hold TSE sequences (p<0.001) in terms of artifacts and definition of lesion edge and intrahepatic vessels. Image quality was also significantly greater in the HASTE sequence (p<0.001). In quantitative terms, the TSE sequence is better than the breath-hold TSE and HASTE sequences, but there are no movement artifacts in the HASTE sequence, which is also significantly superior to TSE and breath-hold TSE sequences in qualitative terms and, thus, can be employed for T2-weighted images in liver studies. (Author) 17 refs.

  20. Two-dimensional x-ray diffraction

    CERN Document Server

    He, Bob B

    2009-01-01

    Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea

  1. Equivalence of two-dimensional gravities

    International Nuclear Information System (INIS)

    Mohammedi, N.

    1990-01-01

    The authors find the relationship between the Jackiw-Teitelboim model of two-dimensional gravity and the SL(2,R) induced gravity. These are shown to be related to a two-dimensional gauge theory obtained by dimensionally reducing the Chern-Simons action of the 2 + 1 dimensional gravity. The authors present an explicit solution to the equations of motion of the auxiliary field of the Jackiw-Teitelboim model in the light-cone gauge. A renormalization of the cosmological constant is also given

  2. Analytical simulation of two dimensional advection dispersion ...

    African Journals Online (AJOL)

    The study was designed to investigate the analytical simulation of two dimensional advection dispersion equation of contaminant transport. The steady state flow condition of the contaminant transport where inorganic contaminants in aqueous waste solutions are disposed of at the land surface where it would migrate ...

  3. Analytical Simulation of Two Dimensional Advection Dispersion ...

    African Journals Online (AJOL)

    ADOWIE PERE

    ABSTRACT: The study was designed to investigate the analytical simulation of two dimensional advection dispersion equation of contaminant transport. The steady state flow condition of the contaminant transport where inorganic contaminants in aqueous waste solutions are disposed of at the land surface where it would ...

  4. Sums of two-dimensional spectral triples

    DEFF Research Database (Denmark)

    Christensen, Erik; Ivan, Cristina

    2007-01-01

    construct a sum of two dimensional modules which reflects some aspects of the topological dimensions of the compact metric space, but this will only give the metric back approximately. At the end we make an explicit computation of the last module for the unit interval in. The metric is recovered exactly...

  5. Stability of two-dimensional vorticity filaments

    International Nuclear Information System (INIS)

    Elhmaidi, D.; Provenzale, A.; Lili, T.; Babiano, A.

    2004-01-01

    We discuss the results of a numerical study on the stability of two-dimensional vorticity filaments around a circular vortex. We illustrate how the stability of the filaments depends on the balance between the strain associated with the far field of the vortex and the local vorticity of the filament, and we discuss an empirical criterion for filament stability

  6. Two-Dimensional Motions of Rockets

    Science.gov (United States)

    Kang, Yoonhwan; Bae, Saebyok

    2007-01-01

    We analyse the two-dimensional motions of the rockets for various types of rocket thrusts, the air friction and the gravitation by using a suitable representation of the rocket equation and the numerical calculation. The slope shapes of the rocket trajectories are discussed for the three types of rocket engines. Unlike the projectile motions, the…

  7. Two-dimensional microstrip detector for neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Oed, A [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Because of their robust design, gas microstrip detectors, which were developed at ILL, can be assembled relatively quickly, provided the prefabricated components are available. At the beginning of 1996, orders were received for the construction of three two-dimensional neutron detectors. These detectors have been completed. The detectors are outlined below. (author). 2 refs.

  8. Conformal invariance and two-dimensional physics

    International Nuclear Information System (INIS)

    Zuber, J.B.

    1993-01-01

    Actually, physicists and mathematicians are very interested in conformal invariance: geometric transformations which keep angles. This symmetry is very important for two-dimensional systems as phase transitions, string theory or node mathematics. In this article, the author presents the conformal invariance and explains its usefulness

  9. Matching Two-dimensional Gel Electrophoresis' Spots

    DEFF Research Database (Denmark)

    Dos Anjos, António; AL-Tam, Faroq; Shahbazkia, Hamid Reza

    2012-01-01

    This paper describes an approach for matching Two-Dimensional Electrophoresis (2-DE) gels' spots, involving the use of image registration. The number of false positive matches produced by the proposed approach is small, when compared to academic and commercial state-of-the-art approaches. This ar...

  10. Two-dimensional membranes in motion

    NARCIS (Netherlands)

    Davidovikj, D.

    2018-01-01

    This thesis revolves around nanomechanical membranes made of suspended two - dimensional materials. Chapters 1-3 give an introduction to the field of 2D-based nanomechanical devices together with an overview of the underlying physics and the measurementtools used in subsequent chapters. The research

  11. Extended Polymorphism of Two-Dimensional Material

    NARCIS (Netherlands)

    Yoshida, Masaro; Ye, Jianting; Zhang, Yijin; Imai, Yasuhiko; Kimura, Shigeru; Fujiwara, Akihiko; Nishizaki, Terukazu; Kobayashi, Norio; Nakano, Masaki; Iwasa, Yoshihiro

    When controlling electronic properties of bulk materials, we usually assume that the basic crystal structure is fixed. However, in two-dimensional (2D) materials, atomic structure or to functionalize their properties. Various polymorphs can exist in transition metal dichalcogenides (TMDCs) from

  12. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao

    2015-02-25

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

  13. Geometrically undistorted MRI in the presence of field inhomogeneities using compressed sensing accelerated broadband 3D phase encoded turbo spin-echo imaging

    International Nuclear Information System (INIS)

    Van Gorp, Jetse S; Bakker, Chris J G; Bouwman, Job G; Zijlstra, Frank; Seevinck, Peter R; Smink, Jouke

    2015-01-01

    In this study, we explore the potential of compressed sensing (CS) accelerated broadband 3D phase-encoded turbo spin-echo (3D-PE-TSE) for the purpose of geometrically undistorted imaging in the presence of field inhomogeneities. To achieve this goal 3D-PE-SE and 3D-PE-TSE sequences with broadband rf pulses and dedicated undersampling patterns were implemented on a clinical scanner. Additionally, a 3D multi-spectral spin-echo (ms3D-SE) sequence was implemented for reference purposes. First, we demonstrated the influence of susceptibility induced off-resonance effects on the spatial encoding of broadband 3D-SE, ms3D-SE, 3D-PE-SE and 3D-PE-TSE using a grid phantom containing a titanium implant (Δχ = 182 ppm) with x-ray CT as a gold standard. These experiments showed that the spatial encoding of 3D-PE-(T)SE was unaffected by susceptibility induced off-resonance effects, which caused geometrical distortions and/or signal hyper-intensities in broadband 3D-SE and, to a lesser extent, in ms3D-SE frequency encoded methods. Additionally, an SNR analysis was performed and the temporally resolved signal of 3D-PE-(T)SE sequences was exploited to retrospectively decrease the acquisition bandwidth and obtain field offset maps. The feasibility of CS acceleration was studied retrospectively and prospectively for the 3D-PE-SE sequence using an existing CS algorithm adapted for the reconstruction of 3D data with undersampling in all three phase encoded dimensions. CS was combined with turbo-acceleration by variable density undersampling and spherical stepwise T 2 weighting by randomly sorting consecutive echoes in predefined spherical k-space layers. The CS-TSE combination resulted in an overall acceleration factor of 60, decreasing the original 3D-PE-SE scan time from 7 h to 7 min. Finally, CS accelerated 3D-PE-TSE in vivo images of a titanium screw were obtained within 10 min using a micro-coil demonstrating the feasibility of geometrically undistorted MRI near severe

  14. MRI of intracranial vertebral artery dissection: evaluation of intramural haematoma using a black blood, variable-flip-angle 3D turbo spin-echo sequence

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Koichi; Yamashita, Shinnichi; Kuwabara, Yasuo; Yoshimitsu, Kengo [Fukuoka University, Department of Radiology, Faculty of Medicine, Fukuoka-shi, Fukuoka (Japan); Takemoto, Koichiro; Inoue, Tooru [Fukuoka University, Department of Neurosurgery, Faculty of Medicine, Fukuoka (Japan)

    2013-07-15

    We investigated the efficacy of three-dimensional black blood T1-weighted imaging (3D-BB-T1WI) using a variable refocusing flip angle turbo spin-echo sequence in the diagnosis of intracranial vertebral artery dissection (VAD). Sixteen consecutive patients diagnosed with intracranial VAD underwent magnetic resonance imaging that included 3D time-of-flight-MRA, axial spin-echo T1-weighted images (SE-T1WI) and oblique coronal 3D-BB-T1WI sequences. The visualization, morphology and extent of intramural haematomas were assessed and compared among the sequences. Results obtained by digital subtraction angiography (DSA), 3D-angiography and/or 3D-CT angiography (CTA) were used as standards of reference. 3D-BB-T1WI revealed intramural haematomas in all cases, whereas SE-T1WI and magnetic resonance angiography (MRA) failed to reveal a haematoma in one case and three cases, respectively. The mean visualization grading score for the intramural haematoma was the highest for 3D-BB-T1WI, and there was a statistically significant difference among the sequences (p < 0.001). At least a portion of the intramural haematoma was distinguishable from the lumen on 3D-BB-T1WI, whereas the haematomas were entirely indistinguishable from intraluminal signals on MRA in two cases (12.5 %) and on SE-T1WI in one case (6.3 %). 3D-BB-T1WI revealed the characteristic crescent shape of the intramural haematoma in 14 cases (87.5 %), whereas SE-T1WI and MRA revealed a crescent shape in only 7 cases (43.8 %) and 8 cases (50 %), respectively. In a consensus reading, 3D-BB-T1WI was considered the most consistent sequence in representing the extent and morphology of the lesion in 14 cases (87.5 %), compared to DSA and CTA. 3D-BB-T1WI is a promising method to evaluate intramural haematoma in patients with suspected intracranial VAD. (orig.)

  15. Calculation of T2 relaxation time from ultrafast single shot sequences for differentiation of liver tumors. Comparison of echo-planar, HASTE, and spin-echo sequences

    International Nuclear Information System (INIS)

    Abe, Yasuko; Yamashita, Yasuyuki; Tang, Yi; Namimoto, Tomohiro; Takahashi, Mutsumasa

    2000-01-01

    The purpose of this study was to evaluate the accuracy of T2 calculation from single shot imaging sequences such as echo-planar imaging (EPI) and half-Fourier single shot turbo spin-echo (HASTE) imaging. For the phantom study, we prepared vials containing different concentrations of agarose, copper sulfate, and nickel chloride. The temperature of the phantom was kept at 22 deg C. MR images were obtained with a 1.5-Tesla superconductive magnet. Spin-echo (SE)-type EPI and HASTE sequences with different TEs were obtained for T2 calculation, and the T2 values were compared with those obtained from the Carr-Purcell-Meiborm-Gill (CPMG) sequence. The clinical study group consisted of 30 consecutive patients referred for MR imaging to characterize focal liver lesions. A total of 40 focal liver lesions were evaluated, including 25 primary or metastatic solid masses and 15 non-solid lesions. Single shot SE-type EPI and HASTE were both performed with TEs of 64 and 90 msec. In the phantom study, the T2 values obtained from both single shot sequences showed significant correlations with those from the CPMG sequence (T2 on EPI vs. T2 on CPMG: r=0.98, p<0.01; T2 on HASTE vs. T2 on CPMG: r=0.99, p<0.01). In the clinical study, mean T2 values for liver calculated from EPI (42 msec) were significantly shorter than those calculated from the HASTE sequence (58 msec) (p<0.001). Mean T2 values for solid tumors were 95 msec with HASTE and 72 msec with EPI, and mean T2 values for non-solid lesions were 128 msec with HASTE and 159 msec with EPI. Although mean T2 values between solid and non-solid lesions were significantly different for both EPI and HASTE sequences (p=0.01 for HASTE, p<0.001 for EPI), the overlap of solid and non-solid lesions was less frequent in EPI than in HASTE. With single shot sequences, it is possible to obtain the T2 values that show excellent correlation with the CPMG sequence. Although both HASTE and EPI are useful to calculate T2 values, EPI appears to be more

  16. Two-dimensional shielding benchmarks for iron at YAYOI, (1)

    International Nuclear Information System (INIS)

    Oka, Yoshiaki; An, Shigehiro; Kasai, Shigeru; Miyasaka, Shun-ichi; Koyama, Kinji.

    The aim of this work is to assess the collapsed neutron and gamma multigroup cross sections for two dimensional discrete ordinate transport code. Two dimensional distributions of neutron flux and gamma ray dose through a 70cm thick and 94cm square iron shield were measured at the fast neutron source reactor ''YAYOI''. The iron shield was placed over the lead reflector in the vertical experimental column surrounded by heavy concrete wall. The detectors used in this experiment were threshold detectors In, Ni, Al, Mg, Fe and Zn, sandwitch resonance detectors Au, W and Co, activation foils Au for neutrons and thermoluminescence detectors for gamma ray dose. The experimental results were compared with the calculated ones by the discrete ordinate transport code ANISN and TWOTRAN. The region-wise, coupled neutron-gamma multigroup cross-sections (100n+20gamma, EURLIB structure) were generated from ENDF/B-IV library for neutrons and POPOP4 library for gamma-ray production cross-sections by using the code system RADHEAT. The effective microscopic neutron cross sections were obtained from the infinite dilution values applying ABBN type self-shielding factors. The gamma ray production multigroup cross-sections were calculated from these effective microscopic neutron cross-sections. For two-dimensional calculations the group constants were collapsed into 10 neutron groups and 3 gamma groups by using ANISN. (auth.)

  17. Human muscle proteins: analysis by two-dimensional electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Giometti, C.S.; Danon, M.J.; Anderson, N.G.

    1983-09-01

    Proteins from single frozen sections of human muscle were separated by two-dimensional gel electrophoresis and detected by fluorography or Coomassie Blue staining. The major proteins were identical in different normal muscles obtained from either sex at different ages, and in Duchenne and myotonic dystrophy samples. Congenital myopathy denervation atrophy, polymyositis, and Becker's muscular dystrophy samples, however, showed abnormal myosin light chain compositions, some with a decrease of fast-fiber myosin light chains and others with a decrease of slow-fiber light chains. These protein alterations did not correlate with any specific disease, and may be cause by generalized muscle-fiber damage.

  18. Three-dimensional gradient echo versus spin echo sequence in contrast-enhanced imaging of the pituitary gland at 3 T

    Energy Technology Data Exchange (ETDEWEB)

    Kakite, Suguru, E-mail: sugkaki@med.tottori-u.ac.jp [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Fujii, Shinya [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Kurosaki, Masamichi [Department of Neurosurgery, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan); Kanasaki, Yoshiko; Matsusue, Eiji; Kaminou, Toshio; Ogawa, Toshihide [Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishicho, Yonago 683-8503 (Japan)

    2011-07-15

    Introduction: To clarify whether a three-dimensional-gradient echo (3D-GRE) or spin echo (SE) sequence is more useful for evaluating sellar lesions on contrast-enhanced T1-weighted MR imaging at 3.0 Tesla (T). Methods: We retrospectively assessed contrast-enhanced T1-weighted images using 3D-GRE and SE sequences at 3.0 T obtained from 33 consecutive patients with clinically suspected sellar lesions. Two experienced neuroradiologists evaluated the images qualitatively in terms of the following criteria: boundary edge of the cavernous sinus and pituitary gland, border of sellar lesions, delineation of the optic nerve and cranial nerves within the cavernous sinus, susceptibility and flow artifacts, and overall image quality. Results: At 3.0 T, 3D-GRE provided significantly better images than the SE sequence in terms of the border of sellar lesions, delineation of cranial nerves, and overall image quality; there was no significant difference regarding the boundary edge of the cavernous sinus and pituitary gland. In addition, the 3D-GRE sequence showed fewer pulsation artifacts but more susceptibility artifacts. Conclusion: Our results indicate that 3D-GRE is the more suitable sequence for evaluating sellar lesions on contrast-enhanced T1-weighted imaging at 3.0 T.

  19. Comparative study of image quality between axial T2-weighted BLADE and turbo spin-echo MRI of the upper abdomen on 3.0 T.

    Science.gov (United States)

    Zhang, Lin; Tian, ChunMei; Wang, PeiYuan; Chen, Liang; Mao, XiJin; Wang, ShanShan; Wang, Xu; Dong, JingMin; Wang, Bin

    2015-09-01

    To compare image quality of turbo spin-echo (TSE) with BLADE [which is also named periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER)] on magnetic resonance imaging (MRI) for upper abdomen. This study involved the retrospective evaluation of 103 patients (63 males, 40 females; age range 19-76 years; median age 53.8 years) who underwent 3.0 T MRI with both conventional TSE T2-weighted imaging (T2WI) and BLADE TSE T2WI. Two radiologists assessed respiratory motion, gastrointestinal peristalsis, and vascular pulsation artifacts, as well as the sharpness of the liver and pancreas edges. Scores for all magnetic resonance (MR) images were recorded. Wilcoxon's rank test was used to compare hierarchical data. Cohen's kappa coefficient was adopted to analyze interobserver consistency. Compared to TSE T2WI, BLADE TSE T2WI reduced all of the examined motion artifacts and increased the sharpness of the liver and pancreas edges (all P image quality.

  20. Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: a dual STIR-CHESS combination prepulse for turbo spin echo pulse sequences.

    Science.gov (United States)

    Tanabe, Koji; Nishikawa, Keiichi; Sano, Tsukasa; Sakai, Osamu; Jara, Hernán

    2010-05-01

    To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl(2) aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl(2) aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Dual-FS could suppress fat sufficiently within the inversion time of 110-140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. Copyright 2010 Wiley-Liss, Inc.

  1. Carcinoma of the uterine cervix. High-resolution turbo spin-echo MR imaging with contrast-enhanced dynamic scanning and T2-weighting

    International Nuclear Information System (INIS)

    Abe, Y.; Yamashita, Y.; Namimoto, T.; Takahashi, M.; Katabuchi, H.; Tanaka, N.; Okamura, H.

    1998-01-01

    Purpose: To compare high-resolution contrast-enhanced (Gd-DTPA) dynamic MR imaging with T2-weighted turbo spin-echo (TSE) imaging in the evaluation of uterine cervical carcinoma. Material and Methods: Thirty-two patients with cervical carcinoma underwent MR imaging on a 1.5 T superconductive unit to have the extension of the disease assessed before treatment. A phased-array coil was used in all patients. In 25 patients, surgical confirmation of the diagnosis was obtained after imaging. Radiation therapy was selected for the remaining 7 patients with advanced carcinoma. Qualitative and quantitative image analyses were also performed. Results: The cervical carcinomas showed maximum contrast in the cervical stroma and myometrium in the early dynamic phase. The tumor/cervical-stroma contrast in the early dynamic phase obtained with the T1-weighted TSE technique (contrast-to-noise ratio 22.6) was significantly higher than that obtained in T2-weighted TSE imaging (contrast-to-noise ratio 4.3). In the evaluation of parametrial invasion, the accuracy of T2-weighted imaging was 71.8% and contrast-enhanced dynamic imaging 81.2%. Conclusion: High-resolution contrast-enhanced (Gd-DTPA) dynamic MR imaging in cervical cancer offers improved tumor/cervical-stroma contrast and provides useful information on parametrial invasion. (orig.)

  2. Solid-state NMR spin-echo investigation of the metalloproteins parvalbumin, concanavalin A, and pea and lentil lectins, substituted with cadmium-113

    Science.gov (United States)

    Marchetti, Paul S.; Bhattacharyya, Lokesh; Ellis, Paul D.; Brewer, C. Fred

    Solid-state 113Cd NMR spectroscopy of static powder samples of 113Cd-substituted metalloproteins, parvalbumin, concanavalin A, and pea and lentil lectins, was carried out. Cross polarization followed by application of a train of uniformly spaced π pulses was employed to investigate the origin of residual cadmium NMR linewidths observed previously in these proteins. Fourier transformation of the resulting spin-echo train yielded spectra consisting of uniformly spaced lines having linewidths of the order of 1-2 ppm. The observed linewidths were not influenced by temperature as low as -50°C or by extent of protein hydration. Since the echo-train pulse sequence is able to eliminate inhomogeneous but not homogeneous contributions to the linewidths, there is a predominant inhomogeneous contribution to cadmium linewidths in the protein CP/MAS spectra. However, significant changes in spectral intensities were observed with change in temperature and extent of protein hydration. These intensity changes are attributed for parvalbumin and concanavalin A to changes in cross-polarization efficiency with temperature and hydration. For pea and lentil lectins, this effect is attributed to the elimination of static disorder at the pea and lentil S2 metal-ion sites due to sugar binding.

  3. Comparison of gradient-recalled echo and spin-echo echo-planar imaging MR elastography in staging liver fibrosis. A meta-analysis

    International Nuclear Information System (INIS)

    Kim, Yong Seek; Jang, Yu Na; Song, Ji Soo

    2018-01-01

    To compare the diagnostic performance of gradient-recalled echo-based magnetic resonance elastography (GRE-MRE) and spin-echo echo-planar imaging-based MRE (SE-EPI-MRE) in liver fibrosis staging. A systematic literature search was performed to identify studies involving the performance of MRE for the diagnosis of liver fibrosis. Pooled sensitivity, specificity, positive and negative likelihood ratios, the diagnostic odds ratio, and a summary receiver operating characteristic (ROC) curve were estimated by using a bivariate random effects model. Subgroup analyses were performed between different study characteristics. Twenty-six studies with a total of 3,200 patients were included in the meta-analysis. Pooled sensitivity and specificity of GRE-MRE and SE-EPI-MRE did not differ significantly. The area under the summary ROC curve for stage diagnosis of any (F ≥ 1), significant (F ≥ 2), advanced (F ≥ 3), and cirrhosis (F = 4) on GRE-MRE and SE-EPI-MRE were 0.93 versus 0.94, 0.95 versus 0.94, 0.94 versus 0.95, and 0.92 versus 0.93, respectively. Substantial heterogeneity was detected for both sequences. Both GRE and SE-EPI-MRE show high sensitivity and specificity for detection of each stage of liver fibrosis, without significant differences. Magnetic resonance elastography (MRE) may be useful for noninvasive evaluation of liver fibrosis in chronic liver disease. (orig.)

  4. Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.

    Science.gov (United States)

    Griffin, John F; Archambault, Nicholas S; Mankin, Joseph M; Wall, Corey R; Thompson, James A; Padua, Abraham; Purdy, David; Kerwin, Sharon C

    2013-11-15

    Laboratory investigation, ex vivo. Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants. Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking. Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (implantation with stainless steel implants. N/A.

  5. Intracranial cerebrospinal fluid spaces imaging using a pulse-triggered three-dimensional turbo spin echo MR sequence with variable flip-angle distribution

    Energy Technology Data Exchange (ETDEWEB)

    Hodel, Jerome [Unite Analyse et Restauration du Mouvement, UMR-CNRS, 8005 LBM ParisTech Ensam, Paris (France); University Paris Est Creteil (UPEC), Creteil (France); Assistance Publique-Hopitaux de Paris, Paris (France); Hopital Henri Mondor, Department of Neuroradiology, Creteil (France); Hopital Henri Mondor, Creteil (France); Silvera, Jonathan [University Paris Est Creteil (UPEC), Creteil (France); Assistance Publique-Hopitaux de Paris, Paris (France); Hopital Henri Mondor, Department of Neuroradiology, Creteil (France); Bekaert, Olivier; Decq, Philippe [Unite Analyse et Restauration du Mouvement, UMR-CNRS, 8005 LBM ParisTech Ensam, Paris (France); University Paris Est Creteil (UPEC), Creteil (France); Assistance Publique-Hopitaux de Paris, Paris (France); Hopital Henri Mondor, Department of Neurosurgery, Creteil (France); Rahmouni, Alain [University Paris Est Creteil (UPEC), Creteil (France); Assistance Publique-Hopitaux de Paris, Paris (France); Hopital Henri Mondor, Department of Radiology, Creteil (France); Bastuji-Garin, Sylvie [University Paris Est Creteil (UPEC), Creteil (France); Assistance Publique-Hopitaux de Paris, Paris (France); Hopital Henri Mondor, Department of Public Health, Creteil (France); Vignaud, Alexandre [Siemens Healthcare, Saint Denis (France); Petit, Eric; Durning, Bruno [Laboratoire Images Signaux et Systemes Intelligents, UPEC, Creteil (France)

    2011-02-15

    To assess the three-dimensional turbo spin echo with variable flip-angle distribution magnetic resonance sequence (SPACE: Sampling Perfection with Application optimised Contrast using different flip-angle Evolution) for the imaging of intracranial cerebrospinal fluid (CSF) spaces. We prospectively investigated 18 healthy volunteers and 25 patients, 20 with communicating hydrocephalus (CH), five with non-communicating hydrocephalus (NCH), using the SPACE sequence at 1.5T. Volume rendering views of both intracranial and ventricular CSF were obtained for all patients and volunteers. The subarachnoid CSF distribution was qualitatively evaluated on volume rendering views using a four-point scale. The CSF volumes within total, ventricular and subarachnoid spaces were calculated as well as the ratio between ventricular and subarachnoid CSF volumes. Three different patterns of subarachnoid CSF distribution were observed. In healthy volunteers we found narrowed CSF spaces within the occipital aera. A diffuse narrowing of the subarachnoid CSF spaces was observed in patients with NCH whereas patients with CH exhibited narrowed CSF spaces within the high midline convexity. The ratios between ventricular and subarachnoid CSF volumes were significantly different among the volunteers, patients with CH and patients with NCH. The assessment of CSF spaces volume and distribution may help to characterise hydrocephalus. (orig.)

  6. Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan.

    1991-10-01

    The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

  7. Intracranial cerebrospinal fluid spaces imaging using a pulse-triggered three-dimensional turbo spin echo MR sequence with variable flip-angle distribution

    International Nuclear Information System (INIS)

    Hodel, Jerome; Silvera, Jonathan; Bekaert, Olivier; Decq, Philippe; Rahmouni, Alain; Bastuji-Garin, Sylvie; Vignaud, Alexandre; Petit, Eric; Durning, Bruno

    2011-01-01

    To assess the three-dimensional turbo spin echo with variable flip-angle distribution magnetic resonance sequence (SPACE: Sampling Perfection with Application optimised Contrast using different flip-angle Evolution) for the imaging of intracranial cerebrospinal fluid (CSF) spaces. We prospectively investigated 18 healthy volunteers and 25 patients, 20 with communicating hydrocephalus (CH), five with non-communicating hydrocephalus (NCH), using the SPACE sequence at 1.5T. Volume rendering views of both intracranial and ventricular CSF were obtained for all patients and volunteers. The subarachnoid CSF distribution was qualitatively evaluated on volume rendering views using a four-point scale. The CSF volumes within total, ventricular and subarachnoid spaces were calculated as well as the ratio between ventricular and subarachnoid CSF volumes. Three different patterns of subarachnoid CSF distribution were observed. In healthy volunteers we found narrowed CSF spaces within the occipital aera. A diffuse narrowing of the subarachnoid CSF spaces was observed in patients with NCH whereas patients with CH exhibited narrowed CSF spaces within the high midline convexity. The ratios between ventricular and subarachnoid CSF volumes were significantly different among the volunteers, patients with CH and patients with NCH. The assessment of CSF spaces volume and distribution may help to characterise hydrocephalus. (orig.)

  8. Silver atom solvation and desolvation in ice matrices: study of solvation shell geometry by electron spin resonance and electron spin echo methods

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, L; Narayana, P A

    1978-01-01

    Results of studies of the solvation shell structure of silver atoms in ice matrix at 4/sup 0/K by electron spin resonance (ESR) and electron spin echo spectrometry are reported. Drastic change in the hyperfine coupling constant of the silver atom was noted when the silver atom initially produced at 4/sup 0/K was warmed to 77/sup 0/K and reexamined by ESR at 4/sup 0/K. This suggested a very drastic rearrangement of the water molecules surrounding the silver atom. The geometric arrangement of water molecules around the silver atom produced at 4/sup 0/K was what would be expected for a solvated silver ion, indicating that no rearrangement had occurred after the silver atom formed. The addition of a little thermal excitation (heating to 77/sup 0/K) results in the geometry changes than can be explained by assuming either that a water molecule rotates around one of its OH bands or by the development of a hydrogen bond between the silver atom and one of the first solvation shell water molecules. Optical excitation in the absorption band of the silver atom in the ice matrix at 400nm resulted in desolvation of the silver ion or a reversion to the structure originally obtained by reaction of solver salts in ic matrix with radiation produced electrons. This was best explained by a charge transfer mechanism. (BLM)

  9. Study on Mo(V) species, location and adsorbates interactions in MoH-SAPO-34 by employing ESR and electron spin-echo modulation spectroscopies

    International Nuclear Information System (INIS)

    Back, Gern Ho; Jang, Chang Ki; Ru, Chang Kuk; Cho, Young Hwan; So, Hyun Soo; Larry, Keven

    2002-01-01

    A solid-state reaction of MoO 3 with as-synthesized H-SAPO-34 generated paramagnetic Mo(V) species. The dehydration resulted in weak Mo(V) species, and subsequent activation resulted in the formation of Mo(V) species such as Mo(V) 5c and Mo(V) 6c that are characterized by ESR. The data of ESR and ESEM show the oxomolybdenum species, to be (MoO 2 ) + or (MoO) 3+ . The (MoO 2 ) + species seems to be more probable. Since H-SAPO-34 has a low framework negative charge, (MoO) 3+ with a high positive charge can not be easily stabilized. A solution reaction between the solution of silico-molybdic acid and calcined H-SAPO-34 resulted in only MoO + 2 species. A rhombic ESR signal is observed on adsorption of D 2 O, CD 3 OH, CH 3 CH 2 OD and ND 3 . The Location and coordination structure of Mo(V) species has been determined by three-pulse electron spin-echo modulation data and their simulations. After the adsorption of methanol, ethylene, ammonia, and water for MoH-SAPO-34, three molecules, one and one molecule, respectively, are directly coordinated to (MoO 2 ) +

  10. MRT versus CT in the diagnosis of pneumonia. Evaluation of a T2-weighted utrafast turbo-spin-echo sequence (UTSE)

    International Nuclear Information System (INIS)

    Leutner, C.; Lutterbey, G.; Kuhl, C.K.; Flacke, S.; Schild, H.H.; Glasmacher, A.; Theisen, A.; Wardelmann, E.; Grohe, C.

    1999-01-01

    Purpose: To evaluate a T 2 -weighted URSE sequence for the assessment of pulmonary infiltrations in comparison to CT. Methods: 28 MRT scans of 22 patients with confirmed pneumonia were recorded on a 1.5 Tesla apparatus with an expiratory and diastolic triggered, T 2 -weighted ultrafast-spin-echo sequence in axial slice mode with the following parameters: TR eff /T E /Turbofactor 2000-4000/90 ms/21-23; slice thickness/separation 6/0.6 mm; FOV 360 mm; 24 slices. 24 spiral CTs (sice thickness/table advance: 1-2 mm/10 mm) were available for comparison. The separate evaluation of MRTs and CTs was performed by three radiologists in a consensus procedure with regard to pulmonary lesions (e.g., infiltration, round foci, net patterns) and image quality of the MRTs (4-step scale). Results: In 71% of the cases the CTs and MRTs agreed with the diagnosis and representation of the lesions, in 25% MRT was superior. MRT was better for the detection of pulmonary abscesses. In 93% the image quality of the MRT was very good to good. Conclusions: MRT in the technique presented here is in most cases equal to CT for the detection of pneumonia. Diagnosis of pulmonary abscesses seems to be better with MRT. (orig.) [de

  11. Comparison of intravoxel incoherent motion diffusion-weighted imaging between turbo spin-echo and echo-planar imaging of the head and neck

    Energy Technology Data Exchange (ETDEWEB)

    Mikayama, Ryoji; Yabuuchi, Hidetake; Nagatomo, Kazuya; Kimura, Mitsuhiro; Kumazawa, Seiji [Kyushu University, Department of Health Sciences, Graduate School of Medical Sciences, Fukuoka (Japan); Sonoda, Shinjiro; Kobayashi, Koji [Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka (Japan); Kawanami, Satoshi; Kamitani, Takeshi; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Fukuoka (Japan)

    2018-01-15

    To compare image quality, apparent diffusion coefficient (ADC), and intravoxel incoherent motion (IVIM)-derived parameters between turbo spin-echo (TSE)-diffusion-weighted imaging (DWI) and echo-planar imaging (EPI)-DWI of the head and neck. Fourteen volunteers underwent head and neck imaging using TSE-DWI and EPI-DWI. Distortion ratio (DR), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), ADC and IVIM-derived parameters were compared between the two techniques. Bland-Altman analysis was performed to analyse reproducibility between the quantitative parameters of TSE-DWI and EPI-DWI. DR of TSE-DWI was significantly smaller than that of EPI-DWI. SNR and CNR of TSE-DWI were significantly higher than those of EPI-DWI. ADC and IVIM-derived parameters of TSE-DWI showed higher values than those of EPI-DWI, although the difference was not significant. Bland-Altman analysis showed wide limits of agreement between the two sequences. TSE-DWI can produce better image quality than EPI-DWI, while TSE-DWI possibly exhibits different values of quantitative parameters. Therefore, TSE-DWI could be a good alternative to EPI-DWI for patients sensitive to distortion. However, it is not recommended to use both TSE-DWI and EPI-DWI on follow-up. (orig.)

  12. Improved fat-suppression homogeneity with mDIXON turbo spin echo (TSE) in pediatric spine imaging at 3.0 T.

    Science.gov (United States)

    Pokorney, Amber L; Chia, Jonathan M; Pfeifer, Cory M; Miller, Jeffrey H; Hu, Houchun H

    2017-11-01

    Background Robust fat suppression remains essential in clinical MRI to improve tissue signal contrast, minimize fat-related artifacts, and enhance image quality. Purpose To compare fat suppression between mDIXON turbo spin echo (TSE) and conventional frequency-selective and inversion-recovery methods in pediatric spine MRI. Material and Methods Images from T1-weighted (T1W) and T2-weighted (T2W) TSE sequences coupled with conventional methods and the mDIXON technique were compared in 36 patients (5.8 ± 5.4 years) at 3.0 T. Images from 42 pairs of T1W (n = 16) and T2W (n = 26) scans were acquired. Two radiologists reviewed the data and rated images using a three-point scale in two categories, including the uniformity of fat suppression and overall diagnostic image quality. The Wilcoxon rank-sum test was used to compare the scores. Results The Cohen's kappa coefficient for inter-rater agreement was 0.69 (95% confidence interval [CI], 0.56-0.83). Images from mDIXON TSE were considered superior in fat suppression ( P 3.0 T and should be considered as a permanent replacement of traditional methods, in particular frequency-selective techniques.

  13. Abnormal intraluminal signal within the pulmonary arteries on MR imaging: Differentiation between slow blood flow and thrombus using an ECG-gated; multiphasic: Spin-echo technique

    International Nuclear Information System (INIS)

    White, R.D.; Higgins, C.B.

    1986-01-01

    The authors evaluated abnormal MR imaging signal patterns in the pulmonary arteries of 22 patients with pulmonary hypertension (n = 13), pulmonary embolus (n = 4), or both (n = 5). Using multiphasic (five or six phases; 19 patients) or standard (three patients with pulmonary embolus) ECG-gated, double spin-echo techniques, they were able to differentiate between causes of such abnormal signal patterns. The pattern of slow blood flow (abnormal signal in systole with fluctuating distribution during cardiac cycle, and intensity increasing visually from first to second echo) was noted in 89% of patients with pulmonary hypertension alone or in combination with pulmonary embolism, and was characteristic of high systolic pulmonary pressures (12 of 12 patients with pressure > 80 mm Hg, vs. 3 of 5 patients with pressure 55 mm Hg vs. 5 of 7 patients with pressures <55 mm Hg). This pattern was differentiated from that of thrombus (persistent signal with fixed distribution during cardiac cycle, and little to no visible intensity change from first to second echo), which was noted in six of seven proved embolus cases. Thus, gated multiphase MR imaging shows potential for the noninvasive visualization of pulmonary embolus and the differentiation of this entity from the slow blood flow of pulmonary hypertension

  14. Retrospective comparison of gradient recalled echo R2* and spin-echo R2 magnetic resonance analysis methods for estimating liver iron content in children and adolescents

    Energy Technology Data Exchange (ETDEWEB)

    Serai, Suraj D.; Fleck, Robert J. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States); Quinn, Charles T. [Cincinnati Children' s Hospital Medical Center, Division of Hematology, Cincinnati, OH (United States); Zhang, Bin [Cincinnati Children' s Hospital Medical Center, Division of Biostatistics and Epidemiology, Cincinnati, OH (United States); Podberesky, Daniel J. [Nemours Children' s Health System Nemours Children' s Hospital, Department of Radiology, Orlando, FL (United States)

    2015-10-15

    Serial surveillance of liver iron concentration (LIC) provides guidance for chelation therapy in patients with iron overload. The diagnosis of iron overload traditionally relies on core liver biopsy, which is limited by invasiveness, sampling error, cost and general poor acceptance by pediatric patients and parents. Thus noninvasive diagnostic methods such as MRI are highly attractive for quantification of liver iron concentration. To compare two MRI-based methods for liver iron quantification in children. 64 studies on 48 children and young adults (age range 4-21 years) were examined by gradient recalled echo (GRE) R2* and spin-echo R2 MRI at 1.5T to evaluate liver iron concentration. Scatter plots and Bland-Altman difference plots were generated to display and assess the relationship between the methods. With the protocols used in this investigation, Bland-Altman agreement between the methods is best when LIC is <20 mg/g dry tissue. Scatter plots show that all values with LIC <20 mg/g dry tissue fall within the 95% prediction limits. Liver iron concentration as determined by the R2* and R2 MR methods is statistically comparable, with no statistical difference between these methods for LIC <20 mg/g. (orig.)

  15. Comparison of Turbo Spin Echo and Echo Planar Imaging for intravoxel incoherent motion and diffusion tensor imaging of the kidney at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Hilbert, Fabian; Wech, Tobias; Neubauer, Henning; Veldhoen, Simon; Bley, Thorsten Alexander; Koestler, Herbert [Wuerzburg Univ. (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie

    2017-10-01

    Echo Planar Imaging (EPI) is most commonly applied to acquire diffusion-weighted MR-images. EPI is able to capture an entire image in very short time, but is prone to distortions and artifacts. In diffusion-weighted EPI of the kidney severe distortions may occur due to intestinal gas. Turbo Spin Echo (TSE) is robust against distortions and artifacts, but needs more time to acquire an entire image compared to EPI. Therefore, TSE is more sensitive to motion during the readout. In this study we compare diffusion-weighted TSE and EPI of the human kidney with regard to intravoxel incoherent motion (IVIM) and diffusion tensor imaging (DTI). Images were acquired with b-values between 0 and 750 s/mm{sup 2} with TSE and EPI. Distortions were observed with the EPI readout in all volunteers, while the TSE images were virtually distortion-free. Fractional anisotropy of the diffusion tensor was significantly lower for TSE than for EPI. All other parameters of DTI and IVIM were comparable for TSE and EPI. Especially the main diffusion directions yielded by TSE and EPI were similar. The results demonstrate that TSE is a worthwhile distortion-free alternative to EPI for diffusion-weighted imaging of the kidney at 3 Tesla.

  16. MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

    Energy Technology Data Exchange (ETDEWEB)

    Radlbauer, Rudolf, E-mail: rudolf.radlbauer@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Lomoschitz, Friedrich, E-mail: friedrich.lomoschitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Salomonowitz, Erich, E-mail: erich.salomonowitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Eberhardt, Knut E., E-mail: info@mrt-kompetenzzentrum.d [MRT Competence Center Schloss Werneck, Balthasar-Neumann-Platz 2, 97440 Werneck (Germany); Stadlbauer, Andreas, E-mail: andi@nmr.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany)

    2010-08-15

    The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

  17. MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

    International Nuclear Information System (INIS)

    Radlbauer, Rudolf; Lomoschitz, Friedrich; Salomonowitz, Erich; Eberhardt, Knut E.; Stadlbauer, Andreas

    2010-01-01

    The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

  18. Three-dimensional isotropic T2-weighted cervical MRI at 3 T: Comparison with two-dimensional T2-weighted sequences

    International Nuclear Information System (INIS)

    Kwon, J.W.; Yoon, Y.C.; Choi, S.-H.

    2012-01-01

    Aim: To compare three-dimensional (3D) isotropic T2-weighted magnetic resonance imaging (MRI) sequences and reformation with two-dimensional (2D) T2-weighted sequences regarding image quality of the cervical spine at 3 T. Materials and methods: A phantom study was performed using a water-filled cylinder. The signal-to-noise and image homogeneity were evaluated. Fourteen (n = 14) volunteers were examined at 3 T using 3D isotropic T2-weighted sagittal and conventional 2D T2-weighted sagittal, axial, and oblique sagittal MRI. Multiplanar reformation (MPR) of the 3D T2-weighted sagittal dataset was performed simultaneously with image evaluation. In addition to artefact assessment, the visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen’s kappa and Wilcoxon signed rank test were used for the statistical analysis. Result: The 3D isotropic T2-weighted sequence resulted in the highest signal-to-noise ratio (SNR) and lowest non-uniformity (NU) among the sequences in the phantom study. Quantitative evaluation revealed lower NU values of the cerebrospinal fluid (CSF) and muscles in 2D T2-weighted sagittal sequences compared to the 3D volume isotropic turbo spin-echo acquisition (VISTA) sequence. The other NU values revealed no statistically significant difference between the 2D turbo spin-echo (TSE) and 3D VISTA sequences (0.059 < p < 0.959). 3D VISTA images showed significantly fewer CSF flow artefacts (p < 0.001) and better delineated intradural nerve rootlets (p = 0.001) and neural foramina (p = 0.016) compared to 2D sequences. Conclusion: A 3D T2 weighted sequence is superior to conventional 2D sequences for the delineation of intradural nerve rootlets and neural foramina and is less affected by CSF flow artefacts.

  19. Two-dimensional confinement of heavy fermions

    International Nuclear Information System (INIS)

    Shishido, Hiroaki; Shibauchi, Takasada; Matsuda, Yuji; Terashima, Takahito

    2010-01-01

    Metallic systems with the strongest electron correlations are realized in certain rare-earth and actinide compounds whose physics are dominated by f-electrons. These materials are known as heavy fermions, so called because the effective mass of the conduction electrons is enhanced via correlation effects up to as much as several hundreds times the free electron mass. To date the electronic structure of all heavy-fermion compounds is essentially three-dimensional. Here we report on the first realization of a two-dimensional heavy-fermion system, where the dimensionality is adjusted in a controllable fashion by fabricating heterostructures using molecular beam epitaxy. The two-dimensional heavy fermion system displays striking deviations from the standard Fermi liquid low-temperature electronic properties. (author)

  20. Two-dimensional sensitivity calculation code: SENSETWO

    International Nuclear Information System (INIS)

    Yamauchi, Michinori; Nakayama, Mitsuo; Minami, Kazuyoshi; Seki, Yasushi; Iida, Hiromasa.

    1979-05-01

    A SENSETWO code for the calculation of cross section sensitivities with a two-dimensional model has been developed, on the basis of first order perturbation theory. It uses forward neutron and/or gamma-ray fluxes and adjoint fluxes obtained by two-dimensional discrete ordinates code TWOTRAN-II. The data and informations of cross sections, geometry, nuclide density, response functions, etc. are transmitted to SENSETWO by the dump magnetic tape made in TWOTRAN calculations. The required input for SENSETWO calculations is thus very simple. The SENSETWO yields as printed output the cross section sensitivities for each coarse mesh zone and for each energy group, as well as the plotted output of sensitivity profiles specified by the input. A special feature of the code is that it also calculates the reaction rate with the response function used as the adjoint source in TWOTRAN adjoint calculation and the calculated forward flux from the TWOTRAN forward calculation. (author)

  1. Two-dimensional ranking of Wikipedia articles

    Science.gov (United States)

    Zhirov, A. O.; Zhirov, O. V.; Shepelyansky, D. L.

    2010-10-01

    The Library of Babel, described by Jorge Luis Borges, stores an enormous amount of information. The Library exists ab aeterno. Wikipedia, a free online encyclopaedia, becomes a modern analogue of such a Library. Information retrieval and ranking of Wikipedia articles become the challenge of modern society. While PageRank highlights very well known nodes with many ingoing links, CheiRank highlights very communicative nodes with many outgoing links. In this way the ranking becomes two-dimensional. Using CheiRank and PageRank we analyze the properties of two-dimensional ranking of all Wikipedia English articles and show that it gives their reliable classification with rich and nontrivial features. Detailed studies are done for countries, universities, personalities, physicists, chess players, Dow-Jones companies and other categories.

  2. Toward two-dimensional search engines

    International Nuclear Information System (INIS)

    Ermann, L; Shepelyansky, D L; Chepelianskii, A D

    2012-01-01

    We study the statistical properties of various directed networks using ranking of their nodes based on the dominant vectors of the Google matrix known as PageRank and CheiRank. On average PageRank orders nodes proportionally to a number of ingoing links, while CheiRank orders nodes proportionally to a number of outgoing links. In this way, the ranking of nodes becomes two dimensional which paves the way for the development of two-dimensional search engines of a new type. Statistical properties of information flow on the PageRank–CheiRank plane are analyzed for networks of British, French and Italian universities, Wikipedia, Linux Kernel, gene regulation and other networks. A special emphasis is done for British universities networks using the large database publicly available in the UK. Methods of spam links control are also analyzed. (paper)

  3. Acoustic phonon emission by two dimensional plasmons

    International Nuclear Information System (INIS)

    Mishonov, T.M.

    1990-06-01

    Acoustic wave emission of the two dimensional plasmons in a semiconductor or superconductor microstructure is investigated by using the phenomenological deformation potential within the jellium model. The plasmons are excited by the external electromagnetic (e.m.) field. The power conversion coefficient of e.m. energy into acoustic wave energy is also estimated. It is shown, the coherent transformation has a sharp resonance at the plasmon frequency of the two dimensional electron gas (2DEG). The incoherent transformation of the e.m. energy is generated by ohmic dissipation of 2DEG. The method proposed for coherent phonon beam generation can be very effective for high mobility 2DEG and for thin superconducting layers if the plasmon frequency ω is smaller than the superconducting gap 2Δ. (author). 21 refs, 1 fig

  4. Confined catalysis under two-dimensional materials

    OpenAIRE

    Li, Haobo; Xiao, Jianping; Fu, Qiang; Bao, Xinhe

    2017-01-01

    Small spaces in nanoreactors may have big implications in chemistry, because the chemical nature of molecules and reactions within the nanospaces can be changed significantly due to the nanoconfinement effect. Two-dimensional (2D) nanoreactor formed under 2D materials can provide a well-defined model system to explore the confined catalysis. We demonstrate a general tendency for weakened surface adsorption under the confinement of graphene overlayer, illustrating the feasible modulation of su...

  5. Two-Dimensional Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Bo Jia

    2015-01-01

    (BP networks. However, like many other methods, ELM is originally proposed to handle vector pattern while nonvector patterns in real applications need to be explored, such as image data. We propose the two-dimensional extreme learning machine (2DELM based on the very natural idea to deal with matrix data directly. Unlike original ELM which handles vectors, 2DELM take the matrices as input features without vectorization. Empirical studies on several real image datasets show the efficiency and effectiveness of the algorithm.

  6. Superintegrability on the two dimensional hyperboloid

    International Nuclear Information System (INIS)

    Akopyan, E.; Pogosyan, G.S.; Kalnins, E.G.; Miller, W. Jr

    1998-01-01

    This work is devoted to the investigation of the quantum mechanical systems on the two dimensional hyperboloid which admit separation of variables in at least two coordinate systems. Here we consider two potentials introduced in a paper of C.P.Boyer, E.G.Kalnins and P.Winternitz, which haven't been studied yet. An example of an interbasis expansion is given and the structure of the quadratic algebra generated by the integrals of motion is carried out

  7. Two-dimensional Kagome photonic bandgap waveguide

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou

    2000-01-01

    The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

  8. Mechanical exfoliation of two-dimensional materials

    Science.gov (United States)

    Gao, Enlai; Lin, Shao-Zhen; Qin, Zhao; Buehler, Markus J.; Feng, Xi-Qiao; Xu, Zhiping

    2018-06-01

    Two-dimensional materials such as graphene and transition metal dichalcogenides have been identified and drawn much attention over the last few years for their unique structural and electronic properties. However, their rise begins only after these materials are successfully isolated from their layered assemblies or adhesive substrates into individual monolayers. Mechanical exfoliation and transfer are the most successful techniques to obtain high-quality single- or few-layer nanocrystals from their native multi-layer structures or their substrate for growth, which involves interfacial peeling and intralayer tearing processes that are controlled by material properties, geometry and the kinetics of exfoliation. This procedure is rationalized in this work through theoretical analysis and atomistic simulations. We propose a criterion to assess the feasibility for the exfoliation of two-dimensional sheets from an adhesive substrate without fracturing itself, and explore the effects of material and interface properties, as well as the geometrical, kinetic factors on the peeling behaviors and the torn morphology. This multi-scale approach elucidates the microscopic mechanism of the mechanical processes, offering predictive models and tools for the design of experimental procedures to obtain single- or few-layer two-dimensional materials and structures.

  9. Rational examination of the greater abdominal veins with 2D-TOF- and turbo-spin-echo sequences

    International Nuclear Information System (INIS)

    Lutterbey, G.; Sommer, T.; Keller, E.; Kuhl, C.; Schild, H.H.

    1998-01-01

    Purpose: Development of a fast and reliable protocol for the detection and exclusion of abdominal venous thrombosis with an optimised T 2 -TSE- and 2D-TOF sequence. Results: The most effective combination of strong flow-void phenomena, signal/noise ratio and scan time was found with the following parameters: T E 120 ms, T R 2000 ms, 5 mm slice gap. In the patient group two complete and two partial thromboses were diagnosed with both sequences. One wrong positive thrombosis occurred in a stenotic anastomosis with the 2D-inflow sequence. Conclusion: With optimum parameters the T 2 -TSE sequence produces a strong 'flow-void' phenomenon suitable for 'black-blood'-MRA. The use of this sequence alone or in combination with 2D-inflow MRA, if 'bright-blood' MRA is recommended, allows a reliable evaluation of thrombosis in abdominal veins without high-tech MRA equipment and contrast media. (orig./AJ) [de

  10. Vector (two-dimensional) magnetic phenomena

    International Nuclear Information System (INIS)

    Enokizono, Masato

    2002-01-01

    In this paper, some interesting phenomena were described from the viewpoint of two-dimensional magnetic property, which is reworded with the vector magnetic property. It shows imperfection of conventional magnetic property and some interested phenomena were discovered, too. We found magnetic materials had the strong nonlinearity both magnitude and spatial phase due to the relationship between the magnetic field strength H-vector and the magnetic flux density B-vector. Therefore, magnetic properties should be defined as the vector relationship. Furthermore, the new Barukhausen signal was observed under rotating flux. (Author)

  11. Two-dimensional Semiconductor-Superconductor Hybrids

    DEFF Research Database (Denmark)

    Suominen, Henri Juhani

    This thesis investigates hybrid two-dimensional semiconductor-superconductor (Sm-S) devices and presents a new material platform exhibiting intimate Sm-S coupling straight out of the box. Starting with the conventional approach, we investigate coupling superconductors to buried quantum well....... To overcome these issues we integrate the superconductor directly into the semiconducting material growth stack, depositing it in-situ in a molecular beam epitaxy system under high vacuum. We present a number of experiments on these hybrid heterostructures, demonstrating near unity interface transparency...

  12. Binding energy of two-dimensional biexcitons

    DEFF Research Database (Denmark)

    Singh, Jai; Birkedal, Dan; Vadim, Lyssenko

    1996-01-01

    Using a model structure for a two-dimensional (2D) biexciton confined in a quantum well, it is shown that the form of the Hamiltonian of the 2D biexciton reduces into that of an exciton. The binding energies and Bohr radii of a 2D biexciton in its various internal energy states are derived...... analytically using the fractional dimension approach. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be 0.228, which agrees very well with the recent experimental value. The results of our approach are compared with those of earlier theories....

  13. Airy beams on two dimensional materials

    Science.gov (United States)

    Imran, Muhammad; Li, Rujiang; Jiang, Yuyu; Lin, Xiao; Zheng, Bin; Dehdashti, Shahram; Xu, Zhiwei; Wang, Huaping

    2018-05-01

    We propose that quasi-transverse-magnetic (quasi-TM) Airy beams can be supported on two dimensional (2D) materials. By taking graphene as a typical example, the solution of quasi-TM Airy beams is studied under the paraxial approximation. The analytical field intensity in a bilayer graphene-based planar plasmonic waveguide is confirmed by the simulation results. Due to the tunability of the chemical potential of graphene, the self-accelerating behavior of the quasi-TM Airy beam can be steered effectively. 2D materials thus provide a good platform to investigate the propagation of Airy beams.

  14. Two-dimensional heat flow apparatus

    Science.gov (United States)

    McDougall, Patrick; Ayars, Eric

    2014-06-01

    We have created an apparatus to quantitatively measure two-dimensional heat flow in a metal plate using a grid of temperature sensors read by a microcontroller. Real-time temperature data are collected from the microcontroller by a computer for comparison with a computational model of the heat equation. The microcontroller-based sensor array allows previously unavailable levels of precision at very low cost, and the combination of measurement and modeling makes for an excellent apparatus for the advanced undergraduate laboratory course.

  15. Whole-brain intracranial vessel wall imaging at 3 Tesla using cerebrospinal fluid-attenuated T1-weighted 3D turbo spin echo.

    Science.gov (United States)

    Fan, Zhaoyang; Yang, Qi; Deng, Zixin; Li, Yuxia; Bi, Xiaoming; Song, Shlee; Li, Debiao

    2017-03-01

    Although three-dimensional (3D) turbo spin echo (TSE) with variable flip angles has proven to be useful for intracranial vessel wall imaging, it is associated with inadequate suppression of cerebrospinal fluid (CSF) signals and limited spatial coverage at 3 Tesla (T). This work aimed to modify the sequence and develop a protocol to achieve whole-brain, CSF-attenuated T 1 -weighted vessel wall imaging. Nonselective excitation and a flip-down radiofrequency pulse module were incorporated into a commercial 3D TSE sequence. A protocol based on the sequence was designed to achieve T 1 -weighted vessel wall imaging with whole-brain spatial coverage, enhanced CSF-signal suppression, and isotropic 0.5-mm resolution. Human volunteer and pilot patient studies were performed to qualitatively and quantitatively demonstrate the advantages of the sequence. Compared with the original sequence, the modified sequence significantly improved the T 1 -weighted image contrast score (2.07 ± 0.19 versus 3.00 ± 0.00, P = 0.011), vessel wall-to-CSF contrast ratio (0.14 ± 0.16 versus 0.52 ± 0.30, P = 0.007) and contrast-to-noise ratio (1.69 ± 2.18 versus 4.26 ± 2.30, P = 0.022). Significant improvement in vessel wall outer boundary sharpness was observed in several major arterial segments. The new 3D TSE sequence allows for high-quality T 1 -weighted intracranial vessel wall imaging at 3 T. It may potentially aid in depicting small arteries and revealing T 1 -mediated high-signal wall abnormalities. Magn Reson Med 77:1142-1150, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  16. Electron spin relaxation governed by Raman processes both for Cu2+ ions and carbonate radicals in KHCO3 crystals: EPR and electron spin echo studies

    Science.gov (United States)

    Hoffmann, Stanislaw K.; Goslar, Janina; Lijewski, Stefan

    2012-08-01

    EPR studies of Cu2+ and two free radicals formed by γ-radiation were performed for KHCO3 single crystal at room temperature. From the rotational EPR results we concluded that Cu2+ is chelated by two carbonate molecules in a square planar configuration with spin-Hamiltonian parameters g|| = 2.2349 and A|| = 18.2 mT. Free radicals were identified as neutral HOCOrad with unpaired electron localized on the carbon atom and a radical anion CO3·- with unpaired electron localized on two oxygen atoms. The hyperfine splitting of the EPR lines by an interaction with a single hydrogen atom of HOCOrad was observed with isotropic coupling constants ao = 0.31 mT. Two differently oriented radical sites were identified in the crystal unit cell. Electron spin-lattice relaxation measured by electron spin echo methods shows that both Cu2+ and free radicals relax via two-phonon Raman processes with almost the same relaxation rate. The temperature dependence of the relaxation rate 1/T1 is well described with the effective Debye temperature ΘD = 175 K obtained from a fit to the Debye-type phonon spectrum. We calculated a more realistic Debye temperature value from available elastic constant values of the crystal as ΘD = 246 K. This ΘD-value and the Debye phonon spectrum approximation give a much worse fit to the experimental results. Possible contributions from a local mode or an optical mode are considered and it is suggested that the real phonon spectrum should be used for the relaxation data interpretation. It is unusual that free radicals in KHCO3 relax similarly to the well localized Cu2+ ions, which suggests a small destruction of the host crystal lattice by the ionizing irradiation allowing well coupling between radical and lattice dynamics.

  17. Comparison of spin-echo echoplanar imaging and gradient recalled echo-based MR elastography at 3 Tesla with and without gadoxetic acid administration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Seek [Chonbuk National University Medical School and Hospital, Department of Radiology, Jeonju, Chonbuk (Korea, Republic of); Song, Ji Soo [Chonbuk National University Medical School and Hospital, Department of Radiology, Jeonju, Chonbuk (Korea, Republic of); Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, Chonbuk (Korea, Republic of); Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Chonbuk (Korea, Republic of); Kannengiesser, Stephan [Siemens Healthcare, MR Applications Development, Erlangen (Germany); Seo, Seung Young [Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, Chonbuk (Korea, Republic of); Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Chonbuk (Korea, Republic of); Chonbuk National University Medical School and Hospital, Department of Internal Medicine, Jeonju (Korea, Republic of)

    2017-10-15

    To compare spin-echo echoplanar imaging (SE-EPI) and gradient recalled echo (GRE) MR elastography (MRE) at 3 T with and without gadoxetic acid administration. We included 84 patients who underwent MRE before and after gadoxetic acid administration, each time using SE-EPI and GRE sequences. Diagnostic performance for predicting clinical liver cirrhosis and high-risk oesophageal varices was assessed using the area under the receiver-operating characteristic curve (AUC). The relationships between T2* and success of MRE, and correlations of liver stiffness (LS) values between the two sequences or before and after gadoxetic acid administration, were investigated. SE-EPI-MRE resulted in a significantly lower failure rate than GRE-MRE (1.19% vs. 10.71%, P = 0.018). Increased T2* was related to higher probability of successful LS measurement (odds ratio, 1.426; P = 0.004). The AUC of SE-EPI-MRE was comparable to that of GRE-MRE for the detection of clinical liver cirrhosis (0.938 vs. 0.948, P = 0.235) and high-risk oesophageal varices (0.839 vs. 0.752, P = 0.354). LS values were not significantly different before and after gadoxetic acid administration. SE-EPI-MRE can substitute for GRE-MRE for the detection of clinical liver cirrhosis and high-risk oesophageal varices. SE-EPI-MRE is particularly useful in patients with iron deposition, with lower failure rates than GRE-MRE. (orig.)

  18. Fat-suppressed volume isotropic turbo spin echo acquisition (VISTA) MR imaging in evaluating radial and root tears of the meniscus: Focusing on reader-defined axial reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Daekeon; Lee, Young Han; Kim, Sungjun; Song, Ho-Taek; Suh, Jin-Suck, E-mail: jss@yuhs.ac

    2013-12-01

    Objective: To assess the diagnostic value of fat-suppressed (FS) three-dimensional (3D) volume isotropic turbo spin echo acquisition (VISTA) imaging in detecting radial and root tears of the meniscus, including the reader-defined reformatted axial (RDA) plane. Materials and methods: Twenty-three patients with arthroscopically confirmed radial or root tears of the meniscus underwent magnetic resonance imaging (MRI) with 2D and FS 3D VISTA sequences. MRIs were reviewed independently by two musculoskeletal radiologists blinded to the arthroscopic findings. Sensitivity, specificity, accuracy, and interobserver agreement were calculated for radial and root tears. Both radiologists reported confidence scale for the presence of meniscal tears in 2D axial imaging, 3D axial imaging, and RDA imaging, based on a five-point scale. Wilcoxon's signed rank test was used to compare confidence scale. Results: The sensitivity, specificity, and accuracy of FS 3D VISTA MR imaging versus 2D MR imaging were as follows: 96%, 96%, and 96% versus 91%, 91%, and 91%, respectively in reader 1, and 96%, 96%, and 96% versus 83%, 91%, and 87%, respectively, in reader 2. Interobserver agreement for detecting meniscal tears was excellent (κ = 1) with FS 3D VISTA. The confidence scale was significantly higher for 3D axial images than 2D imaging (p = 0.03) and significantly higher in RDA images than 3D axial image in detecting radial and root tears. Conclusions: FS 3D VISTA had a better diagnostic performance in evaluating radial and root tears of the meniscus. The reader-defined reformatted axial plane obtained from FS 3D VISTA MR imaging is useful in detecting radial and root tears of the meniscus.

  19. Sub-minute kinetics of human red cell fumarase: 1 H spin-echo NMR spectroscopy and 13 C rapid-dissolution dynamic nuclear polarization.

    Science.gov (United States)

    Shishmarev, Dmitry; Wright, Alan J; Rodrigues, Tiago B; Pileio, Giuseppe; Stevanato, Gabriele; Brindle, Kevin M; Kuchel, Philip W

    2018-03-01

    Fumarate is an important probe of metabolism in hyperpolarized magnetic resonance imaging and spectroscopy. It is used to detect the release of fumarase in cancer tissues, which is associated with necrosis and drug treatment. Nevertheless, there are limited reports describing the detailed kinetic studies of this enzyme in various cells and tissues. Thus, we aimed to evaluate the sub-minute kinetics of human red blood cell fumarase using nuclear magnetic resonance (NMR) spectroscopy, and to provide a quantitative description of the enzyme that is relevant to the use of fumarate as a probe of cell rupture. The fumarase reaction was studied using time courses of 1 H spin-echo and 13 C-NMR spectra. 1 H-NMR experiments showed that the fumarase reaction in hemolysates is sufficiently rapid to make its kinetics amenable to study in a period of approximately 3 min, a timescale characteristic of hyperpolarized 13 C-NMR spectroscopy. The rapid-dissolution dynamic nuclear polarization (RD-DNP) technique was used to hyperpolarize [1,4- 13 C]fumarate, which was injected into concentrated hemolysates. The kinetic data were analyzed using recently developed FmR α analysis and modeling of the enzymatic reaction using Michaelis-Menten equations. In RD-DNP experiments, the decline in the 13 C-NMR signal from fumarate, and the concurrent rise and fall of that from malate, were captured with high spectral resolution and signal-to-noise ratio, which allowed the robust quantification of fumarase kinetics. The kinetic parameters obtained indicate the potential contribution of hemolysis to the overall rate of the fumarase reaction when 13 C-NMR RD-DNP is used to detect necrosis in animal models of implanted tumors. The analytical procedures developed will be applicable to studies of other rapid enzymatic reactions using conventional and hyperpolarized substrate NMR spectroscopy. Copyright © 2018 John Wiley & Sons, Ltd.

  20. SU-E-J-224: Using UTE and T1 Weighted Spin Echo Pulse Sequences for MR-Only Treatment Planning; Phantom Study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H; Fatemi, A [Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Sahgal, A [University of Toronto, Toronto, ON (Canada)

    2015-06-15

    Purpose: Investigating a new approach in MRI based treatment planning using the combination of (Ultrashort Echo Time) UTE and T1 weighted spin echo pulse sequences to delineate air, bone and water (soft tissues) in generating pseudo CT images comparable with CT. Methods: A gel phantom containing chicken bones, ping pang balls filled with distilled water and air bubbles, was made. It scanned with MRI using UTE and 2D T1W SE pulse sequences with (in plane resolution= 0.53mm, slice thickness= 2 mm) and CT with (in plane resolution= 0.5 mm and slice thickness= 0.75mm) as a ground truth for geometrical accuracy. The UTE and T1W SE images were registered with CT using mutual information registration algorithm provided by Philips Pinnacle treatment planning system. The phantom boundaries were detected using Canny edge detection algorithm for CT, and MR images. The bone, air bubbles and water in ping pong balls were segmented from CT images using threshold 300HU, - 950HU and 0HU, respectively. These tissue inserts were automatically segmented from combined UTE and T1W SE images using edge detection and relative intensity histograms of the phantom. The obtained segmentations of air, bone and water inserts were evaluated with those obtained from CT. Results: Bone and air can be clearly differentiated in UTE images comparable to CT. Combining UTE and T1W SE images successfully segmented the air, bone and water. The maximum segmentation differences from combine MRI images (UTE and T1W SE) and CT are within 1.3 mm, 1.1mm for bone, air, respectively. The geometric distortion of UTE sequence is small less than 1 pixel (0.53 mm) of MR image resolution. Conclusion: Our approach indicates that MRI can be used solely for treatment planning and its quality is comparable with CT.

  1. The role of MR imaging with Half Fourier Acquired Single Shot Turbo Spin Echo sequence in the diagnosis of lung lesions in comparison with multislice CT

    International Nuclear Information System (INIS)

    Hekimoglu, B.; Gurgen, F.; Tatar, I.G.; Aydin, H.; Kizilgoz, V.; Keyik, B.

    2013-01-01

    Objective: To compare the diagnostic values of magnetic resonance imaging using Half Fourier Acquired Single Shot Turbo Spin Echo sequence and multidetector computed tomography in patients with pathologically examined pulmonary lesions. Methods: The retrospective, descriptive study was conducted at Radiology Department, Diskapi Research Hospital, Ankara, Turkey, and comprised records of patients with pathologically examined pulmonary lesions between May 2009 and March 2012. Patients were divided into three groups and examined by both multi dedector computed tomography and magnetic resonance imaging. During the imaging, patients were not administered any intravenous contrast medium. Electrocardiogram gating and breath holding were not performed in echo sequence. Pulmonary lesions were evaluated on the basis of their dimensions, numbers, differentiation from atelectasis and consolidation, invasion to the thoracic wall-mediastinal structures and presence of lymphadenopathies. Results: Sensitivity of all patients was 50% (p=0.214) and specificity of CT and MRI were 82.5% (p=0.134) for the detectability of submilimetric nodules . For differentiation of the mass from atelectasis and consolidation, the sensitivity of computed tomography was statistically more significant compared to magnetic resonance imaging (86.6%; p=0.035). For the invasion of the mass to the mediastinal structures and the thoracic wall, the sensitivity of magnetic resonance imaging was statistically more significant compared to tomography (86.6%; p=0.035). Conclusion: HASTE sequence can be used to determine the invasion of the pulmonary mass to the mediastinal structures and the thoracic wall since it is more sensitive than computed tomography. It can also be used to detect submilimetric nodules. It has equal sensitivity and specificity compared to computed tomography. But computed tomography is superior for the differentiation of the mass from atelectasis and consolidation. (author)

  2. Value of Fat-Suppressed Proton-Density-Weighted Turbo Spin-Echo Sequences in Detecting Meniscal Lesions: Comparison with Arthroscopy

    International Nuclear Information System (INIS)

    Schaefer, F.K.W.; Schaefer, P.J.; Brossmann, J.; Frahm, C.; Hilgert, R.E.; Heller, M.; Jahnke, T.

    2006-01-01

    Purpose: To evaluate fat-suppressed (FS) proton-density-weighted (PDw) turbo spin-echo (TSE) magnetic resonance imaging (MRI) compared to arthroscopy in the detection of meniscal lesions. Material and Methods: In a prospective study, 31 knee joints were imaged on a 1.5T MR scanner before arthroscopy using the following sequences: (a) coronal and sagittal FS-PDw TSE (TR/TE: 4009/15 ms); (b) coronal T1w SE (TR/TE: 722/20 ms), and sagittal PDw TSE (TR/TE: 3800/15 ms). Other imaging parameters were: slice thickness 3 mm, FOV 160 mm, matrix 256x256. A total of 186 meniscal regions (62 menisci; anterior horn, body, posterior horn) were evaluated. Standard of reference was arthroscopy. Sensitivity, specificity, negative predictive value (npv), positive predictive value (ppv), and accuracy were calculated. Results: Arthroscopically, meniscal lesions were detected in 55/186 segments (35 medial and 20 lateral meniscal lesions). Sensitivity, specificity, npv, ppv, and accuracy for combination of coronal and sagittal FS PDw TSE were 91.4%, 98.3%, 95%, 97%, and 93.5% for the medial meniscus, and 90%, 98.6%, 97.3%, 94.7%, and 96.8% for the lateral. The results were comparable to the combination of coronal T1w SE and sagittal PDw TSE for the medial (88.6%, 98.3%, 93.4%, 96.9%, 91.4%) and the lateral (90%, 95.9%, 97.2%, 85.7%, 92.5%) meniscus. Conclusion: FS PDw TSE-MR sequences are an excellent alternative for the detection of meniscal lesions in comparison with diagnostic arthroscopy

  3. Supraspinatus tendon tears at 3.0 T shoulder MR arthrography: diagnosis with 3D isotropic turbo spin-echo SPACE sequence versus 2D conventional sequences

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joon-Yong; Jee, Won-Hee; Park, Michael Y.; Lee, So-Yeon [Seoul St. Mary' s Hospital, The Catholic University of Korea, Department of Radiology, Seoul (Korea, Republic of); Kim, Yang-Soo [Seoul St. Mary' s Hospital, The Catholic University of Korea, Department of Orthopedic Surgery, Seoul (Korea, Republic of)

    2012-11-15

    To assess the diagnostic performance of shoulder MR arthrography with 3D isotropic fat-suppressed (FS) turbo spin-echo sequence (TSE-SPACE) for supraspinatus tendon tears in comparison with 2D conventional sequences at 3.0 T. The study was HIPAA-compliant and approved by the institutional review board with a waiver of informed consent. Eighty-seven arthroscopically confirmed patients who underwent 3.0 T shoulder MR arthrography with 2D sequences and 3D TSE-SPACE were included in a consecutive fashion from March 2009 to February 2010. Two reviewers independently analyzed 2D sequences and 3D TSE-SPACE. Sensitivity, specificity, accuracy, and interobserver agreement ({kappa}) were compared between 2D sequences and 3D TSE-SPACE for full-thickness and partial-thickness supraspinatus tendon tears together and for partial-thickness supraspinatus tendon tears alone. There were 33 full-thickness tears and 28 partial-thickness tears of supraspinatus tendons. For full-thickness and partial-thickness supraspinatus tendon tears together, the mean sensitivity, specificity, and accuracy of both readers were 96, 92, and 94% on 2D sequences and 91, 84, and 89% on 3D TSE-SPACE. For partial-thickness supraspinatus tendon tears alone, the mean sensitivity, specificity, and accuracy were 95, 92, and 94% on 2D sequences and 84, 85, and 84% on 3D TSE-SPACE. There was no statistical difference between 2D sequences and 3D TSE-SPACE. Interobserver agreements were almost perfect on 2D conventional sequences and substantial on 3D TSE-SPACE. Compared with 2D conventional sequences, MR arthrography using 3D TSE-SPACE was comparable for diagnosing supraspinatus tendon tears despite limitations in detecting small partial-thickness tears and in discriminating between full-thickness and deep partial-thickness tears. (orig.)

  4. Supraspinatus tendon tears at 3.0 T shoulder MR arthrography: diagnosis with 3D isotropic turbo spin-echo SPACE sequence versus 2D conventional sequences

    International Nuclear Information System (INIS)

    Jung, Joon-Yong; Jee, Won-Hee; Park, Michael Y.; Lee, So-Yeon; Kim, Yang-Soo

    2012-01-01

    To assess the diagnostic performance of shoulder MR arthrography with 3D isotropic fat-suppressed (FS) turbo spin-echo sequence (TSE-SPACE) for supraspinatus tendon tears in comparison with 2D conventional sequences at 3.0 T. The study was HIPAA-compliant and approved by the institutional review board with a waiver of informed consent. Eighty-seven arthroscopically confirmed patients who underwent 3.0 T shoulder MR arthrography with 2D sequences and 3D TSE-SPACE were included in a consecutive fashion from March 2009 to February 2010. Two reviewers independently analyzed 2D sequences and 3D TSE-SPACE. Sensitivity, specificity, accuracy, and interobserver agreement (κ) were compared between 2D sequences and 3D TSE-SPACE for full-thickness and partial-thickness supraspinatus tendon tears together and for partial-thickness supraspinatus tendon tears alone. There were 33 full-thickness tears and 28 partial-thickness tears of supraspinatus tendons. For full-thickness and partial-thickness supraspinatus tendon tears together, the mean sensitivity, specificity, and accuracy of both readers were 96, 92, and 94% on 2D sequences and 91, 84, and 89% on 3D TSE-SPACE. For partial-thickness supraspinatus tendon tears alone, the mean sensitivity, specificity, and accuracy were 95, 92, and 94% on 2D sequences and 84, 85, and 84% on 3D TSE-SPACE. There was no statistical difference between 2D sequences and 3D TSE-SPACE. Interobserver agreements were almost perfect on 2D conventional sequences and substantial on 3D TSE-SPACE. Compared with 2D conventional sequences, MR arthrography using 3D TSE-SPACE was comparable for diagnosing supraspinatus tendon tears despite limitations in detecting small partial-thickness tears and in discriminating between full-thickness and deep partial-thickness tears. (orig.)

  5. Distortion-free diffusion tensor imaging for evaluation of lumbar nerve roots: Utility of direct coronal single-shot turbo spin-echo diffusion sequence.

    Science.gov (United States)

    Sakai, Takayuki; Doi, Kunio; Yoneyama, Masami; Watanabe, Atsuya; Miyati, Tosiaki; Yanagawa, Noriyuki

    2018-06-01

    Diffusion tensor imaging (DTI) based on a single-shot echo planer imaging (EPI-DTI) is an established method that has been used for evaluation of lumbar nerve disorders in previous studies, but EPI-DTI has problems such as a long acquisition time, due to a lot of axial slices, and geometric distortion. To solve these problems, we attempted to apply DTI based on a single-shot turbo spin echo (TSE-DTI) with direct coronal acquisition. Our purpose in this study was to investigate whether TSE-DTI may be more useful for evaluation of lumbar nerve disorders than EPI-DTI. First, lumbar nerve roots of five healthy volunteers were evaluated for optimization of imaging parameters with TSE-DTI including b-values and the number of motion proving gradient (MPG) directions. Subsequently, optimized TSE-DTI was quantitatively compared with conventional EPI-DTI by using fractional anisotropy (FA) values and visual scores in subjective visual evaluation of tractography. Lumbar nerve roots of six patients, who had unilateral neurologic symptoms in one leg, were evaluated by the optimized TSE-DTI. TSE-DTI with b-value of 400 s/mm 2 and 32 diffusion-directions could reduce the image distortion compared with EPI-DTI, and showed that the average FA values on the symptomatic side for six patients were significantly lower than those on the non-symptomatic side (P DTI might show damaged areas of lumbar nerve roots without severe image distortion. TSE-DTI might improve the reproducibility in measurements of FA values for quantification of a nerve disorder, and would become a useful tool for diagnosis of low back pain. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. MR imaging characteristics of intracranial hemorrhage using gradient-echo signal acquisition at 1.5 T: Comparison with spin-echo imaging and clinical applications

    International Nuclear Information System (INIS)

    Atlas, S.W.; Grossman, R.I.; Gomori, J.M.; Hackney, D.B.; Goldberg, H.I.; Bilaniuk, L.T.; Zimmerman, R.A.

    1987-01-01

    Evolving paramagnetic blood-breakdown products create static local magnetic susceptibility gradients, which induce rapid phase dispersion on the basis of T2/sup */ shortening. The authors evaluated 30 patients with 50 separate hemorrhagic intracranial lesions with both spin-echo (SE) and gradient echo signal acquisition (GESA) MR imaging at 1.5 T. GESA sequences used repetition time (TR) of 200-750 msec, echo time (TE) of 50-80 msec, and flip angles of 10 0 to 15 0 to emphasize T2/sup */-based contributions to contrast. SE sequences in all cases utilized both short and long TR (600 and 2,500-3,000 msec), with TE of 20-120 msec. Advantages of GESA imaging with Long TE and short flip angles in the evaluation of intracranial hemorrhage include (1) increased sensitivity to susceptibility-induced phase loss from T2/sup */ shortening, resulting in detection of hemorrhagic lesions not seen on conventional long TR/long TE SE images, and (2) very rapid acquisition of images with T2/sup */-based contrast. Limitations of this sequence include (1) severe diamagnetic susceptibility-induced artifacts, especially near air-brain interfaces, which often obscure large portions of the brain and occasionally simulate serious pathology, (2) characteristic internal signal intensity patterns demonstrated by SE imaging, such as in evolving hematomas, occult vascular malformations, and hemorrhagic malignancies, are often obscured by marked hypointensity on GESA images, and (3) reduced signal-noise ratio. The authors conclude that, although images with marked sensitivity to T2/sup */ effects can be rapidly generated by GESA, there is only a limited role for this sequence when evaluating intracranial hemorrhage at 1.5 T, and, in fact, significant information is lost when compared to SE images

  7. Simultaneous Measurement of T2 and Apparent Diffusion Coefficient (T2+ADC) in the Heart With Motion-Compensated Spin Echo Diffusion-Weighted Imaging

    Science.gov (United States)

    Aliotta, Eric; Moulin, Kévin; Zhang, Zhaohuan; Ennis, Daniel B.

    2018-01-01

    Purpose To evaluate a technique for simultaneous quantitative T2 and apparent diffusion coefficient (ADC) mapping in the heart (T2+ADC) using spin echo (SE) diffusion-weighted imaging (DWI). Theory and Methods T2 maps from T2+ADC were compared with single-echo SE in phantoms and with T2-prepared (T2-prep) balanced steady-state free precession (bSSFP) in healthy volunteers. ADC maps from T2+ADC were compared with conventional DWI in phantoms and in vivo. T2+ADC was also demonstrated in a patient with acute myocardial infarction (MI). Results Phantom T2 values from T2+ADC were closer to a single-echo SE reference than T2-prep bSSFP (−2.3 ± 6.0% vs 22.2 ± 16.3%; P T2 values from T2+ADC were significantly shorter than T2-prep bSSFP (35.8 ± 3.1 vs 46.8 ± 3.8 ms; P T2+ADC and conventional motion-compensated DWI (1.39 ± 0.18 vs 1.38 ± 0.18 mm2/ms; P = N.S.). In the patient, T2 and ADC were both significantly elevated in the infarct compared with remote myocardium (T2: 40.4 ± 7.6 vs 56.8 ± 22.0; P T2+ADC generated coregistered, free-breathing T2 and ADC maps in healthy volunteers and a patient with acute MI with no cost in accuracy, precision, or scan time compared with DWI. PMID:28516485

  8. Comparison of spin-echo and gradient recalled echo T1 weighted MR images for quantitative voxel-based clinical brain research

    International Nuclear Information System (INIS)

    Barnden, L.R.; Crouch, B.

    2010-01-01

    Full text: New methods to normalise inter-subject global variations in T 1 -weighted MR (T I w) signal levels have permitted their use in voxel based population studies of brain dysfunction. Here we address the question of whether a spin-echo (SE) or a gradient recalled echo (GRE) T I w sequence is better for this purpose. GRE images are commonly referred to as 3D MRL SE has superior signal/noise properties to GRE but is slower to acquire so that typical slice thicknesses are 3-5 mm compared to 1-2 mm for GRE. GRE has better grey/white matter contrast which should permit better spatial normalization. However, unlike SE, GRE is affected by subject-specific magnetic field inhomogeneities that distort the images. We acquired T I brain images for 25 chronic fatigue syndrome (CFS) patients and 25 normal controls (NC) with TRITE/flip-angle of 600 ms/l5 ms/90 deg for SE and 5.76 ms/1.9 ms/9 deg for GRE. For GRE, the magnetic field inhomogeneity related signal level distortions could be corrected, but not the spatial distortions. After spatial normalization we subjected them to voxel-based statistical analysis with adjustment for global signal level using the SPM5 package. Initially, the same spatial normalization deformations were applied to both SE and GRE after coregistering them. Although the SPM regressions of SE and GRE yielded similar spatial distributions of significance, the SE regressions were consistently statistically stronger. For example, in one strong regression, the corrected cluster P value was twenty times stronger (I.Oe-5 versus I.Oe-3). T I w SE have proved better than T I GRE images in quantitative analysis in a clinical research study. (author)

  9. Decoherence in two-dimensional quantum walks

    International Nuclear Information System (INIS)

    Oliveira, A. C.; Portugal, R.; Donangelo, R.

    2006-01-01

    We analyze the decoherence in quantum walks in two-dimensional lattices generated by broken-link-type noise. In this type of decoherence, the links of the lattice are randomly broken with some given constant probability. We obtain the evolution equation for a quantum walker moving on two-dimensional (2D) lattices subject to this noise, and we point out how to generalize for lattices in more dimensions. In the nonsymmetric case, when the probability of breaking links in one direction is different from the probability in the perpendicular direction, we have obtained a nontrivial result. If one fixes the link-breaking probability in one direction, and gradually increases the probability in the other direction from 0 to 1, the decoherence initially increases until it reaches a maximum value, and then it decreases. This means that, in some cases, one can increase the noise level and still obtain more coherence. Physically, this can be explained as a transition from a decoherent 2D walk to a coherent 1D walk

  10. Study of two-dimensional interchange turbulence

    International Nuclear Information System (INIS)

    Sugama, Hideo; Wakatani, Masahiro.

    1990-04-01

    An eddy viscosity model describing enstrophy transfer in two-dimensional turbulence is presented. This model is similar to that of Canuto et al. and provides an equation for the energy spectral function F(k) as a function of the energy input rate to the system per unit wavenumber, γ s (k). In the enstrophy-transfer inertial range, F(k)∝ k -3 is predicted by the model. The eddy viscosity model is applied to the interchange turbulence of a plasma in shearless magnetic field. Numerical simulation of the two-dimensional interchange turbulence demonstrates that the energy spectrum in the high wavenumber region is well described by this model. The turbulent transport driven by the interchange turbulence is expressed in terms of the Nusselt number Nu, the Rayleigh number Ra and Prantl number Pr in the same manner as that of thermal convection problem. When we use the linear growth rate for γ s (k), our theoretical model predicts that Nu ∝ (Ra·Pr) 1/2 for a constant background pressure gradient and Nu ∝ (Ra·Pr) 1/3 for a self-consistent background pressure profile with the stress-free slip boundary conditions. The latter agrees with our numerical result showing Nu ∝ Ra 1/3 . (author)

  11. Two-Dimensional Theory of Scientific Representation

    Directory of Open Access Journals (Sweden)

    A Yaghmaie

    2013-03-01

    Full Text Available Scientific representation is an interesting topic for philosophers of science, many of whom have recently explored it from different points of view. There are currently two competing approaches to the issue: cognitive and non-cognitive, and each of them claims its own merits over the other. This article tries to provide a hybrid theory of scientific representation, called Two-Dimensional Theory of Scientific Representation, which has the merits of the two accounts and is free of their shortcomings. To do this, we will argue that although scientific representation needs to use the notion of intentionality, such a notion is defined and realized in a simply structural form contrary to what cognitive approach says about intentionality. After a short introduction, the second part of the paper is devoted to introducing theories of scientific representation briefly. In the third part, the structural accounts of representation will be criticized. The next step is to introduce the two-dimensional theory which involves two key components: fixing and structural fitness. It will be argued that fitness is an objective and non-intentional relation, while fixing is intentional.

  12. Two-dimensional simulation of sintering process

    International Nuclear Information System (INIS)

    Vasconcelos, Vanderley de; Pinto, Lucio Carlos Martins; Vasconcelos, Wander L.

    1996-01-01

    The results of two-dimensional simulations are directly applied to systems in which one of the dimensions is much smaller than the others, and to sections of three dimensional models. Moreover, these simulations are the first step of the analysis of more complex three-dimensional systems. In this work, two basic features of the sintering process are studied: the types of particle size distributions related to the powder production processes and the evolution of geometric parameters of the resultant microstructures during the solid-state sintering. Random packing of equal spheres is considered in the sintering simulation. The packing algorithm does not take into account the interactive forces between the particles. The used sintering algorithm causes the densification of the particle set. (author)

  13. Two dimensional generalizations of the Newcomb equation

    International Nuclear Information System (INIS)

    Dewar, R.L.; Pletzer, A.

    1989-11-01

    The Bineau reduction to scalar form of the equation governing ideal, zero frequency linearized displacements from a hydromagnetic equilibrium possessing a continuous symmetry is performed in 'universal coordinates', applicable to both the toroidal and helical cases. The resulting generalized Newcomb equation (GNE) has in general a more complicated form than the corresponding one dimensional equation obtained by Newcomb in the case of circular cylindrical symmetry, but in this cylindrical case , the equation can be transformed to that of Newcomb. In the two dimensional case there is a transformation which leaves the form of the GNE invariant and simplifies the Frobenius expansion about a rational surface, especially in the limit of zero pressure gradient. The Frobenius expansions about a mode rational surface is developed and the connection with Hamiltonian transformation theory is shown. 17 refs

  14. Pressure of two-dimensional Yukawa liquids

    International Nuclear Information System (INIS)

    Feng, Yan; Wang, Lei; Tian, Wen-de; Goree, J; Liu, Bin

    2016-01-01

    A simple analytic expression for the pressure of a two-dimensional Yukawa liquid is found by fitting results from a molecular dynamics simulation. The results verify that the pressure can be written as the sum of a potential term which is a simple multiple of the Coulomb potential energy at a distance of the Wigner–Seitz radius, and a kinetic term which is a multiple of the one for an ideal gas. Dimensionless coefficients for each of these terms are found empirically, by fitting. The resulting analytic expression, with its empirically determined coefficients, is plotted as isochores, or curves of constant area. These results should be applicable to monolayer dusty plasmas. (paper)

  15. Two dimensional nanomaterials for flexible supercapacitors.

    Science.gov (United States)

    Peng, Xu; Peng, Lele; Wu, Changzheng; Xie, Yi

    2014-05-21

    Flexible supercapacitors, as one of most promising emerging energy storage devices, are of great interest owing to their high power density with great mechanical compliance, making them very suitable as power back-ups for future stretchable electronics. Two-dimensional (2D) nanomaterials, including the quasi-2D graphene and inorganic graphene-like materials (IGMs), have been greatly explored to providing huge potential for the development of flexible supercapacitors with higher electrochemical performance. This review article is devoted to recent progresses in engineering 2D nanomaterials for flexible supercapacitors, which survey the evolution of electrode materials, recent developments in 2D nanomaterials and their hybrid nanostructures with regulated electrical properties, and the new planar configurations of flexible supercapacitors. Furthermore, a brief discussion on future directions, challenges and opportunities in this fascinating area is also provided.

  16. Geometrical aspects of solvable two dimensional models

    International Nuclear Information System (INIS)

    Tanaka, K.

    1989-01-01

    It was noted that there is a connection between the non-linear two-dimensional (2D) models and the scalar curvature r, i.e., when r = -2 the equations of motion of the Liouville and sine-Gordon models were obtained. Further, solutions of various classical nonlinear 2D models can be obtained from the condition that the appropriate curvature two form Ω = 0, which suggests that these models are closely related. This relation is explored further in the classical version by obtaining the equations of motion from the evolution equations, the infinite number of conserved quantities, and the common central charge. The Poisson brackets of the solvable 2D models are specified by the Virasoro algebra. 21 refs

  17. Two-dimensional materials for ultrafast lasers

    International Nuclear Information System (INIS)

    Wang Fengqiu

    2017-01-01

    As the fundamental optical properties and novel photophysics of graphene and related two-dimensional (2D) crystals are being extensively investigated and revealed, a range of potential applications in optical and optoelectronic devices have been proposed and demonstrated. Of the many possibilities, the use of 2D materials as broadband, cost-effective and versatile ultrafast optical switches (or saturable absorbers) for short-pulsed lasers constitutes a rapidly developing field with not only a good number of publications, but also a promising prospect for commercial exploitation. This review primarily focuses on the recent development of pulsed lasers based on several representative 2D materials. The comparative advantages of these materials are discussed, and challenges to practical exploitation, which represent good future directions of research, are laid out. (paper)

  18. Two-dimensional phase fraction charts

    International Nuclear Information System (INIS)

    Morral, J.E.

    1984-01-01

    A phase fraction chart is a graphical representation of the amount of each phase present in a system as a function of temperature, composition or other variable. Examples are phase fraction versus temperature charts used to characterize specific alloys and as a teaching tool in elementary texts, and Schaeffler diagrams used to predict the amount of ferrite in stainless steel welds. Isothermal-transformation diagrams (TTT diagrams) are examples that give phase (or microconstituent) amount versus temperature and time. The purpose of this communication is to discuss the properties of two-dimensional phase fraction charts in more general terms than have been reported before. It is shown that they can represent multi-component, multiphase equilibria in a way which is easier to read and which contains more information than the isotherms and isopleths of multi-component phase diagrams

  19. Two-dimensional motions of rockets

    International Nuclear Information System (INIS)

    Kang, Yoonhwan; Bae, Saebyok

    2007-01-01

    We analyse the two-dimensional motions of the rockets for various types of rocket thrusts, the air friction and the gravitation by using a suitable representation of the rocket equation and the numerical calculation. The slope shapes of the rocket trajectories are discussed for the three types of rocket engines. Unlike the projectile motions, the descending parts of the trajectories tend to be gentler and straighter slopes than the ascending parts for relatively large launching angles due to the non-vanishing thrusts. We discuss the ranges, the maximum altitudes and the engine performances of the rockets. It seems that the exponential fuel exhaustion can be the most potent engine for the longest and highest flights

  20. Two dimensional NMR studies of polysaccharides

    International Nuclear Information System (INIS)

    Byrd, R.A.; Egan, W.; Summers, M.F.

    1987-01-01

    Polysaccharides are very important components in the immune response system. Capsular polysaccharides and lipopolysaccharides occupy cell surface sites of bacteria, play key roles in recognition and some have been used to develop vaccines. Consequently, the ability to determine chemical structures of these systems is vital to an understanding of their immunogenic action. The authors have been utilizing recently developed two-dimensional homonuclear and heteronuclear correlation spectroscopy for unambiguous assignment and structure determination of a number of polysaccharides. In particular, the 1 H-detected heteronuclear correlation experiments are essential to the rapid and sensitive determination of these structures. Linkage sites are determined by independent polarization transfer experiments and multiple quantum correlation experiments. These methods permit the complete structure determination on very small amounts of the polysaccharides. They present the results of a number of structural determinations and discuss the limits of these experiments in terms of their applications to polysaccharides

  1. Two-Dimensional Homogeneous Fermi Gases

    Science.gov (United States)

    Hueck, Klaus; Luick, Niclas; Sobirey, Lennart; Siegl, Jonas; Lompe, Thomas; Moritz, Henning

    2018-02-01

    We report on the experimental realization of homogeneous two-dimensional (2D) Fermi gases trapped in a box potential. In contrast to harmonically trapped gases, these homogeneous 2D systems are ideally suited to probe local as well as nonlocal properties of strongly interacting many-body systems. As a first benchmark experiment, we use a local probe to measure the density of a noninteracting 2D Fermi gas as a function of the chemical potential and find excellent agreement with the corresponding equation of state. We then perform matter wave focusing to extract the momentum distribution of the system and directly observe Pauli blocking in a near unity occupation of momentum states. Finally, we measure the momentum distribution of an interacting homogeneous 2D gas in the crossover between attractively interacting fermions and bosonic dimers.

  2. Two-dimensional electroacoustic waves in silicene

    Science.gov (United States)

    Zhukov, Alexander V.; Bouffanais, Roland; Konobeeva, Natalia N.; Belonenko, Mikhail B.

    2018-01-01

    In this letter, we investigate the propagation of two-dimensional electromagnetic waves in a piezoelectric medium built upon silicene. Ultrashort optical pulses of Gaussian form are considered to probe this medium. On the basis of Maxwell's equations supplemented with the wave equation for the medium's displacement vector, we obtain the effective governing equation for the vector potential associated with the electromagnetic field, as well as the component of the displacement vector. The dependence of the pulse shape on the bandgap in silicene and the piezoelectric coefficient of the medium was analyzed, thereby revealing a nontrivial triadic interplay between the characteristics of the pulse dynamics, the electronic properties of silicene, and the electrically induced mechanical vibrations of the medium. In particular, we uncovered the possibility for an amplification of the pulse amplitude through the tuning of the piezoelectric coefficient. This property could potentially offer promising prospects for the development of amplification devices for the optoelectronics industry.

  3. Versatile two-dimensional transition metal dichalcogenides

    DEFF Research Database (Denmark)

    Canulescu, Stela; Affannoukoué, Kévin; Döbeli, Max

    ), a strategy for the fabrication of 2D heterostructures must be developed. Here we demonstrate a novel approach for the bottom-up synthesis of TMDC monolayers, namely Pulsed Laser Deposition (PLD) combined with a sulfur evaporation beam. PLD relies on the use of a pulsed laser (ns pulse duration) to induce...... material transfer from a solid source (such as a sintered target of MoS2) to a substrate (such as Si or sapphire). The deposition rate in PLD is typically much less than a monolayer per pulse, meaning that the number of MLs can be controlled by a careful selection of the number of laser pulses......Two-dimensional transition metal dichalcogenides (2D-TMDCs), such as MoS2, have emerged as a new class of semiconducting materials with distinct optical and electrical properties. The availability of 2D-TMDCs with distinct band gaps allows for unlimited combinations of TMDC monolayers (MLs...

  4. Two-dimensional fourier transform spectrometer

    Science.gov (United States)

    DeFlores, Lauren; Tokmakoff, Andrei

    2013-09-03

    The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

  5. Equivalency of two-dimensional algebras

    International Nuclear Information System (INIS)

    Santos, Gildemar Carneiro dos; Pomponet Filho, Balbino Jose S.

    2011-01-01

    Full text: Let us consider a vector z = xi + yj over the field of real numbers, whose basis (i,j) satisfy a given algebra. Any property of this algebra will be reflected in any function of z, so we can state that the knowledge of the properties of an algebra leads to more general conclusions than the knowledge of the properties of a function. However structural properties of an algebra do not change when this algebra suffers a linear transformation, though the structural constants defining this algebra do change. We say that two algebras are equivalent to each other whenever they are related by a linear transformation. In this case, we have found that some relations between the structural constants are sufficient to recognize whether or not an algebra is equivalent to another. In spite that the basis transform linearly, the structural constants change like a third order tensor, but some combinations of these tensors result in a linear transformation, allowing to write the entries of the transformation matrix as function of the structural constants. Eventually, a systematic way to find the transformation matrix between these equivalent algebras is obtained. In this sense, we have performed the thorough classification of associative commutative two-dimensional algebras, and find that even non-division algebra may be helpful in solving non-linear dynamic systems. The Mandelbrot set was used to have a pictorial view of each algebra, since equivalent algebras result in the same pattern. Presently we have succeeded in classifying some non-associative two-dimensional algebras, a task more difficult than for associative one. (author)

  6. Chimera patterns in two-dimensional networks of coupled neurons

    Science.gov (United States)

    Schmidt, Alexander; Kasimatis, Theodoros; Hizanidis, Johanne; Provata, Astero; Hövel, Philipp

    2017-03-01

    We discuss synchronization patterns in networks of FitzHugh-Nagumo and leaky integrate-and-fire oscillators coupled in a two-dimensional toroidal geometry. A common feature between the two models is the presence of fast and slow dynamics, a typical characteristic of neurons. Earlier studies have demonstrated that both models when coupled nonlocally in one-dimensional ring networks produce chimera states for a large range of parameter values. In this study, we give evidence of a plethora of two-dimensional chimera patterns of various shapes, including spots, rings, stripes, and grids, observed in both models, as well as additional patterns found mainly in the FitzHugh-Nagumo system. Both systems exhibit multistability: For the same parameter values, different initial conditions give rise to different dynamical states. Transitions occur between various patterns when the parameters (coupling range, coupling strength, refractory period, and coupling phase) are varied. Many patterns observed in the two models follow similar rules. For example, the diameter of the rings grows linearly with the coupling radius.

  7. MRI evaluation of myometrial invasion by endometrial carcinoma. Comparison between fast-spin-echo T2W and coronal FMPSPGR Gadolinium-Dota-Enhanced Sequences

    International Nuclear Information System (INIS)

    Nasi, Francesca; Fiocchi, Federica; Pecchi, Annarita; Torricelli, Pietro; Rivasi, Francesco

    2005-01-01

    Purpose. The depth of myometrial invasion by endometrial carcinoma strongly affects the incidence of metastasis to regional nodes and influences the surgical strategies. The aim of this paper is to compare the results of FSE T2-w and Gadolinium-enhanced FMPSGR MR sequences in assessing the depth of myometrial invasion by endometrial cancer. Materials and methods. Forty-five women with histopathologically-proven endometrial carcinoma underwent preoperative MRI. Axial SE TI w, axial, sagittal and para-coronal FSE T2w and para-coronal Gadolinium enhanced FMPSGR sequences were performed using a high field strength magnet (1.5T). Within one month of MR all patients underwent hysterectomy, and anatomical evaluation of the surgical specimen was done sectioning the uterus along the short axis. Based upon the results of the histological evaluation the results of the FSE T2w and Gadolinium-enhanced sequences were compared and the statistical difference between the results obtained was statistically evaluated. Results. The histological evaluation showed intra mucosal neoplasm in 11 patients, myometrial infiltration less than 50% in 31 patients, myometrial infiltration more than 50% in 12 patients and transmural cancer 1 patient. Statistical evaluation showed that the FSE T2w sequence had a global sensitivity and specificity of 80.6% and 87.6%, respectively, with a mean Negative Predictive Value of 92.6% and a mean Positive Predictive Value of 86%. Gadolinium-enhanced FMPSPGR sequence had a global sensitivity and specificity of 90.6% and 93.3%, respectively, with a mean Negative Predictive Value of 96,3% and a mean Positive Predictive Value of 88%. The staging accuracy (χ 2 test) on FMPSPGR images (95%) was higher than that on FSE T2w images (78%). Conclusions. In our experience Gadolinium-enhanced dynamic sequences increase the accuracy of MR imaging in diagnosing the depth of myometrial invasion. In particular they improve the visualisation of the inner myometrium, the so called sub endometrial enhancing zone, whose disruption or changes are essential for diagnosing myometrial invasion. The major diagnostic advantages of the enhanced sequences were found in postmenopausal women, where visualisation of the junctional zone may be difficult in the T2w sequences. We believe that Gadolinium-enhanced dynamic sequences should be used whenever the diagnosis is unclear at FSE T2w sequences [it

  8. Metal artefact suppression at 3 T MRI: comparison of MAVRIC-SL with conventional fast spin echo sequences in patients with Hip joint arthroplasty

    International Nuclear Information System (INIS)

    Kretzschmar, Martin; Nardo, Lorenzo; Han, Misung M.; Heilmeier, Ursula; Sam, Craig; Joseph, Gabby B.; Krug, Roland; Link, Thomas M.; Koch, Kevin M.

    2015-01-01

    The aim of our study was to evaluate the clinical feasibility and diagnostic value of a new MRI metal artefact reduction pulse sequence called MAVRIC-SL in a 3 T MRI environment. Two MAVRIC-SL sequences obtained in 61 patients with symptomatic total hip replacement were compared with standard FSE-STIR sequences optimized for imaging around metal. Artefact size was measured on the slice of greatest extent. Image quality, fat saturation, image distortion, visibility of anatomical structures, and detectability of joint abnormalities were visually assessed and graded on qualitative scales. Differences between MAVRIC-SL and FSE sequences were tested with the Wilcoxon signed-rank test. MAVRIC-SL sequences at 3 T showed significantly smaller metal artefacts compared to FSE-STIR sequences (p < 0.0001). The general image quality of MAVRIC-SL sequences was reduced with regard to spatial resolution, noise and contrast (p = 0.001), and fat saturation (p < 0.0001). The reduction of artefact size and image distortion significantly improved visualization of joint anatomy (p < 0.0001) and diagnostic confidence regarding implant-associated abnormalities (p = 0.0075 to <0.0001). Although the image quality of MAVRIC-SL sequences is limited at 3 T, its clinical application is feasible and provides important additional diagnostic information for the workup of patients with symptomatic hip replacement through substantially reduced metal artefacts. (orig.)

  9. Metal artefact suppression at 3 T MRI: comparison of MAVRIC-SL with conventional fast spin echo sequences in patients with Hip joint arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, Martin; Nardo, Lorenzo; Han, Misung M.; Heilmeier, Ursula; Sam, Craig; Joseph, Gabby B.; Krug, Roland; Link, Thomas M. [University of California San Francisco, Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Koch, Kevin M. [Medical Collage of Wisconsin, Departments of Biophysics and Radiology, Milwaukee, WI (United States)

    2015-08-15

    The aim of our study was to evaluate the clinical feasibility and diagnostic value of a new MRI metal artefact reduction pulse sequence called MAVRIC-SL in a 3 T MRI environment. Two MAVRIC-SL sequences obtained in 61 patients with symptomatic total hip replacement were compared with standard FSE-STIR sequences optimized for imaging around metal. Artefact size was measured on the slice of greatest extent. Image quality, fat saturation, image distortion, visibility of anatomical structures, and detectability of joint abnormalities were visually assessed and graded on qualitative scales. Differences between MAVRIC-SL and FSE sequences were tested with the Wilcoxon signed-rank test. MAVRIC-SL sequences at 3 T showed significantly smaller metal artefacts compared to FSE-STIR sequences (p < 0.0001). The general image quality of MAVRIC-SL sequences was reduced with regard to spatial resolution, noise and contrast (p = 0.001), and fat saturation (p < 0.0001). The reduction of artefact size and image distortion significantly improved visualization of joint anatomy (p < 0.0001) and diagnostic confidence regarding implant-associated abnormalities (p = 0.0075 to <0.0001). Although the image quality of MAVRIC-SL sequences is limited at 3 T, its clinical application is feasible and provides important additional diagnostic information for the workup of patients with symptomatic hip replacement through substantially reduced metal artefacts. (orig.)

  10. Two-dimensional computer simulation of high intensity proton beams

    CERN Document Server

    Lapostolle, Pierre M

    1972-01-01

    A computer program has been developed which simulates the two- dimensional transverse behaviour of a proton beam in a focusing channel. The model is represented by an assembly of a few thousand 'superparticles' acted upon by their own self-consistent electric field and an external focusing force. The evolution of the system is computed stepwise in time by successively solving Poisson's equation and Newton's law of motion. Fast Fourier transform techniques are used for speed in the solution of Poisson's equation, while extensive area weighting is utilized for the accurate evaluation of electric field components. A computer experiment has been performed on the CERN CDC 6600 computer to study the nonlinear behaviour of an intense beam in phase space, showing under certain circumstances a filamentation due to space charge and an apparent emittance growth. (14 refs).

  11. Subjective and objective image qualities: a comparison of sagittal T2 weighted spin-echo and turbo-spin-eco sequences in magnetic resonance imaging of the spine by use of a subjective ranking system

    Energy Technology Data Exchange (ETDEWEB)

    Goerres, G. [Institut fuer diagnostische Radiologie, Departement Radiologie, Universitaetskliniken, Kantonsspital Basel (Switzerland); Mader, I. [Radiologische Gemeinschaftspraxis Dres. Siems, Grossmann, Bayreuth (Germany); Proske, M. [Klinikum Rosenheim (Germany). Inst. fuer Diagnostische Radiologie

    1998-12-31

    We evaluated the subjective image impression of two different magnetic resonance (MR) sequences by using a subjective ranking system. This ranking system was based on 20 criteria describing several tissue characteristics such as the signal intensity of normal anatomical structures and the changes of signal intensities and shape of lesions as well as artefacts. MR of the vertebral spine was performed in 48 female and 52 male patients (mean age 44.8 years) referred consecutively for investigation of a back problem. Ninety-six pathologies were found in 82 patients. Sagittal and axial T1 weighted spin-echo before and after administration of Gadolinium (Gd-DOTA), and sagittal T2 weighted spin-echo (T2wSE) and Turbo-spin-echo (TSE) sequences were performed by means of surface coils. Using the subjective ranking system the sagittal T2wSE and sagittal TSE were compared. Both sequences were suitable for identification of normal anatomy and pathologic changes and there was no trend for increased detection of disease by one imaging sequence over the other. We found that sagittal TSE sequences can replace sagittal T2wSE sequences in spinal MR and that artefacts at the cervical and lumbar spine are less frequent using TSE, thus confirming previous studies. In this study, our ranking system reveiled, that there are differences between the subjective judgement of image qualities and objective measurement of SNR. However, this approach may not be helpful to compare two different MR sequences as it is limited to the anatomical area investigated and is time consuming. The subjective image impression, i.e. the quality of images, may not always be represented by physical parameters such as a signal-to-noise ratio (SNR), radiologists should try to define influences of image quality also by subjective parameters. (orig.)

  12. Isotropic resolution diffusion tensor imaging of lumbosacral and sciatic nerves using a phase-corrected diffusion-prepared 3D turbo spin echo.

    Science.gov (United States)

    Cervantes, Barbara; Van, Anh T; Weidlich, Dominik; Kooijman, Hendrick; Hock, Andreas; Rummeny, Ernst J; Gersing, Alexandra; Kirschke, Jan S; Karampinos, Dimitrios C

    2018-08-01

    To perform in vivo isotropic-resolution diffusion tensor imaging (DTI) of lumbosacral and sciatic nerves with a phase-navigated diffusion-prepared (DP) 3D turbo spin echo (TSE) acquisition and modified reconstruction incorporating intershot phase-error correction and to investigate the improvement on image quality and diffusion quantification with the proposed phase correction. Phase-navigated DP 3D TSE included magnitude stabilizers to minimize motion and eddy-current effects on the signal magnitude. Phase navigation of motion-induced phase errors was introduced before readout in 3D TSE. DTI of lower back nerves was performed in vivo using 3D TSE and single-shot echo planar imaging (ss-EPI) in 13 subjects. Diffusion data were phase-corrected per k z plane with respect to T 2 -weighted data. The effects of motion-induced phase errors on DTI quantification was assessed for 3D TSE and compared with ss-EPI. Non-phase-corrected 3D TSE resulted in artifacts in diffusion-weighted images and overestimated DTI parameters in the sciatic nerve (mean diffusivity [MD] = 2.06 ± 0.45). Phase correction of 3D TSE DTI data resulted in reductions in all DTI parameters (MD = 1.73 ± 0.26) of statistical significance (P ≤ 0.001) and in closer agreement with ss-EPI DTI parameters (MD = 1.62 ± 0.21). DP 3D TSE with phase correction allows distortion-free isotropic diffusion imaging of lower back nerves with robustness to motion-induced artifacts and DTI quantification errors. Magn Reson Med 80:609-618, 2018. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2018 The Authors Magnetic Resonance

  13. Comparison of a T1-weighted inversion-recovery-, gradient-echo- and spin-echo sequence for imaging of the brain at 3.0 Tesla

    International Nuclear Information System (INIS)

    Stehling, C.; Niederstadt, T.; Kraemer, S.; Kugel, H.; Schwindt, W.; Heindel, W.; Bachmann, R.

    2005-01-01

    Purpose: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). Materials and Methods: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. Results: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the based ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p<0.001), but the CNR of the basal ganglia was not significantly different. Conclusion: For unenhanced T1w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T. (orig.)

  14. Comparison of 3D turbo spin-echo SPACE sequences with conventional 2D MRI sequences to assess the shoulder joint

    Energy Technology Data Exchange (ETDEWEB)

    Kloth, Jost Karsten, E-mail: jost.kloth@med.uni-heidelberg.de [Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg (Germany); Winterstein, Marianne, E-mail: marianne.winterstein@med.uni-heidelberg.de [Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg (Germany); Akbar, Michael, E-mail: michael.akbar@med.uni-heidelberg.de [Orthopedic and Trauma Surgery, University Hospital Heidelberg, Schlierbacher Landstraße 200a, D-69118 Heidelberg (Germany); Meyer, Esther, E-mail: esther.meyer@siemens.com [Siemens Healthcare, Erlangen (Germany); Paul, Dominik, E-mail: dominik.paul@siemens.com [Siemens Healthcare, Erlangen (Germany); Kauczor, Haus-Ulrich, E-mail: hans-ulrich.kauczor@med.uni-heidelberg.de [Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg (Germany); Weber, Marc-André, E-mail: marcandre.weber@med.uni-heidelberg.de [Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg (Germany)

    2014-10-15

    Highlights: • 3D SPACE and conventional 2D TSE MRI for assessment of the shoulder joint were compared. • Concordance for most pathologys was substantial to almost perfect. • Examination time could be reduced up to 8 min (27%). • Regarding rotator cuff injuries an additional sagittal T2w TSE sequence in 3D protocol is recommended. - Abstract: Purpose: To determine the accuracy and reliability of three-dimensional (3D) T1- and proton density (PD)-weighted turbo spin-echo (TSE) sampling perfection with application-optimized contrasts using different flip-angle evolution (SPACE) compared with conventional 2D sequences in assessment of the shoulder-joint. Materials and methods: Ninety-three subjects were examined on a 3-T MRI system with both conventional 2D-TSE sequences in T1-, T2- and PD-weighting and 3D SPACE sequences in T1- and PD-weighting. All examinations were assessed independently by two reviewers for common pathologies of the shoulder-joint. Agreement between 2D- and 3D-sequences and inter-observer-agreement was evaluated using kappa-statistics. Results: Using conventional 2D TSE sequences as standard of reference, sensitivity, specificity, and accuracy values of 3D SPACE were 81.8%, 95.1%, and 93.5% for injuries of the supraspinatus-tendon (SSP), 81.3%, 93.5%, and 91.4% for the cartilage layer and 82.4%, 98.5%, and 97.5% for the long biceps tendon. Concordance between 2D and 3D was almost perfect for tendinopathies of the SSP (κ = 0.85), osteoarthritis (κ = 1), luxation of the biceps tendon (κ = 1) and adjacent bone marrow (κ = 0.92). Inter-observer-agreement was generally higher for conventional 2D TSE sequences (κ, 0.23–1.0), when compared to 3D SPACE sequences (κ, −0.33 to 1.0) except for disorders of the long biceps tendon and supraspinatus tendon rupture. Conclusion: Because of substantial and almost perfect concordance with conventional 2D TSE sequences for common shoulder pathologies, MRI examination-time can be reduced by nearly 40

  15. Stress distribution in two-dimensional silos

    Science.gov (United States)

    Blanco-Rodríguez, Rodolfo; Pérez-Ángel, Gabriel

    2018-01-01

    Simulations of a polydispersed two-dimensional silo were performed using molecular dynamics, with different numbers of grains reaching up to 64 000, verifying numerically the model derived by Janssen and also the main assumption that the walls carry part of the weight due to the static friction between grains with themselves and those with the silo's walls. We vary the friction coefficient, the radii dispersity, the silo width, and the size of grains. We find that the Janssen's model becomes less relevant as the the silo width increases since the behavior of the stresses becomes more hydrostatic. Likewise, we get the normal and tangential stress distribution on the walls evidencing the existence of points of maximum stress. We also obtained the stress matrix with which we observe zones of concentration of load, located always at a height around two thirds of the granular columns. Finally, we observe that the size of the grains affects the distribution of stresses, increasing the weight on the bottom and reducing the normal stress on the walls, as the grains are made smaller (for the same total mass of the granulate), giving again a more hydrostatic and therefore less Janssen-type behavior for the weight of the column.

  16. Asymptotics for Two-dimensional Atoms

    DEFF Research Database (Denmark)

    Nam, Phan Thanh; Portmann, Fabian; Solovej, Jan Philip

    2012-01-01

    We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E^{\\TF}(\\lambd......We prove that the ground state energy of an atom confined to two dimensions with an infinitely heavy nucleus of charge $Z>0$ and $N$ quantum electrons of charge -1 is $E(N,Z)=-{1/2}Z^2\\ln Z+(E^{\\TF}(\\lambda)+{1/2}c^{\\rm H})Z^2+o(Z^2)$ when $Z\\to \\infty$ and $N/Z\\to \\lambda$, where $E......^{\\TF}(\\lambda)$ is given by a Thomas-Fermi type variational problem and $c^{\\rm H}\\approx -2.2339$ is an explicit constant. We also show that the radius of a two-dimensional neutral atom is unbounded when $Z\\to \\infty$, which is contrary to the expected behavior of three-dimensional atoms....

  17. Seismic isolation of two dimensional periodic foundations

    International Nuclear Information System (INIS)

    Yan, Y.; Mo, Y. L.; Laskar, A.; Cheng, Z.; Shi, Z.; Menq, F.; Tang, Y.

    2014-01-01

    Phononic crystal is now used to control acoustic waves. When the crystal goes to a larger scale, it is called periodic structure. The band gaps of the periodic structure can be reduced to range from 0.5 Hz to 50 Hz. Therefore, the periodic structure has potential applications in seismic wave reflection. In civil engineering, the periodic structure can be served as the foundation of upper structure. This type of foundation consisting of periodic structure is called periodic foundation. When the frequency of seismic waves falls into the band gaps of the periodic foundation, the seismic wave can be blocked. Field experiments of a scaled two dimensional (2D) periodic foundation with an upper structure were conducted to verify the band gap effects. Test results showed the 2D periodic foundation can effectively reduce the response of the upper structure for excitations with frequencies within the frequency band gaps. When the experimental and the finite element analysis results are compared, they agree well with each other, indicating that 2D periodic foundation is a feasible way of reducing seismic vibrations.

  18. Two-dimensional transport of tokamak plasmas

    International Nuclear Information System (INIS)

    Hirshman, S.P.; Jardin, S.C.

    1979-01-01

    A reduced set of two-fluid transport equations is obtained from the conservation equations describing the time evolution of the differential particle number, entropy, and magnetic fluxes in an axisymmetric toroidal plasma with nested magnetic surfaces. Expanding in the small ratio of perpendicular to parallel mobilities and thermal conductivities yields as solubility constraints one-dimensional equations for the surface-averaged thermodynamic variables and magnetic fluxes. Since Ohm's law E +u x B =R', where R' accounts for any nonideal effects, only determines the particle flow relative to the diffusing magnetic surfaces, it is necessary to solve a single two-dimensional generalized differential equation, (partial/partialt) delpsi. (delp - J x B) =0, to find the absolute velocity of a magnetic surface enclosing a fixed toroidal flux. This equation is linear but nonstandard in that it involves flux surface averages of the unknown velocity. Specification of R' and the cross-field ion and electron heat fluxes provides a closed system of equations. A time-dependent coordinate transformation is used to describe the diffusion of plasma quantities through magnetic surfaces of changing shape

  19. Two-dimensional topological photonic systems

    Science.gov (United States)

    Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng

    2017-09-01

    The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.

  20. Turbulent equipartitions in two dimensional drift convection

    International Nuclear Information System (INIS)

    Isichenko, M.B.; Yankov, V.V.

    1995-01-01

    Unlike the thermodynamic equipartition of energy in conservative systems, turbulent equipartitions (TEP) describe strongly non-equilibrium systems such as turbulent plasmas. In turbulent systems, energy is no longer a good invariant, but one can utilize the conservation of other quantities, such as adiabatic invariants, frozen-in magnetic flux, entropy, or combination thereof, in order to derive new, turbulent quasi-equilibria. These TEP equilibria assume various forms, but in general they sustain spatially inhomogeneous distributions of the usual thermodynamic quantities such as density or temperature. This mechanism explains the effects of particle and energy pinch in tokamaks. The analysis of the relaxed states caused by turbulent mixing is based on the existence of Lagrangian invariants (quantities constant along fluid-particle or other orbits). A turbulent equipartition corresponds to the spatially uniform distribution of relevant Lagrangian invariants. The existence of such turbulent equilibria is demonstrated in the simple model of two dimensional electrostatically turbulent plasma in an inhomogeneous magnetic field. The turbulence is prescribed, and the turbulent transport is assumed to be much stronger than the classical collisional transport. The simplicity of the model makes it possible to derive the equations describing the relaxation to the TEP state in several limits

  1. Radiation effects on two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Walker, R.C. II; Robinson, J.A. [Department of Materials Science, Penn State, University Park, PA (United States); Center for Two-Dimensional Layered Materials, Penn State, University Park, PA (United States); Shi, T. [Department of Mechanical and Nuclear Engineering, Penn State, University Park, PA (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Silva, E.C. [GlobalFoundries, Malta, NY (United States); Jovanovic, I. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States)

    2016-12-15

    The effects of electromagnetic and particle irradiation on two-dimensional materials (2DMs) are discussed in this review. Radiation creates defects that impact the structure and electronic performance of materials. Determining the impact of these defects is important for developing 2DM-based devices for use in high-radiation environments, such as space or nuclear reactors. As such, most experimental studies have been focused on determining total ionizing dose damage to 2DMs and devices. Total dose experiments using X-rays, gamma rays, electrons, protons, and heavy ions are summarized in this review. We briefly discuss the possibility of investigating single event effects in 2DMs based on initial ion beam irradiation experiments and the development of 2DM-based integrated circuits. Additionally, beneficial uses of irradiation such as ion implantation to dope materials or electron-beam and helium-beam etching to shape materials have begun to be used on 2DMs and are reviewed as well. For non-ionizing radiation, such as low-energy photons, we review the literature on 2DM-based photo-detection from terahertz to UV. The majority of photo-detecting devices operate in the visible and UV range, and for this reason they are the focus of this review. However, we review the progress in developing 2DMs for detecting infrared and terahertz radiation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Buckled two-dimensional Xene sheets.

    Science.gov (United States)

    Molle, Alessandro; Goldberger, Joshua; Houssa, Michel; Xu, Yong; Zhang, Shou-Cheng; Akinwande, Deji

    2017-02-01

    Silicene, germanene and stanene are part of a monoelemental class of two-dimensional (2D) crystals termed 2D-Xenes (X = Si, Ge, Sn and so on) which, together with their ligand-functionalized derivatives referred to as Xanes, are comprised of group IVA atoms arranged in a honeycomb lattice - similar to graphene but with varying degrees of buckling. Their electronic structure ranges from trivial insulators, to semiconductors with tunable gaps, to semi-metallic, depending on the substrate, chemical functionalization and strain. More than a dozen different topological insulator states are predicted to emerge, including the quantum spin Hall state at room temperature, which, if realized, would enable new classes of nanoelectronic and spintronic devices, such as the topological field-effect transistor. The electronic structure can be tuned, for example, by changing the group IVA element, the degree of spin-orbit coupling, the functionalization chemistry or the substrate, making the 2D-Xene systems promising multifunctional 2D materials for nanotechnology. This Perspective highlights the current state of the art and future opportunities in the manipulation and stability of these materials, their functions and applications, and novel device concepts.

  3. Is there an added value of T1-weighted contrast-enhanced fat-suppressed spin-echo MR sequences compared to STIR sequences in MRI of the foot and ankle?

    International Nuclear Information System (INIS)

    Zubler, Veronika; Zanetti, Marco; Dietrich, Tobias J.; Pfirrmann, Christian W.; Mamisch-Saupe, Nadja; Espinosa, Norman

    2017-01-01

    To prospectively compare T1-weighted fat-suppressed spin-echo magnetic resonance (MR) sequences after gadolinium application (T1wGdFS) to STIR sequences in patients with acute and chronic foot pain. In 51 patients referred for MRI of the foot and ankle, additional transverse and sagittal T1wGdFS sequences were obtained. Two sets of MR images (standard protocol with STIR or T1wGdFS) were analysed. Diagnosis, diagnostic confidence, and localization of the abnormality were noted. Standard of reference was established by an expert panel of two experienced MSK radiologists and one experienced foot surgeon based on MR images, clinical charts and surgical reports. Patients reported prospectively localization of pain. Descriptive statistics, McNemar test and Kappa test were used. Diagnostic accuracy with STIR protocol was 80% for reader 1, 67% for reader 2, with contrast-protocol 84%, both readers. Significance was found for reader 2. Diagnostic confidence for reader 1 was 1.7 with STIR, 1.3 with contrast-protocol; reader 2: 2.1/1.7. Significance was found for reader 1. Pain location correlated with STIR sequences in 64% and 52%, with gadolinium sequences in 70% and 71%. T1-weighted contrast material-enhanced fat-suppressed spin-echo magnetic resonance sequences improve diagnostic accuracy, diagnostic confidence and correlation of MR abnormalities with pain location in MRI of the foot and ankle. However, the additional value is small. (orig.)

  4. Is there an added value of T1-weighted contrast-enhanced fat-suppressed spin-echo MR sequences compared to STIR sequences in MRI of the foot and ankle?

    Energy Technology Data Exchange (ETDEWEB)

    Zubler, Veronika; Zanetti, Marco; Dietrich, Tobias J.; Pfirrmann, Christian W.; Mamisch-Saupe, Nadja [University of Zurich, Faculty of Medicine, Zurich (Switzerland); Orthopedic University Hospital Balgrist, Department of Radiology, Zurich (Switzerland); Espinosa, Norman [University of Zurich, Faculty of Medicine, Zurich (Switzerland); Orthopedic University Hospital Balgrist, Orthopedic Surgery, Zurich (Switzerland)

    2017-08-15

    To prospectively compare T1-weighted fat-suppressed spin-echo magnetic resonance (MR) sequences after gadolinium application (T1wGdFS) to STIR sequences in patients with acute and chronic foot pain. In 51 patients referred for MRI of the foot and ankle, additional transverse and sagittal T1wGdFS sequences were obtained. Two sets of MR images (standard protocol with STIR or T1wGdFS) were analysed. Diagnosis, diagnostic confidence, and localization of the abnormality were noted. Standard of reference was established by an expert panel of two experienced MSK radiologists and one experienced foot surgeon based on MR images, clinical charts and surgical reports. Patients reported prospectively localization of pain. Descriptive statistics, McNemar test and Kappa test were used. Diagnostic accuracy with STIR protocol was 80% for reader 1, 67% for reader 2, with contrast-protocol 84%, both readers. Significance was found for reader 2. Diagnostic confidence for reader 1 was 1.7 with STIR, 1.3 with contrast-protocol; reader 2: 2.1/1.7. Significance was found for reader 1. Pain location correlated with STIR sequences in 64% and 52%, with gadolinium sequences in 70% and 71%. T1-weighted contrast material-enhanced fat-suppressed spin-echo magnetic resonance sequences improve diagnostic accuracy, diagnostic confidence and correlation of MR abnormalities with pain location in MRI of the foot and ankle. However, the additional value is small. (orig.)

  5. Contactless friction and the {sup 3}He-{sup 4}He dimer. Studies with the atomic-beam spin-echo spectrometer; Kontaktlose Reibung und das {sup 3}He-{sup 4}He-Dimer. Untersuchungen mit dem Atomstrahlspinechospektrometer

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Matthias

    2016-04-20

    In this thesis the time of flight resolved atomic beam spin echo method (SEToF) is applied to a {sup 3}He-beam for the first time and studied systematically. This method is shown to be superior to the usual atomic beam spin echo technique. With SEToF it is possible to almost completely remove unpolarized background and to reach a beam polarisation close to 100%. The SEToF technique is shown to be crucial for the first experimental proof of the existence of the {sup 3}He-{sup 4}He dimer. This dimer is the weakest bound van-der-Waals-molecule known to date. Furthermore, a drag force between an atom and a dielectric surface is detected originating from the fluctuating dipole moment of the atom. Not only the measured friction coefficients match their theoretical predictions perfectly, but our data also shows the correct temperature dependence. A great many technological renewals and improvements were installed in the apparatus during this thesis work. They have become necessary or sensible due to the relocation of the physics institute. A few of them are documented and motivated in this thesis.

  6. Differentiation between hepatic haemangiomas and cysts with an inversion recovery single-shot turbo spin-echo (SSTSE) sequence using the TI nulling value of hepatic haemangioma with sensitivity encoding

    International Nuclear Information System (INIS)

    Katada, Yoshiaki; Nozaki, Miwako; Yasumoto, Mayumi; Ishii, Chikako; Tanaka, Hiroshi; Nakamoto, Kazuya; Ohashi, Isamu

    2010-01-01

    To evaluate the additional value of inversion recovery (IR) single-shot turbo spin-echo (SSTSE) imaging with sensitivity encoding (SENSE) using the inversion time (TI) value of hepatic haemangioma as a supplement to conventional T2-weighted turbo spin-echo (TSE) imaging for the discrimination of hepatic haemangiomas and cysts. A total of 134 lesions (77 hepatic haemangiomas, 57 hepatic cysts) in 59 patients were evaluated. Three readers evaluated these images and used a five-point scale to evaluate the lesion status. A receiver operating characteristic (ROC) analysis and 2 x 2 table analysis were used. The ROC analysis for all the readers and all the cases revealed a significantly higher area under the curve (AUC) for the combination of moderately and heavily T2-weighted TSE with IR-SSTSE images (0.945) than for moderately and heavily T2-weighted TSE images alone (0.894) (P < 0.001). For the combination of T2-weighted TSE with IR-SSTSE versus T2-weighted TSE alone, the 2 x 2 table analysis revealed a higher true-positive rate; this difference was statistically significant (P < 0.0001). The introduction of IR-SSTSE with SENSE sequences significantly improves the diagnostic accuracy of the differentiation of hepatic haemangioma and cysts while increasing the time required for routine abdominal imaging by only 20 s. (orig.)

  7. The facial nerve in the temporal bone as visualised via thin-layer paratransversal and sagittal MR tomographic images by means of T1 spin-echo and FLASH sequences

    International Nuclear Information System (INIS)

    Mueller-Lisse, U.; Jaeger, L.J.E.; Bruegel, F.J.; Grevers, G.; Reiser, M.F.

    1995-01-01

    It is difficult to effect visualization and delineation of the facial nerve and its neighbouring structures in the temporal bone with conventional MRI examination protocols. We tested temporal bone MRI with 2 mm slices and compared T 1 -weighted FLASH (T R =400 ms, T E =10 ms, 90 flip angle) and spin-echo (T R =540 ms, T E =15 ms) sequences. 5 volunteers and 14 patients were examined with the head coil of a 1.0 T whole body MRI scanner (Impact, Siemens, Erlangen) with para-transversal images orientated parallel to the inferior outline of the clivus and sagittal images orientated along the brainstem. The facial nerve and its neighbouring structures could be reliably visualized and differentiated along its entire course. The FLASH sequence was superior to the spin-echo sequence. 8 of 11 patients with peripheral facial nerve palsy showed contrast enhancement. In two patients, local swelling of the affected facial nerve was evident. (orig./MG) [de

  8. Contrast-enhanced MR imaging of metastatic brain tumor at 3 Tesla. Utility of T1-weighted SPACE compared with 2D spin echo and 3D gradient echo sequence

    International Nuclear Information System (INIS)

    Komada, Tomohiro; Naganawa, Shinji; Ogawa, Hiroshi

    2008-01-01

    We evaluated the newly developed whole-brain, isotropic, 3-dimensional turbo spin-echo imaging with variable flip angle echo train (SPACE) for contrast-enhanced T 1 -weighted imaging in detecting brain metastases at 3 tesla (T). Twenty-two patients with suspected brain metastases underwent postcontrast study with SPACE, magnetization-prepared rapid gradient-echo (MP-RAGE), and 2-dimensional T 1 -weighted spin echo (2D-SE) imaging at 3 T. We quantitatively compared SPACE, MP-RAGE, and 2D-SE images by using signal-to-noise ratios (SNRs) for gray matter (GM) and white matter (WM) and contrast-to-noise ratios (CNRs) for GM-to-WM, lesion-to-GM, and lesion-to-WM. Two blinded radiologists evaluated the detection of brain metastases by segment-by-segment analysis and continuously-distributed test. The CNR between GM and WM was significantly higher on MP-RAGE images than on SPACE images (P 1 -weighted imaging. (author)

  9. Contrast-enhanced Magnetic Resonance Imaging of Pelvic Bone Metastases at 3.0 T: Comparison Between 3-dimensional T1-weighted CAIPIRINHA-VIBE Sequence and 2-dimensional T1-weighted Turbo Spin-Echo Sequence.

    Science.gov (United States)

    Yoon, Min A; Hong, Suk-Joo; Lee, Kyu-Chong; Lee, Chang Hee

    2018-06-12

    This study aimed to compare 3-dimensional T1-weighted gradient-echo sequence (CAIPIRINHA-volumetric interpolated breath-hold examination [VIBE]) with 2-dimensional T1-weighted turbo spin-echo sequence for contrast-enhanced magnetic resonance imaging (MRI) of pelvic bone metastases at 3.0 T. Thirty-one contrast-enhanced MRIs of pelvic bone metastases were included. Two contrast-enhanced sequences were evaluated for the following parameters: overall image quality, sharpness of pelvic bone, iliac vessel clarity, artifact severity, and conspicuity and edge sharpness of the smallest metastases. Quantitative analysis was performed by calculating signal-to-noise ratio and contrast-to-noise ratio of the smallest metastases. Significant differences between the 2 sequences were assessed. CAIPIRINHA-VIBE had higher scores for overall image quality, pelvic bone sharpness, iliac vessel clarity, and edge sharpness of the metastatic lesions, and had less artifacts (all P 0.05). Our results suggest that CAIPIRINHA-VIBE may be superior to turbo spin-echo for contrast-enhanced MRI of pelvic bone metastases at 3.0 T.

  10. Parallel processing of two-dimensional Sn transport calculations

    International Nuclear Information System (INIS)

    Uematsu, M.

    1997-01-01

    A parallel processing method for the two-dimensional S n transport code DOT3.5 has been developed to achieve a drastic reduction in computation time. In the proposed method, parallelization is achieved with angular domain decomposition and/or space domain decomposition. The calculational speed of parallel processing by angular domain decomposition is largely influenced by frequent communications between processing elements. To assess parallelization efficiency, sample problems with up to 32 x 32 spatial meshes were solved with a Sun workstation using the PVM message-passing library. As a result, parallel calculation using 16 processing elements, for example, was found to be nine times as fast as that with one processing element. As for parallel processing by geometry segmentation, the influence of processing element communications on computation time is small; however, discontinuity at the segment boundary degrades convergence speed. To accelerate the convergence, an alternate sweep of angular flux in conjunction with space domain decomposition and a two-step rescaling method consisting of segmentwise rescaling and ordinary pointwise rescaling have been developed. By applying the developed method, the number of iterations needed to obtain a converged flux solution was reduced by a factor of 2. As a result, parallel calculation using 16 processing elements was found to be 5.98 times as fast as the original DOT3.5 calculation

  11. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  12. Two-dimensional silica opens new perspectives

    Science.gov (United States)

    Büchner, Christin; Heyde, Markus

    2017-12-01

    In recent years, silica films have emerged as a novel class of two-dimensional (2D) materials. Several groups succeeded in epitaxial growth of ultrathin SiO2 layers using different growth methods and various substrates. The structures consist of tetrahedral [SiO4] building blocks in two mirror symmetrical planes, connected via oxygen bridges. This arrangement is called a silica bilayer as it is the thinnest 2D arrangement with the stoichiometry SiO2 known today. With all bonds saturated within the nano-sheet, the interaction with the substrate is based on van der Waals forces. Complex ring networks are observed, including hexagonal honeycomb lattices, point defects and domain boundaries, as well as amorphous domains. The network structures are highly tuneable through variation of the substrate, deposition parameters, cooling procedure, introducing dopants or intercalating small species. The amorphous networks and structural defects were resolved with atomic resolution microscopy and modeled with density functional theory and molecular dynamics. Such data contribute to our understanding of the formation and characteristic motifs of glassy systems. Growth studies and doping with other chemical elements reveal ways to tune ring sizes and defects as well as chemical reactivities. The pristine films have been utilized as molecular sieves and for confining molecules in nanocatalysis. Post growth hydroxylation can be used to tweak the reactivity as well. The electronic properties of silica bilayers are favourable for using silica as insulators in 2D material stacks. Due to the fully saturated atomic structure, the bilayer interacts weakly with the substrate and can be described as quasi-freestanding. Recently, a mm-scale film transfer under structure retention has been demonstrated. The chemical and mechanical stability of silica bilayers is very promising for technological applications in 2D heterostacks. Due to the impact of this bilayer system for glass science

  13. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  14. Moment-based method for computing the two-dimensional discrete Hartley transform

    Science.gov (United States)

    Dong, Zhifang; Wu, Jiasong; Shu, Huazhong

    2009-10-01

    In this paper, we present a fast algorithm for computing the two-dimensional (2-D) discrete Hartley transform (DHT). By using kernel transform and Taylor expansion, the 2-D DHT is approximated by a linear sum of 2-D geometric moments. This enables us to use the fast algorithms developed for computing the 2-D moments to efficiently calculate the 2-D DHT. The proposed method achieves a simple computational structure and is suitable to deal with any sequence lengths.

  15. Lie algebra contractions on two-dimensional hyperboloid

    International Nuclear Information System (INIS)

    Pogosyan, G. S.; Yakhno, A.

    2010-01-01

    The Inoenue-Wigner contraction from the SO(2, 1) group to the Euclidean E(2) and E(1, 1) group is used to relate the separation of variables in Laplace-Beltrami (Helmholtz) equations for the four corresponding two-dimensional homogeneous spaces: two-dimensional hyperboloids and two-dimensional Euclidean and pseudo-Euclidean spaces. We show how the nine systems of coordinates on the two-dimensional hyperboloids contracted to the four systems of coordinates on E 2 and eight on E 1,1 . The text was submitted by the authors in English.

  16. One and two dimensional simulations on beat wave acceleration

    International Nuclear Information System (INIS)

    Mori, W.; Joshi, C.; Dawson, J.M.; Forslund, D.W.; Kindel, J.M.

    1984-01-01

    Recently there has been considerable interest in the use of fast-large-amplitude plasma waves as the basis for a high energy particle accelerator. In these schemes, lasers are used to create the plasma wave. To date the few simulation studies on this subject have been limited to one-dimensional, short rise time simulations. Here the authors present results from simulations in which more realistic parameters are used. In addition, they present the first two dimensional simulations on this subject. One dimensional simulations on a 2 1/2-D relativistic electromagnetic particle code, in which only a few cells were used in one direction, on colinear optical mixing are presented. In these simulations the laser rise time, laser intensity, plasma density, plasma temperature and system size were varied. The simulations indicate that the theory of Rosenbluth and Liu is applicable over a wide range of parameters. In addition, simulations with a DC magnetic field are presented in order to study the ''Surfatron'' concept

  17. Emerging terahertz photodetectors based on two-dimensional materials

    Science.gov (United States)

    Yang, Jie; Qin, Hua; Zhang, Kai

    2018-01-01

    Inspired by the innovations in photonics and nanotechnology, the remarkable properties of two-dimensional (2D) materials have renewed interest for the development of terahertz (THz) photodetectors. The versatility of these materials enables ultrafast and ultrasensitive photodetection of THz radiation at room temperature. The atomically thin characteristic together with van der Waals interactions among the layers make it easy to scaling down and integrate with other 2D materials based devices, as well as silicon chips. Efforts have increased fast in the past decade in developing proof-of-concept and the further prospective THz photodetectors based on 2D materials. Here, the recent progress on the exploring of THz photodetectors based on 2D materials is reviewed. We summarized the THz photodetectors under different physical mechanism and introduced the state-of-the-art THz photodetectors based on various promising 2D materials, such as graphene, transition metal dichalcogenides (TMDCs), black phosphorus (BP) and topological insulators (TIs). A brief discussion on the remaining challenges and a perspective of the 2D materials based THz photodetectors are also given.

  18. Noise-induced drift in two-dimensional anisotropic systems

    Science.gov (United States)

    Farago, Oded

    2017-10-01

    We study the isothermal Brownian dynamics of a particle in a system with spatially varying diffusivity. Due to the heterogeneity of the system, the particle's mean displacement does not vanish even if it does not experience any physical force. This phenomenon has been termed "noise-induced drift," and has been extensively studied for one-dimensional systems. Here, we examine the noise-induced drift in a two-dimensional anisotropic system, characterized by a symmetric diffusion tensor with unequal diagonal elements. A general expression for the mean displacement vector is derived and presented as a sum of two vectors, depicting two distinct drifting effects. The first vector describes the tendency of the particle to drift toward the high diffusivity side in each orthogonal principal diffusion direction. This is a generalization of the well-known expression for the noise-induced drift in one-dimensional systems. The second vector represents a novel drifting effect, not found in one-dimensional systems, originating from the spatial rotation in the directions of the principal axes. The validity of the derived expressions is verified by using Langevin dynamics simulations. As a specific example, we consider the relative diffusion of two transmembrane proteins, and demonstrate that the average distance between them increases at a surprisingly fast rate of several tens of micrometers per second.

  19. Assessment of the image quality and tumor detectability of breath-hold T2-weighted imaging of liver tumors using a fast gradient MR system

    International Nuclear Information System (INIS)

    Yoshida, Kotaro; Suto, Yuji; Sugihara, Shuji; Tokuda, Yukiko

    1996-01-01

    Fourteen patients with various types of focal liver tumors were imaged with turbo spin-echo (TSE), breath-hold TSE (BH-TSE) and half-Fourier single-shot TSE (HASTE) pulse sequences using a fast gradient magnetic resonance imaging (MRI) system. We compared the T2-weighted images of the liver with the TSE, BH-TSE, HASTE and conventional spin-echo (SE) pulse sequences in order to determine whether those fast T2-weighted images, including fat suppressed images, could replace SE images. In quantitative and qualitative analysis, the fast T2-weighted images were slightly superior to the SE images, but they were inferior in the conspicuousness of liver tumor to the SE images. These findings suggest that the fast T2-weighted images can shorten the examination time of the liver MRI, but cannot replace the T2-weighted SE images because of the low conspicuousness. (author)

  20. Beginning Introductory Physics with Two-Dimensional Motion

    Science.gov (United States)

    Huggins, Elisha

    2009-01-01

    During the session on "Introductory College Physics Textbooks" at the 2007 Summer Meeting of the AAPT, there was a brief discussion about whether introductory physics should begin with one-dimensional motion or two-dimensional motion. Here we present the case that by starting with two-dimensional motion, we are able to introduce a considerable…

  1. Two-dimensional black holes and non-commutative spaces

    International Nuclear Information System (INIS)

    Sadeghi, J.

    2008-01-01

    We study the effects of non-commutative spaces on two-dimensional black hole. The event horizon of two-dimensional black hole is obtained in non-commutative space up to second order of perturbative calculations. A lower limit for the non-commutativity parameter is also obtained. The observer in that limit in contrast to commutative case see two horizon

  2. Solution of the two-dimensional spectral factorization problem

    Science.gov (United States)

    Lawton, W. M.

    1985-01-01

    An approximation theorem is proven which solves a classic problem in two-dimensional (2-D) filter theory. The theorem shows that any continuous two-dimensional spectrum can be uniformly approximated by the squared modulus of a recursively stable finite trigonometric polynomial supported on a nonsymmetric half-plane.

  3. Two-dimensional Navier-Stokes turbulence in bounded domains

    NARCIS (Netherlands)

    Clercx, H.J.H.; van Heijst, G.J.F.

    In this review we will discuss recent experimental and numerical results of quasi-two-dimensional decaying and forced Navier–Stokes turbulence in bounded domains. We will give a concise overview of developments in two-dimensional turbulence research, with emphasis on the progress made during the

  4. Two-dimensional Navier-Stokes turbulence in bounded domains

    NARCIS (Netherlands)

    Clercx, H.J.H.; Heijst, van G.J.F.

    2009-01-01

    In this review we will discuss recent experimental and numerical results of quasi-two-dimensional decaying and forced Navier–Stokes turbulence in bounded domains. We will give a concise overview of developments in two-dimensional turbulence research, with emphasis on the progress made during the

  5. Cerebral hemodynamic changes measured by gradient-echo or spin-echo bolus tracking and its correlation to changes in ICA blood flow measured by phase-mapping MRI

    DEFF Research Database (Denmark)

    Marstrand, J.R.; Rostrup, Egill; Garde, Ellen

    2001-01-01

    Changes in cerebral blood flow (CBF) induced by Acetazolamide (ACZ) were measured using dynamic susceptibility contrast MRI (DSC-MRI) with both spin echo (SE) EPI and gradient echo (GE) EPI, and related to changes in internal carotid artery (ICA) flow measured by phase-mapping. Also examined...... was the effect of repeated bolus injections. CBF, cerebral blood volume (CBV), and mean transit time (MTT) were calculated by singular value decomposition (SVD) and by deconvolution using an exponential function as kernel. The results showed no dependency on calculation method. GE-EPI measured a significant...... increase in CBF and CBV in response to ACZ, while SE-EPI measured a significant increase in CBV and MTT. CBV and MTT change measured by SE-EPI was sensitive to previous bolus injections. There was a significant linear relation between change in CBF measured by GE-EPI and change in ICA flow. In conclusion...

  6. Cerebral hemodynamic changes measured by gradient-echo or spin-echo bolus tracking and its correlation to changes in ICA blood flow measured by phase-mapping MRI

    DEFF Research Database (Denmark)

    Marstrand, J.R.; Rostrup, Egill; Garde, Ellen

    2001-01-01

    Changes in cerebral blood flow (CBF) induced by Acetazolamide (ACZ) were measured using dynamic susceptibility contrast MRI (DSC-MRI) with both spin echo (SE) EPI and gradient echo (GE) EPI, and related to changes in internal carotid artery (ICA) flow measured by phase-mapping. Also examined...... increase in CBF and CBV in response to ACZ, while SE-EPI measured a significant increase in CBV and MTT. CBV and MTT change measured by SE-EPI was sensitive to previous bolus injections. There was a significant linear relation between change in CBF measured by GE-EPI and change in ICA flow. In conclusion......, GE-EPI under the present condition was superior to SE-EPI in monitoring cerebral vascular changes...

  7. Optimizing separations in online comprehensive two-dimensional liquid chromatography.

    Science.gov (United States)

    Pirok, Bob W J; Gargano, Andrea F G; Schoenmakers, Peter J

    2018-01-01

    Online comprehensive two-dimensional liquid chromatography has become an attractive option for the analysis of complex nonvolatile samples found in various fields (e.g. environmental studies, food, life, and polymer sciences). Two-dimensional liquid chromatography complements the highly popular hyphenated systems that combine liquid chromatography with mass spectrometry. Two-dimensional liquid chromatography is also applied to the analysis of samples that are not compatible with mass spectrometry (e.g. high-molecular-weight polymers), providing important information on the distribution of the sample components along chemical dimensions (molecular weight, charge, lipophilicity, stereochemistry, etc.). Also, in comparison with conventional one-dimensional liquid chromatography, two-dimensional liquid chromatography provides a greater separation power (peak capacity). Because of the additional selectivity and higher peak capacity, the combination of two-dimensional liquid chromatography with mass spectrometry allows for simpler mixtures of compounds to be introduced in the ion source at any given time, improving quantitative analysis by reducing matrix effects. In this review, we summarize the rationale and principles of two-dimensional liquid chromatography experiments, describe advantages and disadvantages of combining different selectivities and discuss strategies to improve the quality of two-dimensional liquid chromatography separations. © 2017 The Authors. Journal of Separation Science published by WILEY-VCH Verlag GmbH & Co. KGaA.

  8. Exploring two-dimensional electron gases with two-dimensional Fourier transform spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Paul, J.; Dey, P.; Karaiskaj, D., E-mail: karaiskaj@usf.edu [Department of Physics, University of South Florida, 4202 East Fowler Ave., Tampa, Florida 33620 (United States); Tokumoto, T.; Hilton, D. J. [Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294 (United States); Reno, J. L. [CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2014-10-07

    The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells of 12 nm and 18 nm thickness and in-well carrier concentration of ∼4 × 10{sup 11} cm{sup −2} was carefully measured using spectrally resolved four-wave mixing (FWM) and two-dimensional Fourier transform (2DFT) spectroscopy. Although the absorption at the Fermi edge is broad at this doping level, the spectrally resolved FWM shows narrow resonances. Two peaks are observed separated by the heavy hole/light hole energy splitting. Temperature dependent “rephasing” (S{sub 1}) 2DFT spectra show a rapid linear increase of the homogeneous linewidth with temperature. The dephasing rate increases faster with temperature in the narrower 12 nm quantum well, likely due to an increased carrier-phonon scattering rate. The S{sub 1} 2DFT spectra were measured using co-linear, cross-linear, and co-circular polarizations. Distinct 2DFT lineshapes were observed for co-linear and cross-linear polarizations, suggesting the existence of polarization dependent contributions. The “two-qua