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Sample records for echo t2-weighted imaging

  1. Fast high resolution whole brain T2* weighted imaging using echo planar imaging at 7T.

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    Zwanenburg, Jaco J M; Versluis, Maarten J; Luijten, Peter R; Petridou, Natalia

    2011-06-15

    Magnetic susceptibility based (T(2)* weighted) contrast in MRI at high magnetic field strength is of great value in research on brain structure and cortical architecture, but its use is hampered by the low signal-to-noise ratio (SNR) efficiency of the conventional spoiled gradient echo sequence (GRE) leading to long scan times even for a limited number of slices. In this work, we show that high resolution (0.5mm isotropic) T(2)* weighted images of the whole brain can be obtained in 6min by utilizing the high SNR efficiency of echo-planar imaging (EPI). A volumetric (3D) EPI protocol is presented and compared to conventional 3D GRE images acquired with the same resolution, amount of T(2)* weighting, and imaging duration. Spatial coverage in 3D EPI was increased by a factor of 4.5 compared to 3D GRE, while also the SNR was increased by a factor of 2. Image contrast for both magnitude and phase between gray and white matter was similar for both sequences, with enhanced conspicuity of anatomic details in the 3D EPI images due to the increased SNR. Even at 7T, image blurring and distortion is limited if the EPI train length remains short (not longer than the T(2)* of the imaged tissue). 3D EPI provides steps (speed, whole brain coverage, and high isotropic resolution) that are necessary to utilize the benefits of high field MRI in research that employs T(2)* weighted imaging. Copyright © 2011 Elsevier Inc. All rights reserved.

  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

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    Wang, Wen Chao; Choi, Byung Ihn; Han, Joon Koo; Kim, Tae Kyoung; Cho, Soon Gu [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-03-01

    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. Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

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    Meindl, T.; Wirth, S.; Dietrich, O.; Reiser, M. [University Hospitals Munich, Department of Clinical Radiology, Munich (Germany); Weckbach, S.; Schoenberg, S.O. [University Hospital Mannheim, Medical Faculty Mannheim-University of Heidelberg, Department of Clinical Radiology, Mannheim (Germany)

    2009-03-15

    To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen's kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences. (orig.)

  4. MR imaging with fluid attenuated inversion recovery sequence of childhood adrenoleukodystrophy : comparison with T2 weighted spin echo imaging

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    Hwang, Asiry; Seo, Jeong-Jin; Jeong, Gwang Woo; Chung, Tae Woong; Jeong, Yong Yeon; Kang, Heoung Keun; Kook, Hoon; Woo, Young Jong; Hwang, Tai Joo [Chonnam Univ. Medical School, Seoul (Korea, Republic of)

    1999-03-01

    The purpose of this study was to evaluate the usefulness of FLAIR(Fluid Attenuated Inversion Recovery) MR imaging in childhood adrenoleukodystrophy by comparing with those of T2-weighted FSE imaging, and to correlate MRI findings with clinical manifestations. Axial FLAIR images(TR/TE/TI=10004/123/2200) and T2-weighted FSE images(TR/TE=4000/104) of brain in six male patients(age range : 6-17 years, mean age : 10.2 years) with biochemically confirmed adrenoleukodystrophy were compared visually by two radiologists for detection, conspicuity, and the extent of lesion. Quantitatively, we compared lesion/CSF contrast, lesion/CSF contrast to noise ratio(CNR), lesion/white matter(WM) contrast, and lesion/WM CNR between FLAIR and T2 weighted image. We correlated MR findings with clinical manifestations of neurologic symptoms and evaluated whether MRI could detect white matter lesions in neurologically asymptomatic patients. Visual detection of lesions was better with FLAIR images in 2 of the 6 cases and it was equal in the remainders. Visual conspicuity and detection of the extent of lesion were superior on FLAIR images than T2-weighted images in all 6 cases. In the quantitative assessment of lesions, FLAIR was superior to T2-weighted image for lesion/CSF contrast and lesion/CSF CNR, but was inferior to T2 weighted image for lesion/WM contrast and lesion/WM CNR. In one case, FLAIR images distinguished the portion of encephalomalacic change from lesions. MR findings of adrenoleukodystrophy were correlated with clinical manifestations in symptomatic 4 cases, and also detected white matter lesions in asymptomatic 2 cases. MR imaging with FLAIR sequence provided images that were equal or superior to T2-weighted images in the evaluation of childhood adrenoleukodystrophy. MRI findings were well correlated with clinical manifestations and could detect white matter lesions in neurologically asymptomatic adrenoleukodystrophy patients.

  5. Hippocampal Microbleed on a Post-Mortem T2*-Weighted Gradient-Echo 7.0-Tesla Magnetic Resonance Imaging

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    J. De Reuck

    2011-09-01

    Full Text Available The present post-mortem study of a brain from an Alzheimer patient showed on a T2*-weighted gradient-echo 7.0-T MRI of a coronal brain section a hyposignal in the hippocampus, suggesting a microbleed. On the corresponding histological examination, only iron deposits around the granular cellular layer and in blood vessel walls of the hippocampus were observed without evidence of a bleeding. This case report illustrates that the detection of microbleeds on MRI has to be interpreted with caution.

  6. Importance of T2*-weighted gradient-echo MRI for diagnosis of cortical vein thrombosis

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    Fellner, Franz A. [Institut fuer Radiologie, Landes-Nervenklinik Wagner Jauregg, Linz (Austria) and Zentrales Radiologie Institut, Allgemeines Krankenhaus der Stadt Linz, Krankenhausstr. 9, 4020 Linz (Austria)]. E-mail: franz.fellner@akh.linz.at; Fellner, Claudia [Institut fuer Radiologie, Landes-Nervenklinik Wagner Jauregg, Linz (Austria); Aichner, Franz T. [Abteilung fuer Neurologie, Landes-Nervenklinik Wagner-Jauregg, Linz (Austria); Moelzer, Guenther [Institut fuer Radiologie, Landes-Nervenklinik Wagner Jauregg, Linz (Austria)

    2005-11-01

    We examined six patients with isolated venous thrombosis (n = 2), or venous thrombosis combined with sinus thrombosis (n = 4) (CVT). The clinical symptoms were non-specific (acute cephalea, paresis, epileptic seizure, progressive speech disorder). All examinations were performed on a 1.5 T system (Magnetom Symphony, Siemens, Erlangen, Germany), maximum gradient field strength 30 mT/m, minimal gradient rise time 450 {mu}s, according to the following protocol: Transverse T2-weighted turbo spin-echo (TSE), fluid attenuated inversion recovery (FLAIR), T1-weighted spin-echo (SE), before and after administration of contrast medium, T2*-weighted conventional gradient-echo (GRE), T2*-weighted spin-echo echo planar imaging (SE EPI), both without and with diffusion weighting as well as two-dimensional (2D) venous time-of-flight (TOF) MRA. The venous thromboses were best detectable in the T2*-weighted conventional GRE sequence in all patients. In two patients, the CVT was discernible only in this sequence. The sinus thrombosis was well discernible only in the T2*-weighted GRE sequence in only one case; in the remaining cases it was detectable only with difficulty. For these cases, other sequences such as SE, diffusion-weighted, or 2D-TOF-MRA sequence were superior. The T2*-weighted conventional GRE sequence was superior to the T2*-weighted SE EPI sequence in all patients. To sum up, it can be concluded, that T2*-weighted conventional GRE sequences are possibly the best method of detection of acute cortical vein thromboses. Therefore, it seems to be of benefit to integrate a T2*-weighted conventional GRE sequence into the MR-protocol for the diagnosis of isolated cortical vein thrombosis.

  7. Differentiation between simple cyst and hepatic hemangioma utilizing T2-weighted magnetic resonance imaging with gradient-echo (b-FFE) technique

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    Burim, Carolina Valente; D' Ippolito, Giuseppe [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. de Diagnostico por Imagem]. E-mail: scoposl@uol.com.br; Pecci Neto, Luiz; Torlai, Fabiola Goda; Tiferes, Dario Ariel [Laboratorio Fleury, Sao Paulo, SP (Brazil). Centro de Medicina Diagnostica

    2008-11-15

    Objective: to establish the role of MRI T2-weighted sequences in the differentiation between simple cysts and hepatic hemangiomas. Materials and methods: a double-blinded, prospective, observational, cross sectional study evaluated 52 patients with 91 hepatic lesions (34 simple cysts and 57 hemangiomas) submitted to abdominal magnetic resonance imaging. The combined analysis of all sequences was considered as the golden-standard. TSE sequences with long echo trains and b-FFE sequences were subjectively analyzed by two independent observers for differentiating cysts from hemangiomas. The kappa test ({kappa}) was utilized in the analysis of the methods accuracy and inter- and intra-observer agreement (p < 0.05{sup *}). Results: cysts and hemangiomas dimensions ranged respectively between 0.5 and 6.5 cm (mean 1.89 cm), and 0.8 and 11 cm (mean = 2.62 cm). The analysis of the sequences with long-TE and the golden-standard demonstrated a non-statistically significant agreement (k: 0.00-0.10). The agreement between the evaluation of the b-FFE sequence and the golden-standard ranged from substantial ({kappa}: 0.62-0.71) to almost perfect ({kappa}: 0.86) for both observers. The inter- and intra-observer agreement for the b-FFE sequence ranged from substantial ({kappa}: 0.62-0.70) to almost perfect ({kappa}: 0.85-0.91). Conclusion: T2-weighted images acquired with the b-FFE technique present a high accuracy and reproducibility in the differentiation between cysts and hepatic hemangiomas. (author)

  8. MR fluid-attenuated inversion recovery imaging as routine brain T2-weighted imaging

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    Arakia, Yutaka; Ashikaga, Ryuichiro; Fujii, Koichi; Nishimura, Yasumasa; Ueda, Jun; Fujita, Norihiko

    1999-11-01

    We tried to investigate if magnetic resonance (MR) fluid-attenuated inversion recovery (FLAIR) imaging can be used as a routine brain screening examination instead of spin-echo T2-weighted imaging. Three hundred and ninety-four patients with clinically suspected brain diseases were randomly selected and examined with both brain MR FLAIR and T2-weighted imaging on the axial plane. These two imaging techniques were evaluated by two neuroradiologists as to which imaging was better for routine brain T2-weighted imaging. In 123 of 394 cases (31%), FLAIR imaging was superior to spin-echo T2-weighted imaging. Especially in cases with inflammatory diseases, traumatic diseases and demyelinating diseases, FLAIR imaging was particularly useful. Small lesions bordering cerebrospinal fluid (CSF) are often detected only by FLAIR imaging. In 259 cases (66%), including 147 normal cases (37%), they were equally evaluated. Only in 12 cases (3%) was conventional T2-weighted imaging superior to FLAIR imaging. Cerebrovascular lesions like cerebral aneurysm and Moyamoya disease could not be detected on FLAIR images because these structures were obscured by a low signal from the CSF. Also, because old infarctions tend to appear as low signal intensity on FLAIR images, the condition was sometimes hard to detect. Finally, FLAIR imaging could be used as routine brain T2-weighted imaging instead of conventional spin-echo T2-weighted imaging if these vascular lesions were watched.

  9. Peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images: correlation with macroscopic and microscopic findings in elderly cadavers

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    Ahn, J.M.; Muhle, C.; Trudell, D.; Resnick, D. [Department of Radiology, Veterans Affairs Medical Center, San Diego, CA (United States); Kang, H.S. [Department of Radiology, Seoul National University, College of Medicine, Seoul (Korea, Republic of); Haghighi, P. [Department of Pathology, Veterans Affairs Medical Center, La Jolla, CA (United States)

    1999-04-01

    Objective. To correlate the peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images with the macroscopic and microscopic findings in cadavers derived from elderly subjects. Design. Twenty-eight intervertebral disks (16 lumbar and 12 cervical) derived from four nonembalmed cadavers were examined with T1-weighted spin echo and proton density-weighted and T2-weighted fast spin echo MR imaging. The signal intensities of the annulus fibrosus were evaluated on sagittal MR images and correlated with the findings on corresponding sagittal anatomic sections. The MR imaging-histologic correlation was then studied. Results. Peripheral focal low signal intensity areas and adjacent regions of high signal intensity were found in five lumbar intervertebral disks. Peripheral focal low signal intensity regions consisted of disorganized compact annular fibers, tiny fissures, and dense fibrosis. The high signal intensity regions, adjacent to the areas of low signal intensity, consisted of mucoid degeneration, tiny fissures, and chondroid metaplasia. Conclusions. Awareness of the histologic findings in regions that reveal peripheral focal low signal intensity with adjacent regions of high signal intensity in the degenerated annulus fibrosus on T2-weighted images may facilitate effective interpretation of clinical MR images of the spine. (orig.) With 2 figs., 21 refs.

  10. Isotropic 3-D T2-weighted spin-echo for abdominal and pelvic MRI in children.

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    Dias, Sílvia Costa; Ølsen, Oystein E

    2012-11-01

    MRI has a fundamental role in paediatric imaging. The T2-weighted fast/turbo spin-echo sequence is important because it has high signal-to-noise ratio compared to gradient-echo sequences. It is usually acquired as 2-D sections in one or more planes. Volumetric spin-echo has until recently only been possible with very long echo times due to blurring of the soft-tissue contrast with long echo trains. A new 3-D spin-echo sequence uses variable flip angles to overcome this problem. It may reproduce useful soft-tissue contrast, with improved spatial resolution. Its isotropic capability allows subsequent reconstruction in standard, curved or arbitrary planes. It may be particularly useful for visualisation of small lesions, or if large lesions distort the usual anatomical relations. We present clinical examples, describe the technical parameters and discuss some potential artefacts and optimisation of image quality.

  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

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    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. 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

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    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.)

  13. Characterization of anomalous relaxation using the time-fractional Bloch equation and multiple echo T2*-weighted magnetic resonance imaging at 7 T.

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    Qin, Shanlin; Liu, Fawang; Turner, Ian W; Yu, Qiang; Yang, Qianqian; Vegh, Viktor

    2017-04-01

    To study the utility of fractional calculus in modeling gradient-recalled echo MRI signal decay in the normal human brain. We solved analytically the extended time-fractional Bloch equations resulting in five model parameters, namely, the amplitude, relaxation rate, order of the time-fractional derivative, frequency shift, and constant offset. Voxel-level temporal fitting of the MRI signal was performed using the classical monoexponential model, a previously developed anomalous relaxation model, and using our extended time-fractional relaxation model. Nine brain regions segmented from multiple echo gradient-recalled echo 7 Tesla MRI data acquired from five participants were then used to investigate the characteristics of the extended time-fractional model parameters. We found that the extended time-fractional model is able to fit the experimental data with smaller mean squared error than the classical monoexponential relaxation model and the anomalous relaxation model, which do not account for frequency shift. We were able to fit multiple echo time MRI data with high accuracy using the developed model. Parameters of the model likely capture information on microstructural and susceptibility-induced changes in the human brain. Magn Reson Med 77:1485-1494, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

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

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    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.)

  15. Ultrasonographic and T2-weighted MR imaging studies on hepatic hemangiomas

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    Niizawa, Makoto; Kuramitsu, Tomoyuki; Naganuma, Toshio; Yoshida, Tsukasa [Akita City Hospital (Japan); Masamune, Osamu

    1995-12-01

    We investigated the correlations between ultrasonography (US) and magnetic resonance (MR) imaging of hepatic hemangiomas to evaluate their heterogeneous echo patterns; we examined 20 hemangiomas (over 20 mm in maximal size) in 18 asymptomatic patients by US and MR imaging, and investigated the correlations between these images. T1-weighted images indicated 8 of 20 lesions as heterogeneous, T2-weighted images indicated 12 heterogeneous lesions, and US indicated 19 heterogeneous lesions. The internal pattern was consistent in US and T2-weighted images in 6 lesions, and inconsistent in 6 lesions. US revealed a heterogeneous pattern in 7 lesions in which T2-weighted images revealed a homogeneous pattern. Both US and T2-weighted images revealed a homogeneous pattern in one lesion. US findings of heterogeneous hepatic hemangioma reflect, to some extent, their histological changes based on MR morphology. In the near future, utilization of US equipment will probably permit the sonographic morphology of the heterogeneous hepatic hemangioma to be clarified. (author)

  16. T2-weighted imaging of the heart—A pictorial review

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    Mirakhur, Anirudh, E-mail: ani.mirakhur@gmail.com [Department of Diagnostic Imaging, Foothills Medical Centre, University of Calgary, Calgary (Canada); Anca, Nicoleta, E-mail: nicoletanca@gmail.com [Department of Diagnostic Imaging, Foothills Medical Centre, University of Calgary, Calgary (Canada); Mikami, Yoko, E-mail: yokomikami@gmail.com [Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary (Canada); Merchant, Naeem, E-mail: n.merchant22@gmail.com [Department of Diagnostic Imaging, Foothills Medical Centre, University of Calgary, Calgary (Canada); Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary (Canada)

    2013-10-01

    Spin-Echo techniques in cardiovascular magnetic resonance (CMR) have been used for decades, primarily to image cardiac anatomy. More recently, T2-weighted (T2W) imaging has seen an increased role in CMR protocols, especially in tissue characterization in acute myocardial processes. This article will review current methodologies of cardiac T2W acquisition and their limitations, as well as approach to both semi-quantitative and quantitative analyses. The appearance and utility of T2W imaging in a myriad of pathologic myocardial processes such as acute myocardial infarction, acute viral myocarditis, reversible stress-related cardiomyopathy, hypertrophic cardiomyopathy, and cardiac sarcoidosis, will also be discussed.

  17. Accuracy of SWI sequences compared to T2*-weighted gradient echo sequences in the detection of cerebral cavernous malformations in the familial form.

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    Sparacia, Gianvincenzo; Speciale, Claudia; Banco, Aurelia; Bencivinni, Francesco; Midiri, Massimo

    2016-10-01

    The purpose of this study was to assess the accuracy of susceptibility-weighted imaging (SWI), compared with T2*-weighted gradient echo (GRE) imaging in assessing cerebral cavernous malformations. We retrospectively evaluated 21 patients with a familial form of cavernous malformation. Magnetic resonance (MR) protocol included non-enhanced and contrast-enhanced fast-spin echo (FSE) T1-weighted sequences, FSE T2-weighted sequences, fluid-attenuated inversion-recovery (FLAIR), GRE T2*-weighted and SWI sequences. Images were reviewed in consensus by two expert neuroradiologists to assess the location, number, size and conspicuity of the lesions on T2*-weighted GRE and SWI sequences. Statistical differences in the number, size and conspicuity of the lesions seen on the SWI images and the T2*-weighted GRE images were assessed with the nonparametric Wilcoxon signed rank test. The number of cavernous malformations was significantly higher (p cavernous malformation that was demonstrated only on the SWI images in the previous MR examination. The SWI sequence, being more sensitive to substances which distort the local magnetic field than the GRE T2*W sequence, showed a higher sensitivity in identifying cerebral cavernous malformations. Thus, routine clinical neuroimaging protocol should contain SWI sequences to evaluate patients with (or suspected) cerebral cavernous malformations. © The Author(s) 2016.

  18. Detection of intratumoral susceptibility signals using T2*-weighted gradient echo MRI in patients with clear cell renal cell carcinoma.

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    Shengnan Yu

    Full Text Available OBJECTIVE: To retrospectively evaluate whether T2*-weighted imaging can be used to grade clear cell renal cell carcinomas (ccRCC based on intratumoral susceptibility signals (ISSs. MATERIALS AND METHODS: MR imaging from 37 patients with pathologically-proven ccRCCs was evaluated. ISSs on T2*WI were classified as linear or conglomerated linear structures (type I and dot-like or patchy foci (type II. Two radiologists assessed the likelihood of the presence of ISS, dominant structure of ISS and ratio of ISS area to tumor area. Results were analyzed by nonparametric Mann-Whitney test. RESULTS: ISSs were seen in all patients except for four patients with low-grade ccRCCs and two patients with high-grade ccRCCs. There was no significant difference of the likelihood of the presence of ISS between low- and high-grade ccRCCs. More type I ISSs and less type II ISSs were predictive of low-grade tumors, whereas more conspicuity type II ISSs correlated with higher occurrence of high-grade tumors (P<0.05. The ratio of ISS area to tumor area was also significantly higher for the high-grade group (1.27±0.79 than that for the low-grade group (0.81±0.40 (P<0.05. CONCLUSION: ISSs on T2*-weighted gradient-echo MR images can help grade ccRCCs before operations.

  19. Detection of intratumoral susceptibility signals using T2*-weighted gradient echo MRI in patients with clear cell renal cell carcinoma.

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    Yu, Shengnan; Qiu, Jianguo; Zhang, Jinggang; Pan, Liang; Xing, Shijun; Zhang, Lijun

    2013-01-01

    To retrospectively evaluate whether T2*-weighted imaging can be used to grade clear cell renal cell carcinomas (ccRCC) based on intratumoral susceptibility signals (ISSs). MR imaging from 37 patients with pathologically-proven ccRCCs was evaluated. ISSs on T2*WI were classified as linear or conglomerated linear structures (type I) and dot-like or patchy foci (type II). Two radiologists assessed the likelihood of the presence of ISS, dominant structure of ISS and ratio of ISS area to tumor area. Results were analyzed by nonparametric Mann-Whitney test. ISSs were seen in all patients except for four patients with low-grade ccRCCs and two patients with high-grade ccRCCs. There was no significant difference of the likelihood of the presence of ISS between low- and high-grade ccRCCs. More type I ISSs and less type II ISSs were predictive of low-grade tumors, whereas more conspicuity type II ISSs correlated with higher occurrence of high-grade tumors (PISSs on T2*-weighted gradient-echo MR images can help grade ccRCCs before operations.

  20. Efficacy of T2*-Weighted Gradient-Echo MRI in Early Diagnosis of Cerebral Venous Thrombosis with Unilateral Thalamic Lesion

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    Shingo Mitaki

    2013-01-01

    Full Text Available Cerebral venous thrombosis (CVT is an uncommon cause of stroke with diverse etiologies and varied clinical presentations. Because of variability in clinical presentation and neuroimaging, CVT remains a diagnostic challenge. Recently, some studies have highlighted the value of T2*-weighted gradient-echo MRI (T2*WI in the diagnosis of CVT. We report the case of a 79-year-old woman with CVT due to a hypercoagulable state associated with cancer. On the initial T2-weighted image (T2WI, there was a diffuse high-intensity lesion in the right thalamus, extending into the posterior limb of the internal capsule and midbrain. T2*WI showed diminished signal and enlargement of the right basilar vein and the vein of Galen. Even though there is a wide range of differential diagnoses in unilateral thalamic lesions, and a single thalamus lesion is a rare entity of CVT, based on T2*WI findings we could make an early diagnosis and perform treatment. Our case report suggests that T2*WI could detect thrombosed veins and be a useful method of early diagnosis in CVT.

  1. Prognostic impact of T2-weighted CMR imaging for cardiac amyloidosis

    Energy Technology Data Exchange (ETDEWEB)

    Wassmuth, Ralf; Schulz-Menger, Jeanette [HELIOS Klinikum Berlin Buch, Charite Campus Buch, Berlin (Germany); Abdel-Aty, Hassan [HELIOS Klinikum Berlin Buch, Charite Campus Buch, Berlin (Germany); Cardio Imaging Center Berlin, Berlin (Germany); Bohl, Steffen [HELIOS Klinikum Berlin Buch, Charite Campus Buch, Berlin (Germany); Unfallkrankenhaus Berlin, Berlin (Germany)

    2011-08-15

    Using cardiac magnetic resonance imaging (MRI) we tested the diagnostic value of various markers for amyloid infiltration. We performed MRI at 1.5 T in 36 consecutive patients with cardiac amyloidosis and 48 healthy volunteers. The protocol included cine imaging, T2-weighted spin echo, T1-weighted spin echo before and early after contrast and late gadolinium enhancement. We compared the frequency of abnormalities and their relation to mortality. Median follow-up was 31 months. Twenty-three patients died. Mean left ventricular (LV) mass was 205 {+-} 70 g. LV ejection fraction (EF) was 55 {+-} 12%. T2 ratio was 1.5 {+-} 0.4. 33/36 patients had pericardial and 22/36 had pleural effusions. All but two had heterogeneous late enhancement. Surviving patients did not differ from those who had died with regard to gender, LV mass or volume. Surviving patients had a significantly higher LVEF (60.4 {+-} 9.9% vs. 51.6 {+-} 11.5%; p = 0.03). The deceased patients had a lower T2 ratio than those who survived (1.38 {+-} 0.42 vs. 1.76 {+-} 0.17; p = 0.005). Low T2 was associated with shorter survival (Chi-squared 11.3; p < 0.001). Cox regression analysis confirmed T2 ratio < 1.5 as the only independent predictors for survival. Cardiac amyloidosis is associated with hypointense signal on T2-weighted images. A lower T2 ratio was independently associated with shortened survival. (orig.)

  2. Cortical and subcortical vascular hypointensity on T2* weighted imaging in moyamoya disease.

    Science.gov (United States)

    Noshiro, Shouhei; Mikami, Takeshi; Komatsu, Katsuya; Miyata, Kei; Akiyama, Yukinori; Wanibuchi, Masahiko; Mikuni, Nobuhiro

    2016-02-01

    Decreased cortical and subcortical vascular signals in gradient echo T2* weighted imaging have been reported in acute stroke due to major artery occlusion. The purpose of this study was to evaluate this cortical and subcortical vascular hypointensity (CSVH) in patients with moyamoya disease. Subjects were 20 consecutive patients with moyamoya disease. The numbers of CSVH in each hemisphere were counted and the numbers were compared between patients with moyamoya disease and controls. The distribution of CSVH, clinical features of cases exhibiting large numbers of CSVH and post-operative changes were analysed. Patients with moyamoya disease had significantly more CSVH in the middle cerebral artery territory (p moyamoya disease. Our small series study shows that revascularization surgery can decrease the number of CSVH.

  3. [Deep white matter hyperintensity in occipital lobe on T2 weighted magnetic resonance imaging].

    Science.gov (United States)

    Miyazaki, M; Hashimoto, T

    1991-09-01

    Magnetic resonance imaging (MRI) was performed in 270 patients with various neurologic complaints (1-15 Y) with a 0.5 tesla superconducting imaging system (MRT-50 A, Toshiba Co.) using a field echo sequence (TR/TE: 300 ms/14 ms) and a spine echo sequence (TR/TE: 2,000 ms/100 ms or 2,000 ms/120 ms, and 2,000 ms/30 ms). The slice thickness was 10 mm. Hyperintensity areas on T2-weighted images were noted at the occipital lobe in 33 patients (12.2%). Twenty-seven of them had hyperintensity within the deep white matter, which revealed iso- or hypointensity on T1-weighted images. The diagnosis for the 27 patients included medulloblastoma after multidisciplinary therapy (1), congenital heart disease (1), neurofibromatosis (1), tuberous sclerosis (1), congenital muscular dystrophy (1), congenital myotonic dystrophy (2), febrile convulsion (2), autism (3), epilepsy (9) and unknown causes (6). Because the hyperintensity areas are age-dependent, they may result from delayed myelination in the central nervous system.

  4. MR of Toxoplasma encephalitis: Signal characteristics on T2-weighted images and pathologic correlation

    Energy Technology Data Exchange (ETDEWEB)

    Brightbill, T.C.; Hensley, G.T.; Ruiz, A. [Univ. of Miami School of Medicine, FL (United States)] [and others

    1996-05-01

    Our goal was to determine if there are any T2-weighted MR signal characteristics of Toxoplasma encephalitis that might be useful in diagnosis and/or in gauging the effectiveness of medical therapy. We retrospectively analyzed the MR, CT, thallium-201 SPECT brain scans, and medical records of 27 patients with medically proven (26) and biopsy proven (1) Toxoplasma encephalitis, supplemented by autopsy findings in 4 additional patients, 2 of whom had postmortem MR correlation. The neuropathologic literature was also reviewed. Among the 27 patients, we discovered three distinct imaging patterns. Ten (37%) patients had predominantly T2-weighted hyperintense lesions and had been on medical therapy an average of 3 days (excluding one outlier). Ten (37%) patients had T2-weighted isointense lesions and had received medical therapy an average of 61 days. Seven (26%) patients had lesions with mixed signal on T2-weighted images and bad been on treatment an average of 6 days. Analysis of autopsy material from the four additional patients revealed the presence of organizing abscesses in three and necrotizing encephalitis in one, while the patient who had a brain biopsy demonstrated both types of pathologic lesions. In both cases having postmortem MRI, organizing abscesses appeared isointense to hypointense on T2-weighted images. There is a definite variation in the appearance of lesions of Toxoplasma encephalitis on T2-weighted images that precludes a definitive diagnosis based on signal characteristics alone. Pathologically, our data suggest that T2-weighted hyperintensity correlates with necrotizing encephalitis and T2-weighted isointensity with organizing abscesses. Furthermore, in patients on medical therapy the T2-weighted MR appearance may be a transition from hyperintensity to isointensity as a function of a positive response to antibiotic treatment, indicating that the signal change might be used to gauge the effectiveness of medical therapy. 15 refs., 6 figs.

  5. Relationship between levels of serum creatinine and perirenal hyperintensity on heavily T2-weighted MR images

    Energy Technology Data Exchange (ETDEWEB)

    Erden, Ayse, E-mail: ayse.erden@medicine.ankara.edu.tr [Ankara University, School of Medicine, Department of Radiology, Talatpasa Bulvari, Sihhiye, 06100 Ankara (Turkey); Sahin, Burcu Savran, E-mail: bsavrans@hotmail.com [Ankara University, School of Medicine, Department of Radiology, Talatpasa Bulvari, Sihhiye, 06100 Ankara (Turkey); Orgodol, Horolsuren, E-mail: hoogii99@yahoo.com [Ankara University, School of Medicine, Department of Radiology, Talatpasa Bulvari, Sihhiye, 06100 Ankara (Turkey); Erden, Ilhan, E-mail: erden@medicine.ankara.edu.tr [Ankara University, School of Medicine, Department of Radiology, Talatpasa Bulvari, Sihhiye, 06100 Ankara (Turkey); Biyikli, Zeynep, E-mail: zeynep.biyikli@gmail.com [Ankara University, School of Medicine, Department of Biostatistics, Talatpasa Bulvari, Sihhiye, 06100 Ankara (Turkey)

    2011-11-15

    Objective: To determine the frequency of perirenal hyperintensity on heavily T2-weighted images and to evaluate its relationship with serum creatinine levels. Subjects and methods: Axial and coronal single-shot fast spin-echo images which have been originally obtained for MR cholangiopancreatography in 150 subjects were examined by two observers individually for the presence of perirenal hyperintensity. The morphologic properties of perirenal hyperintensity (peripheral rim-like, discontinuous, polar) were recorded. Chi square test was used to test whether the frequencies of bilateral perirenal hyperintensity differ significantly in subjects with high serum creatinine levels and those with normal creatinine levels. This test was also used to compare the frequencies of perirenal hyperintensity in patients with and without renal cysts and in patients with and without corticomedullary differentiation. A p value of less than 0.05 was considered to be statistically significant. Results: The perirenal hyperintensity was identified in 40 of 150 cases (26.6%) on heavily T2-weighted image. Serum creatinine levels were high in 18 of 150 cases (12%). The perirenal hyperintensity was present in 11 of 18 subjects (61%) with high serum creatinine levels and 26 of 132 subjects (19.7%) with normal creatinine levels. The difference of rates in two groups was statistically significant. Odds ratio was 6407 (95% confidence interval 2264-18,129). The frequency of perirenal hyperintensity was also significantly higher in subjects with renal cyst or cysts in whom serum creatinine levels were normal (p < 0.05) (37.5% vs. 11.8%). Conclusion: Perirenal hyperintensities are more frequent in patients with high serum creatinine levels. They are also more common in patients with simple renal cysts.

  6. T2-weighted four dimensional magnetic resonance imaging with result-driven phase sorting

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yilin; Yin, Fang-Fang; Cai, Jing, E-mail: jing.cai@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Czito, Brian G. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Bashir, Mustafa R. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States)

    2015-08-15

    Purpose: T2-weighted MRI provides excellent tumor-to-tissue contrast for target volume delineation in radiation therapy treatment planning. This study aims at developing a novel T2-weighted retrospective four dimensional magnetic resonance imaging (4D-MRI) phase sorting technique for imaging organ/tumor respiratory motion. Methods: A 2D fast T2-weighted half-Fourier acquisition single-shot turbo spin-echo MR sequence was used for image acquisition of 4D-MRI, with a frame rate of 2–3 frames/s. Respiratory motion was measured using an external breathing monitoring device. A phase sorting method was developed to sort the images by their corresponding respiratory phases. Besides, a result-driven strategy was applied to effectively utilize redundant images in the case when multiple images were allocated to a bin. This strategy, selecting the image with minimal amplitude error, will generate the most representative 4D-MRI. Since we are using a different image acquisition mode for 4D imaging (the sequential image acquisition scheme) with the conventionally used cine or helical image acquisition scheme, the 4D dataset sufficient condition was not obviously and directly predictable. An important challenge of the proposed technique was to determine the number of repeated scans (N{sub R}) required to obtain sufficient phase information at each slice position. To tackle this challenge, the authors first conducted computer simulations using real-time position management respiratory signals of the 29 cancer patients under an IRB-approved retrospective study to derive the relationships between N{sub R} and the following factors: number of slices (N{sub S}), number of 4D-MRI respiratory bins (N{sub B}), and starting phase at image acquisition (P{sub 0}). To validate the authors’ technique, 4D-MRI acquisition and reconstruction were simulated on a 4D digital extended cardiac-torso (XCAT) human phantom using simulation derived parameters. Twelve healthy volunteers were involved

  7. Performance of PROPELLER relative to standard FSE T2-weighted imaging in pediatric brain MRI

    Energy Technology Data Exchange (ETDEWEB)

    Vertinsky, A.T. [Vancouver General Hospital, Department of Radiology, Vancouver (Canada); University of British Columbia, Department of Radiology, Vancouver (Canada); Rubesova, Erika; Bammer, Sabine; White, Allan; Barnes, Patrick D. [Stanford University Medical Center, Lucile Salter Packard Children' s Hospital, Palo Alto, CA (United States); Krasnokutsky, Michael V. [Madigan Army Medical Center, Department of Radiology, Tacoma, WA (United States); Uniformed Services University of Health Sciences, Department of Radiology, Bethesda, MD (United States); Rosenberg, Jarrett; Bammer, Roland [Lucas Center, Stanford University, Department of Radiology, Palo Alto, CA (United States)

    2009-10-15

    T2-weighted fast spin-echo imaging (T2-W FSE) is frequently degraded by motion in pediatric patients. MR imaging with periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) employs alternate sampling of k-space to achieve motion reduction. To compare T2-W PROPELLER FSE (T2-W PROP) with conventional T2-W FSE for: (1) image quality; (2) presence of artefacts; and (3) ability to detect lesions. Ninety-five pediatric patients undergoing brain MRI (1.5 T) were evaluated with T2-W FSE and T2-W PROP. Three independent radiologists rated T2-W FSE and T2-W PROP, assessing image quality, presence of artefacts, and diagnostic confidence. Chi-square analysis and Wilcoxon signed rank test were used to assess the radiologists' responses. Compared with T2-W FSE, T2-W PROP demonstrated better image quality and reduced motion artefacts, with the greatest benefit in children younger than 6 months. Although detection rates were comparable for the two sequences, blood products were more conspicuous on T2-W FSE. Diagnostic confidence was higher using T2-W PROP in children younger than 6 months. Average inter-rater agreement was 87%. T2-W PROP showed reduced motion artefacts and improved diagnostic confidence in children younger than 6 months. Thus, use of T2-W PROP rather than T2-W FSE should be considered in routine imaging of this age group, with caution required in identifying blood products. (orig.)

  8. Multifocal hemosiderin depositions on T2*-weighted magnetic resonance imaging in a patient with pathology-proven systemic diffuse large B-cell lymphoma.

    Science.gov (United States)

    Yang, Xun-zhe; Ni, Jun; Cui, Li-ying

    2014-09-25

    Intracranial hemorrhage in central nervous system lymphoma is extremely rare. T2*-weighted gradient-echo magnetic resonance imaging is of particularly use in detecting silent hemorrhage as hypointense signals due to the deposition of paramagnetic hemosiderin or mineralization. Multifocal hemosiderin depositions caused by chronic silent hemorrhage have not yet been identified in patients with central nervous system involvement of systemic lymphoma. We present an unexpected radiographic feature on T2*-weighted gradient-echo magnetic resonance imaging in a patient with central nervous system involvement of pathologically confirmed systemic diffuse large B-cell lymphoma. A 56-year-old woman presented with lower extremities weakness and progressive cognitive decline for four months. Conventional brain magnetic resonance imaging demonstrated multiple lesions with hypointensities on T1-weighted images and hyperintensities on T2-weighted images and fluid attenuated inversion recovery in both hemispheres. She was then transferred to our hospital. This is the first report of pathologically confirmed case of CNS involvement of systemic diffuse large B-cell lymphoma with multifocal silent hemosiderin depositions detected by T2*-weighted gradient-echo magnetic resonance imaging. Even though uncommon, our report offers an insight that CNS lymphoma could present with multifocal silent hemosiderin depositions on T2*-weighted gradient-echo magnetic resonance imaging. Further studies were expected for exploring the association between this radiologic feature and systemic lymphoma and their underlying mechanisms.

  9. Usefulness of IDEAL T2-weighted FSE and SPGR imaging in reducing metallic artifacts in the postoperative ankles with metallic hardware

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Bin; Cha, Jang Gyu; Lee, Min Hee; Lee, Eun Hye [Soonchunhyang University Bucheon Hospital, Department of Radiology, Wonmigu Bucheonsi, Gyeonggido (Korea, Republic of); Lee, Young Koo [Soonchunhyang University Bucheon Hospital, Department of Orthopedics, Wonmigu Bucheonsi, Gyunggido (Korea, Republic of); Jeon, Chan Hong [Soonchunhyang University Bucheon Hospital, Division of Rheumatology, Department of Internal medicine, Wonmigu Bucheonsi, Gyunggido (Korea, Republic of)

    2013-02-15

    The aim of this work is to prospectively compare the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL), T2-weighted fast spin-echo (FSE), and spoiled gradient-echo (SPGR) MR imaging to frequency selective fat suppression (FSFS) protocols for minimizing metallic artifacts in postoperative ankles with metallic hardware. The T2-weighted and SPGR imaging with IDEAL and FSFS were performed on 21 ankles of 21 patients with metallic hardware. Two musculoskeletal radiologists independently analyzed techniques for visualization of ankle ligaments and articular cartilage, uniformity of fat saturation, and relative size of the metallic artifacts. A paired t test was used for statistical comparisons of MR images between IDEAL and FSFS groups. IDEAL T2-weighted FSE and SPGR images enabled significantly improved visualization of articular cartilage (p < 0.05), the size of metallic artifact (p < 0.05), and the uniformity of fat saturation (p < 0.05). However, no significant improvement was found in the visibility of ligaments. IDEAL T2-weighted FSE and SPGR imaging effectively reduces the degree of tissue-obscuring artifacts produced by fixation hardware in ankle joints and improves image quality compared to FSFS T2-weighted FSE and SPGR imaging. However, visibility of ligaments was not improved using IDEAL imaging. (orig.)

  10. The image evaluation of iterative motion correction reconstruction algorithm PROPELLER T2-weighted imaging compared with MultiVane T2-weighted imaging

    Science.gov (United States)

    Lee, Suk-Jun; Yu, Seung-Man

    2017-08-01

    The purpose of this study was to evaluate the usefulness and clinical applications of MultiVaneXD which was applying iterative motion correction reconstruction algorithm T2-weighted images compared with MultiVane images taken with a 3T MRI. A total of 20 patients with suspected pathologies of the liver and pancreatic-biliary system based on clinical and laboratory findings underwent upper abdominal MRI, acquired using the MultiVane and MultiVaneXD techniques. Two reviewers analyzed the MultiVane and MultiVaneXD T2-weighted images qualitatively and quantitatively. Each reviewer evaluated vessel conspicuity by observing motion artifacts and the sharpness of the portal vein, hepatic vein, and upper organs. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated by one reviewer for quantitative analysis. The interclass correlation coefficient was evaluated to measure inter-observer reliability. There were significant differences between MultiVane and MultiVaneXD in motion artifact evaluation. Furthermore, MultiVane was given a better score than MultiVaneXD in abdominal organ sharpness and vessel conspicuity, but the difference was insignificant. The reliability coefficient values were over 0.8 in every evaluation. MultiVaneXD (2.12) showed a higher value than did MultiVane (1.98), but the difference was insignificant ( p = 0.135). MultiVaneXD is a motion correction method that is more advanced than MultiVane, and it produced an increased SNR, resulting in a greater ability to detect focal abdominal lesions.

  11. “Hot cross bun” sign in multiple system atrophy with predominant cerebellar ataxia: A comparison between proton density-weighted imaging and T2-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kasahara, Seiko, E-mail: nuun077@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Miki, Yukio, E-mail: yukio.miki@med.osaka-cu.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Department of Radiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545–8585 (Japan); Kanagaki, Mitsunori, E-mail: mitsuk@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Kondo, Takayuki, E-mail: kondotak@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Yamamoto, Akira, E-mail: yakira@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Morimoto, Emiko, E-mail: foresta@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Okada, Tomohisa, E-mail: tomokada@kuhp.kyoto-u.ac.jp [Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Ito, Hidefumi, E-mail: itohid@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); Takahashi, Ryosuke, E-mail: ryosuket@kuhp.kyoto-u.ac.jp [Department of Neurology, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507 (Japan); and others

    2012-10-15

    Objective: To investigate whether proton density-weighted imaging can detect the “hot cross bun” sign in the pons in multiple system atrophy with predominant cerebellar ataxia significantly better than T2-weighted imaging at 3 T. Methods: Sixteen consecutive patients with multiple system atrophy with predominant cerebellar ataxia according to the Consensus Criteria were reviewed. Axial unenhanced proton density-weighted imaging and T2-weighted imaging were obtained using a dual-echo fast spin-echo sequence at 3 T. Two neuroradiologists independently evaluated visualisation of the abnormal pontine signal using a 4-point visual grade from Grade 0 (no “hot cross bun” sign) to Grade 3 (prominent “hot cross bun” sign on two or more sequential slices). Differences in grade between proton density-weighted imaging and T2-weighted imaging were statistically analysed using the Wilcoxon signed-rank test. Results: In 11 patients (69%), a higher grade was given for proton density-weighted imaging than T2-weighted imaging. In 1 patient (6%), grades were the same (Grade 3) on both images. In the remaining 4 patients (25%), signal abnormalities were not detected on either image (Grade 0). The “hot cross bun” sign was thus observed significantly better on proton density-weighted imaging than on T2-weighted imaging (P = 0.001). Conclusions: The “hot cross bun” sign considered diagnostic for multiple system atrophy with predominant cerebellar ataxia is significantly better visualised on proton density-weighted imaging than on T2-weighted imaging at 3 T.

  12. 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.

  13. Dot-like hemosiderin deposition on T2*-weighted MR imaging associated with nonhypertensive intracerebral hemorrhage.

    Science.gov (United States)

    Imaizumi, Toshio; Horita, Yoshifumi; Chiba, Masahiko; Miyata, Kei; Toyama, Kentaro; Yoshifuji, Kazuhisa; Hashimoto, Yuji; Niwa, Jun

    2006-01-01

    Microangiopathy, a disorder often related to hypertension, is an important cause of deep intracerebral hematoma (ICH). The microangiopathy is associated with dot-like low-intensity spots (a dot-like hemosiderin spot: dotHS) on gradient-echo T2*-weighted MR images that have been histologically diagnosed as old microbleeds. The locations of dotHS are consistent with deep ICH. To investigate how dotHS or other risk factors contribute to nonhypertensive deep ICH, the number and location of dotHSs, as well as other risk factors were examined in 213 deep ICH patients (106 males, 107 females, age: 37-94 (65.8 +/- 11.2) years) consecutively admitted to Hakodate Municipal Hospital. Patients were divided into two subgroups according to the presence or absence of hypertension. DotHSs were also divided into deep and subcortical dotHS and investigated independently. Odds ratios (ORs) were estimated from logistic regression analyses. Furthermore, nonhypertensive ICH patients were compared with nonhypertensive healthy volunteers matched for age and sex. No risk factors were identified in the 31 nonhypertensive deep ICH patients that differed from those found in the 182 hypertensive deep ICH patients. Deep dotHS > or = 1 (OR: 25.5; 95% CI: 4.76-137; P = .0002), subcortical dotHS > or = 1 (OR: 9.0; 95% CI: 1.79-44.9; P = .046), diabetes mellitus (OR: 9.0; 95% CI: 1.53-52.3; P = .015), and smoking (OR, 9.6; 95% CI; 1.8-49.8, P = .007) significantly elevated the risk of nonhypertensive ICH, compared to the healthy volunteers. Our findings suggest that deep and subcortical dotHSs may be risk factors for the development of non-hypertensive deep ICH.

  14. Usefulness of IDEAL T2-weighted FSE and SPGR imaging in reducing metallic artifacts in the postoperative ankles with metallic hardware.

    Science.gov (United States)

    Lee, Jung Bin; Cha, Jang Gyu; Lee, Min Hee; Lee, Young Koo; Lee, Eun Hye; Jeon, Chan Hong

    2013-02-01

    The aim of this work is to prospectively compare the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL), T2-weighted fast spin-echo (FSE), and spoiled gradient-echo (SPGR) MR imaging to frequency selective fat suppression (FSFS) protocols for minimizing metallic artifacts in postoperative ankles with metallic hardware. The T2-weighted and SPGR imaging with IDEAL and FSFS were performed on 21 ankles of 21 patients with metallic hardware. Two musculoskeletal radiologists independently analyzed techniques for visualization of ankle ligaments and articular cartilage, uniformity of fat saturation, and relative size of the metallic artifacts. A paired t test was used for statistical comparisons of MR images between IDEAL and FSFS groups. IDEAL T2-weighted FSE and SPGR images enabled significantly improved visualization of articular cartilage (p hardware in ankle joints and improves image quality compared to FSFS T2-weighted FSE and SPGR imaging. However, visibility of ligaments was not improved using IDEAL imaging.

  15. Extraction of Wavelet Based Features for Classification of T2-Weighted MRI Brain Images

    OpenAIRE

    Ms. Yogita K.Dubey; Mushrif, Milind M.

    2012-01-01

    Extraction of discriminate features is very important task in classification algorithms. This paper presents technique for extraction cosine modulated feature for classification of the T2-weighted MRI images of human brain. Better discrimination and low design implementation complexity of the cosine-modulated wavelets has been effectively utilized to give better features and more accurate classification results. The proposed technique consists of two stages, namely, feature extraction, ...

  16. Contrast enhancement by combining T1- and T2-weighted structural brain MR Images.

    Science.gov (United States)

    Misaki, Masaya; Savitz, Jonathan; Zotev, Vadim; Phillips, Raquel; Yuan, Han; Young, Kymberly D; Drevets, Wayne C; Bodurka, Jerzy

    2015-12-01

    In order to more precisely differentiate cerebral structures in neuroimaging studies, a novel technique for enhancing the tissue contrast based on a combination of T1-weighted (T1w) and T2-weighted (T2w) MRI images was developed. The combined image (CI) was calculated as CI = (T1w - sT2w)/(T1w + sT2w), where sT2w is the scaled T2-weighted image. The scaling factor was calculated to adjust the gray- matter (GM) voxel intensities in the T2w image so that their median value equaled that of the GM voxel intensities in the T1w image. The image intensity homogeneity within a tissue and the discriminability between tissues in the CI versus the separate T1w and T2w images were evaluated using the segmentation by the FMRIB Software Library (FSL) and FreeSurfer (Athinoula A. Martinos Center for Biomedical Imaging at Massachusetts General Hospital, Boston, MA) software. The combined image significantly improved homogeneity in the white matter (WM) and GM compared to the T1w images alone. The discriminability between WM and GM also improved significantly by applying the CI approach. Significant enhancements to the homogeneity and discriminability also were achieved in most subcortical nuclei tested, with the exception of the amygdala and the thalamus. The tissue discriminability enhancement offered by the CI potentially enables more accurate neuromorphometric analyses of brain structures. © 2014 Wiley Periodicals, Inc.

  17. 3D T2-weighted imaging to shorten multiparametric prostate MRI protocols.

    Science.gov (United States)

    Polanec, Stephan H; Lazar, Mathias; Wengert, Georg J; Bickel, Hubert; Spick, Claudio; Susani, Martin; Shariat, Shahrokh; Clauser, Paola; Baltzer, Pascal A T

    2018-04-01

    To determine whether 3D acquisitions provide equivalent image quality, lesion delineation quality and PI-RADS v2 performance compared to 2D acquisitions in T2-weighted imaging of the prostate at 3 T. This IRB-approved, prospective study included 150 consecutive patients (mean age 63.7 years, 35-84 years; mean PSA 7.2 ng/ml, 0.4-31.1 ng/ml). Two uroradiologists (R1, R2) independently rated image quality and lesion delineation quality using a five-point ordinal scale and assigned a PI-RADS score for 2D and 3D T2-weighted image data sets. Data were compared using visual grading characteristics (VGC) and receiver operating characteristics (ROC)/area under the curve (AUC) analysis. Image quality was similarly good to excellent for 2D T2w (mean score R1, 4.3 ± 0.81; R2, 4.7 ± 0.83) and 3D T2w (mean score R1, 4.3 ± 0.82; R2, 4.7 ± 0.69), p = 0.269. Lesion delineation was rated good to excellent for 2D (mean score R1, 4.16 ± 0.81; R2, 4.19 ± 0.92) and 3D T2w (R1, 4.19 ± 0.94; R2, 4.27 ± 0.94) without significant differences (p = 0.785). ROC analysis showed an equivalent performance for 2D (AUC 0.580-0.623) and 3D (AUC 0.576-0.629) T2w (p > 0.05, respectively). Three-dimensional acquisitions demonstrated equivalent image and lesion delineation quality, and PI-RADS v2 performance, compared to 2D in T2-weighted imaging of the prostate. Three-dimensional T2-weighted imaging could be used to considerably shorten prostate MRI protocols in clinical practice. • 3D shows equivalent image quality and lesion delineation compared to 2D T2w. • 3D T2w and 2D T2w image acquisition demonstrated comparable diagnostic performance. • Using a single 3D T2w acquisition may shorten the protocol by 40%. • Combined with short DCE, multiparametric protocols of 10 min are feasible.

  18. An intracranial aspergilloma with low signal on T2-weighted images corresponding to iron accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, K. [Dept. of Radiology, Kyoto Prefectural Univ. of Medicine (Japan); Dept. of Radiology, Univ. of Maryland Medical Center, Baltimore MD (United States); Zoarski, G.H.; Rothman, M.I.; Zagardo, M.T. [Dept. of Radiology, Univ. of Maryland Medical Center, Baltimore MD (United States); Nishimura, T. [Dept. of Radiology, Kyoto Prefectural Univ. of Medicine (Japan); Sun, C.C.J. [Dept. of Pathology, Univ. of Maryland Medical Center, Baltimore MD (United States)

    2001-07-01

    We present a case of cerebral aspergillosis in an immunocompetent patient. The MRI signal characteristics were compared with the histologic findings. Irregular low-signal zones were demonstrated between the wall of the abscess and the central necrosis on T2-weighted images; the pathology specimen revealed concentrated iron in these transitional zones but no hemosiderin. Iron is an essential element for the growth of fungal hyphae. The low-signal zones may represent the areas where there was active proliferation of aspergillus, and the unique location of the low signal may be a helpful imaging characteristic for the diagnosis of an aspergillus abscess. (orig.)

  19. Hemosiderin detected by T2*-weighted magnetic resonance imaging in patients with unruptured cerebral aneurysms: indication of previous bleeding?

    Science.gov (United States)

    Takada, Shihomi; Inoue, Takashi; Niizuma, Kuniyasu; Shimizu, Hiroaki; Tominaga, Teiji

    2011-01-01

    Previous bleeding from a cerebral aneurysm indicates a higher risk of rupture. Hemosiderin may be detected during aneurysm surgery or by preoperative imaging sensitive to hemosiderin. The detection of hemosiderin deposits by T(2)*-weighted magnetic resonance (MR) imaging was evaluated in 49 patients with unruptured cerebral aneurysms who underwent open surgery. MR imaging was performed using 3.0 tesla MR scanner. Two sequences of T(2)*-weighted imaging, and proton density images were obtained. Preliminary study in patients with old subarachnoid hemorrhage provided the definitions of likely pathological findings during surgery and on T(2)*-weighted imaging due to previous hemorrhage. Hemosiderin deposits in the subarachnoid space were observed during surgery in 9 of the 49 patients, although no obvious rupture site was detected around the aneurysm wall. Size, presence of bleb, location, and number of aneurysms showed no significant difference between patients with and without hemosiderin deposition. Hypointense areas on T(2)*-weighted imaging were recognized in four patients. The mean size of the aneurysms in these patients was 9.8 mm, significantly larger than those in other patients (p = 0.029). Hemosiderin deposits were observed during surgery in sites close to the lesions on T(2)*-weighted imaging in two of these four patients. Hemosiderin deposits are not rare in patients with unruptured aneurysms, and preoperative T(2)*-weighted imaging can detect such deposits.

  20. Image quality and cancer visibility of T2-weighted Magnetic Resonance Imaging of the prostate at 7 Tesla

    NARCIS (Netherlands)

    Vos, E.K.; Lagemaat, M.W.; Barentsz, J.O.; Futterer, J.J.; Zamecnik, P.; Roozen, H.; Orzada, S.; Bitz, A.K.; Maas, M.C.; Scheenen, T.W.J.

    2014-01-01

    To assess the image quality of T2-weighted (T2w) magnetic resonance imaging of the prostate and the visibility of prostate cancer at 7 Tesla (T).Seventeen prostate cancer patients underwent T2w imaging at 7T with only an external transmit/receive array coil. Three radiologists independently scored

  1. Fast 3D T2 -weighted imaging using variable flip angle transition into driven equilibrium (3D T2 -TIDE) balanced SSFP for prostate imaging at 3T.

    Science.gov (United States)

    Srinivasan, Subashini; Wu, Holden H; Sung, Kyunghyun; Margolis, Daniel J A; Ennis, Daniel B

    2015-08-01

    Three-dimensional (3D) T2 -weighted fast spin echo (FSE) imaging of the prostate currently requires long acquisition times. Our objective was to develop a fast 3D T2 -weighted sequence for prostate imaging at 3T using a variable flip angle transition into driven equilibrium (T2 -TIDE) scheme. 3D T2 -TIDE uses interleaved spiral-out phase encode ordering to efficiently sample the ky -kz phase encodes and also uses the transient balanced steady-state free precession signal to acquire the center of k-space for T2 -weighted imaging. Bloch simulations and images from 10 healthy subjects were acquired to evaluate the performance of 3D T2 -TIDE compared to 3D FSE. 3D T2 -TIDE images were acquired in 2:54 minutes compared to 7:02 minutes for 3D FSE with identical imaging parameters. The signal-to-noise ratio (SNR) efficiency was significantly higher for 3D T2 -TIDE compared to 3D FSE in nearly all tissues, including periprostatic fat (45 ± 12 vs. 31 ± 7, P TIDE images of the prostate can be acquired quickly with SNR efficiency that exceeds that of 3D FSE. © 2014 Wiley Periodicals, Inc.

  2. SU-F-I-16: Short Breast MRI with High-Resolution T2-Weighted and Dynamic Contrast Enhanced T1-Weighted Images

    Energy Technology Data Exchange (ETDEWEB)

    Ma, J; Son, J; Arun, B; Hazle, J; Hwang, K; Madewell, J; Yang, W; Dogan, B [UT MD Anderson Cancer Center, Houston, TX (United States); Wang, K; Bayram, E [GE Healthcare Technologies, Waukesha, Wisconsin (United States)

    2016-06-15

    Purpose: To develop and demonstrate a short breast (sb) MRI protocol that acquires both T2-weighted and dynamic contrast-enhanced T1-weighted images in approximately ten minutes. Methods: The sb-MRI protocol consists of two novel pulse sequences. The first is a flexible fast spin-echo triple-echo Dixon (FTED) sequence for high-resolution fat-suppressed T2-weighted imaging, and the second is a 3D fast dual-echo spoiled gradient sequence (FLEX) for volumetric fat-suppressed T1-weighted imaging before and post contrast agent injection. The flexible FTED sequence replaces each single readout during every echo-spacing period of FSE with three fast-switching bipolar readouts to produce three raw images in a single acquisition. These three raw images are then post-processed using a Dixon algorithm to generate separate water-only and fat-only images. The FLEX sequence acquires two echoes using dual-echo readout after each RF excitation and the corresponding images are post-processed using a similar Dixon algorithm to yield water-only and fat-only images. The sb-MRI protocol was implemented on a 3T MRI scanner and used for patients who had undergone concurrent clinical MRI for breast cancer screening. Results: With the same scan parameters (eg, spatial coverage, field of view, spatial and temporal resolution) as the clinical protocol, the total scan-time of the sb-MRI protocol (including the localizer, bilateral T2-weighted, and dynamic contrast-enhanced T1-weighted images) was 11 minutes. In comparison, the clinical breast MRI protocol took 43 minutes. Uniform fat suppression and high image quality were consistently achieved by sb-MRI. Conclusion: We demonstrated a sb-MRI protocol comprising both T2-weighted and dynamic contrast-enhanced T1-weighted images can be performed in approximately ten minutes. The spatial and temporal resolution of the images easily satisfies the current breast MRI accreditation guidelines by the American College of Radiology. The protocol has the

  3. Driven equilibrium (drive) MR imaging of the cranial nerves V-VIII: comparison with the T2-weighted 3D TSE sequence

    Energy Technology Data Exchange (ETDEWEB)

    Ciftci, E. E-mail: eciftcis7@hotmail.com; Anik, Yonca; Arslan, Arzu; Akansel, Gur; Sarisoy, Tahsin; Demirci, Ali

    2004-09-01

    Purpose: The aim of this study is to evaluate the efficacy of the driven equilibrium radio frequency reset pulse (DRIVE) on image quality and nerve detection when used in adjunction with T2-weighted 3D turbo spin-echo (TSE) sequence. Materials and methods: Forty-five patients with cranial nerve symptoms referable to the cerebellopontine angle (CPA) were examined using a T2-weighted 3D TSE pulse sequence with and without DRIVE. MR imaging was performed on a 1.5-T MRI scanner. In addition to the axial resource images, reformatted oblique sagittal, oblique coronal and maximum intensity projection (MIP) images of the inner ear were evaluated. The nerve identification and image quality were graded for the cranial nerves V-VIII as well as inner ear structures. These structures were chosen because fluid-solid interfaces existed due to the CSF around (the cranial nerves V-VIII) or the endolymph within (the inner ear structures). Statistical analysis was performed using the Wilcoxon test. P<0.05 was considered significant. Results: The addition of the DRIVE pulse shortens the scan time by 25%. T2-weighted 3D TSE sequence with DRIVE performed slightly better than the T2-weighted 3D TSE sequence without DRIVE in identifying the individual nerves. The image quality was also slightly better with DRIVE. Conclusion: The addition of the DRIVE pulse to the T2-weighted 3D TSE sequence is preferable when imaging the cranial nerves surrounded by the CSF, or fluid-filled structures because of shorter scan time and better image quality due to reduced flow artifacts.

  4. Mapping myocardial viability using interleaved T1-T2* weighted imaging.

    Science.gov (United States)

    Li, Gang; Dai, Guangping; Xiang, Bo; Mark, John; Tomanek, Boguslaw; Liu, Hongyu; Deslauriers, Roxanne; Tian, Ganghong

    2004-04-01

    The present study was to evaluate the efficacy of our interleaved T1-T2* weighted imaging for assessing myocardial viability. The left anterior descending coronary artery (LAD) of pig hearts (n = 7) were occluded for 2 h, followed by 1 h reperfusion. After removed from animals, the hearts were perfused in a Langendorff apparatus with a mixture of pig blood and crystalloid solution in 1:1 ratio. T1 relaxation times of the myocardium were measured with a TurboFLASH inversion-recovery sequence. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) (0.05 mmol/kg body wt) was then injected as a bolus into the aortic perfusion line. The first pass of the contrast agent through the heart was followed using the interleaved T1-T2* imaging sequence. Once the concentration of the contrast agent was in an equilibrium state, T1 relaxation times were measured again. It was found that the percentage recovery of T2* intensity (PRT2*) at the maximum T1 intensity measured during the first pass of the contrast agent with the interleaved T1-T2* imaging was significantly higher in infarcted myocardium than in normal myocardium. Moreover, the regions showing a high T2* percentage recovery on PRT2* maps matched well with the infarcted myocardium demarcated with triphenyl tetrazolium chloride (TTC) staining. We therefore conclude that infarcted myocardium can be delineated using the interleaved T1-T2* imaging method.

  5. 3D segmentation of annulus fibrosus and nucleus pulposus from T2-weighted magnetic resonance images

    Science.gov (United States)

    Castro-Mateos, Isaac; Pozo, Jose M.; Eltes, Peter E.; Del Rio, Luis; Lazary, Aron; Frangi, Alejandro F.

    2014-12-01

    Computational medicine aims at employing personalised computational models in diagnosis and treatment planning. The use of such models to help physicians in finding the best treatment for low back pain (LBP) is becoming popular. One of the challenges of creating such models is to derive patient-specific anatomical and tissue models of the lumbar intervertebral discs (IVDs), as a prior step. This article presents a segmentation scheme that obtains accurate results irrespective of the degree of IVD degeneration, including pathological discs with protrusion or herniation. The segmentation algorithm, employing a novel feature selector, iteratively deforms an initial shape, which is projected into a statistical shape model space at first and then, into a B-Spline space to improve accuracy. The method was tested on a MR dataset of 59 patients suffering from LBP. The images follow a standard T2-weighted protocol in coronal and sagittal acquisitions. These two image volumes were fused in order to overcome large inter-slice spacing. The agreement between expert-delineated structures, used here as gold-standard, and our automatic segmentation was evaluated using Dice Similarity Index and surface-to-surface distances, obtaining a mean error of 0.68 mm in the annulus segmentation and 1.88 mm in the nucleus, which are the best results with respect to the image resolution in the current literature.

  6. Prostate cancer identification: quantitative analysis of T2-weighted MR images based on a back propagation artificial neural network model.

    Science.gov (United States)

    Zhao, Kai; Wang, ChengYan; Hu, Juan; Yang, XueDong; Wang, He; Li, FeiYu; Zhang, XiaoDong; Zhang, Jue; Wang, XiaoYing

    2015-07-01

    Computer-aided diagnosis (CAD) systems have been proposed to assist radiologists in making diagnostic decisions by providing helpful information. As one of the most important sequences in prostate magnetic resonance imaging (MRI), image features from T2-weighted images (T2WI) were extracted and evaluated for the diagnostic performances by using CAD. We extracted 12 quantitative image features from prostate T2-weighted MR images. The importance of each feature in cancer identification was compared in the peripheral zone (PZ) and central gland (CG), respectively. The performance of the computer-aided diagnosis system supported by an artificial neural network was tested. With computer-aided analysis of T2-weighted images, many characteristic features with different diagnostic capabilities can be extracted. We discovered most of the features (10/12) had significant difference (Pimages can reach high accuracy and specificity while maintaining acceptable sensitivity. The outcome is convictive and helpful in medical diagnosis.

  7. Intensity of prolactinoma on T2-weighted magnetic resonance imaging: towards another gender difference

    Energy Technology Data Exchange (ETDEWEB)

    Kreutz, Julie [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); Centre Hospitalier Universitaire de Liege, Domaine Universitaire du Sart Tilman, Service d' Imagerie Medicale, Liege (Belgium); Vroonen, Laurent; Petrossians, Patrick; Rostomyan, Liliya; Beckers, Albert [University Hospital Sart-Tilman, Department of Endocrinology, Liege (Belgium); Cattin, Francoise [University Hospital Besancon, Department of Radiology, Besancon (France); Thiry, Albert [University Hospital Sart-Tilman, Department of Pathology, Liege (Belgium); Tshibanda, Luaba [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); Bonneville, Jean-Francois [University Hospital Sart-Tilman, Department of Radiology, Liege (Belgium); University Hospital Sart-Tilman, Department of Endocrinology, Liege (Belgium)

    2015-07-15

    Clinical presentations of prolactinomas are quite different between genders. In comparison with women's prolactinoma, those in men showed predominance of large tumors with high prolactin (PRL) levels. This preponderance could be attributed to a greater proliferative potential of the tumors. Differences in magnetic resonance imaging (MRI) signal at diagnosis have not been yet clearly evaluated. We conduct a retrospective study comparing MRI signal intensity (SI) on T2-weighted images (T2-WI) between 41 men and 41 women to investigate whether or not men prolactinoma present specific features. In addition to the size of the adenoma and PRL levels (P < 0001), prolactinomas in men also exhibit differences from those in women in signal on T2-WI on MRI (P < 0001). Women's prolactinomas are mostly of high SI on T2-WI while men's prolactinomas exhibit a more heterogeneous pattern of SI on T2-WI. Prolactinomas presenting with low SI on T2-WI are almost exclusively encountered in men. Presence of T2-WI hypointensities in pituitary adenoma can be predictive of a different subtype of prolactinoma almost encountered in men and possibly translate the presence of spherical amyloid deposits, in agreement with the literature. (orig.)

  8. Stability of polyelectrolyte-coated iron nanoparticles for T2-weighted magnetic resonance imaging

    Science.gov (United States)

    McGrath, Andrew J.; Dolan, Ciaran; Cheong, Soshan; Herman, David A. J.; Naysmith, Briar; Zong, Fangrong; Galvosas, Petrik; Farrand, Kathryn J.; Hermans, Ian F.; Brimble, Margaret; Williams, David E.; Jin, Jianyong; Tilley, Richard D.

    2017-10-01

    Iron nanoparticles are highly-effective magnetic nanoparticles for T2 magnetic resonance imaging (MRI). However, the stability of their magnetic properties is dependent on good protection of the iron core from oxidation in aqueous media. Here we report the synthesis of custom-synthesized phosphonate-grafted polyelectrolytes (PolyM3) of various chain lengths, for efficient coating of iron nanoparticles with a native iron oxide shell. The size of the nanoparticle-polyelectrolyte assemblies was investigated by transmission electron microscopy and dynamic light scattering, while surface attachment was confirmed by Fourier transform infrared spectroscopy. Low cytotoxicity was observed for each of the nanoparticle-polyelectrolyte (;Fe-PolyM3;) assemblies, with good cell viability (>80%) remaining up to 100 μg mL-1 Fe in HeLa cells. When applied in T2-weighted MRI, corresponding T2 relaxivities (r2) of the Fe-PolyM3 assemblies were found to be dependent on the chain length of the polyelectrolyte. A significant increase in contrast was observed when polyelectrolyte chain length was increased from 6 to 65 repeating units, implying a critical chain length required for stabilization of the α-Fe nanoparticle core.

  9. Intervertebral disc classification by its degree of degeneration from T2-weighted magnetic resonance images.

    Science.gov (United States)

    Castro-Mateos, Isaac; Hua, Rui; Pozo, Jose M; Lazary, Aron; Frangi, Alejandro F

    2016-09-01

    The primary goal of this article is to achieve an automatic and objective method to compute the Pfirrmann's degeneration grade of intervertebral discs (IVD) from MRI. This grading system is used in the diagnosis and management of patients with low back pain (LBP). In addition, biomechanical models, which are employed to assess the treatment on patients with LBP, require this grading value to compute proper material properties. T2-weighted MR images of 48 patients were employed in this work. The 240 lumbar IVDs were divided into a training set (140) and a testing set (100). Three experts manually classified the whole set of IVDs using the Pfirrmann's grading system and the ground truth was selected as the most voted value among them. The developed method employs active contour models to delineate the boundaries of the IVD. Subsequently, the classification is achieved using a trained Neural Network (NN) with eight designed features that contain shape and intensity information of the IVDs. The classification method was evaluated using the testing set, resulting in a mean specificity (95.5 %) and sensitivity (87.3 %) comparable to those of every expert with respect to the ground truth. Our results show that the automatic method and humans perform equally well in terms of the classification accuracy. However, human annotations have inherent inter- and intra-observer variabilities, which lead to inconsistent assessments. In contrast, the proposed automatic method is objective, being only dependent on the input MRI.

  10. 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.)

  11. Automated image quality evaluation of T2 -weighted liver MRI utilizing deep learning architecture.

    Science.gov (United States)

    Esses, Steven J; Lu, Xiaoguang; Zhao, Tiejun; Shanbhogue, Krishna; Dane, Bari; Bruno, Mary; Chandarana, Hersh

    2017-06-03

    To develop and test a deep learning approach named Convolutional Neural Network (CNN) for automated screening of T2 -weighted (T2 WI) liver acquisitions for nondiagnostic images, and compare this automated approach to evaluation by two radiologists. We evaluated 522 liver magnetic resonance imaging (MRI) exams performed at 1.5T and 3T at our institution between November 2014 and May 2016 for CNN training and validation. The CNN consisted of an input layer, convolutional layer, fully connected layer, and output layer. 351 T2 WI were anonymized for training. Each case was annotated with a label of being diagnostic or nondiagnostic for detecting lesions and assessing liver morphology. Another independently collected 171 cases were sequestered for a blind test. These 171 T2 WI were assessed independently by two radiologists and annotated as being diagnostic or nondiagnostic. These 171 T2 WI were presented to the CNN algorithm and image quality (IQ) output of the algorithm was compared to that of two radiologists. There was concordance in IQ label between Reader 1 and CNN in 79% of cases and between Reader 2 and CNN in 73%. The sensitivity and the specificity of the CNN algorithm in identifying nondiagnostic IQ was 67% and 81% with respect to Reader 1 and 47% and 80% with respect to Reader 2. The negative predictive value of the algorithm for identifying nondiagnostic IQ was 94% and 86% (relative to Readers 1 and 2). We demonstrate a CNN algorithm that yields a high negative predictive value when screening for nondiagnostic T2 WI of the liver. 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017. © 2017 International Society for Magnetic Resonance in Medicine.

  12. A new MRI grading system for cervical foraminal stenosis based on axial T2-weighted images

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Su Jin; Lee, Joon Woo; Seo, Ji Woon; Kang, Heung Sik [Dept. of Radiology, , Seoul National University Bundang Hospital, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, Seongnam (Korea, Republic of); Chai, Jee Won [Dept. of Radiology, SMG-SNU Boramae Medical Center, Seoul (Korea, Republic of); Yoo, Hye Jin; Kang, Yu Suhn [Dept. of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul (Korea, Republic of); Ahn, Joong Mo [Dept. of Radiology, University of Pittsburgh Medical Center, Pittsburgh (United States)

    2015-12-15

    The purpose of this study was to evaluate the reliability of a new magnetic resonance imaging (MRI) grading system for cervical neural foraminal stenosis (NFS). Cervical NFS at bilateral C4/5, C5/6, and C6/7 was classified into the following three grades based on the T2-weighted axial images: Grade 0 = absence of NFS, with the narrowest width of the neural foramen greater than the width of the extraforaminal nerve root (EFNR); Grade 1 = the narrowest width of the neural foramen the same or less than (but more than 50% of) the width of the EFNR; Grade 2 = the width of the neural foramen the same or less than 50% of the width of the EFNR. The MRIs of 96 patients who were over 60 years old (M:F = 50:46; mean age 68.4 years; range 61-86 years) were independently analyzed by seven radiologists. Interobserver and intraobserver agreements were analyzed using the percentage agreement, kappa statistics, and intraclass correlation coefficient (ICC). For the distinction among the three individual grades at all six neural foramina, the ICC ranged from 0.68 to 0.73, indicating fair to good reproducibility. The percentage agreement ranged from 60.2% to 70.6%, and the kappa values (κ = 0.50-0.58) indicated fair to moderate agreement. The percentages of intraobserver agreement ranged from 85.4% to 93.8% (κ = 0.80-0.92), indicating near perfect agreement. The new MRI grading system shows sufficient interobserver and intraobserver agreement to reliably assess cervical NFS.

  13. Uterine Artery Embolization for Symptomatic Fibroids with High Signal Intensity on T2-Weighted MR Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Suyon; Kim, Man Deuk; Lee, Myung Su; Lee, Mu Sook; Park, Sung Il; Won, Jong Yun; Lee, Do Yun; Lee, Kwang Hun [Dept. of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Severance Hospital, Seoul (Korea, Republic of)

    2012-09-15

    To evaluate the effectiveness of uterine artery embolization (UAE) for treating symptomatic fibroids with high signal intensity (SI) on magnetic resonance (MR) T2-weighted imaging (T2WI). A total of 537 cases, consisting of 14 patients with high SI fibroids on T2WI (T2 high group), were retrospectively included and compared with 28 randomly selected patients with low SI fibroids on T2WI (control group). High SI of a predominant fibroid on T2WI was defined as having the same or higher SI than the myometrium. Patient ages ranged from 28 to 52 years (mean, 38.1 years). All patients underwent MRI before and after UAE. Predominant fibroid and uterine volumes were calculated with MR images. Symptom status in terms of menorrhagia and dysmenorrhea was scored on a scale of 0-10, with 0 being no symptoms and 10 being the baseline, or initial symptoms. Of the patients in the T2 high group, 13 out of 14 (92.9%) patients demonstrated complete necrosis of the predominant fibroids. The mean volume reduction rates of the predominant fibroids in the T2 high group was 61.7% at three months after UAE, which was significantly higher than the volume reduction rates of 42.1% noted in the control group (p < 0.05). Changes in symptom scores for menorrhagia and dysmenorrhea after UAE (baseline score minus follow-up score) were 4.9 and 7.5 in T2 high group and they were 5.0 and 7.7 in control group, suggesting a significant resolution of symptoms (p < 0.01) in both groups but no significant difference between the two groups. UAE is effective for uttering fibroids showing high SI on T2WI. The mean volume reduction rate of the predominant fibroids three months after UAE was greater in the T2 high group than in the control group.

  14. Cortical pathology in multiple sclerosis detected by the T1/T2-weighted ratio from routine magnetic resonance imaging.

    Science.gov (United States)

    Righart, Ruthger; Biberacher, Viola; Jonkman, Laura E; Klaver, Roel; Schmidt, Paul; Buck, Dorothea; Berthele, Achim; Kirschke, Jan S; Zimmer, Claus; Hemmer, Bernhard; Geurts, Jeroen J G; Mühlau, Mark

    2017-10-01

    In multiple sclerosis, neuropathological studies have shown widespread changes in the cerebral cortex. In vivo imaging is critical, because the histopathological substrate of most measurements is unknown. Using a novel magnetic resonance imaging analysis technique, based on the ratio of T1- and T2-weighted signal intensities, we studied the cerebral cortex of a large cohort of patients in early stages of multiple sclerosis. A total of 168 patients with clinically isolated syndrome or relapsing-remitting multiple sclerosis (Expanded Disability Status Scale: median = 1, range = 0-3.5) and 80 age- and sex-matched healthy controls were investigated. We also searched for the histopathological substrate of the T1/T2-weighted ratio by combining postmortem imaging and histopathology in 9 multiple sclerosis brain donors. Patients showed lower T1/T2-weighted ratio values in parietal and occipital areas. The 4 most significant clusters appeared in the medial occipital and posterior cingulate cortex (each left and right). The decrease of the T1/T2-weighted ratio in the posterior cingulate was related to performance in attention. Analysis of the T1/T2-weighted ratio values of postmortem imaging yielded a strong correlation with dendrite density but none of the other parameters including myelin. The T1/T2-weighted ratio decreases in early stages of multiple sclerosis in a widespread manner, with a preponderance of posterior areas and with a contribution to attentional performance; it seems to reflect dendrite pathology. As the method is broadly available and applicable to available clinical scans, we believe that it is a promising candidate for studying and monitoring cortical pathology or therapeutic effects in multiple sclerosis. Ann Neurol 2017;82:519-529. © 2017 The Authors Annals of Neurology published by Wiley Periodicals, Inc. on behalf of American Neurological Association.

  15. Texture features on T2-weighted magnetic resonance imaging: new potential biomarkers for prostate cancer aggressiveness

    Science.gov (United States)

    Vignati, A.; Mazzetti, S.; Giannini, V.; Russo, F.; Bollito, E.; Porpiglia, F.; Stasi, M.; Regge, D.

    2015-04-01

    To explore contrast (C) and homogeneity (H) gray-level co-occurrence matrix texture features on T2-weighted (T2w) Magnetic Resonance (MR) images and apparent diffusion coefficient (ADC) maps for predicting prostate cancer (PCa) aggressiveness, and to compare them with traditional ADC metrics for differentiating low- from intermediate/high-grade PCas. The local Ethics Committee approved this prospective study of 93 patients (median age, 65 years), who underwent 1.5 T multiparametric endorectal MR imaging before prostatectomy. Clinically significant (volume ≥0.5 ml) peripheral tumours were outlined on histological sections, contoured on T2w and ADC images, and their pathological Gleason Score (pGS) was recorded. C, H, and traditional ADC metrics (mean, median, 10th and 25th percentile) were calculated on the largest lesion slice, and correlated with the pGS through the Spearman correlation coefficient. The area under the receiver operating characteristic curve (AUC) assessed how parameters differentiate pGS = 6 from pGS ≥ 7. The dataset included 49 clinically significant PCas with a balanced distribution of pGS. The Spearman ρ and AUC values on ADC were: -0.489, 0.823 (mean) -0.522, 0.821 (median) -0.569, 0.854 (10th percentile) -0.556, 0.854 (25th percentile) -0.386, 0.871 (C); 0.533, 0.923 (H); while on T2w they were: -0.654, 0.945 (C); 0.645, 0.962 (H). AUC of H on ADC and T2w, and C on T2w were significantly higher than that of the mean ADC (p = 0.05). H and C calculated on T2w images outperform ADC parameters in correlating with pGS and differentiating low- from intermediate/high-risk PCas, supporting the role of T2w MR imaging in assessing PCa biological aggressiveness.

  16. Utility of R2* obtained from T2*-weighted imaging in differentiating hepatocellular carcinomas from cavernous hemangiomas of the liver.

    Directory of Open Access Journals (Sweden)

    Meiyu Sun

    Full Text Available PURPOSE: To evaluate the feasibility of applying R2* values to differentiate hepatocellular carcinomas (HCC from cavernous hemangiomas of the liver (CHL. MATERIALS AND METHODS: This retrospective study was approved by the participating Institutional Review Board and written informed consent for all subjects were obtained. Seventy-three patients with 79 pathologically identified HCCs and 65 patients with 91 clinically or pathologically identified CHLs were enrolled in this study. All subjects underwent a breath-hold multi-echo T2* weighted MR imaging on a 1.5 T clinical MR scanner. R2* values from HCC and CHL groups were compared using the Mann-Whitney non-parametric U test. A cut-off value of R2* was evaluated with receiver operator characteristic (ROC analysis. RESULTS: The mean R2* value was 23.32 ± 12.23 Hz (95% confidence interval [CI]: 20.58 Hz, 26.06 Hz for the HCC group, and 3.66 ± 2.37 Hz (95% CI: 3.17 Hz, 4.15 Hz for the CHL group. The mean R2* value for HCC was significantly higher than that of CHL (p<0.001. A threshold of 9.48 Hz for the minimum R2* value in the diagnosis of HCC resulted in a sensitivity of 96.20% (76 out of 79 patients, and a specificity of 97.80% (89 out of 91 patients. The positive predictive value (PPV, negative predictive value (NPV and diagnostic accuracy for HCC were 97.44% (76 out of 78 patients, 96.74% (89 out of 92 patients and 97.06% (165 out of 170 patients, respectively. The AUC for differentiation between these two groups was 0.994 (95% CI: 0.980, 1.000. CONCLUSIONS: R2* is a significant MRI biomarker to differentiate HCC from CHL with satisfying sensitivity and specificity.

  17. SU-F-R-35: Repeatability of Texture Features in T1- and T2-Weighted MR Images

    Energy Technology Data Exchange (ETDEWEB)

    Mahon, R; Weiss, E; Karki, K; Hugo, G [Virginia Commonwealth University, Richmond, VA (United States); Ford, J [University of Miami Miller School of Medicine, Miami, FL (United States)

    2016-06-15

    Purpose: To evaluate repeatability of lung tumor texture features from inspiration/expiration MR image pairs for potential use in patient specific care models and applications. Repeatability is a desirable and necessary characteristic of features included in such models. Methods: T1-weighted Volumetric Interpolation Breath-Hold Examination (VIBE) and/or T2-weighted MRI scans were acquired for 15 patients with non-small cell lung cancer before and during radiotherapy for a total of 32 and 34 same session inspiration-expiration breath-hold image pairs respectively. Bias correction was applied to the VIBE (VIBE-BC) and T2-weighted (T2-BC) images. Fifty-nine texture features at five wavelet decomposition ratios were extracted from the delineated primary tumor including: histogram(HIST), gray level co-occurrence matrix(GLCM), gray level run length matrix(GLRLM), gray level size zone matrix(GLSZM), and neighborhood gray tone different matrix (NGTDM) based features. Repeatability of the texture features for VIBE, VIBE-BC, T2-weighted, and T2-BC image pairs was evaluated by the concordance correlation coefficient (CCC) between corresponding image pairs, with a value greater than 0.90 indicating repeatability. Results: For the VIBE image pairs, the percentage of repeatable texture features by wavelet ratio was between 20% and 24% of the 59 extracted features; the T2-weighted image pairs exhibited repeatability in the range of 44–49%. The percentage dropped to 10–20% for the VIBE-BC images, and 12–14% for the T2-BC images. In addition, five texture features were found to be repeatable in all four image sets including two GLRLM, two GLZSM, and one NGTDN features. No single texture feature category was repeatable among all three image types; however, certain categories performed more consistently on a per image type basis. Conclusion: We identified repeatable texture features on T1- and T2-weighted MRI scans. These texture features should be further investigated for use

  18. Breast cancer detection using double reading of unenhanced MRI including T1-weighted, T2-weighted STIR, and diffusion-weighted imaging: a proof of concept study.

    Science.gov (United States)

    Trimboli, Rubina M; Verardi, Nicola; Cartia, Francesco; Carbonaro, Luca A; Sardanelli, Francesco

    2014-09-01

    The purpose of this study was to investigate the diagnostic performance of unenhanced MRI in detecting breast cancer and to assess the impact of double reading. A total of 116 breasts of 67 women who were 36-89 years old were studied at 1.5 T using an unenhanced protocol including axial T1-weighted gradient-echo, T2-weighted STIR, and echo-planar diffusion-weighted imaging (DWI). Two blinded readers (R1 and R2) independently evaluated unenhanced images using the BIRADS scale. A combination of pathology and negative follow-up served as the reference standard. McNemar and kappa statistics were used. Per-breast cancer prevalence was 37 of 116 (32%): 30 of 37 (81%) invasive ductal carcinoma, five of 37 (13%) ductal carcinoma in situ, and two of 37 (6%) invasive lobular carcinoma. Per-breast sensitivity of unenhanced MRI was 29 of 37 (78%) for R1, 28 of 37 (76%) for R2, and 29 of 37 (78%) for double reading. Specificity was 71 of 79 (90%) for both R1 and R2 and 69 of 79 (87%) for double reading. Double reading did not provide a significant increase in sensitivity. Interobserver agreement was almost perfect (Cohen κ = 0.873). An unenhanced breast MRI protocol composed of T1-weighted gradient echo, T2-weighted STIR, and echo-planar DWI enabled breast cancer detection with sensitivity of 76-78% and specificity of 90% without a gain in sensitivity from double reading.

  19. Diagnosis of spinal dural arteriovenous fistula using 3D T2-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kralik, Stephen F.; Murph, Daniel; Mehta, Peter; O' Neill, Darren P. [Indiana University School of Medicine, Department of Radiology and Imaging Sciences, Indianapolis, IN (United States)

    2017-10-15

    To evaluate spinal MRIs without and with 3D T2W imaging among patients without and with spinal dural arteriovenous fistula (SDAVF) confirmed by spinal digital subtraction angiography (DSA). A retrospective case-control study was performed among patients without and with SDAVF who had both spinal MRIs and gold standard spinal DSA. Two neuroradiologists independently reviewed spinal MRIs that were performed with either sagittal T2W turbo spin echo (2D group) or sagittal 3D T2W sampling perfection with application-optimized contrasts using different flip-angle evolutions (SPACE) (3D group) and documented the presence or absence of SDAVF. Using spinal DSA diagnosis as a gold standard, the sensitivity, specificity, and interobserver agreement for the 2D-group and 3D-group MRI diagnosis were calculated. The 2D group consisted of 21 patients and the 3D group consisted of 16 patients. For both radiologists, the 2D group demonstrated a sensitivity of 100% and specificity of 100%. Interobserver agreement in the 2D group was perfect (k = 1.0). For both radiologists, the 3D group demonstrated sensitivity of 100.0% and specificity of 92.3%. Interobserver agreement in the 3D group was perfect (k = 1.0). While flow voids were considered more conspicuous, spinal cord signal abnormality was considered less conspicuous with 3D T2W SPACE compared with conventional 2D STIR sequence. 3D T2W SPACE should be used in conjunction with 2D T2W sequences to more accurately detect abnormal cord signal and determine when perimedullary flow voids are pathologically abnormal for the radiologic diagnosis of SDAVF. (orig.)

  20. Whole-brain three-dimensional T2-weighted BOLD functional magnetic resonance imaging at 7 Tesla.

    Science.gov (United States)

    Hua, Jun; Qin, Qin; van Zijl, Peter C M; Pekar, James J; Jones, Craig K

    2014-12-01

    A new acquisition scheme for T2-weighted spin-echo BOLD fMRI is introduced. It uses a T2-preparation module to induce blood-oxygenation-level-dependent (BOLD) contrast, followed by a single-shot three-dimensional (3D) fast gradient-echo readout with short echo time (TE). It differs from most spin-echo BOLD sequences in that BOLD contrast is generated before the readout, which eliminates the "dead time" due to long TE required for T2 contrast, and substantially improves acquisition efficiency. This approach, termed "3D T2prep-GRE," was implemented at 7 Tesla (T) with a typical spatial (2.5 × 2.5 × 2.5 mm(3) ) and temporal (TR = 2.3 s) resolution for functional MRI (fMRI) and whole-brain coverage (55 slices), and compared with the widely used 2D spin-echo EPI sequence. In fMRI experiments of simultaneous visual/motor activities, 3D T2prep-GRE showed minimal distortion and little signal dropout across the whole brain. Its lower power deposition allowed greater spatial coverage (55 versus 17 slices with identical TR, resolution and power level), temporal SNR (60% higher) and CNR (35% higher) efficiency than 2D spin-echo EPI. It also showed smaller T2* contamination. This approach is expected to be useful for ultra-high field fMRI, especially for regions near air cavities. The concept of using T2-preparation to generate BOLD contrast can be combined with many other sequences at any field strength. © 2013 Wiley Periodicals, Inc.

  1. Diferenciação entre cisto simples e hemangioma hepático utilizando seqüência de ressonância magnética ponderada em T2 com técnica gradiente-eco (B-FFE Differentiation between simple cyst and hepatic hemangioma utilizing T2-weighted magnetic resonance imaging with gradient-echo (b-FFE technique

    Directory of Open Access Journals (Sweden)

    Carolina Valente Burim

    2008-12-01

    Full Text Available OBJETIVO: Estabelecer o valor das seqüências ponderadas em T2 para diferenciar cistos simples de hemangiomas hepáticos. MATERIAIS E MÉTODOS: Estudo prospectivo, observacional, transversal e duplo-cego em 52 pacientes com 91 lesões hepáticas (34 cistos simples e 57 hemangiomas submetidos a ressonância magnética de abdome. A análise conjunta de todas as seqüências realizadas foi considerada o padrão-ouro. Dois observadores independentes avaliaram, subjetivamente, as seqüências TSE com TE longo e B-FFE, procurando diferenciar cistos de hemangiomas. Foram calculadas a eficácia das seqüências e a concordância interobservador e intra-observador por meio do teste kappa (κ (p OBJECTIVE: To establish the role of MRI T2-weighted sequences in the differentiation between simple cysts and hepatic hemangiomas. MATERIALS AND METHODS: A double-blinded, prospective, observational, cross-sectional study evaluated 52 patients with 91 hepatic lesions (34 simple cysts and 57 hemangiomas submitted to abdominal magnetic resonance imaging. The combined analysis of all sequences was considered as the golden-standard. TSE sequences with long echo trains and b-FFE sequences were subjectively analyzed by two independent observers for differentiating cysts from hemangiomas. The kappa test (κ was utilized in the analysis of the methods accuracy and inter- and intra-observer agreement (p < 0.05*. RESULTS: Cysts and hemangiomas dimensions ranged respectively between 0.5 and 6.5 cm (mean = 1.89 cm, and 0.8 and 11 cm (mean = 2.62 cm. The analysis of the sequences with long-TE and the golden-standard demonstrated a non-statistically significant agreement (κ: 0.00-0.10. The agreement between the evaluation of the b-FFE sequence and the golden-standard ranged from substantial (κ: 0.62-0.71 to almost perfect (κ: 0.86 for both observers. The inter- and intra-observer agreement for the b-FFE sequence ranged from substantial (κ: 0.62-0.70 to almost perfect (κ

  2. Prostatic ductal adenocarcinoma: an aggressive tumour variant unrecognized on T2 weighted magnetic resonance imaging (MRI)

    Energy Technology Data Exchange (ETDEWEB)

    Schieda, Nicola; Coffey, Niamh; Al-Dandan, Omran; Shabana, Wael [The University of Ottawa, Department of Medical Imaging, The Ottawa Hospital, Ottawa, Ontario (Canada); Gulavita, Previn; Flood, Trevor A. [The University of Ottawa, Department of Anatomical Pathology, The Ottawa Hospital, Ottawa (Canada)

    2014-06-15

    Prostatic ductal adenocarcinoma (DCa) is an aggressive variant. The purpose of this study was to determine if T2 signal intensity (SI) differs from conventional adenocarcinoma (CCa). A retrospective study of patients who underwent preoperative MRI and prostatectomy between 2009 and 2012 was performed. T2 SI ratios (SIR) for tumour (T) to obturator internus muscle (M) and normal peripheral zone (PZ) were compared. Two radiologists evaluated the central gland/PZ to detect tumours and compared diagnostic accuracy. T2 SIR for DCa were 3.60 (T/M), 0.66 (T/PZ); 2.68 (T/M), 0.47 (T/PZ) for Gleason 9; 2.50 (T/M), 0.47 (T/PZ) for Gleason 7/8 and 3.95 (T/M), 0.73 (T/PZ) for Gleason 6 tumours. There was a difference in T2 T/M and T/PZ SIR between DCa and Gleason 9 (p = 0.003, p = 0.004) and Gleason 7/8 (p = 0.006, p = 0.002), but no difference in SIR between DCa and Gleason 6 tumours. The sensitivity for tumour detection was 0-27 % for DCa, 64-82 % for Gleason 9, 44-88 % for Gleason 7-8 and 0-20 % for Gleason 6. There was a difference in the sensitivity of detecting Gleason 9 and 7/8 tumours when compared to DCa (p = 0.004, p = 0.001). DCa resembles Gleason score 6 tumour at T2-weighted MRI, which underestimates tumour grade and renders the tumour occult. (orig.)

  3. Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence.

    Directory of Open Access Journals (Sweden)

    Bastiaan J van Nierop

    Full Text Available Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI. Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using contrast-enhanced T1 mapping. Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.To goal of this paper was to explore the use of a T2*-weighted radial sequence for the visualization of fibrosis in mouse heart.C57BL/6 mice were studied with MI (n = 20, replacement fibrosis, transverse aortic constriction (TAC (n = 18, diffuse fibrosis, and as control (n = 10. 3D center-out radial T2*-weighted images with varying TE were acquired in vivo and ex vivo (TE = 21 μs-4 ms. Ex vivo T2*-weighted signal decay with TE was analyzed using a 3-component model. Subtraction of short- and long-TE images was used to highlight fibrotic tissue with short T2*. The presence of fibrosis was validated using histology and correlated to MRI findings.Detailed ex vivo T2*-weighted signal analysis revealed a fast (T2*fast, slow (T2*slow and lipid (T2*lipid pool. T2*fast remained essentially constant. Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts. T2*slow correlated with the presence of diffuse fibrosis in TAC hearts (r = 0.82, P = 0.01. Ex vivo and in vivo subtraction images depicted a positive contrast in the infarct co-localizing with the scar. Infarct volumes from histology and subtraction images linearly correlated (r = 0.94, P<0.001. Region-of-interest analysis in the in vivo post-MI and TAC hearts revealed significant T2* shortening due to fibrosis, in agreement with the ex vivo results. However, in vivo contrast on subtraction images was rather poor

  4. Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence.

    Science.gov (United States)

    van Nierop, Bastiaan J; Bax, Noortje A M; Nelissen, Jules L; Arslan, Fatih; Motaal, Abdallah G; de Graaf, Larry; Zwanenburg, Jaco J M; Luijten, Peter R; Nicolay, Klaas; Strijkers, Gustav J

    2015-01-01

    Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI). Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using contrast-enhanced T1 mapping. Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis. To goal of this paper was to explore the use of a T2*-weighted radial sequence for the visualization of fibrosis in mouse heart. C57BL/6 mice were studied with MI (n = 20, replacement fibrosis), transverse aortic constriction (TAC) (n = 18, diffuse fibrosis), and as control (n = 10). 3D center-out radial T2*-weighted images with varying TE were acquired in vivo and ex vivo (TE = 21 μs-4 ms). Ex vivo T2*-weighted signal decay with TE was analyzed using a 3-component model. Subtraction of short- and long-TE images was used to highlight fibrotic tissue with short T2*. The presence of fibrosis was validated using histology and correlated to MRI findings. Detailed ex vivo T2*-weighted signal analysis revealed a fast (T2*fast), slow (T2*slow) and lipid (T2*lipid) pool. T2*fast remained essentially constant. Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts. T2*slow correlated with the presence of diffuse fibrosis in TAC hearts (r = 0.82, P = 0.01). Ex vivo and in vivo subtraction images depicted a positive contrast in the infarct co-localizing with the scar. Infarct volumes from histology and subtraction images linearly correlated (r = 0.94, P<0.001). Region-of-interest analysis in the in vivo post-MI and TAC hearts revealed significant T2* shortening due to fibrosis, in agreement with the ex vivo results. However, in vivo contrast on subtraction images was rather poor

  5. Feasibility of ultrasound-guided high intensity focused ultrasound ablating uterine fibroids with hyperintense on T2-weighted MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wen-Peng, E-mail: zwp215@163.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Chen, Jin-Yun, E-mail: chenjinyun2006@126.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Zhang, Lian, E-mail: zhangl@haifu.com.cn [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Clinical Center for Tumor Therapy of 2nd Affiliated Hospital of Chongqing Medical University, 74 Linjiang Road, Chongqing 400010 (China); Li, Quan, E-mail: 1013283493@qq.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); Qin, Juan, E-mail: ant000999@163.com [State Key Laboratory of Ultrasound Engineering in Medicine Co-founded by Chongqing and the Ministry of Science and Technology, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016 (China); and others

    2013-01-15

    Purpose: To retrospectively investigate whether uterine fibroids with hyperintense on pretreatment T2-weighted magnetic resonance imaging (MRI) could be treated with ultrasound-guided high intensity focused ultrasound (USgHIFU). Materials and methods: 282 patients with 282 symptomatic uterine fibroids who underwent USgHIFU treatment were retrospectively analyzed. Based on the signal intensity of T2-weighted MRI, uterine fibroids were classified as hypointense, isointense and hyperintense. Hyperintense fibroids were subjectively further subdivided into heterogeneous hyperintense, slightly homogeneous hyperintense and markedly homogeneous hyperintense based on the signal intensity of fibroid relative to myometrium and endometrium on T2-weighted MRI. Enhanced MRI was performed within one month after HIFU treatment. Non-perfused volume (NPV, indicative of successful ablation) ratio, treatment time, treatment efficiency, energy effect ratio and adverse events were recorded. Results: The median volume of uterine fibroids was 70.3 cm{sup 3} (interquartile range, 41.1–132.5 cm{sup 3}). The average NPV ratio, defined as non-perfused volume divided by the fibroid volume after HIFU treatment, was 76.8 ± 19.0% (range, 0–100%) in the 282 patients. It was 86.3 ± 11.9% (range, 40.9–100.0%) in the group with hypointense fibroids, 77.1 ± 16.5% (range, 32.2–100.0%) in isointense fibroids, and 67.6 ± 23.9% (range, 0–100.0%) in hyperintense fibroids. The lowest NPV ratio, lowest treatment efficiency, more treatment time, more sonication energy and pain scores were observed in the slightly homogeneous hyperintense fibroids, and the NPV ratio was 55.8 ± 26.7% (range, 0–83.9%) in this subgroup. Conclusion: Based on our results, the heterogeneous and markedly homogeneous hyperintense fibroids were suitable for USgHIFU, and only the slightly homogeneous hyperintense fibroids should be excluded.

  6. The extent of myocardium at Risk for LAD, RCA and LCx using contrast enhanced SSFP and T2-weighted imaging

    DEFF Research Database (Denmark)

    Nordlund, D.; Heiberg, E.; Carlsson, Marcus

    2015-01-01

    has been used to describe the coronary perfusion territories during myocardial ischemia. Compared to MPS, CMR offers superior image quality and logistical advantages. The aim of this study was to describe the coronary perfusion territories of LAD, RCA and LCx based on CMR data using CE-SSFP and T2w......Background: Contrast enhanced SSFP (CE-SSFP) and T2-weighted triple inversion recovery imaging (T2w) have both been clinically validated for determining myocardium at risk (MaR) by cardiovascular magnetic resonance (CMR), using myocardial perfusion SPECT (MPS) as reference standard. Previously, MPS...... (12 excluded due to missing data, 53 due to inability to detect MaR) were included. Late gadolinium enhancement (LGE) imaging was used to assess infarct size. Imaging was performed on systems from three different vendors (Siemens, Philips, GE) and data was analyzed by a core laboratory. Culprit vessel...

  7. Foci of decreased signal on T2-weighted MR images in leiomyosarcomas of soft tissue: correlation between MR and histological findings

    Energy Technology Data Exchange (ETDEWEB)

    Pilavaki, M. E-mail: mayiapil@otenet.gr; Drevelegas, A.; Nenopoulou, H.; Scordalaki, A.; Chourmouzi, D.; Sofroniadis, I.; Dimitriadis, A.S

    2004-09-01

    Objective: Leiomyosarcomas are rare soft tissue sarcomas with varying MR signal characteristics and histologic pictures. The purpose of this study was to investigate the histological features of foci, which showed decreased signal on T2-weighted images in leiomyosarcomas of soft tissue. Material and methods: We reviewed the MR images of six histologically proved cases of leiomyosarcomas of soft tissue and correlated the foci, which showed decreased signal on T2-weighted images with the histologic findings. Result: Microscopic examination revealed that these foci were composed of hyalinization of neoplastic tissue, internal septations, deposition of hemosiderin, or corresponded to metaplastic bone. Conclusion: The authors explain that the foci of decreased signal on T2-weighted MR images correspond to tissue components of the lesion, particularly fibrous tissue, hemosiderin and metaplastic bone. So, the suggestion is that leiomyosarcoma should be considered in the differential diagnosis of soft-tissue tumors that show foci of decreased signal on T2-weighted MR images.

  8. Hematoma size in deep intracerebral hemorrhage and its correlation with dot-like hemosiderin spots on gradient echo T2*-weighted MRI.

    Science.gov (United States)

    Imaizumi, Toshio; Honma, Toshimi; Horita, Yoshifumi; Kohama, Ikuhide; Miyata, Kei; Kawamura, Maiko; Niwa, Jun

    2006-07-01

    Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH.

  9. Introduction of High Throughput Magnetic Resonance T2-Weighted Image Texture Analysis for WHO Grade 2 and 3 Gliomas.

    Directory of Open Access Journals (Sweden)

    Manabu Kinoshita

    Full Text Available Reports have suggested that tumor textures presented on T2-weighted images correlate with the genetic status of glioma. Therefore, development of an image analyzing framework that is capable of objective and high throughput image texture analysis for large scale image data collection is needed. The current study aimed to address the development of such a framework by introducing two novel parameters for image textures on T2-weighted images, i.e., Shannon entropy and Prewitt filtering. Twenty-two WHO grade 2 and 28 grade 3 glioma patients were collected whose pre-surgical MRI and IDH1 mutation status were available. Heterogeneous lesions showed statistically higher Shannon entropy than homogenous lesions (p = 0.006 and ROC curve analysis proved that Shannon entropy on T2WI was a reliable indicator for discrimination of homogenous and heterogeneous lesions (p = 0.015, AUC = 0.73. Lesions with well-defined borders exhibited statistically higher Edge mean and Edge median values using Prewitt filtering than those with vague lesion borders (p = 0.0003 and p = 0.0005 respectively. ROC curve analysis also proved that both Edge mean and median values were promising indicators for discrimination of lesions with vague and well defined borders and both Edge mean and median values performed in a comparable manner (p = 0.0002, AUC = 0.81 and p < 0.0001, AUC = 0.83, respectively. Finally, IDH1 wild type gliomas showed statistically lower Shannon entropy on T2WI than IDH1 mutated gliomas (p = 0.007 but no difference was observed between IDH1 wild type and mutated gliomas in Edge median values using Prewitt filtering. The current study introduced two image metrics that reflect lesion texture described on T2WI. These two metrics were validated by readings of a neuro-radiologist who was blinded to the results. This observation will facilitate further use of this technique in future large scale image analysis of glioma.

  10. White Matter Hyperintensities on T2-Weighted MRI Images among DNA-Verified Older Familial Hypercholesterolemia Patients

    Energy Technology Data Exchange (ETDEWEB)

    Hyttinen, L. (Dept. of Internal Medicine, North Karelia Central Hospital, Joensuu (Finland)); Autti, T.; Soljanlahti, S. (Medical Imaging Center, Helsinki Univ. Central Hospital, Helsinki (Finland)); Rauma, S. (Dept. of Radiology, North Karelia Central Hospital, Joensuu (Finland)); Vuorio, A.F. (Dept. of Medicine, Univ. of Helsinki, Helsinki (Finland)); Strandberg, T.E. (Dept. of Health Sciences/Geriatrics, Univ. of Oulu, Oulu (Finland))

    2009-04-15

    Background: Familial hypercholesterolemia (FH) is a genetic disorder, causing an increased risk of coronary heart disease (CHD) if untreated. Silent brain infarctions and white matter hyperintensities (WMHIs) observed on T2-weighted magnetic resonance images (MRI) are associated with increased risk for stroke and myocardial infarction. Age is a strong predictor of WMHIs. Purpose: To use MRI to assess the presence of clinically silent brain lesions in older FH patients, and to compare the occurrence and size of these lesions in older FH patients with middle-aged FH patients and healthy controls. Material and Methods: A total of 43 older (age = 65 years) FH patients with the same FH North Karelia mutation, living in Finland, were identified. In this comprehensive cohort, 1.5T brain MRI was available for 33 individuals (age 65-84 years, M/F 9/24, mean duration of statin treatment 15.3 years). This group was divided into two age categories: 65-74 years (FHe1 group, n=23) and 75-84 years (FHe2 group, n=10). Infarcts, including lacunas, and WMHIs on T2-weighted images were recorded. Data from brain MRI were compared to those of a group of middle-aged FH patients with CHD (n=19, age 48-64 years) and with middle-aged healthy controls (n=29, age 49-63 years). Results: Only two (6%) of the older FH patients had clinically silent brain infarcts detected by MRI. The amount of large WMHIs (>5 mm in diameter) was similar in the FHe1 group compared with the groups of middle-aged FH patients and healthy controls, even though the FHe1 group was 13 years older. The total amount of WMHIs and the amount of large WMHIs were greatest in the FHe2 group. Conclusion: FH patients aged 65 to 74 years receiving long-term statin treatment (15 years) did not have more WMHIs on brain MRI compared to middle-aged FH patients and healthy controls.

  11. Detecting Acute Myocardial Infarction by Diffusion-Weighted versus T2-Weighted Imaging and Myocardial Necrosis Markers.

    Science.gov (United States)

    Jin, Jiyang; Chen, Min; Li, Yongjun; Wang, YaLing; Zhang, Shijun; Wang, Zhen; Wang, Lin; Ju, Shenghong

    2016-10-01

    We used a porcine model of acute myocardial infarction to study the signal evolution of ischemic myocardium on diffusion-weighted magnetic resonance images (DWI). Eight Chinese miniature pigs underwent percutaneous left anterior descending or left circumflex coronary artery occlusion for 90 minutes followed by reperfusion, which induced acute myocardial infarction. We used DWI preprocedurally and hourly for 4 hours postprocedurally. We acquired turbo inversion recovery magnitude T2-weighted images (TIRM T2WI) and late gadolinium enhancement images from the DWI slices. We measured the serum myocardial necrosis markers myoglobin, creatine kinase-MB isoenzyme, and cardiac troponin I at the same time points as the magnetic resonance scanning. We used histochemical staining to confirm injury. All images were analyzed qualitatively. Contrast-to-noise ratio (the contrast between infarcted and healthy myocardium) and relative signal index were used in quantitative image analysis. We found that DWI identified myocardial signal abnormity early (acute myocardial infarction and identified the infarct-related high signal more often than did TIRM T2WI: 7 of 8 pigs (87.5%) versus 3 of 8 (37.5%) ( P =0.046). Quantitative image analysis yielded a significant difference in contrast-to-noise ratio and relative signal index between infarcted and normal myocardium on DWI. However, within 4 hours after infarction, the serologic myocardial injury markers were not significantly positive. We conclude that DWI can be used to detect myocardial signal abnormalities early after acute myocardial infarction-identifying the infarction earlier than TIRM T2WI and widely used clinical serologic biomarkers.

  12. Mapping pathological changes in brain structure by combining T1- and T2-weighted MR imaging data

    Energy Technology Data Exchange (ETDEWEB)

    Ganzetti, Marco; Mantini, Dante [ETH Zurich, Neural Control of Movement Laboratory, Department of Health Sciences and Technology, Zurich (Switzerland); University of Oxford, Department of Experimental Psychology, Oxford (United Kingdom); Wenderoth, Nicole [ETH Zurich, Neural Control of Movement Laboratory, Department of Health Sciences and Technology, Zurich (Switzerland); KU Leuven, Laboratory of Movement Control and Neuroplasticity, Faculty of Kinesiology and Rehabilitation Sciences, Leuven (Belgium)

    2015-09-15

    A workflow based on the ratio between standardized T1-weighted (T1-w) and T2-weighted (T2-w) MR images has been proposed as a new tool to study brain structure. This approach was previously used to map structural properties in the healthy brain. Here, we evaluate whether the T1-w/T2-w approach can support the assessment of structural impairments in the diseased brain. We use schizophrenia data to demonstrate the potential clinical utility of the technique. We analyzed T1-w and T2-w images of 36 schizophrenic patients and 35 age-matched controls. These were collected for the Function Biomedical Informatics Research Network (fBIRN) collaborative project, which had an IRB approval and followed the HIPAA guidelines. We computed T1-w/T2-w images for each individual and compared intensities in schizophrenic and control groups on a voxel-wise basis, as well as in regions of interest (ROIs). Our results revealed that the T1-w/T2-w image permits to discriminate brain regions showing group-level differences between patients and controls with greater accuracy than conventional T1-w and T2-w images. Both the ROIs and the voxel-wise analysis showed globally reduced gray and white matter values in patients compared to controls. Significantly reduced values were found in regions such as insula, primary auditory cortex, hippocampus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. Our findings were consistent with previous meta-analyses in schizophrenia corroborating the hypothesis of a potential ''disconnection'' syndrome in conjunction with structural alterations in local gray matter regions. Overall, our study suggested that the T1-w/T2-w technique permits to reliably map structural differences between the brains of patients and healthy individuals. (orig.)

  13. Value of additional cervicothoracic sagittal T2- weighted images in elderly patients with symptoms suggestive of lumbar spinal stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Hee; Ahn, Joong Mo; Lee, Joon Woo; Lee, Guen Young; Kang, Heung Sik [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2015-07-15

    The purpose of this study was to analyze the incidence and predictive factors of tandem cervical spinal stenosis (CSS) in patients with lumbar spinal stenosis (LSS) based on MR. From January to May of 2011, 140 consecutive patients (36 men, 94 women; mean age, 68.9 years; age range, 60-87 years) were included for the analysis. All patients were at least 60 years old, had undergone lumbar spine MRI including additional cervicothoracic sagittal T2-weighted images, and were clinically suspected of LSS. Two spine radiologists evaluated the risk factors for CSS, considering the possible risk factors such as age, sex, alignment disorder of the lumbar spine, number of levels of LSS, and severity of LSS, based on MR. Of the 140 patients, 42 (30%) patients had tandem spinal stenosis. CSS was more common among patients with LSS (42 of 61, 69%) than among patients without LSS (27 of 79, 34%) (p = 0.000). Grade 2 or 3 CSS was more commonly observed among patients with grade 2 or 3 LSS (15 of 53, 28%), than among patients with grade 0 or 1 LSS (8 of 87, 9%) (p = 0.003). Only the severity of LSS showed a significant association with the severity of CSS (p = 0.045). Tandem CSS is common in LSS, and the severity of LSS is a risk factor of CSS.

  14. High-resolution heavily T2-weighted magnetic resonance imaging for evaluation of the pituitary stalk in children with ectopic neurohypophysis

    Energy Technology Data Exchange (ETDEWEB)

    Sanharawi, Imane El; Tzarouchi, Loukia [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Cardoen, Liesbeth [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Universite Paris Diderot, Paris (France); Martinerie, Laetitia; Leger, Juliane; Carel, Jean-Claude [Universite Paris Diderot, Paris (France); Inserm U1141, DHU PROTECT, Paris (France); Hopital Robert Debre, APHP, Service d' Endocrinologie Pediatrique, Paris (France); Elmaleh-Berges, Monique [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Inserm U1141, DHU PROTECT, Paris (France); Alison, Marianne [Hopital Robert Debre, APHP, Service de Radiologie Pediatrique, Paris (France); Universite Paris Diderot, Paris (France); Inserm U1141, DHU PROTECT, Paris (France)

    2017-05-15

    In anterior pituitary deficiency, patients with non visible pituitary stalk have more often multiple deficiencies and persistent deficiency than patients with visible pituitary stalk. To compare the diagnostic value of a high-resolution heavily T2-weighted sequence to 1.5-mm-thick unenhanced and contrast-enhanced sagittal T1-weighted sequences to assess the presence of the pituitary stalk in children with ectopic posterior pituitary gland. We retrospectively evaluated the MRI data of 14 children diagnosed with ectopic posterior pituitary gland between 2010 and 2014. We evaluated the presence of a pituitary stalk using a sagittal high-resolution heavily T2-weighted sequence and a 1.5-mm sagittal T1-weighted turbo spin-echo sequence before and after contrast medium administration. A pituitary stalk was present on at least one of the sequences in 10 of the 14 children (71%). T2-weighted sequence depicted the pituitary stalk in all 10 children, whereas the 1.5-mm-thick T1-weighted sequence depicted 2/10 (20%) before contrast injection and 8/10 (80%) after contrast injection (P=0.007). Compared with 1.5-mm-thick contrast-enhanced T1-weighted sequences, high-resolution heavily T2-weighted sequence demonstrates better sensitivity in detecting the pituitary stalk in children with ectopic posterior pituitary gland, suggesting that contrast injection is unnecessary to assess the presence of a pituitary stalk in this setting. (orig.)

  15. Myocardial area at risk after ST-elevation myocardial infarction measured with the late gadolinium enhancement after scar remodeling and T2-weighted cardiac magnetic resonance imaging

    DEFF Research Database (Denmark)

    Lønborg, Jacob; Engstrøm, Thomas; Mathiasen, Anders B

    2012-01-01

    To evaluate the myocardial area at risk (AAR) measured by the endocardial surface area (ESA) method on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) when applied after scar remodeling (3 months after index infarction) compared to T2-weighted CMR imaging. One hundred...... and sixty nine patients with ST-elevation myocardial infarction, treated with primary percutaneous coronary intervention, underwent one CMR within 1 week after index treatment to determine the AAR with T2-weighted imaging and a second scan 3 months after to measure AAR with the ESA method...

  16. Myocardial area at risk after ST-elevation myocardial infarction measured with the late gadolinium enhancement after scar remodeling and T2-weighted cardiac magnetic resonance imaging

    DEFF Research Database (Denmark)

    Lønborg, Jacob; Engstrøm, Thomas; Mathiasen, Anders B

    2011-01-01

    To evaluate the myocardial area at risk (AAR) measured by the endocardial surface area (ESA) method on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) when applied after scar remodeling (3 months after index infarction) compared to T2-weighted CMR imaging. One hundred...... and sixty nine patients with ST-elevation myocardial infarction, treated with primary percutaneous coronary intervention, underwent one CMR within 1 week after index treatment to determine the AAR with T2-weighted imaging and a second scan 3 months after to measure AAR with the ESA method...

  17. Monitoring of VX2 tumor growth in rabbit liver using T2-weighted and dynamic contrast-enhanced magnetic resonance imaging at 1.5T

    Science.gov (United States)

    Jao, Jo-Chi; Mac, Ka-Wai; Chang, Chiung-Yun; Wu, Yu-Chiuan; Hsiao, Chia-Chi; Chen, Po-Chou

    2017-03-01

    This study aimed to investigate the VX2 tumor growth in rabbit liver using T2-weighted imaging (T2WI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Five New Zealand white (NZW) rabbits were implanted with VX2 cell suspension in liver. Afterwards, MRI was performed 7, 14, 21 and 28 days after tumor implantation. A 1.5T clinical MRI scanner was used to perform scans. After 3-plane localizer, T1 weighted imaging (T1WI), T2WI, and DCE-MRI using a three-dimensional gradient echo pulse sequence was performed. After 4 pre-contrast images were acquired, each rabbit was injected i.v. with 0.1 mmol/kg Dotarem. The total scan time after Dotarem administration was 30 minutes. All acquired images were analyzed using ImageJ software. Several regions of interest were selected from the rims of tumor, liver, and muscle. The enhancement ratio (ER) was calculated by dividing the MR signal after Dotarem injection to the MR signal before Dotarem injection. The maximum ER (ER_max) value of tumor for each rabbit was observed right after the Dotarem injection. The T2W MR signal intensities (T2W_SI) and the ER_max values obtained 7, 14, 21 and 28 days after tumor implantation were analyzed with a linear regression algorithm. Both T2W_SI and ER_max of tumors increased with time. The changes for T2W_SI and ER_max of tumors between 7 and 28 days after tumor implantation were 32.66% and 18.14%, respectively. T2W_SI is more sensitive than ER_max for monitoring the growth of VX2 tumor in a rabbit liver model.

  18. Dotlike hemosiderin spots on T2*-weighted magnetic resonance imaging as a predictor of stroke recurrence: a prospective study.

    Science.gov (United States)

    Imaizumi, Toshio; Horita, Yoshifumi; Hashimoto, Yuji; Niwa, Jun

    2004-12-01

    Microangiopathy associated with hypertension is a notable cause of cerebral small vessel disease (SVD), including deep intracerebral hemorrhage (ICH) and lacunar infarct. Dotlike low-intensity spots (dotlike hemosiderin spots: dotHSs) on T2*-weighted magnetic resonance (MR) images have been histologically diagnosed as old cerebral microbleeds associated with lipohyalinosis, amyloid angiopathy, or other microangiopathies and located in deep or subcortical regions. The aim of this study was to determine whether dotHSs indicate the severity of microangiopathy, and if so, whether large numbers of deep dotHSs are associated with SVD recurrence. The authors prospectively analyzed the number of dotHSs in 337 patients-191 men and 146 women with a mean age of 66 +/- 10.4 years (range 37-94 years)-with SVD (199 ICHs and 138 lacunar infarcts) who had been consecutively admitted to Hakodate Municipal Hospital. The follow-up period was 3.5 to 42 months (22.5 +/- 13.1 months). Patients were divided into two groups based on the recurrence. The hazard ratio (HR) for recurrence was estimated based on the Cox proportional hazard model by using the number of deep and subcortical dotHSs as well as other factors. Of 337 patients, 20 were readmitted with recurrence. Results of a multivariate analysis revealed an elevated rate of recurrence in patients with many subcortical dotHSs (> or = 5, HR 4.36, p = 0.0019) or a history of ICH (HR 3.82, p = 0.014). A trend toward a positive correlation (Pearson correlation coefficient 0.548, p < 0.0001) was found between the number of deep and subcortical dotHSs. Although a small sample size limited the power of analyses, the findings indicate that a large number of subcortical dotHSs may predict SVD recurrence.

  19. 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.

  20. Volumetric fat-water separated T2-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Vasanawala, Shreyas S.; Sonik, Arvind [Stanford University, Lucile Packard Children' s Hospital, Department of Radiology, Palo Alto, CA (United States); Madhuranthakam, Ananth J. [GE Healthcare, Global Applied Science Laboratory, Boston, MA (United States); Venkatesan, Ramesh [GE Healthcare, MR Engineering, Bangalore (India); Lai, Peng; Brau, Anja C.S. [GE Healthcare, Global Applied Science Laboratory, Menlo Park, CA (United States)

    2011-07-15

    Pediatric body MRI exams often cover multiple body parts, making the development of broadly applicable protocols and obtaining uniform fat suppression a challenge. Volumetric T2 imaging with Dixon-type fat-water separation might address this challenge, but it is a lengthy process. We develop and evaluate a faster two-echo approach to volumetric T2 imaging with fat-water separation. A volumetric spin-echo sequence was modified to include a second shifted echo so two image sets are acquired. A region-growing reconstruction approach was developed to decompose separate water and fat images. Twenty-six children were recruited with IRB approval and informed consent. Fat-suppression quality was graded by two pediatric radiologists and compared against conventional fat-suppressed fast spin-echo T2-W images. Additionally, the value of in- and opposed-phase images was evaluated. Fat suppression on volumetric images had high quality in 96% of cases (95% confidence interval of 80-100%) and were preferred over or considered equivalent to conventional two-dimensional fat-suppressed FSE T2 imaging in 96% of cases (95% confidence interval of 78-100%). In- and opposed-phase images had definite value in 12% of cases. Volumetric fat-water separated T2-weighted MRI is feasible and is likely to yield improved fat suppression over conventional fat-suppressed T2-weighted imaging. (orig.)

  1. Optimized T1- and T2-weighted volumetric brain imaging as a diagnostic tool in very preterm neonates

    Energy Technology Data Exchange (ETDEWEB)

    Nossin-Manor, Revital [Neurosciences and Mental Health, Research Institute, Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto (Canada); Chung, Andrew D.; Morris, Drew; Thomas, Bejoy; Shroff, Manohar M. [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Soares-Fernandes, Joao P. [The Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Hospital de S. Marcos, Neuroradiology Department, Braga (Portugal); Cheng, Hai-Ling M. [The Hospital for Sick Children, Department of Diagnostic Imaging, Physiology Experimental Medicine, Research Institute, Toronto (Canada); University of Toronto, Medical Biophysics Department, Toronto (Canada); Whyte, Hilary E.A. [Neurosciences and Mental Health, Research Institute, Neonatology Department, The Hospital for Sick Children, Toronto (Canada); Taylor, Margot J. [The Hospital for Sick Children, Neurosciences and Mental Health, Research Institute, Department of Diagnostic Imaging, Toronto (Canada); University of Toronto, Medical Imaging, Toronto (Canada); Sled, John G. [University of Toronto, Physiology Experimental Medicine, Research Institute, The Hospital for Sick Children, Medical Biophysics, Toronto (Canada)

    2011-06-15

    T1- and T2-W MR sequences used for obtaining diagnostic information and morphometric measurements in the neonatal brain are frequently acquired using different imaging protocols. Optimizing one protocol for obtaining both kinds of information is valuable. To determine whether high-resolution T1- and T2-W volumetric sequences optimized for preterm brain imaging could provide both diagnostic and morphometric value. Thirty preterm neonates born between 24 and 32 weeks' gestational age were scanned during the first 2 weeks after birth. T1- and T2-W high-resolution sequences were optimized in terms of signal-to-noise ratio, contrast-to-noise ratio and scan time and compared to conventional spin-echo-based sequences. No differences were found between conventional and high-resolution T1-W sequences for diagnostic confidence, image quality and motion artifacts. A preference for conventional over high-resolution T2-W sequences for image quality was observed. High-resolution T1 images provided better delineation of thalamic myelination and the superior temporal sulcus. No differences were found for detection of myelination and sulcation using conventional and high-resolution T2-W images. High-resolution T1- and T2-W volumetric sequences can be used in clinical MRI in the very preterm brain to provide both diagnostic and morphometric information. (orig.)

  2. Diffusion-and T2-weighted MR imaging of lipiodol induced cerebral infarcts in cat: early findings in the first 3 hours

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Dae Chul [Seoul National Univ. Hospital, Seoul (Korea, Republic of); Choe, Ghee Young [Seoul City Boramae Hospital, Seoul (Korea, Republic of); Moon, Chi Woong [Samsung Biomedical Research Institute, Seoul (Korea, Republic of)] [and others

    1997-06-01

    This study was designed to evaluate early parenchymal changes of acute cerebral is chemia/infarct by using T2-weighted, diffusion-weighted, and calculated apparent diffusion coefficient(ADC) MR imaging. The brain MR images were successfully obtained 30, 60, 90, 120, 150 and 180 minutes after intraarterial administration of Lipiodol (0.4-0.6ml) into the common carotid artery in 10 of 11 cats (91%). T2-and diffusion-weighted images and ADC were analyzed and compared with histopathologic findings. High signal intensity on T2-weighted and diffusion-weighted images was found in one cerebral hemisphere 30 minutes after Lipiodol injection, which tended to increase with time until 3 hours. Subcortical white matter showed higher signal intensity than cortical gray matter since 30 minutes after embolization. ADC images showed decreased signal intensity in the embolized hemisphere, which tended to decrease until 3 hours. Microscopic findings of the area corresponding to the abnormal signal intensity on MR images revealed varying degrees of edema in the gray and white matters involved. It is suggested that Lipiodol can be used as a good embolic agent causing early ischemic changes in experimental models. In addition to T2-weighted images, diffusion-weighted and ADC images can provide the further informations in the evaluation of the early parenchymal changes of cerebral infarct.

  3. Pulmonary nodule detection in oncological patients - Value of respiratory-triggered, periodically rotated overlapping parallel T2-weighted imaging evaluated with PET/CT-MR.

    Science.gov (United States)

    de Galiza Barbosa, Felipe; Geismar, Jan Henning; Delso, Gaspar; Messerli, Michael; Huellner, Martin; Stolzmann, Paul; Veit-Haibach, Patrick

    2018-01-01

    To prospectively evaluate the detection and conspicuity of pulmonary nodules in an oncological population, using a tri-modality PET/CT-MR protocol including a respiration-gated T2-PROPELLER sequence for possible integration into a simultaneous PET/MR protocol. 149 patients referred for staging of malignancy were prospectively enrolled in this single-center study. Imaging was performed on a tri-modality PET/CT-MR setup and was comprised of PET/CT and 3T-MR imaging with 3D dual-echo GRE pulse sequence (Dixon) and an axial respiration-gated T2-weighted PROPELLER (T2-P) sequence. Images were assessed for presence, conspicuity, size and interpretation of the pulmonary parenchymal nodules. McNemar's test was used to evaluate paired differences in nodule detection rates between MR and CT from PET/CT. The correlation of pulmonary nodule size in CT and MR imaging was assessed using Pearson correlation coefficient. 299 pulmonary nodules were detected on PET/CT. The detectability was significantly higher on T2-P (60%, p10mm were detected equally well with T2-P (92.2%) and CT (p >0.05). In a per-patient analysis, there was no significant change in the clinical interpretation of the nodules detected with T2-P and CT. Despite the overall lower detection rate compared with CT, the free-breathing respiratory gating T2-w sequence showed higher detectability in all evaluated categories compared to breath-hold T1-weighted MR sequences. Specifically, the T2-P was found to be not statistically different from CT in FDG-positive nodules, in detection of nodules >10mm and concerning conspicuity of pulmonary nodules. Overall, the additional time investment into T2-P seems to be justified since clinical relevant assessment of pulmonary lung nodules can mostly be done by T2-P in a whole body PET/MR staging of oncologic patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Improving the detectability of focal liver lesions on T2-weighted MR images: ultrafast breath-hold or respiratory-triggered thin-section MRI?

    Science.gov (United States)

    Pauleit, D; Textor, J; Bachmann, R; Conrad, R; Flacke, S; Kreft, B; Schild, H

    2001-08-01

    The purpose of this study was to determine whether a respiratory-triggered (RT) T2-weighted turbo spin-echo (TSE) sequence with thin section can improve the detectability of focal liver lesions compared to a breath-hold (BH) T2-weighted TSE sequence. In 25 patients an RT TSE with 8-mm sections (8-TSE RT) and 5-mm sections (5-TSE RT) and a BH TSE sequence with 8-mm sections (8-TSE BH) were performed. Forty-one focal liver lesions (mean: 1.8 +/- 1.2 cm; 14 lesions 1 cm) were evaluated. The 5-TSE RT was significantly better in lesion detection compared to the 8-TSE BH sequence for all sizes of lesions (40/41 vs. 33/41; P = 0.014). For lesions >1 cm no relevant differences in the detection rate of the sequences were found (8-TSE RT, 26/27; 5-TSE RT, 26/27; 8-TSE BH, 25/27), for lesions < or =1 cm the 5-TSE RT provided significantly better sensitivity than the 8-TSE BH (14/14 vs. 8/14, P = 0.015). The results of this study suggest that lesion detection could be significantly improved by using an RT TSE sequence with thin sections compared with a BH TSE sequence. Copyright 2001 Wiley-Liss, Inc.

  5. MR imaging of cranial nerve lesions using six different high-resolution T1- and T2(*)-weighted 3D and 2D sequences

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, J.; Held, P.; Strotzer, M.; Voelk, M.; Nitz, W.R.; Dorenbeck, U.; Feuerbach, S. [Univ. Hospital of Regensburg (Germany). Dept. of Diagnostic Radiology; Stamato, S. [Univ. of California, San Diego, CA (United States). Dept. of Radiology

    2002-07-01

    Purpose: To find a suitable high-resolution MR protocol for the visualization of lesions of all 12 cranial nerves. Material and Methods: Thirty-eight pathologically changed cranial nerves (17 patients) were studied with MR imaging at 1.5T using 3D T2*-weighted CISS, T1-weighted 3D MP-RAGE (without and with i.v. contrast medium), T2-weighted 3D TSE, T2-weighted 2D TSE and T1-weighted fat saturation 2D TSE sequences. Visibility of the 38 lesions of the 12 cranial nerves in each sequence was evaluated by consensus of two radiologists using an evaluation scale from 1 (excellently visible) to 4 (not visible). Results: The 3D CISS sequence provided the best resolution of the cranial nerves and their lesions when surrounded by CSF. In nerves which were not surrounded by CSF, the 2D T1-weighted contrast-enhanced fat suppression technique was the best sequence. Conclusions: A combination of 3D CISS, the 2D T1-weighted fat suppressed sequence and a 3D contrast-enhanced MP-RAGE proved to be the most useful sequence to visualize all lesions of the cranial nerves. For the determination of enhancement, an additional 3D MP-RAGE sequence without contrast medium is required. This sequence is also very sensitive for the detection of hemorrhage.

  6. Imaging of VSOP labeled stem cells in agarose phantoms with susceptibility weighted and T2* weighted MR Imaging at 3T: determination of the detection limit.

    Directory of Open Access Journals (Sweden)

    Donald Lobsien

    Full Text Available OBJECTIVES: This study aimed to evaluate the detectability of stem cells labeled with very small iron oxide particles (VSOP at 3T with susceptibility weighted (SWI and T2* weighted imaging as a methodological basis for subsequent examinations in a large animal stroke model (sheep. MATERIALS AND METHODS: We examined ovine mesenchymal stem cells labeled with VSOP in agarose layer phantoms. The experiments were performed in 2 different groups, with quantities of 0-100,000 labeled cells per layer. 15 different SWI- and T2*-weighted sequences and 3 RF coils were used. All measurements were carried out on a clinical 3T MRI. Images of Group A were analyzed by four radiologists blinded for the number of cells, and rated for detectability according to a four-step scale. Images of Group B were subject to a ROI-based analysis of signal intensities. Signal deviations of more than the 0.95 confidence interval in cell containing layers as compared to the mean of the signal intensity of non cell bearing layers were considered significant. RESULTS: GROUP A: 500 or more labeled cells were judged as confidently visible when examined with a SWI-sequence with 0.15 mm slice thickness. Group B: 500 or more labeled cells showed a significant signal reduction in SWI sequences with a slice thickness of 0.25 mm. Slice thickness and cell number per layer had a significant influence on the amount of detected signal reduction. CONCLUSION: 500 VSOP labeled stem cells could be detected with SWI imaging at 3 Tesla using an experimental design suitable for large animal models.

  7. Entropy of T2-weighted imaging combined with apparent diffusion coefficient in prediction of uterine leiomyoma volume response after uterine artery embolization.

    Science.gov (United States)

    Cao, Meng-Qiu; Suo, Shi-Teng; Zhang, Xue-Bin; Zhong, Yi-Cun; Zhuang, Zhi-Guo; Cheng, Jie-Jun; Chi, Jia-Chang; Xu, Jian-Rong

    2014-04-01

    To determine the potential value of entropy of T2-weighted imaging combined with apparent diffusion coefficient (ADC) before uterine artery embolization (UAE) for prediction of uterine leiomyoma volume reduction (VR) after UAE. In this prospective study, 11 patients with uterine leiomyomas who underwent pelvic magnetic resonance imaging including diffusion-weighted imaging before and 6 months after UAE were included. A total number of 16 leiomyomas larger than 2 cm in diameter were evaluated. The volume of each leiomyoma before and after UAE was determined, and the percentage change in volume was calculated. Entropy of T2-weighted imaging and ADC before UAE were assessed. Pearson correction coefficients were calculated between leiomyoma VR after UAE and age, leiomyoma volume, ADC, and entropy, respectively. Multiple regression analysis was performed to investigate the parameters that determine the VR after UAE. Receiver operating characteristic curve analysis was used to determine the sensitivity and specificity of ADC, entropy and the combination of ADC and entropy for predicting volume response. The mean leiomyoma VR was 58.9% (range 25.8%-95.0%) in the 6-month follow-up. The mean ADC of leiomyomas was 1.37 × 10(-3) mm(2)/s (range 1.05 × 10(-3)-2.32 × 10(-3) mm(2)/s) and the mean entropy of T2-weighted imaging was 5.36 (range 4.62-5.91) before UAE. ADC and entropy were significantly correlated with leiomyoma VR, respectively (r = 0.61, P = .012; r = 0.73, P = .001). On multiple regression analysis, a combination of ADC and entropy constituted the best model for determining leiomyoma VR using Akaike information criterion. For predicting ≥50% VR, the optimal cutoff value of ADC was 1.39 × 10(-3) mm(2)/s (sensitivity 45.5%, specificity 80.0%) and the optimal cutoff value of entropy was 5.15 (sensitivity 90.9%, specificity 60.0%). The combination of ADC and entropy (area under the curve [AUC] 0.86) provided better classification accuracy than ADC or entropy

  8. Non-contrast magnetic resonance imaging for bladder cancer: fused high b value diffusion-weighted imaging and T2-weighted imaging helps evaluate depth of invasion

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minsu; Oh, Young Taik; Jung, Dae Chul; Park, Sung Yoon [Yonsei University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Shin, Su-Jin [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Hanyang University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Cho, Nam Hoon [Yonsei University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Choi, Young Deuk [Yonsei University College of Medicine, Department of Urology, Seoul (Korea, Republic of)

    2017-09-15

    To investigate the utility of fused high b value diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI) for evaluating depth of invasion in bladder cancer. We included 62 patients with magnetic resonance imaging (MRI) and surgically confirmed urothelial carcinoma in the urinary bladder. An experienced genitourinary radiologist analysed the depth of invasion (T stage <2 or ≥2) using T2WI, DWI, T2WI plus DWI, and fused DWI and T2WI (fusion MRI). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were investigated. Area under the curve (AUC) was analysed to identify T stage ≥2. The rate of patients with surgically confirmed T stage ≥2 was 41.9% (26/62). Sensitivity, specificity, PPV, NPV and accuracy were 50.0%, 55.6%, 44.8%, 60.6% and 53.2%, respectively, with T2WI; 57.7%, 77.8%, 65.2%, 71.8% and 69.4%, respectively, with DWI; 65.4%, 80.6%, 70.8%, 76.3% and 74.2%, respectively, with T2WI plus DWI and 80.8%, 77.8%, 72.4%, 84.9% and 79.0%, respectively, with fusion MRI. AUC was 0.528 with T2WI, 0.677 with DWI, 0.730 with T2WI plus DWI and 0.793 with fusion MRI for T stage ≥2. Fused high b value DWI and T2WI may be a promising non-contrast MRI technique for assessing depth of invasion in bladder cancer. (orig.)

  9. Comparison of dynamic contrast-enhanced magnetic resonance imaging with T2-weighted imaging for preoperative staging of early endometrial carcinoma

    Directory of Open Access Journals (Sweden)

    Zheng L

    2015-07-01

    Full Text Available Linfeng Zheng,1,2 Sujuan Zheng,3 Xiaochun Yuan,1 Xifu Wang,1 Zhuoli Zhang,2 Guixiang Zhang1 1Department of Radiology, Shanghai First People’s Hospital, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; 2Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 3Department of Obstetrics and Gynecology, Dengfeng People’s Hospital, Zhengzhou, People’s Republic of China Purpose: This study aimed to compare dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI with T2-weighted imaging (T2WI for the preoperative staging of early endometrial carcinoma. Methods: This retrospective study included 22 subjects with early endometrial carcinoma who underwent 3.0 T MRI examination prior to hysterectomy. DCE-MRI and T2WI were evaluated for the preoperative staging of endometrial carcinoma. The sensitivity, specificity, positive predictive value (PPV, negative predictive value (NPV, and accuracy of DCE-MRI and T2WI were assessed and compared using the revised International Federation of Gynecology and Obstetrics surgical staging guidelines (2009 as the reference standard. Results: Out of the 22 cases of endometrial carcinoma, the use of the reference standard method led to the staging of 14 as IA and eight as IB. The sensitivity, specificity, PPV, NPV, and accuracy of DCE-MRI for preoperative staging were 100% (95% confidence interval: 0.73–1.0, 62.5% (95% CI: 0.26–0.90, 82.4% (95% CI: 0.56–0.95, 100% (95% CI: 0.46–1.0, and 86.4%, respectively, and these values were 85.7% (95% CI: 0.56–0.97, 75% (95% CI: 0.36–0.96, 85.7% (95% CI: 0.56–0.97, 75% (95% CI: 0.36–0.96, and 81.8%, respectively, for T2WI. Thus, the sensitivity and accuracy of DCE-MRI were greater than those of T2WI for preoperative endometrial carcinoma staging. Conclusion: DCE-MRI was more sensitive but less specific than T2WI for the preoperative staging of early endometrial carcinoma. DCE-MRI may serve as a

  10. Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images - Generalized technique for four different MR scanners.

    Science.gov (United States)

    Koivula, Lauri; Kapanen, Mika; Seppälä, Tiina; Collan, Juhani; Dowling, Jason A; Greer, Peter B; Gustafsson, Christian; Gunnlaugsson, Adalsteinn; Olsson, Lars E; Wee, Leonard; Korhonen, Juha

    2017-12-01

    Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2 w ) MR images of the pelvis. This study developed a generalized dual model HU conversion method to convert standard T2 w MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors. For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 ± 6 HUs (34 HUs) and -46 ± 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 ± 0.4% (-1.3%). The study provides a generalized method for sCT creation from standard T2 w images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence

    NARCIS (Netherlands)

    van Nierop, Bastiaan J.; Bax, Noortje A. M.; Nelissen, Jules L.; Arslan, Fatih; Motaal, Abdallah G.; de Graaf, Larry; Zwanenburg, Jaco J. M.; Luijten, Peter R.; Nicolay, Klaas; Strijkers, Gustav J.

    2015-01-01

    Background Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI). Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using

  12. High Signal Intensity on T2-Weighted Cardiovascular Magnetic Resonance Imaging Predicts Life-Threatening Arrhythmic Events in Hypertrophic Cardiomyopathy Patients.

    Science.gov (United States)

    Hen, Yasuki; Takara, Ayako; Iguchi, Nobuo; Utanohara, Yuko; Teraoka, Kunihiko; Takada, Kaori; Machida, Haruhiko; Takamisawa, Itaru; Takayama, Morimasa; Yoshikawa, Tsutomu

    2018-02-21

    The prognostic value of high signal intensity on T2-weighted cardiovascular magnetic resonance imaging (T2 high signal) in hypertrophic cardiomyopathy (HCM) patients in a single-center cohort was investigated.Methods and Results:A total of 237 HCM patients (median age, 62 years; 143 male) underwent T2-weighted, cine and late gadolinium enhancement (LGE) imaging, and were followed (median duration, 3.4 years) for life-threatening arrhythmic events. The clinical and magnetic resonance imaging characteristics were extracted, and predictors of life-threatening arrhythmic events were assessed on multivariate analysis. LGE was present in 180 patients (75.9%). Median LGE score was 3 in a left ventricle 17-segment model. T2 high signal was present in 49 patients (20.7%). The annual events rate was significantly higher in patients with extensive LGE (score ≥4) than in those without (3.0%/year vs. 0.5%/year, P=0.011). On multivariate analysis, extensive LGE (hazard ratio, 5.650; 95% CI: 1.263-25.000, P=0.024) as an independent predictor for life-threatening arrhythmic events. In patients with extensive LGE, the annual events rate was significantly higher in patients with T2 high signal than in those without (5.8%/year vs. 0.9%/year, P=0.008). Extensive LGE was an independent predictor of life-threatening arrhythmic events in HCM patients. Furthermore, T2 high signal is useful for the risk stratification of serious arrhythmic events in patients with extensive LGE.

  13. Mucocele-like lesions of the sphenoid sinus with hypointense foci on T2-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ishibashi, T. [Dept. of Otolaryngology, Social Insurance Central General Hospital, Tokyo (Japan); Kikuchi, S. [Dept. of Otolaryngology, Tokyo Univ. Branch Hospital, Tokyo (Japan)

    2001-12-01

    Lesions limited to the sphenoid sinus are relatively rare, and are obscure with respect to symptoms and physical findings. The differential diagnosis of isolated sphenoid sinus disease includes bacterial sinusitis, fungal infection, granulomatous inflammation, mucocele, and tumors. Magnetic resonance imaging (MRI) can provide information that closely reflects the composition of the tissues, sometimes permitting differentiation between pathologically distinct lesions showing similar density by computed tomography. We describe two cases involving mucocele-like lesions of the sphenoid sinus where preoperative MRI revealed a focus of hypointensity within the lesions. In both patients the sphenoid sinus was opened by a transnasal endoscopic approach, and diseased tissue corresponding to the hypointense area was removed under direct endoscopic vision. Histopathological diagnosis revealed colonies of Aspergillus in one case and necrotic granulation tissue without fungus in the other. We concluded that MRI is a crucial part of preoperative evaluation and that the transnasal endoscopic approach represents a safe and effective method for treating nonmalignant isolated sphenoid sinus disease. (orig.)

  14. Cerebral signal intensity abnormalities on T2-weighted MR images in HIV patients with highly active antiretroviral therapy: relationship with clinical parameters and interval changes.

    Science.gov (United States)

    Hanning, Uta; Husstedt, Ingo W; Niederstadt, Thomas-Ulrich; Evers, Stefan; Heindel, Walter; Kloska, Stephan P

    2011-09-01

    The aim of this study was to assess the relationship between immune state and cerebral signal intensity abnormalities (SIAs) on T2-weighted magnetic resonance images in subjects with human immunodeficiency virus type 1 infection and highly active antiretroviral therapy. Thirty-two subjects underwent a total of 109 magnetic resonance studies. The presence of human immunodeficiency virus-associated neurocognitive disorder, categorized CD4(+) T lymphocyte count, and plasma viral load were assessed for relationship with the severity and interval change of SIAs for different anatomic locations of the brain. Subjects with multifocal patterns of SIAs had CD4(+) cell counts < 200 cells/μL in 66.0%, whereas subjects with diffuse patterns of SIAs had CD4(+) cell counts < 200 cells/μL in only 31.4% (P < .001). Subjects without SIAs in the basal ganglia had CD4(+) cell counts < 200 cells/μL in 37.0%, whereas subjects with minor and moderate SIAs in the basal ganglia had CD4(+) cell counts < 200 cells/μL in 78.3% and 80.0%, respectively (P < .005). The percentage of subjects with CD4(+) cell counts < 200 cells/μL was 85.7% when there were progressive periventricular SIA changes and 45.5% when periventricular SIA changes were stable in follow-up (P < .05). The presence and progression of cerebral SIAs on T2-weighted magnetic resonance images reflecting cerebral infection with human immunodeficiency virus are significantly related to impaired immune state as measured by CD4(+) cell count. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  15. Multiband echo-shifted echo planar imaging

    NARCIS (Netherlands)

    Boyacioǧlu, R.; Schulz, J.; Norris, David Gordon

    2016-01-01

    Purpose To propose the technique multiband echo-shifted (MESH) echo planar imaging (EPI), which combines the principles of echo-shifted acquisition for two-dimensional multislice EPI, with both in-plane and multiband acceleration by means of partial parallel imaging techniques. Methods MESH EPI is

  16. Fast spin-echo MR imaging of the eye

    Energy Technology Data Exchange (ETDEWEB)

    Hosten, N. [Dept. of Radiology, Virchow Klinikum, Humboldt Univ., Berlin (Germany); Lemke, A.J. [Dept. of Radiology, Virchow Klinikum, Humboldt Univ., Berlin (Germany); Bornfeld, N. [Dept. of Ophtalmology, Klinikum Benjamin Franklin, Freie Univ. Berlin (Germany); Wassmuth, R. [Dept. of Radiology, Virchow Klinikum, Humboldt Univ., Berlin (Germany); Schweiger, U. [Dept. of Radiology, Virchow Klinikum, Humboldt Univ., Berlin (Germany); Terstegge, K. [Dept. of Ophtalmology, Klinikum Benjamin Franklin, Freie Univ. Berlin (Germany); Felix, R. [Dept. of Radiology, Virchow Klinikum, Humboldt Univ., Berlin (Germany)

    1996-12-01

    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.)

  17. Predictive value of T2-weighted imaging and contrast-enhanced MR imaging in assessing myometrial invasion in endometrial cancer: a pooled analysis of prospective studies

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Lian-Ming [Shanghai Jiao Tong University School of Medicine, Department of Radiology, Renji Hospital, Shanghai (China); Wayne State University, Department of Radiology, Detroit, MI (United States); Xu, Jian-Rong; Gu, Hai-Yan; Hua, Jia [Shanghai Jiao Tong University School of Medicine, Department of Radiology, Renji Hospital, Shanghai (China); Haacke, E.M.; Hu, Jiani [Wayne State University, Department of Radiology, Detroit, MI (United States)

    2013-02-15

    To obtain diagnostic performance values of T2-weighted imaging (T2WI) and contrast-enhanced magnetic resonance imaging (CE-MRI) in the prediction of myometrial invasion in patients with endometrial cancer. Databases including MEDLINE and EMBASE were searched for relevant original articles published from January1995 to March 2012. Pooled estimation data were obtained by statistical analysis. Eleven articles (548 patients) were included. For assessing any myometrial involvement, the pooled sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for CE-MRI were 0.81 (95% CI, 0.72, 0.88), 0.72 (95% CI, 0.64, 0.79), 0.65 (95% CI, 0.56, 0.73) and 0.85 (95% CI, 0.78, 0.91); for T2WI, they were 0.87 (95% CI, 0.78, 0.94), 0.58 (95% CI, 0.47, 0.69), 0.64 (95% CI, 0.54, 0.73), 0.84 (95% CI, 0.73, 0.92) respectively. The pooled specificity of CE-MRI (0.72) was significantly higher than T2WI (0.58) (P < 0.05). For assessing deep myometrial involvement, there was no statistically significant difference between CE-MRI and T2WI, (P > 0.05). CE-MRI has a good diagnostic performance in the prediction of any myometrial invasion and is superior to T2WI. But its PPV is somewhat suboptimal. For assessing deep myometrial involvement, its NPV appears relative high and negative findings strongly suggest an absence of deep myometrial involvement, which can guide therapeutic decision-making. (orig.)

  18. Design of universal parallel-transmit refocusing kT -point pulses and application to 3D T2 -weighted imaging at 7T.

    Science.gov (United States)

    Gras, Vincent; Mauconduit, Franck; Vignaud, Alexandre; Amadon, Alexis; Le Bihan, Denis; Stöcker, Tony; Boulant, Nicolas

    2017-11-29

    T2 -weighted sequences are particularly sensitive to the radiofrequency (RF) field inhomogeneity problem at ultra-high-field because of the errors accumulated by the imperfections of the train of refocusing pulses. As parallel transmission (pTx) has proved particularly useful to counteract RF heterogeneities, universal pulses were recently demonstrated to save precious time and computational efforts by skipping B1 calibration and online RF pulse tailoring. Here, we report a universal RF pulse design for non-selective refocusing pulses to mitigate the RF inhomogeneity problem at 7T in turbo spin-echo sequences with variable flip angles. Average Hamiltonian theory was used to synthetize a single non-selective refocusing pulse with pTx while optimizing its scaling properties in the presence of static field offsets. The design was performed under explicit power and specific absorption rate constraints on a database of 10 subjects using a 8Tx-32Rx commercial coil at 7T. To validate the proposed design, the RF pulses were tested in simulation and applied in vivo on 5 additional test subjects. The root-mean-square rotation angle error (RA-NRMSE) evaluation and experimental data demonstrated great improvement with the proposed universal pulses (RA-NRMSE ∼8%) compared to the standard circularly polarized mode of excitation (RA-NRMSE ∼26%). This work further completes the spectrum of 3D universal pulses to mitigate RF field inhomogeneity throughout all 3D MRI sequences without any pTx calibration. The approach returns a single pulse that can be scaled to match the desired flip angle train, thereby increasing the modularity of the proposed plug and play approach. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  19. Diffusion-weighted and T2-weighted MR imaging for colorectal liver metastases detection in a rat model at 7 T: a comparative study using histological examination as reference

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Mathilde; Ronot, Maxime; Vilgrain, Valerie; Beers, Bernard E. van [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique- Hopitaux de Paris, Laboratory of Physiological and Molecular Imaging of the Abdomen (IPMA) and Department of Radiology, Clichy Cedex (France); Maggiori, Leon; Panis, Yves [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique-Hopitaux de Paris, Department of Colorectal Surgery, Clichy (France); Paradis, Valerie [University Paris Diderot, Sorbonne Paris Cite, INSERM UMR 773, University Hospitals Paris Nord Val de Seine, Beaujon, Assistance Publique-Hopitaux de Paris, Department of Pathology, Clichy (France)

    2013-08-15

    To compare diffusion-weighted (DW) and T2-weighted MR imaging in detecting colorectal liver metastases in a rat model, using histological examination as a reference method. Eighteen rats had four liver injections of colon cancer cells. MR examinations at 7 T included FSE-T2-weighted imaging and SE-DW MR imaging (b = 0, 20 and 150 s/mm{sup 2}) and were analysed by two independent readers. Histological examination was performed on 0.4-mm slices. McNemar's test was used to compare the sensitivities and the Wilcoxon matched pairs test to compare the average number of false-positives per rat. One hundred and sixty-six liver metastases were identified on histological examination. The sensitivity in detecting liver metastases was significantly higher on DW MR than on T2-weighted images (99/166 (60 %) (reader 1) and 92/166 (55 %) (reader 2) versus 77/166 (46 %), P {<=} 0.001), without an increase in false-positives per rat (P = 0.773/P = 0.850). After stratification according to metastasis diameter, DW MR imaging had a significantly higher sensitivity than T2-weighted imaging only for metastases with a diameter (0.6-1.2 mm) similar to that of the spatial resolution of MR imaging in the current study. This MR study with histological correlations shows the higher sensitivity of DW relative to T2-weighted imaging at 7 T for detecting liver metastases, especially small ones. (orig.)

  20. Histogram Analysis of T1-Weighted, T2-Weighted, and Postcontrast T1-Weighted Images in Primary CNS Lymphoma: Correlations with Histopathological Findings-a Preliminary Study.

    Science.gov (United States)

    Meyer, Hans-Jonas; Schob, Stefan; Münch, Benno; Frydrychowicz, Clara; Garnov, Nikita; Quäschling, Ulf; Hoffmann, Karl-Titus; Surov, Alexey

    2017-09-01

    Previously, some reports mentioned that magnetic resonance imaging (MRI) can predict histopathological features in primary CNS lymphoma (PCNSL). The reported data analyzed diffusion-weighted imaging findings. The aim of this study was to investigate possible associations between histopathological findings, such as tumor cellularity, nucleic areas and proliferation index Ki-67, and signal intensity on T1-weighted and T2-weighted images in PCNSL. For this study, 18 patients with PCNSL were retrospectively investigated by histogram analysis on precontrast and postcontrast T1-weighted and fluid-attenuated inversion recovery (FLAIR) images. For every patient, histopathology parameters, nucleic count, total nucleic area, and average nucleic area, as well as Ki-67 index, were estimated. Correlation analysis identified several statistically significant associations. Skewness derived from precontrast T1-weighted images correlated with Ki-67 index (p = - 0.55, P = 0.028). Furthermore, entropy derived from precontrast T1-weighted images correlated with average nucleic area (p = 0.53, P = 0.04). Several parameters from postcontrast T1-weighted images correlated with nucleic count: maximum signal intensity (p = 0.59, P = 0.017), P75 (p = 0.56, P = 0.02), and P90 (p = 0.52, P = 0.04) as well as SD (p = 0.58, P = 0.02). Maximum signal intensity derived from FLAIR sequence correlated with nucleic count (p = 0.50, P = 0.03). Histogram-derived parameters of conventional MRI sequences can reflect different histopathological features in PSNCL.

  1. Is the Susceptibility Vessel Sign on 3-Tesla Magnetic Resonance T2*-Weighted Imaging a Useful Tool to Predict Recanalization in Intravenous Tissue Plasminogen Activator?

    Science.gov (United States)

    Yamamoto, N; Satomi, J; Harada, M; Izumi, Y; Nagahiro, S; Kaji, R

    2016-09-01

    The aim of this study was to investigate the independent factors associated with the absence of recanalization approximately 24 h after intravenous administration of tissue-type plasminogen activator (IV TPA). The previous studies have been conducted using 1.5-Tesla (T) magnetic resonance imaging (MRI). We studied whether the characteristics of 3-T MRI findings were useful to predict outcome and recanalization after IV tPA. Patients with internal carotid artery (ICA) or middle cerebral artery (MCA) (horizontal portion, M1; Sylvian portion, M2) occlusion and treated by IV tPA were enrolled. We studied whether the presence of susceptibility vessel sign (SVS) at M1 and low clot burden score on T2*-weighted imaging (T2*-CBS) on 3-T MRI were associated with the absence of recanalization. A total of 49 patients were enrolled (27 men; mean age, 73.9 years). MR angiography obtained approximately 24 h after IV tPA revealed recanalization in 21 (42.9 %) patients. Independent factors associated with the absence of recanalization included ICA or proximal M1 occlusion (odds ratio, 69.6; 95 % confidence interval, 5.05-958.8, p = 0.002). In this study, an independent factor associated with the absence of recanalization may be proximal occlusion of the cerebral arteries rather than SVS in the MCA or low T2*-CBS on 3-T MRI.

  2. Measuring the volume of brain tumour and determining its location in T2-weighted MRI images using hidden Markov random field: expectation maximization algorithm

    Science.gov (United States)

    Mat Jafri, Mohd. Zubir; Abdulbaqi, Hayder Saad; Mutter, Kussay N.; Mustapha, Iskandar Shahrim; Omar, Ahmad Fairuz

    2017-06-01

    A brain tumour is an abnormal growth of tissue in the brain. Most tumour volume measurement processes are carried out manually by the radiographer and radiologist without relying on any auto program. This manual method is a timeconsuming task and may give inaccurate results. Treatment, diagnosis, signs and symptoms of the brain tumours mainly depend on the tumour volume and its location. In this paper, an approach is proposed to improve volume measurement of brain tumors as well as using a new method to determine the brain tumour location. The current study presents a hybrid method that includes two methods. One method is hidden Markov random field - expectation maximization (HMRFEM), which employs a positive initial classification of the image. The other method employs the threshold, which enables the final segmentation. In this method, the tumour volume is calculated using voxel dimension measurements. The brain tumour location was determined accurately in T2- weighted MRI image using a new algorithm. According to the results, this process was proven to be more useful compared to the manual method. Thus, it provides the possibility of calculating the volume and determining location of a brain tumour.

  3. Prostate cancer: utility of fusion of T2-weighted and high b-value diffusion-weighted images for peripheral zone tumor detection and localization.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Mannelli, Lorenzo; Kong, Xiangtian; Niver, Ben E; Berkman, Douglas S; Babb, James S; Melamed, Jonathan; Taneja, Samir S

    2011-07-01

    To retrospectively assess the utility of fusion of T2-weighted images (T2WI) and high b-value diffusion-weighted images (DWI) for prostate cancer detection and localization. In this IRB-approved HIPAA-compliant study, 42 patients with prostate cancer underwent MRI including multiplanar T2WI and axial DWI before prostatectomy. Two independent radiologists first assessed multiplanar T2WI and axial DWI(b-1000) images and recorded whether tumor was present in each sextant. Axial T2WI was then fused with axial DWI(b-1000) images, and the radiologists re-evaluated each sextant for tumor. Accuracy was compared using generalized estimating equations based on a binary logistic regression model. The accuracy, sensitivity, specificity, PPV, and NPV for tumor detection on a sextant-basis using separate and fused image sets was 65.1%, 50.8%, 78.0%, 67.8%, and 63.6% and 71.0%, 60.8%, 80.3%, 73.7%, and 69.3%, respectively, for reader 1, and 54.0%, 42.5%, 64.4%, 52.0%, and 55.2%, and 61.1%, 56.7%, 65.2%, 59.6%, and 62.3%, respectively, for reader 2. The improvements in accuracy, sensitivity, and NPV using fused images were statistically significant for both readers, as was the improvement in PPV for reader 2 (P ranging from sextant-basis, with similar specificity. Copyright © 2011 Wiley-Liss, Inc.

  4. Detection of the index tumour and tumour volume in prostate cancer using T2-weighted and diffusion-weighted magnetic resonance imaging (MRI) alone.

    Science.gov (United States)

    Rud, Erik; Klotz, Dagmar; Rennesund, Kristin; Baco, Eduard; Berge, Viktor; Lien, Diep; Svindland, Aud; Lundeby, Eskild; Berg, Rolf E; Eri, Lars M; Eggesbø, Heidi B

    2014-12-01

    To examine the performance of T2-weighted (T2W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) for detecting the index tumour in patients with prostate cancer and to examine the agreement between MRI and histology when assessing tumour volume (TV) and overall tumour burden. The study included 199 consecutive patients with biopsy confirmed prostate cancer randomised to MRI before radical prostatectomy from December 2009 to July 2012. MRI-detected tumours (MRTs) were ranked from 1 to 3 according to decreasing volume and were compared with histologically detected tumours (HTs) ranked from 1 to 3, with HT 1 = index tumour. Whole-mount section histology was used as a reference standard. The TVs of true-positive MRTs (MRTVs 1-3) were compared with the TVs found by histology (HTVs 1-3). All tumours were registered on a 30-sector map and by classifying each sector as positive/negative, the rate of true-positive and -negative sectors was calculated. The detection rate for the HT 1 (index tumour) was 92%; HT 2, 45%; and HT 3, 37%. The MRTV 1-3 vs the HTV 1-3 were 2.8 mL vs 4.0 mL (index tumour, P MRI detects the index tumour in 92% of cases, although MRI underestimates both TV and tumour burden compared with histology. © 2014 The Authors. BJU International © 2014 BJU International.

  5. In vivo assessment of iron content of the cerebral cortex in healthy aging using 7-Tesla T2*-weighted phase imaging.

    Science.gov (United States)

    Buijs, Mathijs; Doan, Nhat Trung; van Rooden, Sanneke; Versluis, Maarten J; van Lew, Baldur; Milles, Julien; van der Grond, Jeroen; van Buchem, Mark A

    2017-05-01

    Accumulation of brain iron has been suggested as a biomarker of neurodegeneration. Increased iron has been seen in the cerebral cortex in postmortem studies of neurodegenerative diseases and healthy aging. Until recently, the diminutive thickness of the cortex and its relatively low iron content have hampered in vivo study of cortical iron accumulation. Using phase images of a T2*-weighted sequence at ultrahigh field strength (7 Tesla), we examined the iron content of 22 cortical regions in 70 healthy subjects aged 22-80 years. The cortex was automatically segmented and parcellated, and phase shift was analyzed using an in-house developed method. We found a significant increase in phase shift with age in 20 of 22 cortical regions, concurrent with current understanding of cortical iron accumulation. Our findings suggest that increased cortical iron content can be assessed in healthy aging in vivo. The high spatial resolution and sensitivity to iron of our method make it a potentially useful tool for studying cortical iron accumulation in healthy aging and neurodegenerative diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Cardiac MRI: T2-Mapping Versus T2-Weighted Dark-Blood TSE Imaging for Myocardial Edema Visualization in Acute Myocardial Infarction.

    Science.gov (United States)

    Naßenstein, K; Nensa, F; Schlosser, T; Bruder, O; Umutlu, L; Lauenstein, T; Maderwald, S; Ladd, M E

    2014-02-01

    To assess the diagnostic accuracy of T2 mapping for the detection of myocardial edema in acute myocardial infarction (AMI), and to compare this diagnostic accuracy with that of the current standard for myocardial edema imaging, which is T2w dark-blood TSE imaging. 29 patients with AMI were examined at 1.5 T. For the visualization of myocardial edema, T2 maps, calculated from three T2w SSFP images, and T2w dark-blood TSE images were acquired in standard short- and long-axis views. Cine SSFP images were acquired for the analysis of left ventricular (LV) function and late gadolinium enhancement images (LGE) for the visualization of myocardial necrosis. The T2 maps as well as the T2w dark-blood TSE images were evaluated twice independently from the cine SSFP and LGE images. The presence or absence of myocardial edema was rated visually for each LV segment. As the standard of reference, the infarct zone was defined based on the cine SSFP and the LGE images. In this segment-based analysis, T2 mapping showed a sensitivity of 82 % and a specificity of 94 % for the detection of edema in the infarct zone. T2w dark-blood TSE imaging revealed a sensitivity of 50 % and a specificity of 98 %. T2 mapping showed a higher intra-rater agreement compared to T2w dark-blood TSE imaging (κ: 0.87 vs. 0.76). T2 mapping allows for the visualization of myocardial edema in AMI with a high sensitivity and specificity, and features better diagnostic accuracy in terms of a higher sensitivity compared to T2w dark-blood TSE imaging. Citation Format: • Naßenstein K, Nensa F, Schlosser T et al. Cardiac MRI: T2-Mapping Versus T2-Weighted Dark-Blood TSE Imaging for Myocardial Edema Visualization in Acute Myocardial Infarction. Fortschr Röntgenstr 2014; 186: 166 - 172. © Georg Thieme Verlag KG Stuttgart · New York.

  7. Markedly high signal intensity lesions in the uterine cervix on T2-weighted imaging. Differentiation between mucin-producing carcinomas and nabothian cysts

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong; Sugimura, Kazuro; Okizuka, Hiromi; Yoshida, Manabu; Maruyama, Riruke; Takahashi, Kentaro; Miyazaki, Kohji [Shimane Medical Univ., Izumo (Japan)

    1999-03-01

    Both mucin-producing carcinomas and nabothian cysts in the cervix show very high signal intensity on T2-weighted images (WI). The purpose of this study was to evaluate the potential of MR imaging in differentiating mucin-producing carcinomas from nabothian cysts. Forty-six patients who underwent hysterectomy and had very high signal intensity lesions in the uterine cervix on T2-WI were included in this study. The pathological diagnoses were mucin-producing carcinoma in 13 patients, non-mucin-producing carcinoma accompanied with nabothian cyst in four patients, and nabothian cyst in 29 patients. T1-WI, T2-WI, and Gd-T1-WI were obtained in all patients. Malignancies were diagnosed on Gd-T1-WI as follows: an enhanced lesion, an irregular margin, iso-intensity on T1WI. In contrast, high signal intensity on T1-WI was considered benign. Thirteen of 17 malignant lesions and three of 29 benign lesions were enhanced. Irregular margins were observed in 12 of 17 malignant lesions and four of 29 benign lesions. Nineteen benign lesions and seven malignant lesions demonstrated high signal intensity on supplemental T1-WI. Combining the lesion criteria of enhancement, irregular lesion margin, and iso-intensity on T1-WI, the overall accuracy, sensitivity, and specificity rates of diagnosing malignancy were 89%, 88%, and 90%, respectively (p<0.01). MR imaging accurately differentiated mucin-producing carcinomas from nabothian cysts that showed high signal intensity on T2-WI in the cervical stroma. For diagnosing mucin-producing carcinomas and nabothian cysts when signal intensity was remarkably high on T2-, Gd-T1-WI findings provided key information for differentiation, and T1-WI was useful for improving specificity. (author)

  8. Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection.

    Science.gov (United States)

    Ubachs, Joey F A; Engblom, Henrik; Erlinge, David; Jovinge, Stefan; Hedström, Erik; Carlsson, Marcus; Arheden, Håkan

    2010-03-29

    In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging. Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method. MaR determined with T2-weighted imaging (34 +/- 10%) was significantly higher (p infarction (23 +/- 12%). There was a weak correlation between the two methods (r2 = 0.17, p = 0.002) with a bias of -11 +/- 12%. Myocardial salvage determined with T2-weighted imaging (58 +/- 22%) was significantly higher (p myocardial salvage determined with endocardial extent of infarction (45 +/- 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction. This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.

  9. Clinically Feasible Microstructural MRI to Quantify Cervical Spinal Cord Tissue Injury Using DTI, MT, and T2*-Weighted Imaging: Assessment of Normative Data and Reliability.

    Science.gov (United States)

    Martin, A R; De Leener, B; Cohen-Adad, J; Cadotte, D W; Kalsi-Ryan, S; Lange, S F; Tetreault, L; Nouri, A; Crawley, A; Mikulis, D J; Ginsberg, H; Fehlings, M G

    2017-06-01

    DTI, magnetization transfer, T2*-weighted imaging, and cross-sectional area can quantify aspects of spinal cord microstructure. However, clinical adoption remains elusive due to complex acquisitions, cumbersome analysis, limited reliability, and wide ranges of normal values. We propose a simple multiparametric protocol with automated analysis and report normative data, analysis of confounding variables, and reliability. Forty healthy subjects underwent T2WI, DTI, magnetization transfer, and T2*WI at 3T in <35 minutes using standard hardware and pulse sequences. Cross-sectional area, fractional anisotropy, magnetization transfer ratio, and T2*WI WM/GM signal intensity ratio were calculated. Relationships between MR imaging metrics and age, sex, height, weight, cervical cord length, and rostrocaudal level were analyzed. Test-retest coefficient of variation measured reliability in 24 DTI, 17 magnetization transfer, and 16 T2*WI datasets. DTI with and without cardiac triggering was compared in 10 subjects. T2*WI WM/GM showed lower intersubject coefficient of variation (3.5%) compared with magnetization transfer ratio (5.8%), fractional anisotropy (6.0%), and cross-sectional area (12.2%). Linear correction of cross-sectional area with cervical cord length, fractional anisotropy with age, and magnetization transfer ratio with age and height led to decreased coefficients of variation (4.8%, 5.4%, and 10.2%, respectively). Acceptable reliability was achieved for all metrics/levels (test-retest coefficient of variation < 5%), with T2*WI WM/GM comparing favorably with fractional anisotropy and magnetization transfer ratio. DTI with and without cardiac triggering showed no significant differences for fractional anisotropy and test-retest coefficient of variation. Reliable multiparametric assessment of spinal cord microstructure is possible by using clinically suitable methods. These results establish normalization procedures and pave the way for clinical studies, with the

  10. Targeting Accuracy of the Subthalamic Nucleus in Deep Brain Stimulation Surgery: Comparison Between 3 T T2-Weighted Magnetic Resonance Imaging and Microelectrode Recording Results.

    Science.gov (United States)

    Nowacki, Andreas; Debove, Ines; Fiechter, Michael; Rossi, Frédéric; Oertel, Markus Florian; Wiest, Roland; Schüpbach, Michael; Pollo, Claudio

    2017-08-02

    Targeting accuracy in deep brain stimulation (DBS) surgery can be defined as the level of accordance between selected and anatomic real target reflected by characteristic electrophysiological results of microelectrode recording (MER). To determine the correspondence between the preoperative predicted target based on modern 3-T magnetic resonance imaging (MRI) and intraoperative MER results separately on the initial and consecutive second side of surgery. Retrospective cohort study of 86 trajectories of DBS electrodes implanted into the subthalamic nucleus (STN) of patients with Parkinson's disease. The entrance point of the electrode into the STN and the length of the electrode trajectory crossing the STN were determined by intraoperative MER findings and 3 T T2-weighted magnetic resonance images with 1-mm slice thickness. Average difference between MRI- and MER-based trajectory lengths crossing the STN was 0.28 ± 1.02 mm (95% CI: -0.51 to -0.05 mm). There was a statistically significant difference between the MRI- and MER-based entry points on the initial and second side of surgery ( P = .04). Forty-three percent of the patients had a difference of more than ±1 mm of the MRI-based-predicted and the MER-based-determined entry points into the STN with values ranging from -3.0 to + 4.5 mm. STN MRI-based targeting is accurate in the majority of cases on the first and second side of surgery. In 43% of implanted electrodes, we found a relevant deviation of more than 1 mm, supporting the concept of MER as an important tool to guide and optimize targeting and electrode placement.

  11. Independent value of image fusion in unenhanced breast MRI using diffusion-weighted and morphological T2-weighted images for lesion characterization in patients with recently detected BI-RADS 4/5 X-ray mammography findings

    Energy Technology Data Exchange (ETDEWEB)

    Bickelhaupt, Sebastian; Tesdorff, Jana; Delorme, Stefan; Schlemmer, Heinz-Peter [German Cancer Research Center (dkfz), Department of Radiology, Heidelberg (Germany); Laun, Frederik Bernd; Kuder, Tristan Anselm [German Cancer Research Center (dkfz), Medical Physics in Radiology, Heidelberg (Germany); Lederer, Wolfgang; Teiner, Susanne [Radiological Practice at the ATOS Clinic Heidelberg, Heidelberg (Germany); Maier-Hein, Klaus [German Cancer Research Center (dkfz), Junior Group Medical Image Computing, Heidelberg (Germany); Daniel, Heidi [Radiology Center Mannheim (RZM), Mannheim (Germany); Stieber, Anne [University Hospital Heidelberg, Department of Clinical and Interventional Radiology, Heidelberg (Germany)

    2017-02-15

    The aim of this study was to evaluate the accuracy and applicability of solitarily reading fused image series of T2-weighted and high-b-value diffusion-weighted sequences for lesion characterization as compared to sequential or combined image analysis of these unenhanced sequences and to contrast- enhanced breast MRI. This IRB-approved study included 50 female participants with suspicious breast lesions detected in screening X-ray mammograms, all of which provided written informed consent. Prior to biopsy, all women underwent MRI including diffusion-weighted imaging (DWIBS, b = 1500s/mm{sup 2}). Images were analyzed as follows: prospective image fusion of DWIBS and T2-weighted images (FU), side-by-side analysis of DWIBS and T2-weighted series (CO), combination of the first two methods (CO+FU), and full contrast-enhanced diagnostic protocol (FDP). Diagnostic indices, confidence, and image quality of the protocols were compared by two blinded readers. Reading the CO+FU (accuracy 0.92; NPV 96.1 %; PPV 87.6 %) and the CO series (0.90; 96.1 %; 83.7 %) provided a diagnostic performance similar to the FDP (0.95; 96.1 %; 91.3 %; p > 0.05). FU reading alone significantly reduced the diagnostic accuracy (0.82; 93.3 %; 73.4 %; p = 0.023). MR evaluation of suspicious BI-RADS 4 and 5 lesions detected on mammography by using a non-contrast-enhanced T2-weighted and DWIBS sequence protocol is most accurate if MR images were read using the CO+FU protocol. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Umek, W.; Ba-Ssalamah, A.; Prokesch, R. [Department of Radiology, University of Vienna (Austria); Mallek, R.; Heimberger, K. [Division of Neuroradiology, University of Vienna (Austria); Hittmair, K. [Department of Radiology, University of Vienna (Austria)]|[Department of Radiology, AKH Linz (Austria)

    1998-03-27

    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.) With 3 figs., 4 tabs., 29 refs.

  13. T(1) mapping for the diagnosis of acute myocarditis using CMR: comparison to T2-weighted and late gadolinium enhanced imaging.

    Science.gov (United States)

    Ferreira, Vanessa M; Piechnik, Stefan K; Dall'Armellina, Erica; Karamitsos, Theodoros D; Francis, Jane M; Ntusi, Ntobeko; Holloway, Cameron; Choudhury, Robin P; Kardos, Attila; Robson, Matthew D; Friedrich, Matthias G; Neubauer, Stefan

    2013-10-01

    This study sought to test the diagnostic performance of native T1 mapping in acute myocarditis compared with cardiac magnetic resonance (CMR) techniques such as dark-blood T2-weighted (T2W)-CMR, bright-blood T2W-CMR, and late gadolinium enhancement (LGE) imaging. The diagnosis of acute myocarditis on CMR often requires multiple techniques, including T2W, early gadolinium enhancement, and LGE imaging. Novel techniques such as T1 mapping and bright-blood T2W-CMR are also sensitive to changes in free water content. We hypothesized that these techniques can serve as new and potentially superior diagnostic criteria for myocarditis. We investigated 50 patients with suspected acute myocarditis (age 42 ± 16 years; 22% women) and 45 controls (age 42 ± 14 years; 22% women). CMR at 1.5-T (median 3 days from presentation) included: 1) dark-blood T2W-CMR (short-tau inversion recovery); 2) bright-blood T2W-CMR (acquisition for cardiac unified T2 edema); 3) native T1 mapping (shortened modified look-locker inversion recovery); and 4) LGE. Image analysis included: 1) global T2 signal intensity ratio of myocardium compared with skeletal muscle; 2) myocardial T1 relaxation times; and 3) areas of LGE. Compared with controls, patients had significantly higher global T2 signal intensity ratios by dark-blood T2W-CMR (1.73 ± 0.27 vs. 1.56 ± 0.15, p T1 (1,010 ± 65 ms vs. 941 ± 18 ms, p T1 mapping (0.95), LGE (0.96), dark-blood T2 (0.78), and bright-blood T2 (0.76). A T1 cutoff of 990 ms had a sensitivity, specificity, and diagnostic accuracy of 90%, 91%, and 91%, respectively. Native T1 mapping as a novel criterion for the detection of acute myocarditis showed excellent and superior diagnostic performance compared with T2W-CMR. It also has a higher sensitivity compared with T2W and LGE techniques, which may be especially useful in detecting subtle focal disease and when gadolinium contrast imaging is not feasible. Copyright © 2013. Published by Elsevier Inc.

  14. Myocardium at risk in ST-segment elevation myocardial infarction comparison of T2-weighted edema imaging with the MR-assessed endocardial surface area and validation against angiographic scoring.

    Science.gov (United States)

    Fuernau, Georg; Eitel, Ingo; Franke, Vinzenz; Hildebrandt, Lysann; Meissner, Josefine; de Waha, Suzanne; Lurz, Philipp; Gutberlet, Matthias; Desch, Steffen; Schuler, Gerhard; Thiele, Holger

    2011-09-01

    The objective of this study was to assess the area at risk (AAR) in ST-segment elevation myocardial infarction with 2 different cardiac magnetic resonance (CMR) imaging methods and to compare them with the validated angiographic Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease Score (APPROACH-score) in a large consecutive patient cohort. Edema imaging with T(2)-weighted CMR and the endocardial surface area (ESA) assessed by late gadolinium enhancement have been introduced as relatively new methods for AAR assessment in ST-segment elevation myocardial infarction. However, data on the utility and validation of these techniques are limited. A total of 197 patients undergoing primary percutaneous coronary intervention in acute ST-segment elevation myocardial infarction were included. AAR (assessed with T(2)-weighted edema imaging and the ESA method), infarct size, and myocardial salvage (AAR minus infarct size) were determined by CMR 2 to 4 days after primary angioplasty. Angiographic AAR scoring was performed by use of the APPROACH-score. All measurements were done offline by blinded observers. The AAR assessed by T(2)-weighted imaging showed good correlation with the angiographic AAR (r = 0.87; p myocardial salvage index. In contrast, no dependence of T(2)-weighted edema imaging or the APPROACH-score on myocardial salvage index was seen. The AAR can be reliably assessed by T(2)-weighted CMR, whereas assessment of the AAR by ESA seems to be dependent on the degree of myocardial salvage, thereby underestimating the AAR in patients with high myocardial salvage such as aborted infarction. Thus, assessment of the AAR with the ESA method cannot be recommended. (Myocardial Salvage and Contrast Dye Induced Nephropathy Reduction by N-Acetylcystein [LIPSIA-N-ACC]; NCT00463749). Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  15. Independent value of image fusion in unenhanced breast MRI using diffusion-weighted and morphological T2-weighted images for lesion characterization in patients with recently detected BI-RADS 4/5 x-ray mammography findings.

    Science.gov (United States)

    Bickelhaupt, Sebastian; Tesdorff, Jana; Laun, Frederik Bernd; Kuder, Tristan Anselm; Lederer, Wolfgang; Teiner, Susanne; Maier-Hein, Klaus; Daniel, Heidi; Stieber, Anne; Delorme, Stefan; Schlemmer, Heinz-Peter

    2017-02-01

    The aim of this study was to evaluate the accuracy and applicability of solitarily reading fused image series of T2-weighted and high-b-value diffusion-weighted sequences for lesion characterization as compared to sequential or combined image analysis of these unenhanced sequences and to contrast- enhanced breast MRI. This IRB-approved study included 50 female participants with suspicious breast lesions detected in screening X-ray mammograms, all of which provided written informed consent. Prior to biopsy, all women underwent MRI including diffusion-weighted imaging (DWIBS, b = 1500s/mm(2)). Images were analyzed as follows: prospective image fusion of DWIBS and T2-weighted images (FU), side-by-side analysis of DWIBS and T2-weighted series (CO), combination of the first two methods (CO+FU), and full contrast-enhanced diagnostic protocol (FDP). Diagnostic indices, confidence, and image quality of the protocols were compared by two blinded readers. Reading the CO+FU (accuracy 0.92; NPV 96.1 %; PPV 87.6 %) and the CO series (0.90; 96.1 %; 83.7 %) provided a diagnostic performance similar to the FDP (0.95; 96.1 %; 91.3 %; p > 0.05). FU reading alone significantly reduced the diagnostic accuracy (0.82; 93.3 %; 73.4 %; p = 0.023). MR evaluation of suspicious BI-RADS 4 and 5 lesions detected on mammography by using a non-contrast-enhanced T2-weighted and DWIBS sequence protocol is most accurate if MR images were read using the CO+FU protocol. • Unenhanced breast MRI with additional DWIBS/T2w-image fusion allows reliable lesion characterization. • Abbreviated reading of fused DWIBS/T2w-images alone decreases diagnostic confidence and accuracy. • Reading fused DWIBS/T2w-images as the sole diagnostic method should be avoided.

  16. 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 E-mail: mikiy@kuhp.kyoto-u.ac.jp; 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.

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

    Science.gov (United States)

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

    2003-12-01

    To compare the magnetic resonance image contrasts due to ferritin and hemosiderin in the brain tissue among different pulse sequences. 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. 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). 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.

  18. Acute versus Chronic Myocardial Infarction: Diagnostic Accuracy of Quantitative Native T1 and T2 Mapping versus Assessment of Edema on Standard T2-weighted Cardiovascular MR Images for Differentiation.

    Science.gov (United States)

    Tahir, Enver; Sinn, Martin; Bohnen, Sebastian; Avanesov, Maxim; Säring, Dennis; Stehning, Christian; Schnackenburg, Bernhard; Eulenburg, Christine; Wien, Joshua; Radunski, Ulf K; Blankenberg, Stefan; Adam, Gerhard; Higgins, Charles B; Saeed, Maythem; Muellerleile, Kai; Lund, Gunnar K

    2017-10-01

    Purpose To analyze the diagnostic accuracy of native T1 and T2 mapping compared with visual and quantitative assessment of edema on T2-weighted cardiac magnetic resonance (MR) images to differentiate between acute and chronic myocardial infarction. Materials and Methods This study had institutional ethics committee approval. Written informed consent was obtained from 67 consecutive patients (57 years ± 12; 78% men) with a first acute myocardial infarction, who were prospectively enrolled between April 2011 and June 2015. Four serial 1.5-T MR imaging examinations were performed at 8 days ± 5, 7 weeks ± 2, 3 months ± 0.5, and 6 months ± 1.4 after infarction and included T2-weighted, native T1/T2 mapping, and late gadolinium enhancement MR imaging. Complete follow-up data were obtained in 42 patients. Regional native T1/T2 relaxation time, T2-weighted ratio, and extracellular volume were serially measured in infarcted and remote myocardium. Receiver operating characteristic (ROC) analysis was used to determine the diagnostic accuracy of the MR imaging parameters for discriminating between acute and chronic myocardial infarction. Results Native T1 of infarcted myocardium decreased from 1286 msec ± 99 at baseline to 1077 msec ± 50 at 6 months (P acute and chronic myocardial infarction. Visual analysis of the presence of edema at standard T2-weighted cardiac MR imaging resulted in an inferior AUC of 0.863 (P infarcted myocardium are excellent discriminators between acute and chronic myocardial infarction and are superior to all other MR imaging parameters. Online supplemental material is available for this article.

  19. Ultrasound guided high-intensity focused ultrasound combined with gonadotropin releasing hormone analogue (GnRHa) ablating uterine leiomyoma with homogeneous hyperintensity on T2 weighted MR imaging.

    Science.gov (United States)

    Yang, Shenghua; Kong, Fanjing; Hou, Ruijie; Rong, Fengmei; Ma, Nana; Li, Shaoping; Yang, Jun

    2017-05-01

    The study aimed to evaluate the safety and efficiency of ultrasound-guided high-intensity focused ultrasound (USgHIFU) combined with gonadotropin-releasing hormone analogue (GnRHa)-ablating symptomatic uterine leiomyoma with homogeneous hyperintensity on T2 weighted MRI prospectively. A total of 34 patients with 42 symptomatic uterine leiomyomas with homogeneous hyperintensity on T2 weighted MRI were enrolled in our study. In the patient who had multiple uterine leiomyomas, only one dominant leiomyoma was treated. According to the principles of voluntariness, 18 patients underwent a 3-month therapy of GnRHa (once a month) before the high-intensity focused ultrasound (HIFU) treatment, while 16 patients received only HIFU treatment. Enhanced MRI was performed before and after GnRHa and HIFU treatment. Evaluation of the main indicators included treatment time, sonication time, treatment efficiency, non-perfused volume (NPV) (indicative of successful ablation) ratio and energy effect ratio; adverse events were also recorded. The treatment time and sonication time of the combination group were 102.0 min (55.8-152.2 min) and 25.4 min (12.2-34.1 min); however, they were 149.0 min (87.0-210.0 min) and 38.9 min (14.0-46.7 min) in the simple USgHIFU group. The treatment and sonication time for the combination group was significantly shorter than that for the simple USgHIFU group. Treatment efficiency, NPV ratio and energy effect ratio were 46.7 mm3 s-1 (28.5-95.8 mm3 s-1), 69.2 ± 29.8% (35.5-97.4%) and 9.9 KJ mm-3 (4.5-15.7 KJ mm-3) in the combination group, respectively; but, the lowest treatment efficiency, lowest NPV ratio and more energy effect ratio were observed in the simple HIFU group, which were 16.8 mm3 s-1 (8.9-32.9 mm3 s-1), 50.2 ± 27.3% (0-78.6%) and 23.8 KJ mm-3 (12.4-46.2 KJ mm-3), respectively. Pain scores in the combination group were 3.0 ± 0.5 points (2-4 points)-significantly less than the

  20. Linear signal hyperintensity adjacent to the subchondral bone plate at the knee on T2-weighted fat-saturated sequences: imaging aspects and association with structural lesions

    Energy Technology Data Exchange (ETDEWEB)

    Gondim Teixeira, Pedro Augusto; Balaj, Clemence [CHU Hopital Central, Service D' Imagerie Guilloz, Nancy (France); Universite de Lorraine, IADI, UMR S 947, Nancy (France); Marie, Beatrice [CHU Hopital Central, Service d' Anatomo-Pathologie, Nancy (France); Lecocq, Sophie; Louis, Matthias; Blum, Alain [CHU Hopital Central, Service D' Imagerie Guilloz, Nancy (France); Braun, Marc [CHU Hopital Central, Service de Neuroradiologie, Nancy (France)

    2014-11-15

    To describe the association between linear T2 signal abnormalities in the subchondral bone and structural knee lesions. MR studies of patients referred for the evaluation of knee pain were retrospectively evaluated and 133 of these patients presented bone marrow edema pattern (BMEP) (study group) and while 61 did not (control group). The presence of linear anomalies of the subchondral bone on T2-weighted fat-saturated sequences was evaluated. The findings were correlated to the presence of structural knee lesions and to the duration of the patient's symptoms. Histologic analysis of a cadaveric specimen was used for anatomic correlation. Linear T2 hyperintensities at the subchondral bone were present in 41 % of patients with BMEP. None of the patients in the control group presented this sign. When a subchondral linear hyperintensity was present, the prevalence of radial or root tears was high and that of horizontal tears was low (71.4 and 4.8 %, respectively). Sixty-nine percent of the patients with a subchondral insufficiency fracture presented a subchondral linear hyperintensity. It was significantly more prevalent in patients with acute or sub-acute symptoms (p < 0.0001). The studied linear T2 hyperintensity is located at the subchondral spongiosa and can be secondary to local or distant joint injuries. Its presence should evoke acute and sub-acute knee injuries. This sign is closely related to subchondral insufficiency fractures and meniscal tears with a compromise in meniscal function. (orig.)

  1. Comparison of two fat-suppressed magnetic resonance imaging pulse sequences to standard t2-weighted images for brain parenchymal contrast and lesion detection in dogs with inflammatory intracranial disease.

    Science.gov (United States)

    Young, Benjamin D; Mankin, Joseph M; Griffin, John F; Fosgate, Geoffrey T; Fowler, Jennifer L; Levine, Jonathan M

    2015-01-01

    T2-weighted (T2w) sequences are commonly relied upon in magnetic resonance imaging protocols for the detection of brain lesions in dogs. Previously, the effect of fluid suppression via fluid-attenuated inversion recovery (FLAIR) has been compared to T2-weighting with mixed results. Short tau inversion recovery (STIR) has been reported to increase the detection of some CNS lesions in people. The purpose of the current study was to evaluate the effect of fat suppression on brain parenchymal contrast resolution and lesion detection in dogs. We compared three sequences: T2w images, STIR, and T2w FLAIR with chemical fat suppression (T2-FLAIR-FS) in dogs with meningoencephalitis. Dogs with meningoencephalitis and dogs with idiopathic epilepsy were retrospectively identified and anonymized. Evaluators recorded the presence or absence of lesions within 12 predetermined brain regions on randomized sequences, viewing and scoring each sequence individually. Additionally, signal-to-noise ratios, contrast-to-noise ratios, and relative contrast (RC) were measured in a reference population. Short tau inversion recovery sequences had the highest RC between gray and white matter. While descriptively more lesions were identified by evaluators on T2-FLAIR-FS images, there was no statistical difference in the relative sensitivity of lesion detection between the sequences. Nor was there a statistical difference in false lesion detection within our reference population. Short tau inversion recovery may be favored for enhanced anatomic contrast depiction in brain imaging. No benefit of the inclusion of a fat-suppressed T2-FLAIR sequence was found. © 2014 American College of Veterinary Radiology.

  2. Development and Evaluation of a Semi-automated Segmentation Tool and a Modified Ellipsoid Formula for Volumetric Analysis of the Kidney in Non-contrast T2-Weighted MR Images.

    Science.gov (United States)

    Seuss, Hannes; Janka, Rolf; Prümmer, Marcus; Cavallaro, Alexander; Hammon, Rebecca; Theis, Ragnar; Sandmair, Martin; Amann, Kerstin; Bäuerle, Tobias; Uder, Michael; Hammon, Matthias

    2017-04-01

    Volumetric analysis of the kidney parenchyma provides additional information for the detection and monitoring of various renal diseases. Therefore the purposes of the study were to develop and evaluate a semi-automated segmentation tool and a modified ellipsoid formula for volumetric analysis of the kidney in non-contrast T2-weighted magnetic resonance (MR)-images. Three readers performed semi-automated segmentation of the total kidney volume (TKV) in axial, non-contrast-enhanced T2-weighted MR-images of 24 healthy volunteers (48 kidneys) twice. A semi-automated threshold-based segmentation tool was developed to segment the kidney parenchyma. Furthermore, the three readers measured renal dimensions (length, width, depth) and applied different formulas to calculate the TKV. Manual segmentation served as a reference volume. Volumes of the different methods were compared and time required was recorded. There was no significant difference between the semi-automatically and manually segmented TKV (p = 0.31). The difference in mean volumes was 0.3 ml (95% confidence interval (CI), -10.1 to 10.7 ml). Semi-automated segmentation was significantly faster than manual segmentation, with a mean difference = 188 s (220 vs. 408 s); p segmentation and volumetric analysis of the kidney in native T2-weighted MR data delivers accurate and reproducible results and was significantly faster than manual segmentation. Applying a modified ellipsoid formula quickly provides an accurate kidney volume.

  3. Spin echo magnetic resonance imaging.

    Science.gov (United States)

    Jung, Bernd André; Weigel, Matthias

    2013-04-01

    The spin echo sequence is a fundamental pulse sequence in MRI. Many of today's applications in routine clinical use are based on this elementary sequence. In this review article, the principles of the spin echo formation are demonstrated on which the generation of the fundamental image contrasts T1, T2, and proton density is based. The basic imaging parameters repetition time (TR) and echo time (TE) and their influence on the image contrast are explained. Important properties such as the behavior in multi-slice imaging or in the presence of flow are depicted and the basic differences with gradient echo imaging are illustrated. The characteristics of the spin echo sequence for different magnetic field strengths with respect to clinical applications are discussed. Copyright © 2013 Wiley Periodicals, Inc.

  4. Prostate cancer evaluated with ferumoxtran-10-enhanced T2*-weighted MR Imaging at 1.5 and 3.0 T: early experience.

    NARCIS (Netherlands)

    Heesakkers, R.A.M.; Futterer, J.J.; Hovels, A.M.; Bosch, H.C. van den; Scheenen, T.W.J.; Hoogeveen, Y.L.; Barentsz, J.O.

    2006-01-01

    PURPOSE: To prospectively evaluate the feasibility of ferumoxtran-10-enhanced magnetic resonance (MR) imaging at high magnetic field strength (3.0 T) and to compare image quality between 1.5- and 3.0-T MR imaging in terms of lymph node detection in patients with prostate cancer. MATERIALS AND

  5. Cardiac MRI. T2-mapping versus T2-weighted dark-blood TSE imaging for myocardial edema visualization in acute myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Nassenstein, K.; Nensa, F.; Schlosser, T.; Umutlu, L.; Lauenstein, T. [University Hospital Essen (Germany). Dept. of Diagnostic and Interventional Radiology and Neuroradiology; Bruder, O. [Elisabeth Hospital, Essen (Germany). Dept. of Cardiology and Angiology; Maderwald, S.; Ladd, M.E. [Duisburg-Essen Univ., Essen (Germany). Erwin L. Hahn Institute for Magnetic Resonance Imaging

    2014-02-15

    Purpose: To assess the diagnostic accuracy of T2 mapping for the detection of myocardial edema in acute myocardial infarction (AMI), and to compare this diagnostic accuracy with that of the current standard for myocardial edema imaging, which is T2w dark-blood TSE imaging. Materials and Methods: 29 patients with AMI were examined at 1.5 T. For the visualization of myocardial edema, T2 maps, calculated from three T2w SSFP images, and T2w dark-blood TSE images were acquired in standard short- and long-axis views. Cine SSFP images were acquired for the analysis of left ventricular (LV) function and late gadolinium enhancement images (LGE) for the visualization of myocardial necrosis. The T2 maps as well as the T2w dark-blood TSE images were evaluated twice independently from the cine SSFP and LGE images. The presence or absence of myocardial edema was rated visually for each LV segment. As the standard of reference, the infarct zone was defined based on the cine SSFP and the LGE images. Results: In this segment-based analysis, T2 mapping showed a sensitivity of 82 % and a specificity of 94 % for the detection of edema in the infarct zone. T2w dark-blood TSE imaging revealed a sensitivity of 50 % and a specificity of 98 %. T2 mapping showed a higher intra-rater agreement compared to T2w dark-blood TSE imaging ({kappa}: 0.87 vs. 0.76). Conclusions: T2 mapping allows for the visualization of myocardial edema in AMI with a high sensitivity and specificity, and features better diagnostic accuracy in terms of a higher sensitivity compared to T2w dark-blood TSE imaging. (orig.)

  6. Detection of non-palpable breast cancer in asymptomatic women by using unenhanced diffusion-weighted and T2-weighted MR imaging: comparison with mammography and dynamic contrast-enhanced MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Yabuuchi, Hidetake; Matsuo, Yoshio; Sunami, Shunya; Kamitani, Takeshi; Kawanami, Satoshi; Setoguchi, Taro; Hatakenaka, Masamitsu; Honda, Hiroshi [Kyushu University, Department of Clinical Radiology, Graduate School of Medical Sciences, Fukuoka (Japan); Sakai, Shuji [Kyushu University, Department of Health Sciences, Graduate School of Medical Sciences, Fukuoka (Japan); Kubo, Makoto [Kyushu University, Department of Clinical Oncology and Surgery, Graduate School of Medical Sciences, Fukuoka (Japan); Tokunaga, Eriko [Kyushu University, Department of Surgery and Science, Graduate School of Medical Sciences, Fukuoka (Japan); Yamamoto, Hidetaka [Kyushu University, Department of Anatomic Pathology, Graduate School of Medical Sciences, Fukuoka (Japan)

    2011-01-15

    To compare the detectability of non-palpable breast cancer in asymptomatic women by using mammography (MMG), dynamic contrast-enhanced MR imaging (DCE-MRI) and unenhanced MR imaging with combined diffusion-weighted and T2-weighted images (DWI + T2WI). Forty-two lesions in 42 patients with non-palpable breast cancer in asymptomatic women were enrolled. For the reading test, we prepared a control including 13 normal and 8 benign cases. Each imaging set included biplane MMG, DCE-MRI and DWI + T2WI. Five readers were asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of cancer and the BI-RADS category. Confidence level results were used to construct receiver operating characteristic analysis. Sensitivity and specificity were calculated for each technique. DWI + T2WI showed higher observer performances (area under the curve, AUC, 0.73) and sensitivity (50%) for the detection of non-palpable breast cancer than MMG alone (AUC 0.64; sensitivity 40%) but lower than those of DCE-MRI (AUC 0.93; sensitivity 86%). A combination of MMG and DWI + T2WI exhibited higher sensitivity (69%) compared with that of MMG alone (40%). DWI + T2WI could be useful in screening breast cancer for patients who cannot receive contrast medium and could be used as a new screening technique for breast cancer. (orig.)

  7. Detection of non-palpable breast cancer in asymptomatic women by using unenhanced diffusion-weighted and T2-weighted MR imaging: comparison with mammography and dynamic contrast-enhanced MR imaging.

    Science.gov (United States)

    Yabuuchi, Hidetake; Matsuo, Yoshio; Sunami, Shunya; Kamitani, Takeshi; Kawanami, Satoshi; Setoguchi, Taro; Sakai, Shuji; Hatakenaka, Masamitsu; Kubo, Makoto; Tokunaga, Eriko; Yamamoto, Hidetaka; Honda, Hiroshi

    2011-01-01

    To compare the detectability of non-palpable breast cancer in asymptomatic women by using mammography (MMG), dynamic contrast-enhanced MR imaging (DCE-MRI) and unenhanced MR imaging with combined diffusion-weighted and T2-weighted images (DWI+T2WI). Forty-two lesions in 42 patients with non-palpable breast cancer in asymptomatic women were enrolled. For the reading test, we prepared a control including 13 normal and 8 benign cases. Each imaging set included biplane MMG, DCE-MRI and DWI+T2WI. Five readers were asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of cancer and the BI-RADS category. Confidence level results were used to construct receiver operating characteristic analysis. Sensitivity and specificity were calculated for each technique. DWI+T2WI showed higher observer performances (area under the curve, AUC, 0.73) and sensitivity (50%) for the detection of non-palpable breast cancer than MMG alone (AUC 0.64; sensitivity 40%) but lower than those of DCE-MRI (AUC 0.93; sensitivity 86%). A combination of MMG and DWI+T2WI exhibited higher sensitivity (69%) compared with that of MMG alone (40%). DWI+T2WI could be useful in screening breast cancer for patients who cannot receive contrast medium and could be used as a new screening technique for breast cancer.

  8. T2-weighted cardiovascular magnetic resonance in acute cardiac disease.

    Science.gov (United States)

    Eitel, Ingo; Friedrich, Matthias G

    2011-02-18

    Cardiovascular magnetic resonance (CMR) using T2-weighted sequences can visualize myocardial edema. When compared to previous protocols, newer pulse sequences with substantially improved image quality have increased its clinical utility. The assessment of myocardial edema provides useful incremental diagnostic and prognostic information in a variety of clinical settings associated with acute myocardial injury. In patients with acute chest pain, T2-weighted CMR is able to identify acute or recent myocardial ischemic injury and has been employed to distinguish acute coronary syndrome (ACS) from non-ACS as well as acute from chronic myocardial infarction.T2-weighted CMR can also be used to determine the area at risk in reperfused and non-reperfused infarction. When combined with contrast-enhanced imaging, the salvaged area and thus the success of early coronary revascularization can be quantified. Strong evidence for the prognostic value of myocardial salvage has enabled its use as a primary endpoint in clinical trials. The present article reviews the current evidence and clinical applications for T2-weighted CMR in acute cardiac disease and gives an outlook on future developments."The principle of all things is water"Thales of Miletus (624 BC - 546 BC). © 2011 Eitel and Friedrich; licensee BioMed Central Ltd.

  9. Image domain propeller fast spin echo.

    Science.gov (United States)

    Skare, Stefan; Holdsworth, Samantha J; Lilja, Anders; Bammer, Roland

    2013-04-01

    A new pulse sequence for high-resolution T2-weighted (T2-w) imaging is proposed - image domain propeller fast spin echo (iProp-FSE). Similar to the T2-w PROPELLER sequence, iProp-FSE acquires data in a segmented fashion, as blades that are acquired in multiple TRs. However, the iProp-FSE blades are formed in the image domain instead of in the k-space domain. Each iProp-FSE blade resembles a single-shot fast spin echo (SSFSE) sequence with a very narrow phase-encoding field of view (FOV), after which N rotated blade replicas yield the final full circular FOV. Our method of combining the image domain blade data to a full FOV image is detailed, and optimal choices of phase-encoding FOVs and receiver bandwidths were evaluated on phantom and volunteers. The results suggest that a phase FOV of 15-20%, a receiver bandwidth of ±32-63 kHz and a subsequent readout time of about 300 ms provide a good tradeoff between signal-to-noise ratio (SNR) efficiency and T2 blurring. Comparisons between iProp-FSE, Cartesian FSE and PROPELLER were made on single-slice axial brain data, showing similar T2-w tissue contrast and SNR with great anatomical conspicuity at similar scan times - without colored noise or streaks from motion. A new slice interleaving order is also proposed to improve the multislice capabilities of iProp-FSE. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Dynamic contrast-enhanced imaging has limited added value over T2-weighted imaging and diffusion-weighted imaging when using PI-RADSv2 for diagnosis of clinically significant prostate cancer in patients with elevated PSA.

    Science.gov (United States)

    De Visschere, P; Lumen, N; Ost, P; Decaestecker, K; Pattyn, E; Villeirs, G

    2017-01-01

    To determine the added value of dynamic contrast-enhanced imaging (DCE) over T2-weighted imaging (T2-WI) and diffusion-weighted imaging (DWI) for detection of clinically significant prostate cancer (csPC) in patients with elevated prostate-specific antigen (PSA). Two hundred and forty-five patients with elevated PSA underwent multiparametric (mp) magnetic resonance imaging (MRI) of the prostate before biopsy. mpMRI was performed using a 3 T MRI system without an endorectal coil. Patients underwent transrectal ultrasound-guided systematic 12 core biopsy followed by radical prostatectomy (n=68), radiation therapy (n=91), or clinical follow-up for at least 2 years (n=86). csPC was defined as Gleason score ≥3+4 and/or tumour volume of ≥0.5 ml, and/or tumour stage ≥T3a. The MRI findings were scored according to the Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) and an alternative overall assessment category (PI-RADSv2Alt) based on only T2-WI and DWI. In 144 patients (58.8%), csPC was found within 2 years after MRI. With scoring according to the PI-RADSv2 guidelines, DCE was not needed for determination of the overall assessment category in 80.8% (198/245) of patients. Receiver operating characteristic (ROC) analysis showed an area under the curve of 0.79 (95% confidence interval [CI]: 0.74-0.85) for PI-RADSv2 and 0.79 (95% CI: 0.73-0.85) for PI-RADSv2Alt. The added value of DCE over T2-WI and DWI is limited when using PI-RADSv2 for diagnosis of csPC in patients with elevated PSA before biopsy. An alternative overall assessment score using only T2-WI and DWI yielded similar performance to PI-RADSv2. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  11. The value of diffusion tensor imaging in the differential diagnosis of subcortical ischemic vascular dementia and Alzheimer's disease in patients with only mild white matter alterations on T2-weighted images

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Jian-Liang; Zhang, Ting (Dept. of Neurology, Shanghai Jiaotong Univ. Affiliated Sixth People' s Hospital, Shanghai (China)); Chang, Cheng; Zhang, Yu-Zhen; Li, Wen-Bin (Inst. of Diagnostic and Interventional Radiology, Shanghai Jiaotong Univ. Affiliated Sixth People' s Hospital, Shanghai (China)), Email: liwenbin@sh163.net

    2012-04-15

    Background: Diffusion tensor imaging (DTI) is a form of functional magnetic resonance imaging (MRI) that allows examination of the microstructural integrity of white matter in the brain. Dementia is a neurodegenerative disease, and DTI can provide indirect insights of the microstructural characteristics of brains in individuals with different forms of dementia. Purpose: To evaluate the value of DTI in the diagnosis and differential diagnosis of patients with subcortical ischemic vascular dementia (SIVD) and Alzheimer's disease (AD). Material and Methods: The study included 40 patients (20 AD patients and 20 SIVD patients) and 20 normal controls (NC). After routine MRI and DTI, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured and compared in regions of interest (ROI). Results: Compared to NC and AD patients, SIVD patients had lower FA values and higher ADC values in the inferior-fronto-occipital fascicles (IFOF), genu of the corpus callosum (GCC), splenium of the corpus callosum (SCC), and superior longitudinal fasciculus (SLF). Compared to controls and SIVD patients, AD patients had lower FA values in the anterior frontal lobe, temporal lobe, hippocampus, IFOF, GCC, and CF; and higher ADC values in the temporal lobe and hippocampus. Conclusion: DTI can be used to estimate the white matter impairment in dementia patients. There were significant regional reductions of FA values and heightened ADC values in multiple regions in SIVD patients compared to AD patients. When compared with conventional MRI, DTI may provide a more objective method for the differential diagnosis of SIVD and AD disease patients who have only mild white matter alterations on T2-weighted imaging

  12. SU-E-P-33: Critical Role of T2-Weighted Imaging Combined with Diffusion-Weighted Imaging of MRI in Diagnosis of Loco-Regional Recurrent Esophageal Cancer After Radical Surgery

    Energy Technology Data Exchange (ETDEWEB)

    Deng, G; Qiao, L [Department of Oncology, Shandong University School of Medicine, Jinan, Shandong (China); Liang, N; Xie, J; Zhang, J [Department of Radiation Oncology, Qianfoshan Hospital Affiliated to Shandon, Jinan, Shandong (China); Luo, H; Zhang, J [Division of Oncology, Department of Graduate, Weifang Medical College, Weifang, Shandong (China)

    2015-06-15

    Purpose: We perform this study to investigate the diagnostic efficacy of T2-weighted MRI (T2WI) and diffusion-weighted MRI (DWI) in confirming local relapses of esophageal cancer in patients highly suspected of recurrence after eradicating surgery. Methods: Forty-two postoperative esophageal cancer patients with clinical suspicions of cancer recurrence underwent 3.0T MRI applying axial, coronal, sagittal T2WI and axial DWI sequences. Two experienced radiologists (R1 and R2) both used two methods (T2WI, T2WI+DWI) to observe the images, and graded the patients ranging from 1 to 5 to represent severity of the disease based on visual signal intensity (patients equal to or more than grade 3 was confirmed as recurrent disease) Results: 27/42patients were verified of recurrent disease by pathologic findings and/or imaging findings during follow-up. The sensitivity, specificity and accuracy of R1 applying T2WI+DWI are 96%, 87% and 93% versus 81%, 80% and 77% on T2WI, these figures by R2 were 96%, 93% and 95% versus 89%, 93% and 90%. The receiver operating curve (ROC) analyses suggest that both of the two readers can obtain better accuracy when adding DWI to T2WI compared with T2WI alone. Kappa test between R1 and R2 indicates excellent inter-observer agreement on T2WI+DWI. Conclusion: Standard T2WI in combination DWI can achieve better accuracy than T2WI alone in diagnosing local recurrence of esophageal cancer, and improve consistency between different readers.

  13. Stellar Echo Imaging of Exoplanets

    Science.gov (United States)

    Mann, Chris; Lerch, Kieran; Lucente, Mark; Meza-Galvan, Jesus; Mitchell, Dan; Ruedin, Josh; Williams, Spencer; Zollars, Byron

    2016-01-01

    All stars exhibit intensity fluctuations over several timescales, from nanoseconds to years. These intensity fluctuations echo off bodies and structures in the star system. We posit that it is possible to take advantage of these echoes to detect, and possibly image, Earth-scale exoplanets. Unlike direct imaging techniques, temporal measurements do not require fringe tracking, maintaining an optically-perfect baseline, or utilizing ultra-contrast coronagraphs. Unlike transit or radial velocity techniques, stellar echo detection is not constrained to any specific orbital inclination. Current results suggest that existing and emerging technology can already enable stellar echo techniques at flare stars, such as Proxima Centauri, including detection, spectroscopic interrogation, and possibly even continent-level imaging of exoplanets in a variety of orbits. Detection of Earth-like planets around Sun-like stars appears to be extremely challenging, but cannot be fully quantified without additional data on micro- and millisecond-scale intensity fluctuations of the Sun. We consider survey missions in the mold of Kepler and place preliminary constraints on the feasibility of producing 3D tomographic maps of other structures in star systems, such as accretion disks. In this report we discuss the theory, limitations, models, and future opportunities for stellar echo imaging.

  14. Scaled signal intensity of uterine fibroids based on T2-weighted MR images: a potential objective method to determine the suitability for magnetic resonance-guided focused ultrasound surgery of uterine fibroids.

    Science.gov (United States)

    Park, Hyun; Yoon, Sang-Wook; Sokolov, Amit

    2015-12-01

    Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive method to treat uterine fibroids. To help determine the patient suitability for MRgFUS, we propose a new objective measure: the scaled signal intensity (SSI) of uterine fibroids in T2 weighted MR images (T2WI). Forty three uterine fibroids in 40 premenopausal women were included in this retrospective study. SSI of each fibroid was measured from the screening T2WI by standardizing its mean signal intensity to a 0-100 scale, using reference intensities of rectus abdominis muscle (0) and subcutaneous fat (100). Correlation between the SSI and the non-perfused volume (NPV) ratio (a measure for treatment success) was calculated. Pre-treatment SSI showed a significant inverse-correlation with post treatment NPV ratio (p < 0.05). When dichotomizing NPV ratio at 45 %, the optimal cut off value of the SSI was found to be 16.0. A fibroid with SSI value 16.0 or less can be expected to have optimal responses. The SSI of uterine fibroids in T2WI can be suggested as an objective parameter to help in patient selection for MRgFUS. • Signal intensity of fibroid in MR images predicts treatment response to MRgFUS. • Signal intensity is standardized into scaled form using adjacent tissues as references. • Fibroids with SSI less than 16.0 are expected to have optimal responses.

  15. Feasibility of post mortem cardiac proton density weighted fast field echo imaging in two cases of sudden death.

    Science.gov (United States)

    Crooijmans, Hendrikus J A; Ruder, Thomas D; Eggert, Sebastian; Paula, Pia; Thali, Michael J; Bieri, Oliver; Schweitzer, Wolf

    2013-11-01

    The aim of this work is to investigate and compare cardiac proton density (PD) weighted fast field echo (FFE) post-mortem magnetic resonance (PMMR) imaging with standard cardiac PMMR imaging (T1-weighted and T2-weighted turbo spin-echo (TSE)), postmortem CT (PMCT) as well as autopsy. Two human cadavers sequentially underwent cardiac PMCT and PMMR imaging (PD-weighted FFE, T1-weighted and T2-weighted TSE) and autopsy. The cardiac PMMR images were compared to each other as well as to PMCT and autopsy findings. For the first case, cardiac PMMR exhibited a focal region of low signal in PD-weighted FFE and T2-weighted TSE images, surrounded by a signal intense rim in the T2-weighted images. T1-weighted TSE and PMCT did not appear to identify any focal abnormality. Macroscopic inspection identified a blood clot; histology confirmed this to be a thrombus with an adhering myocardial infarction. In the second case, a myocardial rupture with heart tamponade was identified in all PMMR images, located at the anterior wall of the left ventricle; PMCT excluded additional ruptures. In PD-weighted FFE and T2-weighted TSE images, it occurred hypo-intense, while resulting in small clustered hyper-intense spots in T1-weighted TSE. Autopsy confirmed the PMMR and PMCT findings. Presented initial results have shown PD-weighted FFE to be a valuable imaging sequence in addition to traditional T2-weighted TSE imaging for blood clots and myocardial haemorrhage with clearer contrast between affected and healthy myocardium. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  16. Scaled signal intensity of uterine fibroids based on T2-weighted MR images: a potential objective method to determine the suitability for magnetic resonance-guided focused ultrasound surgery of uterine fibroids

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun [CHA University, Comprehensive Gynecologic Cancer Center, CHA Bundang Medical Center, Gyunggi-do (Korea, Republic of); Yoon, Sang-Wook [CHA University, Department of Diagnostic Radiology, CHA Bundang Medical Center, Sungnam-si, Gyunggi-do (Korea, Republic of); Sokolov, Amit [InSightec Ltd., Haifa (Israel)

    2015-12-15

    Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive method to treat uterine fibroids. To help determine the patient suitability for MRgFUS, we propose a new objective measure: the scaled signal intensity (SSI) of uterine fibroids in T2 weighted MR images (T2WI). Forty three uterine fibroids in 40 premenopausal women were included in this retrospective study. SSI of each fibroid was measured from the screening T2WI by standardizing its mean signal intensity to a 0-100 scale, using reference intensities of rectus abdominis muscle (0) and subcutaneous fat (100). Correlation between the SSI and the non-perfused volume (NPV) ratio (a measure for treatment success) was calculated. Pre-treatment SSI showed a significant inverse-correlation with post treatment NPV ratio (p < 0.05). When dichotomizing NPV ratio at 45 %, the optimal cut off value of the SSI was found to be 16.0. A fibroid with SSI value 16.0 or less can be expected to have optimal responses. The SSI of uterine fibroids in T2WI can be suggested as an objective parameter to help in patient selection for MRgFUS. (orig.)

  17. MRI texture analysis (MRTA) of T2-weighted images in Crohn's disease may provide information on histological and MRI disease activity in patients undergoing ileal resection

    Energy Technology Data Exchange (ETDEWEB)

    Makanyanga, Jesica; Bhatnagar, Gauraang; Halligan, Steve; Taylor, Stuart A. [University College London and University College London Hospitals NIHR Biomedical Research Centre, Center for Medical Imaging, London (United Kingdom); Ganeshan, Balaji; Groves, Ashley; Miles, Ken [University College London, University College Hospital, Institute of Nuclear Medicine, London (United Kingdom); Rodriguez-Justo, Manuel [University College London, Department of Research Pathology, University College London Cancer Institute, London (United Kingdom)

    2017-02-15

    To associate MRI textural analysis (MRTA) with MRI and histological Crohn's disease (CD) activity. Sixteen patients (mean age 39.5 years, 9 male) undergoing MR enterography before ileal resection were retrospectively analysed. Thirty-six small (≤3 mm) ROIs were placed on T2-weighted images and location-matched histological acute inflammatory scores (AIS) measured. MRI activity (mural thickness, T2 signal, T1 enhancement) (CDA) was scored in large ROIs. MRTA features (mean, standard deviation, mean of positive pixels (MPP), entropy, kurtosis, skewness) were extracted using a filtration histogram technique. Spatial scale filtration (SSF) ranged from 2 to 5 mm. Regression (linear/logistic) tested associations between MRTA and AIS (small ROIs), and CDA/constituent parameters (large ROIs). Skewness (SSF = 2 mm) was associated with AIS [regression coefficient (rc) 4.27, p = 0.02]. Of 120 large ROI analyses (for each MRI, MRTA feature and SSF), 15 were significant. Entropy (SSF = 2, 3 mm) and kurtosis (SSF = 3 mm) were associated with CDA (rc 0.9, 1.0, -0.45, p = 0.006-0.01). Entropy and mean (SSF = 2-4 mm) were associated with T2 signal [odds ratio (OR) 2.32-3.16, p = 0.02-0.004], [OR 1.22-1.28, p = 0.03-0.04]. MPP (SSF = 2 mm) was associated with mural thickness (OR 0.91, p = 0.04). Kurtosis (SSF = 3 mm), standard deviation (SSF = 5 mm) were associated with decreased T1 enhancement (OR 0.59, 0.42, p = 0.004, 0.007). MRTA features may be associated with CD activity. (orig.)

  18. Diagnostic Accuracy of 3.0-T Magnetic Resonance T1 and T2 Mapping and T2-Weighted Dark-Blood Imaging for the Infarct-Related Coronary Artery in Non-ST-Segment Elevation Myocardial Infarction.

    Science.gov (United States)

    Layland, Jamie; Rauhalammi, Samuli; Lee, Matthew M Y; Ahmed, Nadeem; Carberry, Jaclyn; Teng Yue May, Vannesa; Watkins, Stuart; McComb, Christie; Mangion, Kenneth; McClure, John D; Carrick, David; O'Donnell, Anna; Sood, Arvind; McEntegart, Margaret; Oldroyd, Keith G; Radjenovic, Aleksandra; Berry, Colin

    2017-03-31

    Patients with recent non-ST-segment elevation myocardial infarction commonly have heterogeneous characteristics that may be challenging to assess clinically. We prospectively studied the diagnostic accuracy of 2 novel (T1, T2 mapping) and 1 established (T2-weighted short tau inversion recovery [T2W-STIR]) magnetic resonance imaging methods for imaging the ischemic area at risk and myocardial salvage in 73 patients with non-ST-segment elevation myocardial infarction (mean age 57±10 years, 78% male) at 3.0-T magnetic resonance imaging within 6.5±3.5 days of invasive management. The infarct-related territory was identified independently using a combination of angiographic, ECG, and clinical findings. The presence and extent of infarction was assessed with late gadolinium enhancement imaging (gadobutrol, 0.1 mmol/kg). The extent of acutely injured myocardium was independently assessed with native T1, T2, and T2W-STIR methods. The mean infarct size was 5.9±8.0% of left ventricular mass. The infarct zone T1 and T2 times were 1323±68 and 57±5 ms, respectively. The diagnostic accuracies of T1 and T2 mapping for identification of the infarct-related artery were similar (P=0.125), and both were superior to T2W-STIR (PT1 (15.8±10.6%) and T2 maps (16.0±11.8%) was similar (P=0.838) and moderately well correlated (r=0.82, PT1 (Pmaps (Pinfarction, T1 and T2 magnetic resonance imaging mapping have higher diagnostic performance than T2W-STIR for identifying the infarct-related artery. Compared with conventional STIR, T1 and T2 maps have superior value to inform diagnosis and revascularization planning in non-ST-segment elevation myocardial infarction. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02073422. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  19. Reference-tissue correction of T2-weighted signal intensity for prostate cancer detection

    Science.gov (United States)

    Peng, Yahui; Jiang, Yulei; Oto, Aytekin

    2014-03-01

    The purpose of this study was to investigate whether correction with respect to reference tissue of T2-weighted MRimage signal intensity (SI) improves its effectiveness for classification of regions of interest (ROIs) as prostate cancer (PCa) or normal prostatic tissue. Two image datasets collected retrospectively were used in this study: 71 cases acquired with GE scanners (dataset A), and 59 cases acquired with Philips scanners (dataset B). Through a consensus histology- MR correlation review, 175 PCa and 108 normal-tissue ROIs were identified and drawn manually. Reference-tissue ROIs were selected in each case from the levator ani muscle, urinary bladder, and pubic bone. T2-weighted image SI was corrected as the ratio of the average T2-weighted image SI within an ROI to that of a reference-tissue ROI. Area under the receiver operating characteristic curve (AUC) was used to evaluate the effectiveness of T2-weighted image SIs for differentiation of PCa from normal-tissue ROIs. AUC (+/- standard error) for uncorrected T2-weighted image SIs was 0.78+/-0.04 (datasets A) and 0.65+/-0.05 (datasets B). AUC for corrected T2-weighted image SIs with respect to muscle, bladder, and bone reference was 0.77+/-0.04 (p=1.0), 0.77+/-0.04 (p=1.0), and 0.75+/-0.04 (p=0.8), respectively, for dataset A; and 0.81+/-0.04 (p=0.002), 0.78+/-0.04 (pmuscle yielded the most consistent results between GE and Phillips images. Correction of T2-weighted image SI in reference to three types of extra-prostatic tissue can improve its effectiveness for differentiation of PCa from normal-tissue ROIs, and correction in reference to the levator ani muscle produces consistent T2-weighted image SIs between GE and Phillips MR images.

  20. Extent of myocardium at risk for left anterior descending artery, right coronary artery, and left circumflex artery occlusion depicted by contrast-enhanced steady state free precession and T2-weighted short tau inversion recovery magnetic resonance imaging

    DEFF Research Database (Denmark)

    Nordlund, David; Heiberg, Einar; Carlsson, Marcus

    2016-01-01

    Background - Contrast-enhanced steady state free precession (CE-SSFP) and T2-weighted short tau inversion recovery (T2-STIR) have been clinically validated to estimate myocardium at risk (MaR) by cardiovascular magnetic resonance while using myocardial perfusion single-photon emission computed to...... and at a group level. Clinical Trial Registration - URL: http://www.clinicaltrials.gov. Unique identifiers: NCT01379261 and NCT01374321....

  1. Sub-millimeter T2 weighted fMRI at 7 T: comparison of 3D-GRASE and 2D SE-EPI.

    Science.gov (United States)

    Kemper, Valentin G; De Martino, Federico; Vu, An T; Poser, Benedikt A; Feinberg, David A; Goebel, Rainer; Yacoub, Essa

    2015-01-01

    Functional magnetic resonance imaging (fMRI) allows studying human brain function non-invasively up to the spatial resolution of cortical columns and layers. Most fMRI acquisitions rely on the blood oxygenation level dependent (BOLD) contrast employing T(*) 2 weighted 2D multi-slice echo-planar imaging (EPI). At ultra-high magnetic field (i.e., 7 T and above), it has been shown experimentally and by simulation, that T2 weighted acquisitions yield a signal that is spatially more specific to the site of neuronal activity at the cost of functional sensitivity. This study compared two T2 weighted imaging sequences, inner-volume 3D Gradient-and-Spin-Echo (3D-GRASE) and 2D Spin-Echo EPI (SE-EPI), with evaluation of their imaging point-spread function (PSF), functional specificity, and functional sensitivity at sub-millimeter resolution. Simulations and measurements of the imaging PSF revealed that the strongest anisotropic blurring in 3D-GRASE (along the second phase-encoding direction) was about 60% higher than the strongest anisotropic blurring in 2D SE-EPI (along the phase-encoding direction). In a visual paradigm, the BOLD sensitivity of 3D-GRASE was found to be superior due to its higher temporal signal-to-noise ratio (tSNR). High resolution cortical depth profiles suggested that the contrast mechanisms are similar between the two sequences, however, 2D SE-EPI had a higher surface bias owing to the higher T(*) 2 contribution of the longer in-plane EPI echo-train for full field of view compared to the reduced field of view of zoomed 3D-GRASE.

  2. Rank Awareness in Group-Sparse Recovery of Multi-Echo MR Images

    Directory of Open Access Journals (Sweden)

    Rabab Ward

    2013-03-01

    Full Text Available This work addresses the problem of recovering multi-echo T1 or T2 weighted images from their partial K-space scans. Recent studies have shown that the best results are obtained when all the multi-echo images are reconstructed by simultaneously exploiting their intra-image spatial redundancy and inter-echo correlation. The aforesaid studies either stack the vectorised images (formed by row or columns concatenation as columns of a Multiple Measurement Vector (MMV matrix or concatenate them as a long vector. Owing to the inter-image correlation, the thus formed MMV matrix or the long concatenated vector is row-sparse or group-sparse respectively in a transform domain (wavelets. Consequently the reconstruction problem was formulated as a row-sparse MMV recovery or a group-sparse vector recovery. In this work we show that when the multi-echo images are arranged in the MMV form, the thus formed matrix is low-rank. We show that better reconstruction accuracy can be obtained when the information about rank-deficiency is incorporated into the row/group sparse recovery problem. Mathematically, this leads to a constrained optimization problem where the objective function promotes the signal’s groups-sparsity as well as its rank-deficiency; the objective function is minimized subject to data fidelity constraints. The experiments were carried out on ex vivo and in vivo T2 weighted images of a rat's spinal cord. Results show that this method yields considerably superior results than state-of-the-art reconstruction techniques.

  3. MR fetography using heavily T2-weighted sequences: comparison of thin- and thick-slab acquisitions.

    Science.gov (United States)

    Huisman, Thierry A G M; Solopova, Alina

    2009-09-01

    To evaluate the use of MR-fetography sequences in identifying the major fetal structures and to compare thick- and thin-slab acquisitions for their diagnostic value. Twenty-one consecutive, pregnant women with suspected fetal pathology underwent fetal magnetic resonance imaging (MRI) using a 1.5 T MRI unit. Heavily T2-weighted, single-shot fast spin-echo (SSFSE) sequences with a long echo train (MR-fetography) were acquired in a thick- and thin-slab modus. Thick- and thin-slab acquisitions were reviewed by two experienced radiologists with regard to the overall image quality and landmark anatomical structures (spinal canal, spinal cord, posterior fossa, cerebellum, brainstem, basal cisterns, stomach, urinary bladder and umbilical cord according to a three-scale grading system (good, moderate and poor). Visibility scores were calculated and compared between both sequences. Overall image quality was graded good in 76.2%, moderate in 19.0% and poor in 4.8% for thick-slab images and good in 81%, moderate in 14.3% and poor in 4.8% for thin-slab images. The visibility scores of the thick/thin-slab images for evaluation of the main fetal structures were as follows: for the spinal canal 2.8+/-0.4/2.9+/-0.54 (p>0.05), spinal cord 2.4+/-0.75/2.7+/-0.66 (p>0.05), posterior fossa components (cerebellum, brainstem and basal cisterns) 2.4+/-0.68/2.8+/-0.54; 2.4+/-0.67/2.7+/-0.66; 2.5+/-0.51/2.7+/-0.56 (p0.05), urinary bladder 2.8+/-0.51/2.8+/-0.54 (p>0.05) and umbilical cord 2.9+/-0.30/2.6+/-0.60 (pslab acquisitions render complementary information. Thick-slab images display the entire fetus in one projection while thin-slab images provide more detailed anatomical information. The short imaging time usually allows measuring both thick- and thin-slab images. MR-fetography is as a helpful addition to conventional fetal MRI. MR-fetography should not be viewed as a single, stand alone sequence but as a supporting fast MR sequence in a well-designed multisequence fetal MRI protocol

  4. Effects of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid on T2-weighted MRCP.

    Science.gov (United States)

    Nakamura, Yuko; Ohmoto, Toshifumi; Saito, Tomoko; Kajima, Toshio; Nishimaru, Eiji; Ito, Katsuhide

    2009-01-01

    Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is a recently developed liver-specific contrast agent for magnetic resonance (MR) imaging that is excreted equally via the kidneys and the biliary system. To our knowledge, its effects on T(2)-weighted MR cholangiopancreatography (MRCP) images have not been explored. Acquisition of the hepatobiliary phase is recommended 20 min after administration of Gd-EOB-DTPA. Examination time cannot be extended if the contrast does not take effect on T(2)-weighted MRCP within 20 min after administration. We attempted to assess the change in signal of T(2)-weighted MRCP by excretion of Gd-EOB-DTPA. Between March and July 2008, 40 patients (15 women, 25 men; mean age 70.8 years) were examined with abdominal MR imaging. T(2)-weighted MRCP was performed before and 10 and 20 min after administration of Gd-EOB-DTPA. We analyzed signal intensity of the bile duct, gallbladder, cystic duct, and pancreatic duct on MRCP for changes in intensity. T(2)-weighted MRCP 20 min after contrast administration showed loss of signal of the bile duct (intrahepatic bile duct in all cases, upper extrahepatic duct in 36 [90%], middle extrahepatic duct in 33 [85%], and lower extrahepatic duct in 26 [67%]), the gallbladder in 23 cases (72%), and the cystic duct in 25 (64%). This signal change increased with time. We observed no change in signal of the pancreatic duct. T(2)-weighted MRCP sequences should not be obtained after administration of Gd-EOB-DTPA because this contrast agent decreases signal intensity of the biliary structure on these images.

  5. MR fetography using heavily T2-weighted sequences: Comparison of thin- and thick-slab acquisitions

    Energy Technology Data Exchange (ETDEWEB)

    Huisman, Thierry A.G.M. [Department of Diagnostic Imaging, University Children' s Hospital Zurich (Switzerland); Division Pediatric Radiology, Johns Hopkins Hospital, Baltimore (United States)], E-mail: thuisma1@jhmi.edu; Solopova, Alina [Department of Diagnostic Imaging, University Children' s Hospital Zurich (Switzerland)

    2009-09-15

    Purpose: To evaluate the use of MR-fetography sequences in identifying the major fetal structures and to compare thick- and thin-slab acquisitions for their diagnostic value. Materials and methods: Twenty-one consecutive, pregnant women with suspected fetal pathology underwent fetal magnetic resonance imaging (MRI) using a 1.5 T MRI unit. Heavily T2-weighted, single-shot fast spin-echo (SSFSE) sequences with a long echo train (MR-fetography) were acquired in a thick- and thin-slab modus. Thick- and thin-slab acquisitions were reviewed by two experienced radiologists with regard to the overall image quality and landmark anatomical structures (spinal canal, spinal cord, posterior fossa, cerebellum, brainstem, basal cisterns, stomach, urinary bladder and umbilical cord according to a three-scale grading system (good, moderate and poor). Visibility scores were calculated and compared between both sequences. Results: Overall image quality was graded good in 76.2%, moderate in 19.0% and poor in 4.8% for thick-slab images and good in 81%, moderate in 14.3% and poor in 4.8% for thin-slab images. The visibility scores of the thick/thin-slab images for evaluation of the main fetal structures were as follows: for the spinal canal 2.8 {+-} 0.4/2.9 {+-} 0.54 (p > 0.05), spinal cord 2.4 {+-} 0.75/2.7 {+-} 0.66 (p > 0.05), posterior fossa components (cerebellum, brainstem and basal cisterns) 2.4 {+-} 0.68/2.8 {+-} 0.54; 2.4 {+-} 0.67/2.7 {+-} 0.66; 2.5 {+-} 0.51/2.7 {+-} 0.56 (p < 0.05), stomach 2.8 {+-} 0.44/2.9 {+-} 0.48 (p > 0.05), urinary bladder 2.8 {+-} 0.51/2.8 {+-} 0.54 (p > 0.05) and umbilical cord 2.9 {+-} 0.30/2.6 {+-} 0.60 (p < 0.05). Conclusion: Heavily T2-weighted MR-fetography renders a quick overview of fetal contours, fetal position, amount of amniotic fluid and integrity and presence of several major fluid containing structures. Thick- and thin-slab acquisitions render complementary information. Thick-slab images display the entire fetus in one projection while

  6. High T2-weighted signal intensity is associated with elevated troponin T in hypertrophic cardiomyopathy

    NARCIS (Netherlands)

    Gommans, D.H.F.; Cramer, G.E.; Bakker, J.; Michels, M; Dieker, H.J.; Timmermans, J.; Fouraux, M.A.; Marcelis, C.L.M.; Verheugt, F.W.A.; Brouwer, M.A.; Kofflard, M.J.M.

    2017-01-01

    OBJECTIVE: Areas of high signal intensity (HighT2) on T2-weighted cardiovascular magnetic resonance (CMR) imaging have been demonstrated in hypertrophic cardiomyopathy (HCM). It has been hypothesised that HighT2 may indicate active tissue injury in HCM. In this context, we studied HighT2 in relation

  7. Dynamics of dot-like hemosiderin spots on T2*-weighted MRIs associated with stroke recurrence.

    Science.gov (United States)

    Imaizumi, Toshio; Honma, Toshimi; Horita, Yoshifumi; Chiba, Masahiko; Kawamura, Maiko; Miyata, Kei; Kohama, Ikuhide; Niwa, Jun

    2007-07-01

    Dot-like low-intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted (-w) brain magnetic resonance imaging (MRIs) are frequently associated with cerebral small vessel disease (SVD), including deep intracerebral hemorrhages and lacunar infarctions. This study investigated how numbers of newly appeared dotHSs contribute to recurrent SVD. We prospectively analyzed numbers of newly appeared dotHSs in 12 patients with prior SVD (8 males, 4 females; mean 67.6 +/- 10.7 years old) readmitted with recurring SVD between October 2001 and March 2003. Numbers of appeared dotHSs per year were counted on T2*-w MRI scans after SVD recurrence and compared to previous MRIs. Seventy-one outpatients (35 males, 36 females; mean 64.3 +/- 9.6 years old) with histories of intracerebral hemorrhages (ICH) that came to the hospital during the study period served as controls. The hazard ratio (HR) for recurrence was estimated from a multivariate logistic regression model, using the number of appeared dotHSs (per year) and other risk factors. Multivariate analyses revealed that an elevated rate of recurrence was found in patients with substantial numbers of appeared dotHSs (>or=5/year) (HR, 7.34; P= 0.0008). We also analyzed factors associated with the numbers of appeared dotHSs. A number of appeared dotHSs (>or=5/year) was significantly and independently associated with the initial number of dotHSs (>or=10) on T2*-w MRIs following the first SVD (HR, 18.6; P= 0.0001). Though a small sample size limited the power of our analyses, our findings suggest that a number of newly appeared dotHSs may be associated with SVD recurrence.

  8. Chronic lower extremity lymphedema: A comparative study of high-resolution interstitial MR lymphangiography and heavily T2-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Lu Qing [Department of Radiology, Shanghai Renji Hospital, Shanghai Jiao Tong University School of Medicine, 1630 Dong Fang Rd, Shanghai 200127 (China)], E-mail: luqingshan@sjtu.edu.cn; Xu Jianrong [Department of Radiology, Shanghai Renji Hospital, Shanghai Jiao Tong University School of Medicine, 1630 Dong Fang Rd, Shanghai 200127 (China)], E-mail: jiangrongx@hotmail.com; Liu Ningfei [Department of Plastic and Reconstructive Surgery, Shanghai 9th People' s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Second Medical University, 639 Zhi Zao Ju Rd, Shanghai 200011 (China)], E-mail: luqing_1973@163.com

    2010-02-15

    Purpose: To assess the role of heavily T2-weighted image and interstitial MR lymphangiography (MRL) for the visualization of lymphatic vessels in patients with disorders of the lymphatic circulation. Methods: Forty lower extremities in 31 patients (9 bilateral and 22 unilateral) with primary lymphedema were examined by heavily T2-weighted image and indirect MRL. Maximum-intensity projection (MIP) was used to reconstruct the images of the lymphatic system. Two experienced radiologists analyzed the images with regard to the differences in image quality, number of lymphatic vessels, its maximum diameter and two other findings: accumulated lymph fluid in the tissue and honeycombing pattern. Results: The beaded appearance of the affected vessels in 73 leg segments of 40 lower extremities were present on both modalities 3D MIP. Larger amount of the dilated lymphatic vessels were visualized on heavily T2-weighted image than that on MRL (p = 0.003) and the maximum diameter of it was 4.28 {+-} 1.53 mm on heavily T2-weighted image, whereas 3.41 {+-} 1.05 mm on MRL (p < 0.01). The dilated lymphatic vessels on MRL showed better image quality and greater SNR and CNR than that on heavily T2-weighted image (p < 0.01). The regions of accumulated lymph fluid and the honeycombing pattern extent were identified on heavily T2-weighted image scored statistically higher than that on MRL (p < 0.01). Conclusion: The heavily T2-weighted imaging has greater sensitivity and the MRL image has higher legibility for detecting the pathologically modified lymphatic vessels and accompanying complications non-invasively. Combining these two MR techniques can accurately access the pathological changes in the lower extremity with lymphedema.

  9. Visualization of cranial nerves I-XII: value of 3D CISS and T2-weighted FSE sequences

    Energy Technology Data Exchange (ETDEWEB)

    Yousry, I.; Camelio, S.; Wiesmann, M.; Brueckmann, H.; Yousry, T.A. [Department of Neuroradiology, Klinikum Grosshadern, Ludwig-Maximilians University, Marchioninistrasse 15, D-81377 Munich (Germany); Schmid, U.D. [Neurosurgical Unit, Klinik im Park, 8000 Zurich (Switzerland); Horsfield, M.A. [Department of Medical Physics, University of Leicester, Leicester LE1 5WW (United Kingdom)

    2000-07-01

    The aim of this study was to evaluate the sensitivity of the three-dimensional constructive interference of steady state (3D CISS) sequence (slice thickness 0.7 mm) and that of the T2-weighted fast spin echo (T2-weighted FSE) sequence (slice thickness 3 mm) for the visualization of all cranial nerves in their cisternal course. Twenty healthy volunteers were examined using the T2-weighted FSE and the 3D CISS sequences. Three observers evaluated independently the cranial nerves NI-NXII in their cisternal course. The rates for successful visualization of each nerve for 3D CISS (and for T2-weighted FSE in parentheses) were as follows: NI, NII, NV, NVII, NVIII 40 of 40 (40 of 40), NIII 40 of 40 (18 of 40), NIV 19 of 40 (3 of 40), NVI 39 of 40 (5 of 40), NIX, X, XI 40 of 40 (29 of 40), and NXII 40 of 40 (4 of 40). Most of the cranial nerves can be reliably assessed when using the 3D CISS and the T2-weighted FSE sequences. Increasing the spatial resolution when using the 3D CISS sequence increases the reliability of the identification of the cranial nerves NIII-NXII. (orig.)

  10. MR appearance of Virchow-Robin spaces along lenticulostriate arteries: spin-echo and two-dimensional fast low-angle shot imaging.

    Science.gov (United States)

    Hirabuki, N; Fujita, N; Fujii, K; Hashimoto, T; Kozuka, T

    1994-02-01

    To delineate the appearance of normal Virchow-Robin spaces on routine spin-echo images and demonstrate the lenticulostriate arteries within them with a flow-sensitive fast low-angle shot (FLASH) pulse sequence. Seventy subjects, free of cerebrovascular diseases and other neurologic disorders, ranging in age from 1 to 75 years, were examined. On a 1.5-T MR system, axial spin-echo images of 5 mm thickness were obtained in all subjects. In 45 of 70 subjects axial two-dimensional FLASH images of 3 mm thickness were continuously imaged. On T1- and spin density-weighted images Virchow-Robin spaces were detected as small foci of cerebrospinal fluid intensity around the anterior commissure in all subjects (100%), and in the basal ganglia at the level of the foramen of Monro in 40 (57%). T2-weighted images equally showed Virchow-Robin spaces around the anterior commissure but were less sensitive than T1- and spin-density weighted images at the level of the foramen of Monro (14%). Virchow-Robin spaces identified on T2-weighted images should be isointense with cerebrospinal fluid. However, one or two spaces in 11 younger subjects were hypointense relative to adjacent brain tissue. On FLASH images most Virchow-Robin spaces identified on spin-echo images were delineated as high-intensity foci, corresponding to lenticulostriate arteries. Normal Virchow-Robin spaces along the lenticulostriate arteries are frequently detected on spin-echo images. Their appearance, affected by the flow of associated lenticulostriate arteries, varies from hyper- to hypointensity to brain tissue on T2-weighted images. The two-dimensional FLASH sequence can demonstrate the flow of the arteries, thereby helping confirm that these are truly Virchow-Robin spaces.

  11. Effect of magnetic susceptibility contrast medium on myocardial signal intensity with fast gradient-recalled echo and spin-echo MR imaging: initial experience in humans.

    Science.gov (United States)

    Sakuma, H; O'Sullivan, M; Lucas, J; Wendland, M F; Saeed, M; Dulce, M C; Watson, A; Bleyl, K L; LaFrance, N D; Higgins, C B

    1994-01-01

    To show the effect of dysprosium diethylenetriaminepentaacetic acid bis-methylamine injection on the images of normal human myocardium. T2-sensitive fast gradient-recalled echo (GRE) (repetition time [TR], 10.8 msec; echo time [TE], 4.2 msec) and spin-echo (SE) (TR, three RR intervals; TE, 60 msec) magnetic resonance (MR) imaging with driven equilibrium-preparation pulse was used to produce T2 contrast material enhancement. The contrast agent was injected into 12 healthy subjects at doses of 0.05, 0.1, 0.2, 0.4, and 0.6 mmol/kg. Driven equilibrium-prepared GRE images showed a transient decrease of myocardial signal intensity at doses of 0.2-0.6 mmol/kg. Postcontrast T2-weighted SE images showed a myocardial signal attenuation (30%-45% decrease) at a dose of 0.4 mmol/kg or higher. Dynamic MR imaging with a magnetic susceptibility contrast medium can be used to monitor the first pass of contrast media through human myocardium with a conventional MR imager and a fast GRE sequence.

  12. Comparison of optimised endovaginal vs external array coil T2-weighted and diffusion-weighted imaging techniques for detecting suspected early stage (IA/IB1) uterine cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Downey, Kate; Morgan, Veronica A.; Giles, Sharon L.; MacDonald, A.; DeSouza, Nandita M. [The Institute of Cancer Research and Royal Marsden NHS Foundation Trust, CRUK Cancer Imaging Centre, Surrey (United Kingdom); Attygalle, Ayoma D. [The Royal Marsden NHS Foundation Trust, Department of Histopathology, London (United Kingdom); Davis, M. [Kingston Hospital, Department of Gynaecology, Kingston-upon-Thames, Surrey (United Kingdom); Ind, Thomas E.J.; Shepherd, John H. [The Royal Marsden NHS Foundation Trust, Gynecology Unit, London (United Kingdom)

    2016-04-15

    To compare sensitivity and specificity of endovaginal versus external-array coil T2-W and T2-W + DWI for detecting and staging small cervical tumours. Optimised endovaginal and external array coil MRI at 3.0-T was done prospectively in 48 consecutive patients with stage Ia/Ib1 cervical cancer. Sensitivity/specificity for detecting tumour and parametrial extension against histopathology for a reading radiologist were determined on coronal T2-W and T2W + DW images. An independent radiologist also scored T2-W images without and with addition of DWI for the external-array and endovaginal coils on separate occasions >2 weeks apart. Cohen's kappa assessed inter- and intra-observer agreement. Median tumour volume in 19/38 cases positive on subsequent histology was 1.75 cm{sup 3}. Sensitivity, specificity, PPV, NPV were: reading radiologist 91.3 %, 89.5 %, 91.3 %, 89.5 %, respectively; independent radiologist T2-W 82.6 %, 73.7 %, 79.1 %, 77.8 % for endovaginal, 73.9 %, 89.5 %, 89.5 %, 73.9 % for external-array coil. Adding DWI improved sensitivity and specificity of endovaginal imaging (78.2 %, 89.5 %); adding DWI to external-array imaging improved specificity (94.7 %) but reduced sensitivity (66.7 %). Inter- and intra-observer agreement on T2-W + DWI was good (kappa = 0.67 and 0.62, respectively). Endovaginal coil T2-W MRI is more sensitive than external-array coil for detecting tumours <2 cm{sup 3}; adding DWI improves specificity of endovaginal imaging but reduces sensitivity of external-array imaging. (orig.)

  13. Fat-suppressed T2-weighted MRI appearance of subchondral insufficiency fracture of the femoral head

    Energy Technology Data Exchange (ETDEWEB)

    Sonoda, Kazuhiko; Yamamoto, Takuaki; Motomura, Goro; Karasuyama, Kazuyuki; Kubo, Yusuke; Iwamoto, Yukihide [Kyushu University, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Higashi-ku, Fukuoka (Japan)

    2016-11-15

    Our aims were to investigate the imaging appearance of subchondral insufficiency fracture (SIF) of the femoral head based on fat-suppressed T2-weighted MRI, and evaluate its correlation with the clinical outcomes following conservative treatment. We retrospectively evaluated 40 hips in 37 patients with SIF of the femoral head (12 males and 25 females; mean age 55.8 years, range 22-78 years). MRI examinations were performed within 3 months after the onset of hip pain. Using fat-suppressed T2-weighted imaging, we evaluated the hips for the intensity of the subchondral bone (corresponding to the area superior to the low intensity band on T1-weighted images) as well as bone marrow edema, joint effusion, and presence of the band lesion. We then correlated the intensity of the subchondral bone with clinical outcomes. The hips were classified into three types based on subchondral intensity on fat-suppressed T2-weighted images: type 1 (21 hips) showed high intensity, type 2 (eight hips) showed heterogeneous intensity, and type 3 (11 hips) showed low intensity. The mean period between pain onset and MRI examination was significantly longer for type 2 hips than for type 1. Healing rates were 86 % for type 1, 75 % for type 2, and 18 % for type 3. SIF cases were classified into three types based on subchondral intensity on fat-suppressed T2-weighted imaging performed within 3 months after pain onset. Type 3 SIF tended to be intractable to conservative treatment compared to type 1 and type 2. (orig.)

  14. Abdominal MR imaging using a HASTE sequence : image comparison on the different echo times

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kwang Bo; Lee, Moon Gyu; Lim, Tae Hwan; Jeong, Yoong Ki; Ha, Hyun Kwon; Kim, Pyo Nyun; Auh, Yong Ho [Ulsan Univ. College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

    1999-11-01

    To determine the optimal parameters of abdominal HASTE imaging by means of a comparison of intermediate and long TE (echo time). We evaluated 30 consecutive patients who had undergone liver MR during a three-month period. Twelve patients were diagnosed as normal, four as having liver cirrhosis, and 14 were found to be suffering form hepatic hemangioma. On the basis of measured signal intensity of the liver, spleen, pancreas and gallbladder, and of fat, muscle, hemangioma, and background, we calculated the ratios of signal to noise (S/N), signal difference to noise (SD/N), and signal intensity (SI). Image quality was compared using these three ratios, and using two HASTE sequences with TEs of 90 msec and 134 msec, images were qualitatively evaluated. S/N ratio of the liver was higher when TE was 90 msec(p<.05), though S/N, SD/N and SI rations of the spleen, gallbladder, and pancreas-and of hemangiom-were higher when TE was 134 msec (p<.05). However, in muscle, all these three ratios were higher at a TE of 90 msec. SD/N ratio and SI of fat were higher at a TE of 134 msec. Overall image quality was better at a TE of 134 msec than at one of 90msec. A HASTE sequence with a TE of 134msec showed greater tissue contrast and stronger T2-weighted images than one with a TE of 90msec.

  15. A neurotological study of patients with pontine hyperintense lesions on T2 weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Toru; Tominaga, Satoru; Yukimasa, Akiko; Oku, Masaya; Sakagami, Masafumi [Hyogo Coll. of Medicine, Nishinomiya (Japan)

    2002-03-01

    Pontine hyperintense lesions seen on T2-weighted MRI were thought to be related to disequilibrium. Some of these lesions have a low signal on T1-weighted imaging, while others have an iso-signal. The purpose of this study was to clarify the relationship between neurological findings and pontine lesions detected by MRI. The subjects were 11 patients (6 males, 5 females; age range: 30 to 83 years [mean: 64.1 years]) with pontine hyperintense lesions identified on T2-weighted MRI. We compared the clinical signs and the MRI findings. Six of the patients had low-intensity areas on T1-weighted images, and the other 5 had iso-intensity areas. Six patients complained of vertigo, and 5 complained of dizziness. Eight complained of positionaly evoked disequilibrium. Positional nystagmus was seen in 4 patients. In 9 patients, abnormalities were found on the ENG test, including the saccadic eye movement test, ETT, and OKP. Numbness on the lips occurred in 2 patients, and cerebellar signs were present in 4. None of the patients had facial paralysis. Disequilibrium originating in the central nervous system was suggested in 10 patients. Clinical examinations revealed similar findings in patients with a low signal on T1-weighted MRI and those with an iso-signal. Our results indicate that pontine lesions identified by T2-weighted MRI cause vertigo or dizziness, and, in most cases, these lesions cause abnormal neurological or neurological abnormalities. (author)

  16. Feasibility of similarity coefficient map for improving morphological evaluation of T2* weighted MRI for renal cancer

    Science.gov (United States)

    Wang, Hao-Yu; Hu, Jiani; Xie, Yao-Qin; Chen, Jie; Yu, Amy; Wei, Xin-Hua; Dai, Yong-Ming; Li, Meng; Bao, Shang-Lian; M. Haacke, E.

    2013-03-01

    The purpose of this paper is to investigate the feasibility of using a similarity coefficient map (SCM) in improving the morphological evaluation of T2* weighted (T2*W) magnatic resonance imaging (MRI) for renal cancer. Simulation studies and in vivo 12-echo T2*W experiments for renal cancers were performed for this purpose. The results of the first simulation study suggest that an SCM can reveal small structures which are hard to distinguish from the background tissue in T2*W images and the corresponding T2* map. The capability of improving the morphological evaluation is likely due to the improvement in the signal-to-noise ratio (SNR) and the carrier-to-noise ratio (CNR) by using the SCM technique. Compared with T2*W images, an SCM can improve the SNR by a factor ranging from 1.87 to 2.47. Compared with T2* maps, an SCM can improve the SNR by a factor ranging from 3.85 to 33.31. Compared with T2*W images, an SCM can improve the CNR by a factor ranging from 2.09 to 2.43. Compared with T2* maps, an SCM can improve the CNR by a factor ranging from 1.94 to 8.14. For a given noise level, the improvements of the SNR and the CNR depend mainly on the original SNRs and CNRs in T2*W images, respectively. In vivo experiments confirmed the results of the first simulation study. The results of the second simulation study suggest that more echoes are used to generate the SCM, and higher SNRs and CNRs can be achieved in SCMs. In conclusion, an SCM can provide improved morphological evaluation of T2*W MR images for renal cancer by unveiling fine structures which are ambiguous or invisible in the corresponding T2*W MR images and T2* maps. Furthermore, in practical applications, for a fixed total sampling time, one should increase the number of echoes as much as possible to achieve SCMs with better SNRs and CNRs.

  17. Whole brain 3D T2-weighted BOLD fMRI at 7T

    Science.gov (United States)

    Hua, Jun; Qin, Qin; van Zijl, Peter C. M.; Pekar, James J.; Jones, Craig K.

    2014-01-01

    Purpose A new acquisition scheme for T2-weighted spin-echo BOLD fMRI is introduced. Methods It employs a T2-preparation module to induce BOLD contrast, followed by a single-shot 3D fast gradient-echo readout with short TE. It differs from most spin-echo BOLD sequences in that BOLD contrast is generated before the readout, which eliminates the “dead time” due to long TE required for T2 contrast, and substantially improves acquisition efficiency. This approach, termed “3D T2prep-GRE”, was implemented at 7T with a typical spatial (2.5×2.5×2.5mm3) and temporal (TR=2.3s) resolution for fMRI and whole-brain coverage (55 slices), and compared with the widely used 2D spin-echo EPI sequence. Results In fMRI experiments of simultaneous visual/motor activities, 3D T2prep-GRE showed minimal distortion and little signal dropout across the whole brain. Its lower power deposition allowed greater spatial coverage (55 versus 17 slices with identical TR, resolution and power level), temporal SNR (60% higher) and CNR (35% higher) efficiency than 2D spin-echo EPI. It also showed smaller T2* contamination. Conclusion This approach is expected to be useful for ultra-high field fMRI, especially for regions near air cavities. The concept of using T2-preparation to generate BOLD contrast can be combined with many other sequences at any field strength. PMID:24338901

  18. Microscopic imaging of slow flow and diffusion: a pulsed field gradient stimulated echo sequence combined with turbo spin echo imaging

    NARCIS (Netherlands)

    Scheenen, T.W.J.; Vergeldt, F.J.; Windt, C.W.; Jager, de P.A.; As, van H.

    2001-01-01

    In this paper we present a pulse sequence that combines a displacement-encoded stimulated echo with rapid sampling of k-space by means of turbo spin echo imaging. The stimulated echo enables the use of long observation times between the two pulsed field gradients that sample q-space completely.

  19. Optimal Echo Spacing for Multi-Echo Imaging measurements of Bi-exponential T2 relaxation

    OpenAIRE

    Dula, Adrienne N.; Gochberg, Daniel F.; Does, Mark D.

    2008-01-01

    Calculations, analytical solutions, and simulations were used to investigate the trade-off of echo spacing and receiver bandwidth for the characterization of bi-exponential transverse relaxation using a multi-echo imaging pulse sequence. The Cramer-Rao lower bound of the standard deviation of the four parameters of a two-pool model were computed for a wide range of component T2 values and echo spacing. The results demonstrate that optimal echo spacing (TEopt) is not generally the minimal avai...

  20. T2 weighted MRI for assessing renal lesions in transgenic mouse models of tuberous sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Kalogerou, Maria; Zhang, Yadan; Yang, Jian; Garrahan, Nigel [Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN (United Kingdom); Paisey, Stephen; Tokarczuk, Paweł; Stewart, Andrew [School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX (United Kingdom); Gallacher, John [Department of Primary Care and Public Health, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4YS (United Kingdom); Sampson, Julian R. [Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN (United Kingdom); Shen, Ming Hong, E-mail: shenmh@cf.ac.uk [Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN (United Kingdom)

    2012-09-15

    Objective: Transgenic mouse models of tuberous sclerosis (TSC) develop renal cysts, cystadenomas, solid adenomas and carcinomas. Identification and characterisation of these lesions in vivo may help in TSC pre-clinical trials. This study was to evaluate T2 weighted MRI for assessment of renal lesions in two Tsc mouse models. Materials and Methods: Tsc1{sup +/−}, Tsc2{sup +/−} and wild type mice were subjected to a first MRI scan at 12 months of age and a second scan 2 months later. One Tsc2{sup +/−} mouse was treated with rapamycin for two months after the initial scan. Immediately following the second scan, mice were sacrificed and MRI images were compared to renal histological findings. Results: MRI identified all types of Tsc-associated renal lesions in both Tsc1{sup +/−} and Tsc2{sup +/−} mice. The smallest detectable lesions were <0.1 mm{sup 3}. Eighty three percent of all renal lesions detected in the first scan were re-identified in the second scan. By MRI, these lesions demonstrated significant growth in the 9 untreated Tsc1{sup +/−} and Tsc2{sup +/−} mice but shrinkage in the rapamycin treated Tsc2{sup +/−} mouse. Between the two scans, MRI also revealed significant increase in both the total number and volume of lesions in untreated mice and decrease in the rapamycin treated mouse, respectively. In comparison to histological analysis MRI detected most cysts and cystadenomas (66%) but only a minority of solid tumours (29%). Conclusion: These results suggest that T2 weighted MRI may be a useful tool for assessing some renal lesions in pre-clinical studies using Tsc mouse models. However, improved sensitivity for T2 weighted MRI is required, particularly for solid renal lesions.

  1. Diffusion-and T2-weighted MRI of the transverse pontine fibres in spinocerebellar degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, M.; Hosoya, T.; Yamaguchi, K. [Dept. of Radiology, Yamagata University School of Medicine (Japan); Kawanami, T.; Kato, T. [3. Dept. of Internal Medicine, Yamagata University School of Medicine (Japan)

    2000-11-01

    Because the transverse pontine fibres degenerate in some subtypes of spinocerebellar degeneration (SCD), demonstration of these fibres may be helpful for radiological diagnosis of SCD. Using multishot diffusion-weighted MRI, we attempted to find a way to show the transverse pontine fibres. We assessed the quality of demonstration of these fibres on DWI and of abnormal high signal in the pons and middle cerebellar peduncles on T2-weighted images. We examined evaluated 24 control subjects and 12 patients with SCD: two with sporadic olivopontocerebellar atrophy (OPCA), five with spinocerebellar ataxia type 1 (SCA1), two with SCA3, and three with SCA6. In all control subjects and patients with SCA6, we succeeded in demonstrating the transverse pontine fibres as clear low-signal bundles using DWI. In two patients with SCA3, these fibres were identified less distinctly. In contrast, in two patients with sporadic OPCA and in four of five patients with SCA1, the fibres were not identified. In both patients with sporadic OPCA, abnormal high-signal foci were seen in the base of the pons and middle cerebellar peduncles on T2-weighted images; no such foci were detected in any patient with SCA1, SCA3 or SCA6. DWI seems to be useful for demonstrating transverse pontine fibres. Abnormal high signal in the pons and middle cerebellar peduncles may provide a clue to differentiation of sporadic OPCA from other types of SCD. (orig.)

  2. MR-Guided Sclerotherapy of Low-Flow Vascular Malformations Using T2-Weighted Interrupted bSSFP (T2W-iSSFP): Comparison of Pulse Sequences for Visualization and Needle Guidance

    Science.gov (United States)

    Xu, Di; Herzka, Daniel A.; Gilson, Wesley D.; McVeigh, Elliot R.; Lewin, Jonathan S.; Weiss, Clifford R.

    2017-01-01

    Purpose Image-guided treatment of low-flow vascular (venous or lymphatic) malformations presents a challenging visualization problem, regardless of the imaging modality being used for guidance. The purpose of this study was to employ a new magnetic resonance imaging (MRI) sequence, T2-weighted interrupted balanced steady-state free precession (T2W-iSSFP), for real-time image guidance of needle insertion. Materials and Methods T2W-iSSFP uses variable flip angle balanced steady-state free precession (bSSFP, a.k.a. SSFP) to establish T2-weighting and fat suppression. Swine (n = 3) and patients (n = 4, three female, all with venous malformations) were enrolled in the assessment. T2-weighted turbo spin echo (T2-TSE) with spectral adiabatic inversion recovery (SPAIR), SPAIR-T2-TSE or T2-TSE for short, was used as the reference. T2-weighted half Fourier acquired single shot turbo spin echo (T2-HASTE) with SPAIR (SPAIR-T2-HASTE, T2-HASTE for short), fat saturated bSSFP (FS-SSFP), and T2W-iSSFP were imaged. Numeric metrics, namely, contrast-to-noise ratio (CNR) efficiency (CNR divided by the square root of acquisition time) and local sharpness (the reciprocal of edge width), were used to assess image quality. MR-guided sclerotherapy was performed on the same patients using real-time T2W-iSSFP to guide needle insertion. Results Comparing the visualization of needles in the images of swine, the local sharpness (mm−1) was: 0.21 ± 0.06 (T2-HASTE), 0.48 ± 0.02 (FS-SSFP), and 0.49 ± 0.03 (T2W-iSSFP). T2W-iSSFP is higher than T2-HASTE (P images, their CNR efficiencies were: 797 ± 66 (T2-HASTE), 281 ± 44 (FS-SSFP), and 860 ± 29 (T2W-iSSFP). T2W-iSSFP is higher than FS-SSFP (P images are needed. PMID:24395498

  3. Cerebral vascular malformations: Applications of magnetic resonance imaging to differential diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Imakita, S.; Nishimura, T.; Yamada, N.; Naito, H.; Takamiya, M.; Yamada, Y.; Kikuchi, H.; Yonekawa, Y.; Sawada, T.; Yamaguchi, T.

    1989-09-01

    Twelve patients with cerebral vascular malformations (5 cavernous angiomas, 1 thrombosed arteriovenous malformation, and 6 venous angiomas) were studied with magnetic resonance (MR) imaging. All lesions were clearly depicted. Characteristic MR findings were obtained mainly on T2-weighted images: A markedly low intensity area was always seen. The margins of arteriovenous malformation (AVM) and venous angioma were irregular while those of cavernous angioma were smooth in all planes on T2-weighted images. Gradient-echo (GrE) pulse sequence were more sensitive than T2-weighted spin echo (SE) in AVM detection. MR imaging could play an important role in the differential diagnosis of cerebral vascular malformations. (orig.).

  4. Positive contrast MR imaging of tendons, ligaments, and menisci by subtraction of signals from a double echo steady state sequence (Sub-DESS).

    Science.gov (United States)

    Martirosian, Petros; Schraml, Christina; Springer, Fabian; Schwenzer, Nina F; Würslin, Christian; Schick, Fritz; Deimling, Michael

    2014-01-01

    To improve the visualization of fibrous tissues as tendons, ligaments and fibrocartilage structures as menisci by positive contrast using a new 3D Double Echo Steady State (DESS) sequence. The proposed 3D DESS sequence works with separate acquisition of a first echo with an echo time (TE1 ) of 1.2 ms followed by a more heavily T2 -weighted second echo recorded at time TE2 . Subtraction of images from both echoes leads to positive signal from fibrous tissues, whereas in other tissues as musculature and fat the subtraction signal nearly vanishes due to almost similar signal strength in both echoes. Systematic measurements in healthy volunteers with different sets of pulse repetition time (TR), TE1 , readout bandwidth and flip angle were performed to determine optimal sequence parameters. The presented 3D sequence with Cartesian readout requires relatively short measuring time, provides reasonable signal-to-noise ratio and can be easily implemented in protocols for clinical musculoskeletal MR imaging. Degenerative changes or tears of tendons, ligaments and fibrocartilage are known to cause increased water content and therefore prolongation of transverse relaxation times, which leads to reduced signal intensities in the "subtraction images." Positive contrast of fibrous tissue as demonstrated by the proposed sub-DESS approach provides improved conspicuity and allows for three-dimensional reconstruction especially of structures with curved geometry. Copyright © 2013 Wiley Periodicals, Inc.

  5. Correction for Eddy Current-Induced Echo-Shifting Effect in Partial-Fourier Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Trong-Kha Truong

    2015-01-01

    Full Text Available In most diffusion tensor imaging (DTI studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR. However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types of artifacts in partial-Fourier DTI. Here, we present an improved DTI acquisition and reconstruction scheme, capable of generating high-quality and high-SNR DTI data without eddy current-induced artifacts. This new scheme consists of three components, respectively, addressing the three distinct types of artifacts. First, a k-space energy-anchored DTI sequence is designed to recover eddy current-induced signal loss (i.e., Type 1 artifact. Second, a multischeme partial-Fourier reconstruction is used to eliminate artificial signal elevation (i.e., Type 2 artifact associated with the conventional partial-Fourier reconstruction. Third, a signal intensity correction is applied to remove artificial signal modulations due to eddy current-induced erroneous T2*-weighting (i.e., Type 3 artifact. These systematic improvements will greatly increase the consistency and accuracy of DTI measurements, expanding the utility of DTI in translational applications where quantitative robustness is much needed.

  6. Gradient-echo magnetic resonance imaging study of pancreatic iron overload in young Egyptian beta-thalassemia major patients and effect of splenectomy

    Directory of Open Access Journals (Sweden)

    Matter Randa M

    2010-04-01

    Full Text Available Abstract Background Thalassemic patients suffer from diabetes mellitus secondary to hemosiderosis. Aims The study aimed to evaluate pancreatic iron overload by T2*-weighted Gradient-echo magnetic resonance imaging (MRI in young beta-thalassemia major patients and to correlate it with glucose disturbances, hepatic hemosiderosis, serum ferritin and splenectomy. Methods Forty thalassemic patients (20 non diabetic, 10 diabetic, and 10 with impaired glucose tolerance were recruited from Pediatric Hematology Clinic, in addition to 20 healthy controls. All patients underwent clinical assessment and laboratory investigations included complete blood count, liver function tests, serum ferritin and oral glucose tolerance test (OGTT. A T2*-weighted gradient-echo sequence MRI was performed with 1.5 T scanner and signal intensity ratio (SIR of the liver and the pancreas to noise were calculated. Results Significant reduction in signal intensity ratio (SIR of the liver and the pancreas was shown in thalassemic patients compared to controls (P Conclusions pancreatic siderosis can be detected by T2* gradient-echo MRI since childhood in thalassemic patients, and is more evident in patients with abnormal glucose tolerance. After splenectomy, iron deposition may be accelerated in the pancreas. Follow up of thalassemic patients using pancreatic MRI together with intensive chelation therapy may help to prevent the development of overt diabetes.

  7. Should less motion sensitive T2-weighted BLADE TSE replace Cartesian TSE for female pelvic MRI?

    Science.gov (United States)

    Froehlich, Johannes M; Metens, Thierry; Chilla, Bianka; Hauser, Nik; Klarhoefer, Markus; Kubik-Huch, Rahel A

    2012-12-01

    To prospectively compare the diagnostic performance of a non-Cartesian k-space sampling T2-weighted TSE BLADE sequence with a conventional T2-weighted TSE sequence in female pelvic organs. Forty-seven patients with sonographically indeterminate adnexal masses or uterine lesions underwent sagittal BLADE and conventional TSE at 1.5 T after glucagon administration. Two radiologists independently determined their preferred sequence by rating: overall image diagnostic quality, conspicuity of the zonal anatomy and delineation of pathologies of the uterus and cervix, presence of artefacts, and of fluid in the pouch of Douglas (Wilcoxon signed rank test). Signal-to noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured for the myometrium versus the rectus abdominis muscle (Student's t-test). BLADE significantly (p TSE κ = 0.84). In the majority of cases (53.2 % vs 59.6 %, respectively, κ = 0.82) radiologists preferred conventional TSE due to better image contrast (p TSE 57.5 ± 37.7; BLADE 16.6 ± 12.2) and CNR (TSE 40.4 ± 33.5; BLADE 7.2 ± 8.8) were significantly higher on conventional TSE (p TSE, this comes at the expense of overall contrast. • Use of BLADE may reduce T2 contrast and thus visibility of free pelvic fluid or cystic structures • Non-Cartesian sampling of k-space such as BLADE is beneficial due to less motion sensitivity • BLADE provides clearer delineation and conspicuity of uterine zonal anatomy on pelvic MRIs.

  8. Detectability of low and intermediate or high risk prostate cancer with combined T2-weighted and diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Doo, Kyung Won; Sung, Deuk Jae; Park, Beom Jin; Kim, Min Ju; Cho, Sung Bum; Oh, Yu Whan [Department of Radiology, Anam Hospital, Korea University, Seoul (Korea, Republic of); Ko, Young Hwii [College of Medicine, Department of Urology, Anam Hospital, Korea University, Seoul (Korea, Republic of); Yang, Kyung Sook [College of Medicine, Department of Biostatistics, Korea University, Seoul (Korea, Republic of)

    2012-08-15

    To evaluate the incremental value of diffusion-weighted imaging (DWI) in combination with T2-weighted imaging to detect low (Gleason score, {<=} 6) and intermediate or high risk (Gleason score, {>=} 7) prostate cancer. Fifty-one patients who underwent MRI before prostatectomy were evaluated. Two readers independently scored the probability of tumour in eight regions of prostate on T2-weighted images (T2WI) and T2WI combined with apparent diffusion coefficient (ADC) maps. Data were divided into two groups - low risk and intermediate or high risk prostate cancer - and correlated with histopathological results. Diagnostic performance parameters, areas under the receiver-operating characteristic curve (AUCs) and interreader agreement were calculated. For both readers, AUCs of combined T2WI and ADC maps were greater than those of T2WI in intermediate or high risk (reader 1, 0.887 vs. 0.859; reader 2, 0.732 vs 0.662, P < 0.05) prostate cancers, but not in low risk (reader 1, 0.719 vs 0.725; reader 2, 0.685 vs. 0.680, P > 0.05) prostate cancers. Weighted {kappa} value of combined T2WI and ADC maps was 0.689. The addition of DWI to T2-weighted imaging improves the accuracy of detecting intermediate or high risk prostate cancers, but not for low risk prostate cancer detection. (orig.)

  9. Focal liver lesions segmentation and classification in nonenhanced T2-weighted MRI.

    Science.gov (United States)

    Gatos, Ilias; Tsantis, Stavros; Karamesini, Maria; Spiliopoulos, Stavros; Karnabatidis, Dimitris; Hazle, John D; Kagadis, George C

    2017-07-01

    To automatically segment and classify focal liver lesions (FLLs) on nonenhanced T2-weighted magnetic resonance imaging (MRI) scans using a computer-aided diagnosis (CAD) algorithm. 71 FLLs (30 benign lesions, 19 hepatocellular carcinomas, and 22 metastases) on T2-weighted MRI scans were delineated by the proposed CAD scheme. The FLL segmentation procedure involved wavelet multiscale analysis to extract accurate edge information and mean intensity values for consecutive edges computed using horizontal and vertical analysis that were fed into the subsequent fuzzy C-means algorithm for final FLL border extraction. Texture information for each extracted lesion was derived using 42 first- and second-order textural features from grayscale value histogram, co-occurrence, and run-length matrices. Twelve morphological features were also extracted to capture any shape differentiation between classes. Feature selection was performed with stepwise multilinear regression analysis that led to a reduced feature subset. A multiclass Probabilistic Neural Network (PNN) classifier was then designed and used for lesion classification. PNN model evaluation was performed using the leave-one-out (LOO) method and receiver operating characteristic (ROC) curve analysis. The mean overlap between the automatically segmented FLLs and the manual segmentations performed by radiologists was 0.91 ± 0.12. The highest classification accuracies in the PNN model for the benign, hepatocellular carcinoma, and metastatic FLLs were 94.1%, 91.4%, and 94.1%, respectively, with sensitivity/specificity values of 90%/97.3%, 89.5%/92.2%, and 90.9%/95.6% respectively. The overall classification accuracy for the proposed system was 90.1%. Our diagnostic system using sophisticated FLL segmentation and classification algorithms is a powerful tool for routine clinical MRI-based liver evaluation and can be a supplement to contrast-enhanced MRI to prevent unnecessary invasive procedures. © 2017 American

  10. Echo

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Dustin Yewell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-25

    This document is a white paper marketing proposal for Echo™ is a data analysis platform designed for efficient, robust, and scalable creation and execution of complex workflows. Echo’s analysis management system refers to the ability to track, understand, and reproduce workflows used for arriving at results and decisions. Echo improves on traditional scripted data analysis in MATLAB, Python, R, and other languages to allow analysts to make better use of their time. Additionally, the Echo platform provides a powerful data management and curation solution allowing analysts to quickly find, access, and consume datasets. After two years of development and a first release in early 2016, Echo is now available for use with many data types in a wide range of application domains. Echo provides tools that allow users to focus on data analysis and decisions with confidence that results are reported accurately.

  11. Noncontrast peripheral MRA with spiral echo train imaging.

    Science.gov (United States)

    Fielden, Samuel W; Mugler, John P; Hagspiel, Klaus D; Norton, Patrick T; Kramer, Christopher M; Meyer, Craig H

    2015-03-01

    To develop a spin echo train sequence with spiral readout gradients with improved artery-vein contrast for noncontrast angiography. Venous T2 becomes shorter as the echo spacing is increased in echo train sequences, improving contrast. Spiral acquisitions, due to their data collection efficiency, facilitate long echo spacings without increasing scan times. Bloch equation simulations were performed to determine optimal sequence parameters, and the sequence was applied in five volunteers. In two volunteers, the sequence was performed with a range of echo times and echo spacings to compare with the theoretical contrast behavior. A Cartesian version of the sequence was used to compare contrast appearance with the spiral sequence. Additionally, spiral parallel imaging was optionally used to improve image resolution. In vivo, artery-vein contrast properties followed the general shape predicted by simulations, and good results were obtained in all stations. Compared with a Cartesian implementation, the spiral sequence had superior artery-vein contrast, better spatial resolution (1.2 mm(2) versus 1.5 mm(2) ), and was acquired in less time (1.4 min versus 7.5 min). The spiral spin echo train sequence can be used for flow-independent angiography to generate three-dimensional angiograms of the periphery quickly and without the use of contrast agents. © 2014 Wiley Periodicals, Inc.

  12. Unenhanced breast MRI (STIR, T2-weighted TSE, DWIBS): An accurate and alternative strategy for detecting and differentiating breast lesions.

    Science.gov (United States)

    Telegrafo, Michele; Rella, Leonarda; Stabile Ianora, Amato Antonio; Angelelli, Giuseppe; Moschetta, Marco

    2015-10-01

    To assess the role of STIR, T2-weighted TSE and DWIBS sequences for detecting and characterizing breast lesions and to compare unenhanced (UE)-MRI results with contrast-enhanced (CE)-MRI and histological findings, having the latter as the reference standard. Two hundred eighty consecutive patients (age range, 27-73 years; mean age±standard deviation (SD), 48.8±9.8years) underwent MR examination with a diagnostic protocol including STIR, T2-weighted TSE, THRIVE and DWIBS sequences. Two radiologists blinded to both dynamic sequences and histological findings evaluated in consensus STIR, T2-weighted TSE and DWIBS sequences and after two weeks CE-MRI images searching for breast lesions. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy for UE-MRI and CE-MRI were calculated. UE-MRI results were also compared with CE- MRI. UE-MRI sequences obtained sensitivity, specificity, diagnostic accuracy, PPV and NPV values of 94%, 79%, 86%, 79% and 94%, respectively. CE-MRI sequences obtained sensitivity, specificity, diagnostic accuracy, PPV and NPV values of 98%, 83%, 90%, 84% and 98%, respectively. No statistically significant difference between UE-MRI and CE-MRI was found. Breast UE-MRI could represent an accurate diagnostic tool and a valid alternative to CE-MRI for evaluating breast lesions. STIR and DWIBS sequences allow to detect breast lesions while T2-weighted TSE sequences and ADC values could be useful for lesion characterization. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. High angular resolution diffusion imaging with stimulated echoes

    DEFF Research Database (Denmark)

    Lundell, Henrik; Alexander, Daniel C; Dyrby, Tim B

    2014-01-01

    Stimulated echo acquisition mode (STEAM) diffusion MRI can be advantageous over pulsed-gradient spin-echo (PGSE) for diffusion times that are long compared with T2 . It therefore has potential for biomedical diffusion imaging applications at 7T and above where T2 is short. However, gradient pulses...... angular resolution diffusion imaging (HARDI) data were acquired with and without the proposed compensation. The data were processed to derive standard diffusion tensor imaging (DTI) maps, which highlight the need for the compensation. Ignoring the other gradient pulses, a bias in DTI parameters from STEAM...

  14. View Angle Tilting Echo Planar Imaging for Distortion Correction

    OpenAIRE

    Ahn, Sinyeob; Hu, Xiaoping

    2011-01-01

    Geometric distortion caused by field inhomogeneity along the phase-encode (PE) direction is one of the most prominent artifacts due to a relatively low effective bandwidth along that direction in magnetic resonance echo planar imaging (EPI). This work describes a method for correcting in-plane image distortion along the PE direction using a view angle tilting (VAT) imaging technique in spin-echo EPI (SE-EPI). SE-EPI with VAT (SE-EPI-VAT) utilizes the addition of gradient blips along the slice...

  15. Correcting dynamic distortions in 7T echo planar imaging using a jittered echo time sequence

    Science.gov (United States)

    Dymerska, Barbara; Poser, Benedikt A.; Bogner, Wolfgang; Visser, Eelke; Eckstein, Korbinian; Cardoso, Pedro; Barth, Markus; Trattnig, Siegfried

    2015-01-01

    Purpose To develop a distortion correction method for echo planar imaging (EPI) that is able to measure dynamic changes in B0. Theory and Methods The approach we propose is based on single‐echo EPI with a jittering of the echo time between two values for alternate time points. Field maps are calculated between phase images from adjacent volumes and are used to remove distortion from corresponding magnitude images. The performance of our approach was optimized using an analytical model and by comparison with field maps from dual‐echo EPI. The method was tested in functional MRI experiments at 7T with motor tasks and compared with the conventional static approach. Results Unwarping using our method was accurate even for head rotations up to 8.2°, where the static approach introduced errors up to 8.2 mm. Jittering the echo time between 19 and 25 ms had no measurable effect on blood oxygenation level–dependent (BOLD) sensitivity. Our approach reduced the distortions in activated regions to distortion correction in the presence of motion. No reduction in BOLD sensitivity was observed. As such, it is suitable for application in a wide range of functional MRI experiments. Magn Reson Med 76:1388–1399, 2016. © 2015 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 License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26584148

  16. Familial form of cerebral cavernous malformations: evaluation of gradient-spin-echo (GRASE) imaging in lesion detection and characterization at 1.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Brunereau, L. [Service de Radiologie Adultes Bretonneau, CHRU Tours (France); INSERM Faculte de Medecine, Tours (France); Leveque, C.; Cordoliani, Y. [Service de Radiologie et d' Imagerie Medicale, HIA Val de Grace, Paris (France); Bertrand, P.; Rouleau, P. [Service de Radiologie Adultes Bretonneau, CHRU Tours (France); Tranquart, F. [INSERM Faculte de Medecine, Tours (France); Labauge, P. [INSERM EPI Faculte de Medecine Lariboisiere-Saint-Louis, Paris (France)

    2001-11-01

    The purpose of this study was to evaluate the turbo gradient-spin-echo sequence (GRASE) in the MR assessment of the familial form of cerebral cavernous malformations (CCM). Twenty-one patients (15 male, six female) aged from 21 to 68 years (mean = 42.2 years) were prospectively examined with cerebral MR imaging, including T2-weighted turbo gradient-spin-echo (TGSE), turbo spin-echo (TSE) and gradient-echo (GRE) sequences. All sequences were performed in the same plane, the same matrix and the same field of view and were analyzed for signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), susceptibility effects, number of CCM, size of CCM and signal of CCM. It was found that SNR and CNR in the TGSE sequence were significantly inferior to those in both TSE and GRE sequences. TGSE and TSE sequences were significantly less prone to susceptibility effects than the GRE sequence. The sensitivity of TGSE and TSE sequences in detecting CCM was significantly lower than that of the GRE sequence. TGSE and TSE sequences provided comparable information about CCM size and signal. It was concluded that GRASE imaging was less sensitive than the GRE sequence in the detection of CCM and provided information similar to that yielded by the TSE sequence in the characterization of lesions, but with a higher number of artifacts. GRASE imaging cannot therefore replace TSE or GRE sequences in the MR evaluation of the familial form of CCM. (orig.)

  17. Volume T1-weighted gradient echo MRI in multiple sclerosis patients.

    Science.gov (United States)

    Shah, M; Ross, J S; VanDyke, C; Rudick, R A; Goodkin, D E; Obuchowski, N; Modic, M T

    1992-01-01

    Three-dimensional (3D) volume turbo fast low angle shot (FLASH) techniques have become available which produce heavily T1-weighted images, similar to inversion recovery scans, utilizing the appropriate flip angle and inversion time. The purpose of this study was to compare the sensitivity of a rapid volume gradient echo technique [3D magnetization prepared rapid acquisition gradient echo (MP RAGE)] in identifying multiple sclerosis (MS) plaques with a conventional T2-weighted spin echo (SE) sequence. Ten patients with clinical MS were evaluated. Patients underwent a routine examination consisting of an axial T2-weighted SE sequence (2,500,22/90) and a coronal 3D MP RAGE, 10/4/10, acquired as 128 two mm partitions. In six patients, area measurements of 22 plaques were determined on both the axial T2-weighted SE examinations and the axial reformatted MP RAGE examinations. The overall number of plaques utilizing each technique was approximately the same. One hundred twenty-two plaques were visualized for the 3D MP RAGE sequence, and 128 plaques for the T2-weighted SE sequence. There were differences in detection of plaques in different regions, with plaques in gray matter better demonstrated utilizing the conventional T2-weighted SE sequence. Plaques in the corpus callosum, pons, and brachia pontis were better demonstrated utilizing 3D MP RAGE. No significant difference was found between the areas measured on the MP RAGE sequence and on the T2-weighted SE sequence. Three-dimensional MP RAGE provides a sensitive and complementary method to conventional T2-weighted SE sequences in the evaluation of patients with MS.

  18. T2-weighted MRI-derived textural features reflect prostate cancer aggressiveness: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Nketiah, Gabriel; Elschot, Mattijs; Kim, Eugene; Teruel, Jose R. [NTNU, Norwegian University of Science and Technology, Department of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); Scheenen, Tom W. [Radboud University Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Bathen, Tone F.; Selnaes, Kirsten M. [NTNU, Norwegian University of Science and Technology, Department of Circulation and Medical Imaging, Faculty of Medicine, Trondheim (Norway); St. Olavs Hospital, Trondheim University Hospital, Trondheim (Norway)

    2017-07-15

    To evaluate the diagnostic relevance of T2-weighted (T2W) MRI-derived textural features relative to quantitative physiological parameters derived from diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in Gleason score (GS) 3+4 and 4+3 prostate cancers. 3T multiparametric-MRI was performed on 23 prostate cancer patients prior to prostatectomy. Textural features [angular second moment (ASM), contrast, correlation, entropy], apparent diffusion coefficient (ADC), and DCE pharmacokinetic parameters (K{sup trans} and V{sub e}) were calculated from index tumours delineated on the T2W, DW, and DCE images, respectively. The association between the textural features and prostatectomy GS and the MRI-derived parameters, and the utility of the parameters in differentiating between GS 3+4 and 4+3 prostate cancers were assessed statistically. ASM and entropy correlated significantly (p < 0.05) with both GS and median ADC. Contrast correlated moderately with median ADC. The textural features correlated insignificantly with K{sup trans} and V{sub e}. GS 4+3 cancers had significantly lower ASM and higher entropy than 3+4 cancers, but insignificant differences in median ADC, K{sup trans}, and V{sub e}. The combined texture-MRI parameters yielded higher classification accuracy (91%) than the individual parameter sets. T2W MRI-derived textural features could serve as potential diagnostic markers, sensitive to the pathological differences in prostate cancers. (orig.)

  19. Multi-echo GRE imaging of knee cartilage.

    Science.gov (United States)

    Yuen, Joanna; Hung, Jachin; Wiggermann, Vanessa; Robinson, Simon D; McCormack, Robert; d'Entremont, Agnes G; Rauscher, Alexander

    2017-05-01

    To visualize healthy and abnormal articular cartilage, we investigated the potential of using the 3D multi-echo gradient echo (GRE) signal's magnitude and frequency and maps of T2* relaxation. After optimizing imaging parameters in five healthy volunteers, 3D multi-echo GRE magnetic resonance (MR) images were acquired at 3T in four patients with chondral damage prior to their arthroscopic surgery. Average magnitude and frequency information was extracted from the GRE images, and T2* maps were generated. Cartilage abnormalities were confirmed after arthroscopy and were graded using the Outerbridge classification scheme. Regions of interest were identified on average magnitude GRE images and compared to arthroscopy. All four patients presented with regions of Outerbridge Grade I and II cartilage damage on arthroscopy. One patient had Grade III changes. Grade I, II, and III changes were detectable on average magnitude and T2* maps, while Grade II and higher changes were also observable on MR frequency maps. For average magnitude images of healthy volunteers, the signal-to-noise ratio of the magnitude image averaged over three echoes was 4.26 ± 0.32, 12.26 ± 1.09, 14.31 ± 1.93, and 13.36 ± 1.13 in bone, femoral, tibial, and patellar cartilage, respectively. This proof-of-principle study demonstrates the feasibility of using different imaging contrasts from the 3D multi-echo GRE scan to visualize abnormalities of the articular cartilage. © 2016 International Society for Magnetic Resonance in Medicine Level of Evidence: 1 J. MAGN. RESON. IMAGING 2017;45:1502-1513. © 2016 International Society for Magnetic Resonance in Medicine.

  20. Improved visualization of collateral ligaments of the ankle: multiplanar reconstructions based on standard 2D turbo spin-echo MR images

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Sylvain R.; Mengiardi, Bernard; Pfirrmann, Christian W.A.; Hodler, Juerg; Zanetti, Marco [University Hospital, Balgrist, From the Departments of Radiology, Zurich (Switzerland)

    2007-05-15

    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.)

  1. Quiet echo planar imaging for functional and diffusion MRI.

    Science.gov (United States)

    Hutter, Jana; Price, Anthony N; Cordero-Grande, Lucilio; Malik, Shaihan; Ferrazzi, Giulio; Gaspar, Andreia; Hughes, Emer J; Christiaens, Daan; McCabe, Laura; Schneider, Torben; Rutherford, Mary A; Hajnal, Joseph V

    2018-03-01

    To develop a purpose-built quiet echo planar imaging capability for fetal functional and diffusion scans, for which acoustic considerations often compromise efficiency and resolution as well as angular/temporal coverage. The gradient waveforms in multiband-accelerated single-shot echo planar imaging sequences have been redesigned to minimize spectral content. This includes a sinusoidal read-out with a single fundamental frequency, a constant phase encoding gradient, overlapping smoothed CAIPIRINHA blips, and a novel strategy to merge the crushers in diffusion MRI. These changes are then tuned in conjunction with the gradient system frequency response function. Maintained image quality, SNR, and quantitative diffusion values while reducing acoustic noise up to 12 dB (A) is illustrated in two adult experiments. Fetal experiments in 10 subjects covering a range of parameters depict the adaptability and increased efficiency of quiet echo planar imaging. Purpose-built for highly efficient multiband fetal echo planar imaging studies, the presented framework reduces acoustic noise for all echo planar imaging-based sequences. Full optimization by tuning to the gradient frequency response functions allows for a maximally time-efficient scan within safe limits. This allows ambitious in-utero studies such as functional brain imaging with high spatial/temporal resolution and diffusion scans with high angular/spatial resolution to be run in a highly efficient manner at acceptable sound levels. Magn Reson Med 79:1447-1459, 2018. © 2017 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. © 2017 The Authors Magnetic Resonance in

  2. Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI

    Energy Technology Data Exchange (ETDEWEB)

    Rouviere, Olivier; Lyonnet, Denis [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urinary and Vascular Radiology, Lyon (France); Universite de Lyon, Lyon (France); Universite de Lyon 1, Faculte de medecine Lyon Nord, Lyon (France); Inserm, U556, Lyon (France); Girouin, Nicolas; Glas, Ludivine; Ben Cheikh, Alexandre [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urinary and Vascular Radiology, Lyon (France); Universite de Lyon, Lyon (France); Universite de Lyon 1, Faculte de medecine Lyon Nord, Lyon (France); Gelet, Albert [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urology, Lyon (France); Inserm, U556, Lyon (France); Mege-Lechevallier, Florence [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Pathology, Lyon (France); Rabilloud, Muriel [Hospices Civils de Lyon, Department of Biostatistics, Lyon (France); Universite de Lyon 1, UMR CNRS, Laboratoire Biostatistiques-Sante, Pierre-Benite (France); Chapelon, Jean-Yves [Inserm, U556, Lyon (France)

    2010-01-15

    The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies (''routine biopsies''); operator 2 obtained up to three cores per suspicious lesion on MRI (''targeted biopsies''). Seventy-seven suspicious lesions were detected on DCE images (n=52), T2w images (n=2) or both (n=23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p=0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p<0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05-3.64) and 1.38 (95% CI 1.13-1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue. (orig.)

  3. A Novel MRI Biomarker of Spinal Cord White Matter Injury : T2*-Weighted White Matter to Gray Matter Signal Intensity Ratio

    NARCIS (Netherlands)

    Martin, A. R.; De Leener, B.; Cohen-Adad, J.; Cadotte, D. W.; Kalsi-Ryan, S.; Lange, S. F.; Tetreault, L.; Nouri, A.; Crawley, A.; Mikulis, D. J.; Ginsberg, H.; Fehlings, M. G.

    BACKGROUND AND PURPOSE: T2*-weighted imaging provides sharp contrast between spinal cord GM and WM, allowing their segmentation and cross-sectional area measurement. Injured WM demonstrates T2*WI hyperintensity but requires normalization for quantitative use. We introduce T2*WI WM/GM

  4. T2-weighted MRI-derived textural features reflect prostate cancer aggressiveness: preliminary results

    NARCIS (Netherlands)

    Nketiah, G.; Elschot, M.; Kim, E.; Teruel, J.R.; Scheenen, T.W.J.; Bathen, T.F.; Selnaes, K.M.

    2017-01-01

    PURPOSE: To evaluate the diagnostic relevance of T2-weighted (T2W) MRI-derived textural features relative to quantitative physiological parameters derived from diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in Gleason score (GS) 3+4 and 4+3 prostate cancers. MATERIALS AND METHODS:

  5. Detection of hemosiderin deposition by T2*-weighted MRI after subarachnoid hemorrhage.

    Science.gov (United States)

    Imaizumi, Toshio; Chiba, Masahiko; Honma, Toshimi; Niwa, Jun

    2003-07-01

    Subarachnoid hemorrhage (SAH) is very difficult to diagnose several months after its onset. We thus investigated subarachnoid hemosiderin deposition well after SAH by T2*-weighted MRI, a sensitive method for hemosiderin detection. To investigate how hemosiderin deposition as confirmed by T2*-weighted MRI contributes to the determination of prior SAH and how the extent of hemosiderin deposition is associated with a number of clinical factors, we retrospectively analyzed 58 patients >3 months after SAH associated with ruptured aneurysms. We also investigated 209 healthy volunteers as controls. T2*-weighted MRI demonstrated subarachnoid hemosiderin deposition in 72.4% of the SAH patients, whereas no deposition was seen in the healthy volunteer group. The hemosiderin was preferentially deposited in the subarachnoid space near a ruptured aneurysm. Odds ratios (ORs) were estimated from logistic regression analyses correlating hemosiderin deposition with other factors. Age (>or=54 years) (OR, 5.1; 95% CI, 1.03 to 25.0; P=0.046), Fisher grade 3 on initial CT (OR, 8.0; 95% CI, 1.26 to 50.4; P=0.027), and Karnofsky Scale score hemosiderin deposition levels. T2*-weighted MRI is an effective means of diagnosing prior SAH and may also reveal the location of a ruptured aneurysm. The extent of hemosiderin deposition was significantly associated with several factors, including age, CT findings, and poor prognosis.

  6. Determination of the Association Between T2-weighted MRI and Gleason Sub-pattern: A Proof of Principle Study.

    Science.gov (United States)

    Downes, Michelle R; Gibson, Eli; Sykes, Jenna; Haider, Masoom; van der Kwast, Theo H; Ward, Aaron

    2016-11-01

    The study aimed to determine the relationship between T2-weighted magnetic resonance imaging (MRI) signal and histologic sub-patterns in prostate cancer areas with different Gleason grades. MR images of prostates (n = 25) were obtained prior to radical prostatectomy. These were processed as whole-mount specimens with tumors and the peripheral zone was annotated digitally by two pathologists. Gleason grade 3 was the most prevalent grade and was subdivided into packed, intermediate, and sparse based on gland-to-stroma ratio. Large cribriform, intraductal carcinoma, and small cribriform glands (grade 4 group) were separately annotated but grouped together for statistical analysis. The log MRI signal intensity for each contoured region (n = 809) was measured, and pairwise comparisons were performed using the open-source software R version 3.0.1. Packed grade 3 sub-pattern has a significantly lower MRI intensity than the grade 4 group (P pattern (P pattern grade 3 group (P = 0.54). In multivariable analysis adjusting for peripheral zone, the P values maintained significance (packed grade 3 group vs grade 4 group, P pattern vs packed grade 3 sub-pattern, P study demonstrated that T2-weighted MRI signal is dependent on histologic sub-patterns within Gleason grades 3 and 4 cancers, which may have implications for directed biopsy sampling and patient management. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  7. Logical Operation of Set Intersection for Images in Optical Echo Holography

    Science.gov (United States)

    Sakhbieva, A. R.; Nefed'ev, L. A.; Garnaeva, G. I.

    2017-07-01

    We use a stimulated echo hologram to consider performing logical operations on sets represented in the form of images. We show that a stimulated echo hologram can be used to perform the logical operation of set intersection.

  8. Echo decorrelation imaging of ex vivo HIFU and bulk ultrasound ablation using image-treat arrays

    Science.gov (United States)

    Fosnight, Tyler R.; Hooi, Fong Ming; Colbert, Sadie B.; Keil, Ryan D.; Barthe, Peter G.; Mast, T. Douglas

    2017-03-01

    In this study, the ability of ultrasound echo decorrelation imaging to map and predict heat-induced cell death was tested using bulk ultrasound thermal ablation, high intensity focused ultrasound (HIFU) thermal ablation, and pulse-echo imaging of ex vivo liver tissue by a custom image-treat array. Tissue was sonicated at 5.0 MHz using either pulses of unfocused ultrasound (N=12) (7.5 s, 50.9-101.8 W/cm2 in situ spatial-peak, temporal-peak intensity) for bulk ablation or focused ultrasound (N=21) (1 s, 284-769 W/cm2 in situ spatial-peak, temporal-peak intensity and focus depth of 10 mm) for HIFU ablation. Echo decorrelation and integrated backscatter (IBS) maps were formed from radiofrequency pulse-echo images captured at 118 frames per second during 5.0 s rest periods, beginning 1.1 s after each sonication pulse. Tissue samples were frozen at -80˚C, sectioned, vitally stained, imaged, and semi-automatically segmented for receiver operating characteristic (ROC) analysis. ROC curves were constructed to assess prediction performance for echo decorrelation and IBS. Logarithmically scaled mean echo decorrelation in non-ablated and ablated tissue regions before and after electronic noise and motion correction were compared. Ablation prediction by echo decorrelation and IBS was significant for both focused and bulk ultrasound ablation. The log10-scaled mean echo decorrelation was significantly greater in regions of ablation for both HIFU and bulk ultrasound ablation. Echo decorrelation due to electronic noise and motion was significantly reduced by correction. These results suggest that ultrasound echo decorrelation imaging is a promising approach for real-time prediction of heat-induced cell death for guidance and monitoring of clinical thermal ablation, including radiofrequency ablation and HIFU.

  9. View Angle Tilting Echo Planar Imaging for Distortion Correction

    Science.gov (United States)

    Ahn, Sinyeob; Hu, Xiaoping

    2011-01-01

    Geometric distortion caused by field inhomogeneity along the phase-encode (PE) direction is one of the most prominent artifacts due to a relatively low effective bandwidth along that direction in magnetic resonance echo planar imaging (EPI). This work describes a method for correcting in-plane image distortion along the PE direction using a view angle tilting (VAT) imaging technique in spin-echo EPI (SE-EPI). SE-EPI with VAT (SE-EPI-VAT) utilizes the addition of gradient blips along the slice-select (SS) direction, concurrently applied with the PE gradient blips, producing an additional phase. This phase effectively offsets an unwanted phase accumulation caused by field inhomogeneity, resulting in the removal of image distortion along the PE direction. The proposed method is simple and straightforward both in implementation and application with no scan time penalty. Therefore, it is readily applicable on commercial scanners without having any customized post-processing. The efficacy of the SE-EPI-VAT technique in the correction of image distortion is demonstrated in phantom and in vivo brain imaging. PMID:22213567

  10. Fast low-angle shot diffusion tensor imaging with stimulated echo encoding in the muscle of rabbit shank.

    Science.gov (United States)

    Hiepe, Patrick; Herrmann, Karl-Heinz; Güllmar, Daniel; Ros, Christian; Siebert, Tobias; Blickhan, Reinhard; Hahn, Klaus; Reichenbach, Jürgen R

    2014-02-01

    In the past, spin-echo (SE) echo planar imaging(EPI)-based diffusion tensor imaging (DTI) has been widely used to study the fiber structure of skeletal muscles in vivo. However, this sequence has several shortcomings when measuring restricted diffusion in small animals, such as its sensitivity to susceptibility-related distortions and a relatively short applicable diffusion time. To address these limitations, in the current work, a stimulated echo acquisition mode (STEAM) MRI technique, in combination with fast low-angle shot (FLASH) readout (turbo-STEAM MRI), was implemented and adjusted for DTI in skeletal muscles. Signal preparation using stimulated echoes enables longer effective diffusion times, and thus the detection of restricted diffusion within muscular tissue with intracellular distances up to 100 µm. Furthermore, it has a reduced penalty for fast T2 muscle signal decay, but at the expense of 50% signal loss compared with a SE preparation. Turbo-STEAM MRI facilitates high-resolution DTI of skeletal muscle without introducing susceptibility-related distortions. To demonstrate its applicability, we carried out rabbit in vivo measurements on a human whole-body 3 T scanner. DTI parameters of the shank muscles were extracted, including the apparent diffusion coefficient, fractional anisotropy, eigenvalues and eigenvectors. Eigenvectors were used to calculate maps of structural parameters, such as the planar index and the polar coordinates θ and ϕ of the largest eigenvector. These parameters were compared between three muscles. θ and ϕ showed clear differences between the three muscles, reflecting different pennation angles of the underlying fiber structures. Fiber tractography was performed to visualize and analyze the architecture of skeletal pennate muscles. Optimization of tracking parameters and utilization of T2 -weighted images for improved muscle boundary detection enabled the determination of additional parameters, such as the mean fiber length

  11. The effect of echo-sampling strategy on the accuracy of out-of-phase and in-phase multi-echo gradient-echo magnetic resonance imaging hepatic fat fraction estimation

    Science.gov (United States)

    Levin, Yakir S.; Yokoo, Takeshi; Wolfson, Tanya; Gamst, Anthony C.; Collins, Julie; Achmad, Emil A.; Hamilton, Gavin; Middleton, Michael S.; Loomba, Rohit; Sirlin, Claude B.

    2013-01-01

    Purpose To assess the effect of echo-sampling strategy on the accuracy of out-of-phase (OP) and in-phase (IP) multi-echo gradient-echo magnetic resonance imaging (MRI) hepatic fat fraction (FF) estimation, using MR spectroscopy (MRS) proton density FF (PDFF) as a reference standard. Materials and Methods In this IRB-approved, HIPAA-compliant prospective study, 84 subjects underwent proton MRS and non-T1-weighted gradient-echo imaging of the liver at 3T. Imaging data were collected at 16 nominally OP and IP echo times (TEs). MRI-FF was estimated while varying two echo-sampling parameters (number of consecutive echoes, starting echo number). For each combination of these parameters, MRI-FF estimation accuracy was assessed with slope, intercept, average bias and R2 from a linear regression of MRS-PDFF on MRI-FF. The relationship between accuracy metrics and echo-sampling parameters was assessed by Spearman rank correlation. Results For FF calculations using 3-16 echoes and a starting echo number of 1, the intercept ranged from 0.0046 to 0.0124, slope from 0.941 to 0.96, average bias from 0.0034 to 0.0078, and R2 from 0.968 to 0.976. All four accuracy metrics were the best with the 3- and 4- echo calculations and worsened progressively with increasing number of echoes. For a given number of echoes, there was an overall trend toward decreasing accuracy as starting echo number increased. Spearman correlation coefficients between starting echo number and intercept, slope, average bias and R2 were 0.911, -.64, -.889 and -.954, respectively, indicating progressive loss of accuracy in each case. Conclusion Multi-echo OP and IP imaging provided high FF estimation accuracy. Accuracy was highest using the earliest 3 or 4 echoes. Incorporation of additional echoes or delaying the starting echo number progressively reduced accuracy. PMID:23720420

  12. Improved T2* imaging without increase in scan time: SWI processing of 2D gradient echo.

    Science.gov (United States)

    Soman, S; Holdsworth, S J; Barnes, P D; Rosenberg, J; Andre, J B; Bammer, R; Yeom, K W

    2013-01-01

    2D gradient-echo imaging is sensitive to T2* lesions (hemorrhages, mineralization, and vascular lesions), and susceptibility-weighted imaging is even more sensitive, but at the cost of additional scan time (SWI: 5-10 minutes; 2D gradient-echo: 2 minutes). The long acquisition time of SWI may pose challenges in motion-prone patients. We hypothesized that 2D SWI/phase unwrapped images processed from 2D gradient-echo imaging could improve T2* lesion detection. 2D gradient-echo brain images of 50 consecutive pediatric patients (mean age, 8 years) acquired at 3T were retrospectively processed to generate 2D SWI/phase unwrapped images. The 2D gradient-echo and 2D SWI/phase unwrapped images were compared for various imaging parameters and were scored in a blinded fashion. Of 50 patients, 2D gradient-echo imaging detected T2* lesions in 29 patients and had normal findings in 21 patients. 2D SWI was more sensitive than standard 2D gradient-echo imaging in detecting T2* lesions (P echo images were more sensitive in detecting T2* lesions and delineating normal venous structures and nonpathologic mineralization, and they also helped distinguish calcification at no additional scan time. SWI processing of 2D gradient-echo images may be a useful adjunct in cases in which longer scan times of 3D SWI are difficult to implement.

  13. Highly automatic quantification of myocardial oedema in patients with acute myocardial infarction using bright blood T2-weighted CMR

    Science.gov (United States)

    2013-01-01

    Background T2-weighted cardiovascular magnetic resonance (CMR) is clinically-useful for imaging the ischemic area-at-risk and amount of salvageable myocardium in patients with acute myocardial infarction (MI). However, to date, quantification of oedema is user-defined and potentially subjective. Methods We describe a highly automatic framework for quantifying myocardial oedema from bright blood T2-weighted CMR in patients with acute MI. Our approach retains user input (i.e. clinical judgment) to confirm the presence of oedema on an image which is then subjected to an automatic analysis. The new method was tested on 25 consecutive acute MI patients who had a CMR within 48 hours of hospital admission. Left ventricular wall boundaries were delineated automatically by variational level set methods followed by automatic detection of myocardial oedema by fitting a Rayleigh-Gaussian mixture statistical model. These data were compared with results from manual segmentation of the left ventricular wall and oedema, the current standard approach. Results The mean perpendicular distances between automatically detected left ventricular boundaries and corresponding manual delineated boundaries were in the range of 1-2 mm. Dice similarity coefficients for agreement (0=no agreement, 1=perfect agreement) between manual delineation and automatic segmentation of the left ventricular wall boundaries and oedema regions were 0.86 and 0.74, respectively. Conclusion Compared to standard manual approaches, the new highly automatic method for estimating myocardial oedema is accurate and straightforward. It has potential as a generic software tool for physicians to use in clinical practice. PMID:23548176

  14. Cholesteatoma imaging using modified echo-planar diffusion-weighted magnetic resonance imaging.

    Science.gov (United States)

    Flook, E; Izzat, S; Ismail, A

    2011-01-01

    Imaging of cholesteatomas can be useful especially in cases of recurrent disease. Computed tomography scans have been recommended before primary surgery, but cholesteatoma tissue looks similar to inflammatory tissue. Diffusion-weighted magnetic resonance imaging is both sensitive and specific in detecting cholesteatoma, which appears as a bright signal on a dark background. Non-echo-planar diffusion-weighted magnetic resonance imaging is superior to routine echo-planar diffusion-weighted magnetic resonance imaging as it minimises susceptibility artefacts; however, the addition of this facility involves expensive magnetic resonance scanner upgrading. To avoid the cost of such upgrading, we modified our echo-planar diffusion-weighted magnetic resonance imaging parameters and then scanned 15 consecutive cases of suspected cholesteatoma or suspected recurrent cholesteatoma. Imaging results correlated well with clinical and/or operative findings. These results indicate that software adjustments can enable echo-planar diffusion-weighted magnetic resonance imaging to detect cholesteatomas reliably, and as effectively as non-echo-planar diffusion-weighted magnetic resonance imaging. This discovery has the potential to facilitate reliable delayed post-operative screening of canal wall up mastoidectomies, avoiding the need for a 'second look' procedure.

  15. Compensation of slice profile mismatch in combined spin- and gradient-echo echo-planar imaging pulse sequences.

    Science.gov (United States)

    Schmiedeskamp, Heiko; Straka, Matus; Bammer, Roland

    2012-02-01

    Combined acquisition of gradient-echo and spin-echo signals in MRI time series reveals additional information for perfusion-weighted imaging and functional MRI because of differences in the sensitivity of gradient-echo and spin-echo measurements to the properties of the underlying vascular architecture. The acquisition of multiple echo trains within one time frame facilitates the simultaneous estimation of the transversal relaxation parameters R2 and R2*. However, the simultaneous estimation of these parameters tends to be incorrect in the presence of slice profile mismatches between signal excitation and subsequent refocusing pulses. It is shown here that improvements in pulse design reduced R2 and R2* estimation errors. Further improvements were achieved by augmented parameter estimation through the introduction of an additional parameter δ to correct for discordances in slice profiles to facilitate more quantitative measurements. Moreover, the analysis of time-resolved acquisitions revealed that the temporal stability of R2 estimates could be increased with improved pulse design, counteracting low contrast-to-noise ratios in spin-echo-based perfusion and functional MRI. Copyright © 2011 Wiley Periodicals, Inc.

  16. Shuffled magnetization-prepared multicontrast rapid gradient-echo imaging.

    Science.gov (United States)

    Cao, Peng; Zhu, Xucheng; Tang, Shuyu; Leynes, Andrew; Jakary, Angela; Larson, Peder E Z

    2018-01-01

    To develop a novel acquisition and reconstruction method for magnetization-prepared 3-dimensional multicontrast rapid gradient-echo imaging, using Hankel matrix completion in combination with compressed sensing and parallel imaging. A random k-space shuffling strategy was implemented in simulation and in vivo human experiments at 7 T for 3-dimensional inversion recovery, T2 /diffusion preparation, and magnetization transfer imaging. We combined compressed sensing, based on total variation and spatial-temporal low-rank regularizations, and parallel imaging with pixel-wise Hankel matrix completion, allowing the reconstruction of tens of multicontrast 3-dimensional images from 3- or 6-min scans. The simulation result showed that the proposed method can reconstruct signal-recovery curves in each voxel and was robust for typical in vivo signal-to-noise ratio with 16-times acceleration. In vivo studies achieved 4 to 24 times accelerations for inversion recovery, T2 /diffusion preparation, and magnetization transfer imaging. Furthermore, the contrast was improved by resolving pixel-wise signal-recovery curves after magnetization preparation. The proposed method can improve acquisition efficiencies for magnetization-prepared MRI and tens of multicontrast 3-dimensional images could be recovered from a single scan. Furthermore, it was robust against noise, applicable for recovering multi-exponential signals, and did not require any previous knowledge of model parameters. Magn Reson Med 79:62-70, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  17. 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.

  18. Range imaging results from polar mesosphere summer echoes

    Science.gov (United States)

    Zecha, Marius; Hoffmann, Peter; Rapp, Markus; Chen, Jenn-Shyong

    The range resolution of pulsed radars is usually limited by the transmitting pulse length and the sampling time. The so-called range imaging (RIM) has been developed to reduce these lim-itations. To apply this method the radar operates alternately over a set of distinct frequencies. Then the phase differences of the receiving signals can be used for optimization methods to generate high-resolution maps of reflections as function of range insight the pulse length. The technique has been implemented on the ALWIN VHF radar in Andenes (69) and the OSWIN VHF radar in Kühlungsborn (54N). Here we present results of the RIM method from measurements in polar mesosphere summer echoes -PMSE. These strong radar echoes are linked to ice particle clouds in the mesopause region. The dynamic of the PMSE can be reflected very well by RIM. The movement of PMSE and the edges of the extension can be tracked with a high altitude resolution. Comparisons between simultaneous measurements by RIM and by standard radar techniques demonstrate the advan-tages of RIM. Wave structures can be identified with RIM whereas they are not detectable with the lesser resolution of the standard measurements. Gravity wave parameter associated with these variations are estimated using the simultaneous measured velocity field.

  19. Diuretic-enhanced gadolinium excretory MR urography: comparison of conventional gradient-echo sequences and echo-planar imaging.

    Science.gov (United States)

    Nolte-Ernsting, C C; Tacke, J; Adam, G B; Haage, P; Jung, P; Jakse, G; Günther, R W

    2001-01-01

    The aim of this study was to investigate the utility of different gadolinium-enhanced T1-weighted gradient-echo techniques in excretory MR urography. In 74 urologic patients, excretory MR urography was performed using various T1-weighted gradient-echo (GRE) sequences after injection of gadolinium-DTPA and low-dose furosemide. The examinations included conventional GRE sequences and echo-planar imaging (GRE EPI), both obtained with 3D data sets and 2D projection images. Breath-hold acquisition was used primarily. In 20 of 74 examinations, we compared breath-hold imaging with respiratory gating. Breath-hold imaging was significantly superior to respiratory gating for the visualization of pelvicaliceal systems, but not for the ureters. Complete MR urograms were obtained within 14-20 s using 3D GRE EPI sequences and in 20-30 s with conventional 3D GRE sequences. Ghost artefacts caused by ureteral peristalsis often occurred with conventional 3D GRE imaging and were almost completely suppressed in EPI sequences (p urography, the entire pelvicaliceal system was imaged by acquisition of a fast single-slice sequence and the conventional 2D GRE technique provided superior morphological accuracy than 2D GRE EPI projection images (p excretory MR urography especially in old or critically ill patients unable to suspend breathing for more than 20 s. Conventional GRE sequences are superior to EPI in high-resolution detail MR urograms and in projection imaging.

  20. T2*-based MR imaging (gradient echo or susceptibility-weighted imaging) in midline and off-midline intracranial germ cell tumors: a pilot study.

    Science.gov (United States)

    Morana, Giovanni; Alves, Cesar Augusto; Tortora, Domenico; Finlay, Jonathan L; Severino, Mariasavina; Nozza, Paolo; Ravegnani, Marcello; Pavanello, Marco; Milanaccio, Claudia; Maghnie, Mohamad; Rossi, Andrea; Garrè, Maria Luisa

    2018-01-01

    The role of T2*-based MR imaging in intracranial germ cell tumors (GCTs) has not been fully elucidated. The aim of this study was to evaluate the susceptibility-weighted imaging (SWI) or T2* gradient echo (GRE) features of germinomas and non-germinomatous germ cell tumors (NGGCTs) in midline and off-midline locations. We retrospectively evaluated all consecutive pediatric patients referred to our institution between 2005 and 2016, for newly diagnosed, treatment-naïve intracranial GCT, who underwent MRI, including T2*-based MR imaging (T2* GRE sequences or SWI). Standard pre- and post-contrast T1- and T2-weighted imaging characteristics along with T2*-based MR imaging features of all lesions were evaluated. Diagnosis was performed in accordance with the SIOP CNS GCT protocol criteria. Twenty-four subjects met the inclusion criteria (17 males and 7 females). There were 17 patients with germinomas, including 5 basal ganglia primaries, and 7 patients with secreting NGGCT. All off-midline germinomas presented with SWI or GRE hypointensity; among midline GCT, all NGGCTs showed SWI or GRE hypointensity whereas all but one pure germinoma were isointense or hyperintense to normal parenchyma. A significant difference emerged on T2*-based MR imaging among midline germinomas, NGGCTs, and off-midline germinomas (p < 0.001). Assessment of the SWI or GRE characteristics of intracranial GCT may potentially assist in differentiating pure germinomas from NGGCT and in the characterization of basal ganglia involvement. T2*-based MR imaging is recommended in case of suspected intracranial GCT.

  1. Diuretic-enhanced gadolinium excretory MR urography: comparison of conventional gradient-echo sequences and echo-planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nolte-Ernsting, C.C.A.; Tacke, J.; Adam, G.B.; Haage, P.; Guenther, R.W. [Univ. of Technology, Aachen (Germany). Dept. of Diagnostic Radiology; Jung, P.; Jakse, G. [Univ. of Technology, Aachen (Germany). Dept. of Urology

    2001-01-01

    The aim of this study was to investigate the utility of different gadolinium-enhanced T1-weighted gradient-echo techniques in excretory MR urography. In 74 urologic patients, excretory MR urography was performed using various T1-weighted gradient-echo (GRE) sequences after injection of gadolinium-DTPA and low-dose furosemide. The examinations included conventional GRE sequences and echo-planar imaging (GRE EPI), both obtained with 3D data sets and 2D projection images. Breath-hold acquisition was used primarily. In 20 of 74 examinations, we compared breath-hold imaging with respiratory gating. Breath-hold imaging was significantly superior to respiratory gating for the visualization of pelvicaliceal systems, but not for the ureters. Complete MR urograms were obtained within 14-20 s using 3D GRE EPI sequences and in 20-30 s with conventional 3D GRE sequences. Ghost artefacts caused by ureteral peristalsis often occurred with conventional 3D GRE imaging and were almost completely suppressed in EPI sequences (p < 0.0001). Susceptibility effects were more pronounced on GRE EPI MR urograms and calculi measured 0.8-21.7% greater in diameter compared with conventional GRE sequences. Increased spatial resolution degraded the image quality only in GRE-EPI urograms. (orig.)

  2. High temporal resolution functional MRI using parallel echo volumar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rabrait, C.; Ciuciu, P.; Ribes, A.; Poupon, C.; Dehaine-Lambertz, G.; LeBihan, D.; Lethimonnier, F. [CEA Saclay, DSV, I2BM, Neurospin, F-91191 Gif Sur Yvette (France); Le Roux, P. [GEHC, Buc (France); Dehaine-Lambertz, G. [Unite INSERM 562, Gif Sur Yvette (France)

    2008-07-01

    Purpose: To combine parallel imaging with 3D single-shot acquisition (echo volumar imaging, EVI) in order to acquire high temporal resolution volumar functional MRI (fMRI) data. Materials and Methods: An improved EVI sequence was associated with parallel acquisition and field of view reduction in order to acquire a large brain volume in 200 msec. Temporal stability and functional sensitivity were increased through optimization of all imaging parameters and Tikhonov regularization of parallel reconstruction. Two human volunteers were scanned with parallel EVI in a 1.5 T whole-body MR system, while submitted to a slow event-related auditory paradigm. Results: Thanks to parallel acquisition, the EVI volumes display a low level of geometric distortions and signal losses. After removal of low-frequency drifts and physiological artifacts,activations were detected in the temporal lobes of both volunteers and voxel-wise hemodynamic response functions (HRF) could be computed. On these HRF different habituation behaviors in response to sentence repetition could be identified. Conclusion: This work demonstrates the feasibility of high temporal resolution 3D fMRI with parallel EVI. Combined with advanced estimation tools,this acquisition method should prove useful to measure neural activity timing differences or study the nonlinearities and non-stationarities of the BOLD response. (authors)

  3. A method for unwrapping highly wrapped multi-echo phase images at very high field: UMPIRE.

    Science.gov (United States)

    Robinson, Simon; Schödl, Horst; Trattnig, Siegfried

    2014-07-01

    To develop a method of unwrapping phase images from multi-echo scans that works even where there are several wraps between echoes, and which generates unwrapped phase images in addition to phase difference (PD) images. The difference between the echo spacings in an acquisition with three unevenly spaced echoes (an imposed delay) can be selected such that the phase evolution in that time is in the range -π to +π in all voxels of interest. Under this condition, an image of the difference between the phase evolutions in the two inter-echo periods, an estimate of ΔB0 , is free of wraps. This ΔB0 estimate can be used to identify and remove receiver phase offsets and wraps in phase images. The approach was tested on simulated data and high-resolution in vivo brain data acquired from six subjects at 7 Tesla. The method generated wrap-free phase images. It was able to remove more wraps than is possible with PD imaging and was faster and more reliable than spatial unwrapping. Unwrapping Multi-echo Phase Images with iRregular Echo spacings (UMPIRE) is conceptually simple, fast, reliable, and requires no fitting, thresholds, or operator intervention. Copyright © 2013 Wiley Periodicals, Inc.

  4. Signal changes in gradient echo images of human brain induced by hypo- and hyperoxia

    DEFF Research Database (Denmark)

    Rostrup, Egill; Larsson, H B; Toft, P B

    1995-01-01

    The effect of hypoxia (inspired oxygen fraction, FiO2 of 10% and 16%) and hyperoxia (FiO2) of 100%) on gradient echo images of the brain using long echo times was investigated in six healthy volunteers (age 24-28 years). Different flip angles were used with an FiO2 of 10% to assess the importance...

  5. Combined Spin-And Gradient-Echo Perfusion-Weighted Imaging

    Science.gov (United States)

    Schmiedeskamp, Heiko; Straka, Matus; Newbould, Rexford D.; Zaharchuk, Greg; Andre, Jalal B.; Olivot, Jean-Marc; Moseley, Michael E.; Albers, Gregory W.; Bammer, Roland

    2011-01-01

    In this study, a spin- and gradient-echo echo-planar imaging (SAGE EPI) MRI pulse sequence is presented that allows simultaneous measurements of gradient-echo and spin-echo dynamic susceptibility-contrast perfusion-weighted imaging (DSC-PWI) data. Following signal excitation, five EPI readout trains were acquired using SAGE EPI, all of them with echo times of less than 100 ms. Contrast agent concentrations in brain tissue were determined based on absolute R2* and R2 estimates rather than relative changes in the signals of individual echo trains, producing T1-independent DSC-PWI data. Moreover, this acquisition technique enabled vessel size imaging through the simultaneous quantification of R2* and R2, without an increase in acquisition time. In this work, the concepts of the SAGE EPI pulse sequence and results in stroke and tumor imaging are presented. Overall, SAGE EPI combined the advantages of higher sensitivity of gradient-echo DSC-PWI acquisitions to the contrast agent passage with the better selectivity of spin-echo DSC-PWI measurements to the microvasculature. PMID:22114040

  6. Readout-segmented echo-planar imaging in diffusion-weighted mr imaging in breast cancer: comparison with single-shot echo-planar imaging in image quality.

    Science.gov (United States)

    Kim, Yun Ju; Kim, Sung Hun; Kang, Bong Joo; Park, Chang Suk; Kim, Hyeon Sook; Son, Yo Han; Porter, David Andrew; Song, Byung Joo

    2014-01-01

    The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer. Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated. The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR. Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast.

  7. Gradient-echo MR imaging of the cervical spine: evaluation of extradural disease.

    Science.gov (United States)

    VanDyke, C; Ross, J S; Tkach, J; Masaryk, T J; Modic, M T

    1989-08-01

    A prospective study was undertaken on 204 consecutive patients comparing low flip angle gradient-echo and T1-weighted spin-echo techniques in the MR evaluation of cervical extradural disease. Four patient groups were studied with varying gradient-echo TEs (6 or 13 msec) and flip angles (10 degrees or 60 degrees). Images were evaluated independently for contrast behavior and anatomy, then directly compared for conspicuity of lesions. The FLASH sequences (especially with a 10 degrees flip angle) produced better conspicuity of disease in half the imaging time. T1-weighted spin-echo sequences were more sensitive to marrow changes and intradural disease. The short TE sequence (6 msec) did not produce any diagnostic advantage over the longer TE sequence (13 msec). A fast and sensitive MR examination for cervical extradural disease combines a sagittal T1-weighted spin-echo acquisition with sagittal and axial FLASH 10 degrees sequences.

  8. Imaging diagnosis of temporomandibular disorders (TMD). MR imaging of the disk of the temporomandibular joint

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Tsukasa; Yamamoto, Mika; Sakuma, Katsuya [Showa Univ., Tokyo (Japan). School of Dentistry] [and others

    2001-03-01

    Since its introduction in the 1980s, magnetic resonance imaging has become the preferred method for diagnosing soft tissue abnormalities of temporomandibular joint (TMJ). MR imaging is non-invasive and more accurate than arthorography. In addition, it requires less operator skill and is well tolerated by patients. We are usually taking MR images of the TMJ with the fast spin echo technique that can simultaneously obtain both T2-weighted and proton density images. The purpose of this study was to determine the utility of T2-weighed and proton density images for diagnosing the disk status in TMJ, comparing the results with those obtained by T1-weighted images. We studied 104 TMJs in 52 patients with both T2-weighted and proton density images, and 80 TMJs in 40 patients with only T1-weighted images. The joints were evaluated by two oral radiologists who looked at three aspects of the joints-disk displacement, disk reduction and disk shape - giving ratings of good'' or ''fair'' in each category. Ratings of ''good'' were significant higher in all three categories in T2-weighted and proton density images than in T1-weighted images (p<0.01). Based on these results, we conclude that T2-weighted and proton density images taken with the fast spin echo technique are useful for diagnosing the disk status of the TMJ. (author)

  9. Mapping human cortical areas in vivo based on myelin content as revealed by T1- and T2-weighted MRI.

    Science.gov (United States)

    Glasser, Matthew F; Van Essen, David C

    2011-08-10

    Noninvasively mapping the layout of cortical areas in humans is a continuing challenge for neuroscience. We present a new method of mapping cortical areas based on myelin content as revealed by T1-weighted (T1w) and T2-weighted (T2w) MRI. The method is generalizable across different 3T scanners and pulse sequences. We use the ratio of T1w/T2w image intensities to eliminate the MR-related image intensity bias and enhance the contrast to noise ratio for myelin. Data from each subject were mapped to the cortical surface and aligned across individuals using surface-based registration. The spatial gradient of the group average myelin map provides an observer-independent measure of sharp transitions in myelin content across the surface--i.e., putative cortical areal borders. We found excellent agreement between the gradients of the myelin maps and the gradients of published probabilistic cytoarchitectonically defined cortical areas that were registered to the same surface-based atlas. For other cortical regions, we used published anatomical and functional information to make putative identifications of dozens of cortical areas or candidate areas. In general, primary and early unimodal association cortices are heavily myelinated and higher, multimodal, association cortices are more lightly myelinated, but there are notable exceptions in the literature that are confirmed by our results. The overall pattern in the myelin maps also has important correlations with the developmental onset of subcortical white matter myelination, evolutionary cortical areal expansion in humans compared with macaques, postnatal cortical expansion in humans, and maps of neuronal density in non-human primates.

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

    Science.gov (United States)

    Muzamil, Akhmad; Haries Firmansyah, Achmad

    2017-05-01

    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 (p0.05) 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.

  11. A fast screening protocol for carotid plaques imaging using 3D multi-contrast MRI without contrast agent.

    Science.gov (United States)

    Zhang, Na; Zhang, Lei; Yang, Qi; Pei, Anqi; Tong, Xiaoxin; Chung, Yiu-Cho; Liu, Xin

    2017-06-01

    To implement a fast (~15min) MRI protocol for carotid plaque screening using 3D multi-contrast MRI sequences without contrast agent on a 3Tesla MRI scanner. 7 healthy volunteers and 25 patients with clinically confirmed transient ischemic attack or suspected cerebrovascular ischemia were included in this study. The proposed protocol, including 3D T1-weighted and T2-weighted SPACE (variable-flip-angle 3D turbo spin echo), and T1-weighted magnetization prepared rapid acquisition gradient echo (MPRAGE) was performed first and was followed by 2D T1-weighted and T2-weighted turbo spin echo, and post-contrast T1-weighted SPACE sequences. Image quality, number of plaques, and vessel wall thicknesses measured at the intersection of the plaques were evaluated and compared between sequences. Average examination time of the proposed protocol was 14.6min. The average image quality scores of 3D T1-weighted, T2-weighted SPACE, and T1-weighted magnetization prepared rapid acquisition gradient echo were 3.69, 3.75, and 3.48, respectively. There was no significant difference in detecting the number of plaques and vulnerable plaques using pre-contrast 3D images with or without post-contrast T1-weighted SPACE. The 3D SPACE and 2D turbo spin echo sequences had excellent agreement (R=0.96 for T1-weighted and 0.98 for T2-weighted, pagent. Copyright © 2016. Published by Elsevier Inc.

  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 fat suppression was superior using inversion-recovery and likewise in one case mDIXON had poorer image diagnostic quality. Lastly, mDIXON and conventional fat-suppression methods performed similarly in 17 (rater 1) and 14 (rater 2) cases, and yielded equal diagnostic image quality in 28 (rater 1) and 30 (rater 2) cases. Conclusion Robust fat suppression can be achieved with mDixon TSE pediatric spine imaging at 3.0 T and should be considered as a permanent replacement of traditional methods, in particular frequency-selective techniques.

  13. Echo Planar Diffusion-Weighted Imaging: Possibilities and Considerations with 12- and 32-Channel Head Coils

    Directory of Open Access Journals (Sweden)

    John N Morelli

    2012-01-01

    Full Text Available Interest in clinical brain magnetic resonance imaging using 32-channel head coils for signal reception continues to increase. The present investigation assesses possibilities for improving diffusion-weighted image quality using a 32-channel in comparison to a conventional 12-channel coil. The utility of single-shot (ss and an approach to readout-segmented (rs echo planar imaging (EPI are examined using both head coils. Substantial image quality improvements are found with rs-EPI. Imaging with a 32-channel head coil allows for implementation of greater parallel imaging acceleration factors or acquisition of scans at a higher resolution. Specifically, higher resolution imaging with rs-EPI can be achieved by increasing the number of readout segments without increasing echo-spacing or echo time to the degree necessary with ss-EPI - a factor resulting in increased susceptibility artifact and reduced signal-to-noise with the latter.

  14. A simple prescan calibration procedure for Ultrashort echo time imaging

    Czech Academy of Sciences Publication Activity Database

    Latta, P.; Starčuk jr., Zenon; Gruwel, M.; Tománek, B.

    2016-01-01

    Roč. 29, S1 (2016), S42 E-ISSN 1352-8661. [ESMRMB 2016 Congress. 29.09.2016-01.10.2016, Vienna] R&D Projects: GA ČR(CZ) GA15-12607S Institutional support: RVO:68081731 Keywords : ultrashort echo time * calibration * prescan procedure Subject RIV: FS - Medical Facilities ; Equipment

  15. [Optimization of Three-dimensional Ultrashort Echo Time Magnetic Resonance Imaging at a Low Field].

    Science.gov (United States)

    Huang, Yuli; Du, Yiping

    2015-12-01

    Conventional magnetic resonance (MR) pulse sequences typically have an echo time (TE) of 1 ms or longer, providing an excellent contrast between different soft tissues. However, some short T2 tissues appear dark in conventional MR images because the signal from these tissues has decayed to nearly zero before the center of k-space is acquired. Because of the ability of directly imaging short T2 tissues, ultrashort echo time technique has been widely studied in recent years. An overwhelming majority of the studies were carried out at high fields, while many low- field scanner systems are still used in developing countries. To investigate the effects of the delay between analog-to-digital converter sampling and the readout gradient, the TE of the second echo used to calculate the R2 * map, and the undersampling ratio on the results of three-dimensional (3D) ultrashort echo time imaging at a low field, we implemented a 3D ultrashort echo time sequence on a 0. 35T scanner. Different parameters were used and the reconstructed images and R2 * maps were compared. Images reconstructed with slightly varying delays appeared quite different. Different contrast between short and long T2 tissues were found in R2 * maps calculated with different echoes. The result of undersampling study indicated that excessive undersampling could cause unwanted blurring, making it difficult to better visualize the short T2 tissues in the R2 * map. The results suggested that cautions should be taken in the choice of these parameters in 3D ultrashort echo time imaging. Short T2 tissues can be visualized with appropriate imaging parameters at this low field.

  16. Clinical efficacy of MRI fast spin echo imaging in the evaluation of retroperitoneal tumors

    Energy Technology Data Exchange (ETDEWEB)

    Shiono, Tosihiro; Tanaka, Junji; Teshima, Yasuaki; Arima, Takeshi; Iwasaki, Naoya [Dokkyo Medical Coll., Koshigaya Saitama (Japan). Koshigaya Hospital; Yoshikawa, Koki; Takahashi, Yoshiyuki

    1995-05-01

    T2-weighted fast and conventional SE image were compared in 14 patients (5 with renal tumor, 4 with adrenal tumor and 5 with no abnormality). The contrast ratio between the retroperitoneal fat and the kidney (F/K), the tumor (F/T), between the tumor and kidney (T/K) were calculated for both sequences. In all patients, F/K and F/T for fast SE were higher than those of conventional SE. T/K for fast SE was higher in 6 of 9 cases. All tumors were clearly demonstrated on fast SE, although two tumors were difficult to be identified with conventional SE due to the low contrast resolution and the artifact. The each retroperitoneal structure including tumor was demonstrated with high contrast resolution and clear margin. In addition, fast SE with breath holding provided the less artifact. These efficacy makes fast SE promising for diagnosis of retroperitoneal tumor. (author).

  17. Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Regini, F., E-mail: francesco.regini@yahoo.it [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Department of Experimental and Clinical Biomedical Sciences – Radiodiagnostic Unit 2 – University of Florence- Azienda Ospedaliero-Universitaria Careggi, Firenze (Italy); Gourtsoyianni, S., E-mail: sofia.gourtsoyianni@gstt.nhs.uk [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Division of Imaging Sciences and Biomedical Engineering, King' s College London, King' s Health Partners, St. Thomas’ Hospital, London (United Kingdom); Cardoso De Melo, R., E-mail: rafaelgoiein@gmail.com [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Charles-Edwards, G.D., E-mail: geoff.charles-edwards@kcl.ac.uk [Division of Imaging Sciences and Biomedical Engineering, King' s College London, King' s Health Partners, St. Thomas’ Hospital, London (United Kingdom); Medical Physics, Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Griffin, N., E-mail: nyree.griffin@gatt.nhs.uk [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Division of Imaging Sciences and Biomedical Engineering, King' s College London, King' s Health Partners, St. Thomas’ Hospital, London (United Kingdom); Parikh, J., E-mail: jyoti.parikh@gstt.nhs.uk [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); Rottenberg, G., E-mail: giles.rottenberg@gstt.nhs.uk [Department of Radiology,Guy' s and St Thomas’ NHS Foundation Trust, London (United Kingdom); and others

    2014-05-15

    Purpose: To compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI. Material and methods: 27 consecutive patients (15 male, range 27.1–88.8 years, mean 66.9 years) underwent 1.5 T MRI prior to chemoradiation (45 Gy in 25 fractions; oral capecitabine 850 mg/m{sup 2}), including axial T2W MRI (TR = 6600 ms, TE = 90 ms) and DWI (TR = 3000 ms, TE = 77 ms, b = 0, 100, 800 s/mm{sup 2}). 3D tumour volume (cm{sup 3}) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann–Whitney test. Observer agreement was assessed using Bland–Altman statistics. Significance was at 5%. Results: Artefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b = 800 s/mm{sup 2}) 3D GTVin cm{sup 3} were 33.97 (4.44–199.8) and 31.38 (2.43–228), respectively, for Reader One and 43.78 (7.57–267.7) and 42.45 (3.68–251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p = 0.52 Reader One; p = 0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were −9.84 (−54.96 to +35.28) cm{sup 3} and −14.79 (−54.01 to +24.43) cm{sup 3} respectively. Conclusion: Smaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.

  18. Study of turbulent flow using Half-Fourier Echo-Planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, A.O. [Universidad Autonoma Metropolitana Iztapalapa, Mexico, D.F. (Mexico). Centro de Investigacion en Imagenologia e Instrumentacion Medica

    2006-03-15

    The Echo-Planar Imaging technique combined with a partial Fourier acquisition method was used to obtain velocity images for liquid flows in a circular cross-section pipe at Reynolds number of up to 8000. This partial-Fourier imaging scheme is able to generate shorter echo times than the full-Fourier Echo-Planar Imaging methods, reducing the signal attenuation due to T2{sup *} and flow. Velocity images along the z axis were acquired with a time-scale of 80 ms thus obtaining a real-time description of flow in both the laminar and turbulent regimes. Velocity values and velocity fluctuations were computed with the flow image data. A comparison plot of NMR velocity and bulk velocity and a plot of velocity fluctuations were calculated to investigate the feasibility of this imaging technique. Flow encoded Echo-Planar Imaging together with a reduced data acquisition method can provide us with a real-time technique to capture instantaneous images of the flow field for both laminar and turbulent regimes. (author)

  19. Designing hyperbolic secant excitation pulses to reduce signal dropout in gradient-echo echo-planar imaging.

    Science.gov (United States)

    Wastling, Stephen J; Barker, Gareth J

    2015-09-01

    To design hyperbolic secant (HS) excitation pulses to reduce signal dropout in the orbitofrontal and inferior temporal regions in gradient-echo echo-planar imaging (GE-EPI) for functional MRI (fMRI) applications. An algorithm based on Bloch simulations optimizes the HS pulse parameters needed to give the desired signal response across the range of susceptibility gradients observed in the human head (approximately ±250 μT·m(-1) ). The impact of the HS pulse on the signal, temporal signal-to-noise ratio, blood oxygen level-dependent (BOLD) sensitivity, and ability to detect resting state BOLD signal changes was assessed in six healthy male volunteers at 3T. The optimized HS pulse (μ = 4.25, β = 3040 Hz, A0 = 12.3 μT, Δf = 4598 Hz) had a near uniform signal response for through-plane susceptibility gradients in the range ±250 μT·m(-1) . Signal, temporal signal-to-noise ratio, BOLD sensitivity, and the detectability of resting state networks were all partially recovered in the orbitofrontal and inferior temporal regions; however, there were signal losses of up to 50% in regions of homogeneous field (and signal loss from in-plane susceptibility gradients remained). The HS pulse reduced signal dropout and could be used to acquire task and resting state fMRI data without loss of spatial coverage or temporal resolution. © 2014 Wiley Periodicals, Inc.

  20. Liver imaging at 3.0 T: Diffusion-induced black-blood echo-planar imaging with large anatomic volumetric coverage as an alternative for specific absorption rate-intensive echo-train spin-echo sequences: Feasibility study

    NARCIS (Netherlands)

    I.C. van den Bos (Indra); S.M. Hussain (Shahid); G.P. Krestin (Gabriel); P.A. Wielopolski (Piotr)

    2008-01-01

    textabstractInstitutional Review Board approval and signed informed consent were obtained by all participants for an ongoing sequence optimization project at 3.0 T. The purpose of this study was to evaluate breath-hold diffusion-induced blackblood echo-planar imaging (BBEPI) as a potential

  1. Magnetic resonance imaging of pulmonary infection in immunocompromised children: comparison with multidetector computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ozcan, H.N.; Gormez, Aysegul; Oguz, Berna; Haliloglu, Mithat [Hacettepe University School of Medicine, Department of Radiology, Ankara (Turkey); Ozsurekci, Yasemin; Ceyhan, Mehmet [Hacettepe University School of Medicine, Department of Pediatric Infectious Disease, Ankara (Turkey); Karakaya, Jale [Hacettepe University School of Medicine, Department of Biostatistics, Ankara (Turkey); Unal, Sule; Cetin, Mualla [Hacettepe University School of Medicine, Department of Pediatric Hematology, Ankara (Turkey)

    2017-02-15

    Computed tomography (CT) is commonly used to detect pulmonary infection in immunocompromised children. To compare MRI and multidetector CT findings of pulmonary abnormalities in immunocompromised children. Seventeen neutropaenic children (6 girls; ages 2-18 years) were included. Non-contrast-enhanced CT was performed with a 64-detector CT scanner. Axial and coronal non-enhanced thoracic MRI was performed using a 1.5-T scanner within 24 h of the CT examination (true fast imaging with steady-state free precession, fat-saturated T2-weighted turbo spin echo with motion correction, T2-weighted half-Fourier single-shot turbo spin echo [HASTE], fat-saturated T1-weighted spoiled gradient echo). Pulmonary abnormalities (nodules, consolidations, ground glass opacities, atelectasis, pleural effusion and lymph nodes) were evaluated and compared among MRI sequences and between MRI and CT. The relationship between MRI sequences and nodule sizes was examined by chi- square test. Of 256 CT lesions, 207 (81%, 95% confidence interval [CI] 76-85%) were detected at MRI. Of 202 CT-detected nodules, 157 (78%, 95% CI 71-83%) were seen at motion-corrected MRI. Of the 1-5-mm nodules, 69% were detected by motion-corrected T2-weighted MRI and 38% by HASTE MRI. Sensitivity of MRI (both axial fat-saturated T2-weighted turbo spin echo with variable phase encoding directions (BLADE) images and HASTE sequences) to detect pulmonary abnormalities is promising. (orig.)

  2. Hybrid echo and x-ray image guidance for cardiac catheterization procedures by using a robotic arm: a feasibility study.

    Science.gov (United States)

    Ma, YingLiang; Penney, Graeme P; Bos, Dennis; Frissen, Peter; Rinaldi, C Aldo; Razavi, Reza; Rhode, Kawal S

    2010-07-07

    We present a feasibility study on hybrid echocardiography (echo) and x-ray image guidance for cardiac catheterization procedures. A self-tracked, remotely operated robotic arm with haptic feedback was developed that attached to a standard x-ray table. This was used to safely manipulate a three-dimensional (3D) trans-thoracic echo probe during simultaneous x-ray fluoroscopy and echo acquisitions. By a combination of calibration and tracking of the echo and x-ray systems, it was possible to register the 3D echo images with the 2D x-ray images. Visualization of the combined data was achieved by either overlaying triangulated surfaces extracted from segmented echo data onto the x-ray images or by overlaying volume rendered 3D echo data. Furthermore, in order to overcome the limited field of view of the echo probe, it was possible to create extended field of view (EFOV) 3D echo images by co-registering multiple tracked echo data to generate larger roadmaps for procedure guidance. The registration method was validated using a cross-wire phantom and showed a 2D target registration error of 3.5 mm. The clinical feasibility of the method was demonstrated during two clinical cases for patients undergoing cardiac pacing studies. The EFOV technique was demonstrated using two healthy volunteers.

  3. Hybrid echo and x-ray image guidance for cardiac catheterization procedures by using a robotic arm: a feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yingliang; Penney, Graeme P; Razavi, Reza; Rhode, Kawal S [Division of Imaging Sciences, King' s College, London SE1 7EH (United Kingdom); Bos, Dennis; Frissen, Peter [Philips Applied Technologies, High Tech. Campus 7, 5656 AE Eindhoven (Netherlands); Rinaldi, C Aldo, E-mail: y.ma@kcl.ac.u [Department of Cardiology, Guy' s and St Thomas' NHS Foundation Trust, London SE1 7EH (United Kingdom)

    2010-07-07

    We present a feasibility study on hybrid echocardiography (echo) and x-ray image guidance for cardiac catheterization procedures. A self-tracked, remotely operated robotic arm with haptic feedback was developed that attached to a standard x-ray table. This was used to safely manipulate a three-dimensional (3D) trans-thoracic echo probe during simultaneous x-ray fluoroscopy and echo acquisitions. By a combination of calibration and tracking of the echo and x-ray systems, it was possible to register the 3D echo images with the 2D x-ray images. Visualization of the combined data was achieved by either overlaying triangulated surfaces extracted from segmented echo data onto the x-ray images or by overlaying volume rendered 3D echo data. Furthermore, in order to overcome the limited field of view of the echo probe, it was possible to create extended field of view (EFOV) 3D echo images by co-registering multiple tracked echo data to generate larger roadmaps for procedure guidance. The registration method was validated using a cross-wire phantom and showed a 2D target registration error of 3.5 mm. The clinical feasibility of the method was demonstrated during two clinical cases for patients undergoing cardiac pacing studies. The EFOV technique was demonstrated using two healthy volunteers. (note)

  4. T2-weighted prostate MRI at 7 Tesla using a simplified external transmit-receive coil array: correlation with radical prostatectomy findings in two prostate cancer patients.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Zhang, Bei; Ben-Eliezer, Noam; Le Nobin, Julien; Melamed, Jonathan; Deng, Fang-Ming; Taneja, Samir S; Wiggins, Graham C

    2015-01-01

    To report design of a simplified external transmit-receive coil array for 7 Tesla (T) prostate MRI, including demonstration of the array for tumor localization using T2-weighted imaging (T2WI) at 7T before prostatectomy. Following simulations of transmitter designs not requiring parallel transmission or radiofrequency-shimming, a coil array was constructed using loop elements, with anterior and posterior rows comprising one transmit-receive element and three receive-only elements. This coil structure was optimized using a whole-body phantom. In vivo sequence optimization was performed to optimize achieved flip angle (FA) and signal to noise ratio (SNR) in prostate. The system was evaluated in a healthy volunteer at 3T and 7T. The 7T T2WI was performed in two prostate cancer patients before prostatectomy, and localization of dominant tumors was subjectively compared with histopathological findings. Image quality was compared between 3T and 7T in these patients. Simulations of the B1(+) field in prostate using two-loop design showed good magnitude (B1(+) of 0.245 A/m/w(1/2)) and uniformity (nonuniformity [SD/mean] of 10.4%). In the volunteer, 90° FA was achieved in prostate using 225 v 1 ms hard-pulse (indicating good efficiency), FA maps confirmed good uniformity (14.1% nonuniformity), and SNR maps showed SNR gain of 2.1 at 7T versus 3T. In patients, 7T T2WI showed excellent visual correspondence with prostatectomy findings. 7T images demonstrated higher estimated SNR (eSNR) in benign peripheral zone (PZ) and tumor compared with 3T, but lower eSNR in fat and slight decreases in tumor-to-PZ contrast and PZ-homogeneity. We have demonstrated feasibility of a simplified external coil array for high-resolution T2-weighted prostate MRI at 7T. © 2013 Wiley Periodicals, Inc.

  5. Comparison of Turbo Spin Echo and Echo Planar Imaging for intravoxel incoherent motion and diffusion tensor imaging of the kidney at 3Tesla.

    Science.gov (United States)

    Hilbert, Fabian; Wech, Tobias; Neubauer, Henning; Veldhoen, Simon; Bley, Thorsten Alexander; Köstler, Herbert

    2017-09-01

    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 750s/mm 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 3Tesla. Copyright © 2017. Published by Elsevier GmbH.

  6. 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.

  7. Subarachnoid hemosiderin deposition after subarachnoid hemorrhage on T2*-weighted MRI correlates with the location of disturbed cerebrospinal fluid flow on computed tomography cisternography.

    Science.gov (United States)

    Horita, Yoshifumi; Imaizumi, Toshio; Hashimoto, Yuji; Niwa, Jun

    2008-01-01

    A 72-year-old male was admitted with subarachnoid hemorrhage associated with a ruptured cerebral aneurysm. The aneurysm was treated with clipping soon after radiological examination. Eight weeks after the treatment, the patient suffered from secondary hydrocephalus resulting from blockage of the subarachnoid space due to subarachnoid granulation. Previous pathological examination revealed the granulation was associated with hemosiderin deposition. We investigated subarachnoid hemosiderin deposition in this patient using T2*-weighted (T2*-w) magnetic resonance image (MRI), a sensitive method for hemosiderin detection. computed tomography (CT) cisternography demonstrated that cerebrospinal fluid (CSF) flow was disturbed adjacent to sites of subarachnoid hemosiderin deposition on T2*-w MRI. Placement of a ventriculo-peritoneal shunt contributed to neurological improvement. In this case, T2*-w MRI was an effective means of diagnosing the location of disturbed CSF flow associated with subarachnoid hemosiderin deposition.

  8. Sensory neuronopathy involves the spinal cord and brachial plexus: a quantitative study employing multiple-echo data image combination (MEDIC) and turbo inversion recovery magnitude (TIRM)

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Yi-Fang; Tang, Wei-Jun; Li, Yu-Xin; Geng, Dao-Ying [Fudan University, Department of Radiology, Huashan Hospital, Shanghai (China); Zhu, Dong-Qing; Chen, Xiang-Jun [Fudan University, Department of Neurology, Huashan Hospital, Shanghai (China); Zee, Chi-Shing [University of Southern California Keck School of Medicine, Department of Radiology, Los Angeles, CA (United States)

    2013-01-15

    Sensory neuronopathy (SNN) is a distinctive subtype of peripheral neuropathies, specifically targeting dorsal root ganglion (DRG). We utilized MRI to demonstrate the imaging characteristics of DRG, spinal cord (SC), and brachial plexus at C7 level in SNN. We attempted multiple-echo data image combination (MEDIC) and turbo inversion recovery magnitude (TIRM) methods in nine patients with sensory neuronopathy and compared with those in 16 disease controls and 20 healthy volunteers. All participants underwent MRI for the measurement of DRG, posterior column (PC), lateral column, and spinal cord area (SCA) at C7 level. DRG diameters were obtained through its largest cross section, standardized by dividing sagittal diameter of mid-C7 vertebral canal. We also made comparisons of standardized anteroposterior diameter (APD) and left-right diameters of SC and PC in these groups. Signal intensity and diameter of C7 spinal nerve were assessed on TIRM. Compared to control groups, signal intensities of DRG and PC were higher in SNN patients when using MEDIC, but the standardized diameters were shorter in either DRG or PC. Abnormal PC signal intensities were identified in eight out of nine SNN patients (89 %) with MEDIC and five out of nine (56 %) with T2-weighted images. SCA, assessed with MEDIC, was smaller in SNN patients than in the other groups, with significant reduction of its standardized APD. C7 nerve root diameters, assessed with TIRM, were decreased in SNN patients. MEDIC and TIRM sequences demonstrate increased signal intensities and decreased area of DRG and PC, and decreased diameter of nerve roots in patients with SNN, which can play a significant role in early diagnosis. (orig.)

  9. MRI appearances of the asymptomatic patellar tendon on gradient echo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Reiff, D.B. [Dept. of Diagnostic Radiology, St. George`s Hospital, London (United Kingdom); Heenan, S.D. [Dept. of Diagnostic Radiology, St. George`s Hospital, London (United Kingdom); Heron, C.W. [Dept. of Diagnostic Radiology, St. George`s Hospital, London (United Kingdom)

    1995-02-01

    Thickening of the patellar tendon and foci of increased signal intensity have been described as characteristic features of ``jumper`s knee`` (chronic patellar tendinitis) on magnetic resonance imaging (MRI). It was our impression that such appearances may be seen in the patellar tendons of patients without symptoms referable to the anterior part of the knee when using gradient echo images. The appearances of the asymptomatic patellar tendon on three-dimensional gradient echo sequences were studied by retrospectively reviewing the images of 60 patients, none of whom had symptoms related to the anterior part of the knee. The anteroposterior width of the patellar tendon was measured at three levels (superior, middle and inferior) on the central sagittal image of a gradient echo sequence. The relative signal intensities at the same levels were recorded. In 97% of subjects the superior part of the tendon was wider than the midpoint, and in 97% the inferior part was wider than the midpoint. The range of widths was wide, and there was no significant difference between sexes. Focal increased signal intensity in the superior part was shown in 75%, and in the inferior part in 43%. The asymptomatic patellar tendon shows uniform thickness throughout most of its length, but there are focal expansions at the proximal and distal ends. It usually demonstrates low signal on MRI, but may contain foci of increased signal intensity at either or both ends when imaged on gradient-echo sequences. (orig.)

  10. Multishot echo-planar MREIT for fast imaging of conductivity, current density, and electric field distributions.

    Science.gov (United States)

    Chauhan, Munish; Vidya Shankar, Rohini; Ashok Kumar, Neeta; Kodibagkar, Vikram D; Sadleir, Rosalind

    2018-01-01

    Magnetic resonance electrical impedance tomography (MREIT) sequences typically use conventional spin or gradient echo-based acquisition methods for reconstruction of conductivity and current density maps. Use of MREIT in functional and electroporation studies requires higher temporal resolution and faster sequences. Here, single and multishot echo planar imaging (EPI) based MREIT sequences were evaluated to see whether high-quality MREIT phase data could be obtained for rapid reconstruction of current density, conductivity, and electric fields. A gel phantom with an insulating inclusion was used as a test object. Ghost artifact, geometric distortion, and MREIT correction algorithms were applied to the data. The EPI-MREIT-derived phase-projected current density and conductivity images were compared with simulations and spin-echo images as a function of EPI shot number. Good agreement among measures in simulated, spin echo, and EPI data was achieved. Current density errors were stable and below 9% as the shot number decreased from 64 to 2, but increased for single-shot images. Conductivity reconstruction relative contrast ratios were stable as the shot number decreased. The derived electric fields also agreed with the simulated data. The EPI methods can be combined successfully with MREIT reconstruction algorithms to achieve fast imaging of current density, conductivity, and electric field. Magn Reson Med 79:71-82, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  11. [The MRT of focal liver lesions: the value of gadolinium-enhanced dynamic studies of the whole organ with a fast 3D-turbo-gradient echo sequence].

    Science.gov (United States)

    Pauleit, D; Textor, J; Conrad, R; Flacke, S; Gieseke, J; Born, M; Bachmann, R; Kreft, B; Schild, H

    1999-04-01

    To determine the value of a dynamic Gd-enhanced ultrafast T1-weighted 3D-turbo-gradient-echo sequence (3D-TFE) in the detection and characterization of focal liver lesions. 51 patients with 124 focal liver lesions (35 hemangiomas, 30 HCC, 24 metastases, 22 cysts, 5 FNH/adenoma, 8 other lesions) were examined using a 1.5 T system. The dynamic 3D-TFE sequence, achieving 40 slices with a thickness of 4.5 mm in a 17-s breath-hold, was compared with a fat-suppressed T2-weighted fast-spin-echo sequence (TSE SPIR), unenhanced and Gd-enhanced T1-weighted spin-echo sequences (SE), and a T1-weighted gradient-echo sequence (FFE). On 3D-TFE images more lesions (107/124) were identified than on T1-weighted SE (101/124) and T1-weighted FFE images (106/124), but less compared to T2-weighted TSE SPIR images (115/124). The 3D-TFE-sequence provided additional information in 65/107 (61%) detected lesions by delineating the dynamic enhancement pattern, most valuable in patients with HCCs in 90%. On dynamic 3D-TFE images more lesions could be depicted than on conventional T1-weighted SE and T1-weighted FFE images. Visualization of the dynamic enhancement pattern provided additional information for tumor characterization in 61% of the detected lesions on the 3D-TFE images.

  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

    2018-01-29

    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, 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 in Medicine

  13. The value of 3D T1-weighted gradient-echo MR imaging for evaluation of the appendix during pregnancy: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Kyung Mi; Kim, Seong Hyun; Choi, Dongil; Lee, Soon Jin; Rhim, Hyunchul; Park, Min Jung (Depts. of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan Univ. School of Medicine, Seoul (Korea, Republic of)), email: kshyun@skku.edu

    2011-10-15

    Background The use of oral contrast has been essential for the identification of a normal appendix on MR imaging during pregnancy. However, stool could be used as a positive oral contrast as it is characterized by a relatively high signal on T1-weighted imaging, and 3D T1-weighted gradient-echo (T1W-GRE) MR imaging has been used to evaluate 3 mm diameter intestines in fetuses. Purpose To evaluate the added value of 3D T1W-GRE MR imaging in combination with T2-weighted imaging (T2WI) compared to T2WI alone for evaluating the appendix during pregnancy. Material and Methods Eighteen consecutive pregnant patients who were clinically suspected of having acute appendicitis underwent appendix MR imaging which included T2WI with or without spectral presaturation attenuated inversion-recovery (SPAIR) fat suppression, and 3D T1W-GRE with SPAIR fat suppression. Two radiologists reviewed the two image sets (the T2WI set and the combined set of T2WI and 3D T1W-GRE images). Pathologic and clinical results served as the reference standard. The differences in the degree of visibility of the appendix and confidence scale for diagnosing acute appendicitis between two image sets were compared by using the paired Wilcoxon signed rank test. Results For both reviewers, the degree of visibility of the appendix using the combined T2WI and 3D T1W-GRE images was significantly higher than using T2WI alone (P < 0.01), and the confidence levels for acute appendicitis using combined T2WI and 3D T1W-GRE images were significantly different from those using T2WI alone (P < 0.01). In the 13 patients with a normal appendix, both reviewers showed improved confidence levels for appendicitis using combined T2WI and 3D T1W-GRE images than T2WI alone. Conclusion Adding 3D T1W-GRE images to T2WI is helpful for identification of the appendix, as compared to T2WI alone in pregnant women without ingestion of oral contrast material. This may improve diagnostic confidence for acute appendicitis in pregnant

  14. Characterization of high-resolution Gradient Echo and Spin Echo EPI for fMRI in the human visual cortex at 7T.

    Science.gov (United States)

    Rua, Catarina; Costagli, Mauro; Symms, Mark R; Biagi, Laura; Donatelli, Graziella; Cosottini, Mirco; Del Guerra, Alberto; Tosetti, Michela

    2017-07-01

    The increased signal-to-noise ratio (SNR) offered by functional Magnetic Resonance Imaging (fMRI) at 7T allows the acquisition of functional data at sub-millimetric spatial resolutions. However, simply reducing partial volume effects is not sufficient to precisely localize task-induced activation due to the indirect mechanisms that relate brain function and the changes in the measured signal. In this work T2* and T2 weighted Echo Planar Imaging (EPI) schemes based on Gradient Recalled Echo (GRE) and Spin Echo (SE) were evaluated in terms of temporal SNR, percent signal change, contrast to noise ratio (CNR), activation volume, and sensitivity and specificity to gray matter. Datasets were acquired during visual stimulation at in-plane resolutions ranging between 1.5×1.5mm(2) and 0.75×0.75mm(2) targeting the early visual cortex. While similar activation foci were obtained in all acquisitions, at in-plane resolutions of 1.0×1.0mm(2) and larger voxel sizes the T2 weighted contrast of SE-EPI allowed the identification of the activation site with better spatial accuracy. However, at sub-millimetric resolutions the decrease in temporal SNR significantly hampered the sensitivity and the extent of the activation site. On the other hand, high resolution T2* weighted data collected with GRE-EPI provided higher CNR and sensitivity, benefiting from the decreased physiological and partial volume effects. However, spurious activations originating from regions of blood drainage were still present in GRE data, and simple thresholding techniques were found to be inadequate for the removal of such contributions. The combination of 2-class and 3-class automated segmentations, performed directly in EPI space, allowed the selection of active voxels in gray matter. This approach could enable GRE-EPI to accurately map functional activity with satisfactory CNR and specificity to the true site of activation. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Using ultrasound CBE imaging without echo shift compensation for temperature estimation.

    Science.gov (United States)

    Tsui, Po-Hsiang; Chien, Yu-Ting; Liu, Hao-Li; Shu, Yu-Chen; Chen, Wen-Shiang

    2012-09-01

    Clinical trials have demonstrated that hyperthermia improves cancer treatments. Previous studies developed ultrasound temperature imaging methods, based on the changes in backscattered energy (CBE), to monitor temperature variations during hyperthermia. Echo shift, induced by increasing temperature, contaminates the CBE image, and its tracking and compensation should normally ensure that estimations of CBE at each pixel are correct. To obtain a simplified algorithm that would allow real-time computation of CBE images, this study evaluated the usefulness of CBE imaging without echo shift compensation in detecting distributions in temperature. Experiments on phantoms, using different scatterer concentrations, and porcine livers were conducted to acquire raw backscattered data at temperatures ranging from 37°C to 45°C. Tissue samples of pork tenderloin were ablated in vitro by microwave irradiation to evaluate the feasibility of using the CBE image without compensation to monitor tissue ablation. CBE image construction was based on a ratio map obtained from the envelope image divided by the reference envelope image at 37°C. The experimental results demonstrated that the CBE image obtained without echo shift compensation has the ability to estimate temperature variations induced during uniform heating or tissue ablation. The magnitude of the CBE as a function of temperature obtained without compensation is stronger than that with compensation, implying that the CBE image without compensation has a better sensitivity to detect temperature. These findings suggest that echo shift tracking and compensation may be unnecessary in practice, thus simplifying the algorithm required to implement real-time CBE imaging. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Microscopic Displacement Imaging with Pulsed Field Gradient Turbo Spin-Echo NMR

    NARCIS (Netherlands)

    Scheenen, T.W.J.; Dusschoten, van D.; Jager, de P.A.; As, van H.

    2000-01-01

    We present a pulse sequence that enables the accurate and spatially resolved measurements of the displacements of spins in a variety of (biological) systems. The pulse sequence combines pulsed field gradient (PFG) NMR with turbo spin–echo (TSE) imaging. It is shown here that by ensuring that the

  17. High-resolution constructive interference in a steady state imaging of cervicothoracic adhesive arachnoiditis.

    Science.gov (United States)

    Ikushima, I; Korogi, Y; Hirai, T; Yamashita, Y

    2007-01-01

    To assess the usefulness of constructive interference in a steady state (CISS) sequence for an evaluation of cervicothoracic adhesive arachnoiditis. Seven patients with arachnoiditis underwent magnetic resonance imaging with T1- and T2-weighted fast spin-echo (FSE) and 3-dimensional CISS sequences. Three observers compared T2-weighted FSE and 3-dimensional CISS images with regard to image quality for spinal adhesive arachnoiditis. Magnetic resonance appearances accompanied with cervicothoracic adhesive arachnoiditis on CISS coupled with T2-weighted FSE sequences were also evaluated. The CISS images were superior to T2-weighted FSE images in the demarcation of spinal cord, dura matter, nerve root, and adhesive point. In our 7 cases with cervicothoracic adhesive arachnoiditis, dural thickening in 2 cases, syringomyelia in 6, arachnoidal cysts in 3, findings of presyrinx in 2, intramedullary microcyst in 2, and deformity of the spinal cord were present. A CISS sequence was more desirable for an evaluation of the cervicothoracic adhesive arachnoiditis than T2-weighted FSE images and could provide useful additional information.

  18. Initial experience in perfusion MR imaging of intracranial major artery occlusion with echo-planar technique

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Kazuhiro; Mizutani, Yoshiyuki; Inaoka, Sayuki; Hachiya, Junichi [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    1997-09-01

    The purpose of this study was to evaluate the usefulness of perfusion MR imaging using a single-shot echo-planar technique in occlusion of intracranial main arteries. Our patient group consisted of 16 patients with internal carotid artery occlusion (n=9), Moyamoya disease (n=4), and middle cerebral artery occlusion (n=3). We performed the echo-planar perfusion studies with a 1.5-T unit using a free-induction-decay-type echo-planar sequence. With a bolus injection of Gd-DTPA, 30 consecutive scans were obtained at 10 sections every 2 seconds. The data were analyzed in three ways: a time-intensity curves in the territory of the involved artery (n=16); semiquantitative flow map of each section representing signal changes due to passage of Gd-DTPA (n=15); and serial images at a selected section (n=7). The time intensity curves were abnormal in 13 patients. The peak of signal drop was delayed in all of them. Flow maps showed focal flow abnormalities in 11 patients, but they were apparently normal in 4 patients probably due to collateral flow. In serial images, delay in appearance and/or disappearance of Gd-DTPA was noted in 6 patients. In patients with occlusion of intracranial main arteries, MR single-shot echo-planar technique is of clinical use because it can provide information about hemodynamic changes in a short examination time, in multiple sections, and with good temporal resolution. (author)

  19. An efficient ultrasonic SAFT imaging for pulse-echo immersion testing

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Hong Wei [Changsha University of Science and Technology, Changsha (China); Jeong, Hyun Jo [Div. of Mechanical and Automotive Engineering, Wonkwang University, Iksan (Korea, Republic of)

    2017-04-15

    An ultrasonic synthetic aperture focusing technique (SAFT) using a root mean square (RMS) velocity model is proposed for pulse-echo immersion testing to improve the computational efficiency. Considering the immersion ultrasonic testing of a steel block as an example, three kinds of imaging were studied (B-Scan, SAFT imaging based on ray tracing technology and RMS velocity). The experimental results show that two kinds of SAFT imaging have almost the same imaging performance, while the efficiency of RMS velocity SAFT imaging is almost 25 times greater than the SAFT based on Snell's law.

  20. 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.

  1. Comparison of intravoxel incoherent motion diffusion-weighted imaging between turbo spin-echo and echo-planar imaging of the head and neck.

    Science.gov (United States)

    Mikayama, Ryoji; Yabuuchi, Hidetake; Sonoda, Shinjiro; Kobayashi, Koji; Nagatomo, Kazuya; Kimura, Mitsuhiro; Kawanami, Satoshi; Kamitani, Takeshi; Kumazawa, Seiji; Honda, Hiroshi

    2018-01-01

    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. • Head and neck DWI is especially sensitive to magnetic inhomogeneity. • The distortion of images was less with TSE-DWI than with EPI-DWI. • TSE-DWI can possibly exhibit higher ADC and IVIM-derived parameters than EPI-DWI. • Bland-Altman analysis showed unacceptable LoA in quantitative analysis between TSE-DWI and EPI-DWI. • It is not recommended to use both TSE-DWI and EPI-DWI for follow-up.

  2. MR imaging in solvent-induced chronic toxic encephalopathy

    Energy Technology Data Exchange (ETDEWEB)

    Thuomas, K.AA. [Dept. of Diagnostic Radiology, Environmental Medicine, Univ. Hospital, Linkoeping (Sweden); Moeller, C. [Dept. of Otolaryngology, Univ. Hospital, Linkoeping (Sweden); Oedkvist, L.M. [Dept. of Otolaryngology, Univ. Hospital, Linkoeping (Sweden); Flodin, U. [Dept. of Occupational and Environmental Medicine, Univ. Hospital, Linkoeping (Sweden); Dige, N. [Dept. of Occupational and Environmental Medicine, Univ. Hospital, Linkoeping (Sweden)

    1996-03-01

    To use MR to examine patients with CNS symptoms indicating chronic intoxication. Thirty-two subjects exposed to industrial solvents for 5 to 28 years and 40 age-matched, healthy controls were examined. All patients showed decreased signal in the basal ganglia on T2-weighted images. In 11 of the patients the white matter showed diffuse hyperintensity with loss of the grey-white matter discrimination and with distinct periventricular hyperintensities in 5 of the patients. The controls had no pathological changes in the brain. Although the relatively small number of patients may obscure the significance, findings observed on T2-weighted images were patchy periventricular hyperintensities and hypointensities in the basal ganglia. Fast spin-echo is a good technique with fast acquisition of images with true spin-echo contrast features. (orig.).

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

    Energy Technology Data Exchange (ETDEWEB)

    Mitsui, Hideaki [Yamagata City Hospital Saiseikan (Japan); 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)

  4. Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance

    Science.gov (United States)

    2012-01-01

    Background T2w-CMR is used widely to assess myocardial edema. Quantitative T1-mapping is also sensitive to changes in free water content. We hypothesized that T1-mapping would have a higher diagnostic performance in detecting acute edema than dark-blood and bright-blood T2w-CMR. Methods We investigated 21 controls (55 ± 13 years) and 21 patients (61 ± 10 years) with Takotsubo cardiomyopathy or acute regional myocardial edema without infarction. CMR performed within 7 days included cine, T1-mapping using ShMOLLI, dark-blood T2-STIR, bright-blood ACUT2E and LGE imaging. We analyzed wall motion, myocardial T1 values and T2 signal intensity (SI) ratio relative to both skeletal muscle and remote myocardium. Results All patients had acute cardiac symptoms, increased Troponin I (0.15-36.80 ug/L) and acute wall motion abnormalities but no LGE. T1 was increased in patient segments with abnormal and normal wall motion compared to controls (1113 ± 94 ms, 1029 ± 59 ms and 944 ± 17 ms, respectively; p T1-mapping had a significantly larger area-under-the-curve (AUC = 0.94) compared to T2-weighted methods, whether the reference ROI was skeletal muscle or remote myocardium (AUC = 0.58-0.89; p T1 value of greater than 990 ms most optimally differentiated segments affected by edema from normal segments at 1.5 T, with a sensitivity and specificity of 92 %. Conclusions Non-contrast T1-mapping using ShMOLLI is a novel method for objectively detecting myocardial edema with a high diagnostic performance. T1-mapping may serve as a complementary technique to T2-weighted imaging for assessing myocardial edema in ischemic and non-ischemic heart disease, such as quantifying area-at-risk and diagnosing myocarditis. PMID:22720998

  5. Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance.

    Science.gov (United States)

    Ferreira, Vanessa M; Piechnik, Stefan K; Dall'Armellina, Erica; Karamitsos, Theodoros D; Francis, Jane M; Choudhury, Robin P; Friedrich, Matthias G; Robson, Matthew D; Neubauer, Stefan

    2012-06-21

    T2w-CMR is used widely to assess myocardial edema. Quantitative T1-mapping is also sensitive to changes in free water content. We hypothesized that T1-mapping would have a higher diagnostic performance in detecting acute edema than dark-blood and bright-blood T2w-CMR. We investigated 21 controls (55 ± 13 years) and 21 patients (61 ± 10 years) with Takotsubo cardiomyopathy or acute regional myocardial edema without infarction. CMR performed within 7 days included cine, T1-mapping using ShMOLLI, dark-blood T2-STIR, bright-blood ACUT2E and LGE imaging. We analyzed wall motion, myocardial T1 values and T2 signal intensity (SI) ratio relative to both skeletal muscle and remote myocardium. All patients had acute cardiac symptoms, increased Troponin I (0.15-36.80 ug/L) and acute wall motion abnormalities but no LGE. T1 was increased in patient segments with abnormal and normal wall motion compared to controls (1113 ± 94 ms, 1029 ± 59 ms and 944 ± 17 ms, respectively; p T1-mapping had a significantly larger area-under-the-curve (AUC = 0.94) compared to T2-weighted methods, whether the reference ROI was skeletal muscle or remote myocardium (AUC = 0.58-0.89; p T1 value of greater than 990 ms most optimally differentiated segments affected by edema from normal segments at 1.5 T, with a sensitivity and specificity of 92 %. Non-contrast T1-mapping using ShMOLLI is a novel method for objectively detecting myocardial edema with a high diagnostic performance. T1-mapping may serve as a complementary technique to T2-weighted imaging for assessing myocardial edema in ischemic and non-ischemic heart disease, such as quantifying area-at-risk and diagnosing myocarditis.

  6. Comparison of GRASE and turbo spin echo sequences in brain MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Youk; Lee, Young Joon; Eun, Choong Ki; Jeon, Young Seup; Kim, Ig Dae; Cha, Seong Sook [Inje Univ., Pusan (Korea, Republic of). Coll. of Medicine

    1998-04-01

    The purpose of this study was to evaluate the utility of GRASE images of the brain, which combine gradient echo-EPI and turbo spin echo, and to compare the results with those of the turbo spin echo (TSE) technique. We analyzed and compared brain MR images obtained in 25 patients between October, 1996 and January, 1997, both TSE and GRASE techniques. Diagnosis was normal (n=5), infarct or ischemia (n=10), intracerebral hemorrhage (n=6), and neoplasm (n=4). TSE and GRASE MR images were obtained using a 1.5 T Gyroscan ACS-NT (Philips, Netherlands). For qualitative assessment, overall image quality, discrimination between cortical gray-white matter and basal ganglia-white matter, lesion conspicuity, and MR artifact were evaluated using a subjective grading system ranging from 1 to 5 (1=TSE better than GRASE, 5=GRASE better than TSE). For quantitative assessment, signal-to-noise ratios (SNRs) were calculated for cortical gray matter, white matter, basal ganglia, and lesions, and contrast-to-noise ratios (CNRs) were calculated for cortical gray-white matter, basal ganglia-white matter and lesions-white matter. We measured image acquisition time and RF specific absorption rate (SAR) on TSE and GRASE. With regard to MR artifact, GRASE is more sensitive than TSE, but as regards image quality and lesion distinction, the two modalities show no distinct difference. Since GRASE is superior to TSE for the detection of hemosiderin, and image acquisition time is three times shorter using GRASE, GRASE might usefully be applied during the evaluation by MR imaging of certain brain conditions. (author). 17 refs., 3 tabs., 5 figs.

  7. Effect of hyoscine butylbromide (HBB) on the uterine corpus: quantitative assessment with T2-weighted (T2W) MRI in healthy volunteers.

    Science.gov (United States)

    Fujimoto, Koji; Nakai, Asako; Okada, Tomohisa; Ikeuchi, Takashi; Satogami, Naoe; Daido, Sayaka; Yakami, Masahiro; Togashi, Kaori

    2010-08-01

    To investigate effects of hyoscine butylbromide (HBB) on the appearance of three zonal anatomy of the uterine corpus on T2-weighted images (T2WI). Sagittal T2WI of the pelvis were acquired before and after intramuscular administration of HBB with interval of 10 minutes in 22 healthy volunteers. By drawing polygonal regions of interest (ROIs), the uterine corpus was delineated into outer myometrium (OM), junctional zone (JZ), and endometrium (EM) in 20 subjects. Areas (mm(2)) and relative signal intensity (rSI) of each layer were compared between pre-HBB and post-HBB administration images by using paired t-tests. Histogram analysis was conducted for the uterine layers and changes were visualized. Areas of OM were significantly increased (P = 0.014) and mean rSI of JZ and OM were significantly increased (P = 0.007 and 0.001, respectively) after administration of HBB. Histogram showed an increase in the number of pixels with higher rSI in the OM, which was considered to be caused by an increase in interstitial fluid and vascular dilatation. EM did not show significant changes. Layer-wise ROI analyses demonstrated changes in the area and rSI in T2WI of the uterus after HBB administration. Histogram analysis contributed to the investigation of signal changes. 2010 Wiley-Liss, Inc.

  8. Reduction of B1 sensitivity in selective single-slab 3D turbo spin echo imaging with very long echo trains.

    Science.gov (United States)

    Park, Jaeseok; Mugler, John P; Hughes, Timothy

    2009-10-01

    Single-slab 3D turbo/fast spin echo (SE) imaging with very long echo trains was recently introduced with slab selection using a highly selective excitation pulse and short, nonselective refocusing pulses with variable flip angles for high imaging efficiency. This technique, however, is vulnerable to image degradation in the presence of spatially varying B(1) amplitudes. In this work we develop a B(1) inhomogeneity-reduced version of single-slab 3D turbo/fast SE imaging based on the hypothesis that it is critical to achieve spatially uniform excitation. Slab selection was performed using composite adiabatic selective excitation wherein magnetization is tipped into the transverse plane by a nonselective adiabatic-half-passage pulse and then slab is selected by a pair of selective adiabatic-full-passage pulses. Simulations and experiments were performed to evaluate the proposed technique and demonstrated that this approach is a simple and efficient way to reduce B(1) sensitivity in single-slab 3D turbo/fast SE imaging with very long echo trains. (c) 2009 Wiley-Liss, Inc.

  9. Breath-hold MR cholangiopancreatography with three-dimensional, segmented, echo-planar imaging and volume rendering

    NARCIS (Netherlands)

    P.A. Wielopolski (Piotr); J. Gaa; D.R. Wielopolski; M. Oudkerk (Matthijs)

    1999-01-01

    textabstractEnd-expiration, 21-second breath-hold, three-dimensional magnetic resonance (MR) cholangiopancreatography (MRCP) was developed with segmented echo-planar imaging. In 15 healthy subjects and 14 randomly selected patients undergoing liver studies,

  10. MRI of the cervical spine with 3D gradient echo sequence at 3 T: initial experience.

    Science.gov (United States)

    Xiao, L; Siu, C W J; Yeung, K; Leung, A; Yuen, M K; Wong, Y C

    2015-09-01

    The aim of this study was to compare three-dimensional (3D) high resolution T2*-weighted gradient echo (3D FFE) magnetic resonance (MR) sequence with conventional 2D T2-weighted turbo spin echo (TSE) MR sequence for imaging of the cervical spine, especially to assess the detectability of the internal anatomy of the cervical spinal cord, i.e. to distinguish the grey and white matter. Fifteen volunteers were examined at 3.0T MR unit. Signal-to-noise (SNR), contrast-to-noise (CNR) and image homogeneity were evaluated. In the visual analysis, the visibility of anatomical structures of the cervical spine and artifacts were assessed. The nonparametric method of paired sample t-test was adopted to evaluate the differences between the sequences. The 3D FFE sequence provided better results for CNR, cerebrospinal fluid (CSF) versus white matter, grey matter, disk and bone. Moreover, it yielded good results for the CNR grey matter versus white matter. The butterfly-shaped "H" is clearly displayed in the 3D FFE sequence. The statistical analysis revealed the statistically significant difference between the 2D TSE and 3D FFE sequences for the contrast of CSF versus spinal cord (both grey matter and white matter). The 3D FFE sequence in MR imaging of the cervical spinal cord is superior in delineation of spinal cord anatomical structures compared to 2D TSE sequence. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  11. Phase-aligned multiple spin-echo averaging: a simple way to improve signal-to-noise ratio of in vivo mouse spinal cord diffusion tensor image.

    Science.gov (United States)

    Tu, Tsang-Wei; Budde, Matthew D; Xie, Mingqiang; Chen, Ying-Jr; Wang, Qing; Quirk, James D; Song, Sheng-Kwei

    2014-12-01

    To improve signal-noise-ratio of in vivo mouse spinal cord diffusion tensor imaging using-phase aligned multiple spin-echo technique. In vivo mouse spinal cord diffusion tensor imaging maps generated by multiple spin-echo and conventional spin-echo diffusion weighting were examined to demonstrate the efficacy of multiple spin-echo diffusion sequence to improve image quality and throughput. Effects of signal averaging using complex, magnitude and phased images from multiple spin-echo diffusion weighting were also assessed. Bayesian probability theory was used to generate phased images by moving the coherent signals to the real channel to eliminate the effect of phase variation between echoes while preserving the Gaussian noise distribution. Signal averaging of phased multiple spin-echo images potentially solves both the phase incoherence problem and the bias of the elevated Rician noise distribution in magnitude image. The proposed signal averaging with Bayesian phase-aligned multiple spin-echo images approach was compared to the conventional spin-echo data acquired with doubling the scan time. The diffusion tensor imaging parameters were compared in the mouse contusion spinal cord injury. Significance level (p-value) and effect size (Cohen's d) were reported between the control and contused spinal cord to inspect the sensitivity of each approach in detecting white matter pathology. Compared to the spin-echo image, the signal-noise-ratio increased to 1.84-fold using the phased image averaging and to 1.30-fold using magnitude image averaging in the spinal cord white matter. Multiple spin-echo phased image averaging showed improved image quality of the mouse spinal cord among the tested methods. Diffusion tensor imaging metrics obtained from multiple spin-echo phased images using three echoes and two averages closely agreed with those derived by spin-echo magnitude data with four averages (two times more in acquisition time). The phased image averaging correctly

  12. [Evaluation of imaging parameters for T1 dynamic contrast enhanced MRI with fast spin-echo].

    Science.gov (United States)

    Kanazawa, Yuuki; Miyati, Tosiaki; Inoue, Yusuke; Sato, Osamu

    2007-10-20

    For the purpose of continual measurement of the T1 value using the FSE (fast spin-echo) sequence and evaluation of the hemodynamics, we assessed T1 values when the imaging parameters were changed. Moreover, with the imaging parameters derived from this study, dynamic contrast-enhanced MR imaging (MRI) was examined in prostatic disease. First, the T1 value before contrast agent injection was measured with imaging parameters that had different TR and fixed TE. Next, dynamic contrast-enhanced imaging data were acquired for the imaging parameters using TE and TR in the same way as before contrast agent injection, and the T1 value of the tissue at contrast enhancement was measured. In the phantom studies, the TSE imaging parameters with short TE, long TR, and few ETL were connected with the mixed sequence. In dynamic study of the prostate, the difference between normal prostate and prostate cancer became clearer with the time-relaxation rate curve than the time-signal curve. This method using TSE is able to evaluate in greater detail information on hemodynamics and to perform dynamic study with the spin-echo sequence in extensive tissues.

  13. Imaging tooth enamel using zero echo time (ZTE) magnetic resonance imaging

    Science.gov (United States)

    Rychert, Kevin M.; Zhu, Gang; Kmiec, Maciej M.; Nemani, Venkata K.; Williams, Benjamin B.; Flood, Ann B.; Swartz, Harold M.; Gimi, Barjor

    2015-03-01

    In an event where many thousands of people may have been exposed to levels of radiation that are sufficient to cause the acute radiation syndrome, we need technology that can estimate the absorbed dose on an individual basis for triage and meaningful medical decision making. Such dose estimates may be achieved using in vivo electron paramagnetic resonance (EPR) tooth biodosimetry, which measures the number of persistent free radicals that are generated in tooth enamel following irradiation. However, the accuracy of dose estimates may be impacted by individual variations in teeth, especially the amount and distribution of enamel in the inhomogeneous sensitive volume of the resonator used to detect the radicals. In order to study the relationship between interpersonal variations in enamel and EPR-based dose estimates, it is desirable to estimate these parameters nondestructively and without adding radiation to the teeth. Magnetic Resonance Imaging (MRI) is capable of acquiring structural and biochemical information without imparting additional radiation, which may be beneficial for many EPR dosimetry studies. However, the extremely short T2 relaxation time in tooth structures precludes tooth imaging using conventional MRI methods. Therefore, we used zero echo time (ZTE) MRI to image teeth ex vivo to assess enamel volumes and spatial distributions. Using these data in combination with the data on the distribution of the transverse radio frequency magnetic field from electromagnetic simulations, we then can identify possible sources of variations in radiation-induced signals detectable by EPR. Unlike conventional MRI, ZTE applies spatial encoding gradients during the RF excitation pulse, thereby facilitating signal acquisition almost immediately after excitation, minimizing signal loss from short T2 relaxation times. ZTE successfully provided volumetric measures of tooth enamel that may be related to variations that impact EPR dosimetry and facilitate the development

  14. Simultaneous assessment of vessel size index, relative blood volume, and vessel permeability in a mouse brain tumor model using a combined spin echo gradient echo echo-planar imaging sequence and viable tumor analysis.

    Science.gov (United States)

    Kording, Fabian; Weidensteiner, Claudia; Zwick, Stefan; Osterberg, Nadja; Weyerbrock, Astrid; Staszewski, Ori; von Elverfeldt, Dominik; Reichardt, Wilfried

    2014-12-01

    Combining multiple imaging biomarkers in one magnetic resonance imaging (MRI) session would be beneficial to gain more data pertaining to tumor vasculature under therapy. Therefore, simultaneous measurement of perfusion, permeability, and vessel size imaging (VSI) using a gradient echo spin echo (GE-SE) sequence with injection of a clinically approved gadolinium (Gd)-based contrast agent was assessed in an orthotopic glioma model. A combined spin echo gradient echo echo-planar imaging sequence was implemented using a single contrast agent Gd diethylenetriaminepentaacetic acid (Gd-DTPA). This sequence was tested in a mouse brain tumor model (U87_MG), also under treatment with an antiangiogenic agent (bevacizumab). T2 maps and the apparent diffusion coefficient (ADC) were used to differentiate regions of cell death and viable tumor tissue. In viable tumor tissue regional blood volume was 5.7 ± 0.6% in controls and 5.2 ± 0.3% in treated mice. Vessel size was 18.1 ± 2.4 μm in controls and 12.8 ± 2.0 μm in treated mice, which correlated with results from immunohistochemistry. Permeability (K(trans) ) was close to zero in treated viable tumor tissue and 0.062 ± 0.024 min(-1) in controls. Our MRI method allows simultaneous assessment of several physiological and morphological parameters and extraction of MRI biomarkers for vasculature. These could be used for treatment monitoring of novel therapeutic agents such as antiangiogenic drugs. © 2014 Wiley Periodicals, Inc.

  15. 3-D photoacoustic and pulse echo imaging of prostate tumor progression in the mouse window chamber

    Science.gov (United States)

    Bauer, Daniel R.; Olafsson, Ragnar; Montilla, Leonardo G.; Witte, Russell S.

    2011-01-01

    Understanding the tumor microenvironment is critical to characterizing how cancers operate and predicting their response to treatment. We describe a novel, high-resolution coregistered photoacoustic (PA) and pulse echo (PE) ultrasound system used to image the tumor microenvironment. Compared to traditional optical systems, the platform provides complementary contrast and important depth information. Three mice are implanted with a dorsal skin flap window chamber and injected with PC-3 prostate tumor cells transfected with green fluorescent protein. The ensuing tumor invasion is mapped during three weeks or more using simultaneous PA and PE imaging at 25 MHz, combined with optical and fluorescent techniques. Pulse echo imaging provides details of tumor structure and the surrounding environment with 100-μm3 resolution. Tumor size increases dramatically with an average volumetric growth rate of 5.35 mm3∕day, correlating well with 2-D fluorescent imaging (R = 0.97, p < 0.01). Photoacoustic imaging is able to track the underlying vascular network and identify hemorrhaging, while PA spectroscopy helps classify blood vessels according to their optical absorption spectrum, suggesting variation in blood oxygen saturation. Photoacoustic and PE imaging are safe, translational modalities that provide enhanced depth resolution and complementary contrast to track the tumor microenvironment, evaluate new cancer therapies, and develop molecular contrast agents in vivo. PMID:21361696

  16. Conjugate echoes of artificially injected electron beams detected optically by means of new image processing

    Science.gov (United States)

    Hallinan, Thomas J.; Stenbaek-Nielsen, Hans C.; Baldridge, James; Winckler, John; Malcolm, Perry

    1990-01-01

    Artificial auroral streaks were detected following two upward injections of energetic electrons (38 keV and 26 keV) from the Echo 4 rocket-borne electron accelerator. Newly developed image processing techniques are used to detect and describe the streaks. It is found that the potential of the payload remained below 1 kV during 45 mA injections at an altitude of 210 km. The echo streaks show little dispersion in time or space, suggesting that the portion of the beam returning to the northern hemisphere loss cone remained collimated and nearly monoenergetic. There was, however, a 70 percent loss in the return flux. The causes of this loss are discussed.

  17. Tissue Electrical Property Mapping from Zero Echo-Time Magnetic Resonance Imaging

    OpenAIRE

    Lee, Seung-Kyun; Bulumulla, Selaka; Wiesinger, Florian; Sacolick, Laura; Sun, Wei; Hancu, Ileana

    2014-01-01

    The capability of magnetic resonance imaging (MRI) to produce spatially resolved estimation of tissue electrical properties (EPs) in vivo has been a subject of much recent interest. In this work we introduce a method to map tissue EPs from low-flip-angle, zero-echo-time (ZTE) imaging. It is based on a new theoretical formalism that allows calculation of EPs from the product of transmit and receive radio-frequency (RF) field maps. Compared to conventional methods requiring separation of the tr...

  18. Comparison of Fourier transform and continuous wavelet transform to study echo-planar imaging flow maps

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez G, A.; Bowtell, R.; Mansfield, P. [Area de Procesamiento Digital de Senales e Imagenes Biomedicas. Universidad Autonoma Metropolitana Iztapalapa. Mexico D.F. 09340 Mexico (Mexico)

    1998-12-31

    Velocity maps were studied combining Doyle and Mansfield method (1986) with each of the following transforms: Fourier, window Fourier and wavelet (Mexican hat). Continuous wavelet transform was compared against the two Fourier transform to determine which technique is best suited to study blood maps generated by Half Fourier Echo-Planar Imaging. Coefficient images were calculated and plots of the pixel intensity variation are presented. Finally, contour maps are shown to visualize the behavior of the blood flow in the cardiac chambers for the wavelet technique. (Author)

  19. Derivation of a T2-weighted MRI total colonic inflammation score (TCIS) for assessment of patients with severe acute inflammatory colitis - a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Hafeez, Rehana; Boulos, Paul [University College London Hospitals NHS Trust, Department of Surgery, London (United Kingdom); Punwani, Shonit; Halligan, Steve [University College London, Centre for Medical Imaging, London (United Kingdom); University College London Hospitals NHS Trust, Department of Specialist X-ray, Level 2 podium, London (United Kingdom); Pendse, Doug [University College London, Centre for Medical Imaging, London (United Kingdom); Bloom, Stuart [University College London Hospitals NHS Trust, Department of Gastroenterology, London (United Kingdom); Taylor, Stuart A. [University College London, Centre for Medical Imaging, London (United Kingdom); University College London Hospitals NHS Trust, Department of Specialist X-ray, Level 2 podium, London (United Kingdom)

    2011-02-15

    To derive an MRI score for assessing severity, therapeutic response and prognosis in acute severe inflammatory colitis. Twenty-one patients with acute severe colitis underwent colonic MRI after admission and again (n = 16) after median 5 days of treatment. Using T2-weighted images, two radiologists in consensus graded segmental haustral loss, mesenteric and mural oedema, mural thickness, and small bowel and colonic dilatation producing a total colonic inflammatory score (TCIS, range 6-95). Pre- and post-treatment TCIS were compared, and correlated with CRP, stool frequency, and number of inpatient days (therapeutic response marker). Questionnaire assessment of patient worry, satisfaction and discomfort graded 1 (bad) to 7 (good) was administered Admission TCIS correlated significantly with CRP (Kendall's tau=0.45, 95% confidence interval [CI] 0.11-0.79, p = 0.006), and stool frequency (Kendall's tau 0.39, 95% CI 0.14-0.64, p = 0.02). TCIS fell after treatment (median [22 range 15-31]) to median 20 [range 8-25], p = 0.01. Admission TCIS but not CRP or stool frequency was correlated with length of inpatient stay (Kendall's tau 0.40, 95% CI 0.11-0.69, p = 0.02). Patients reported some discomfort (median score 4) during MRI. MRI TCIS falls after therapy, correlates with existing markers of disease severity, and in comparison may better predict therapeutic response. (orig.)

  20. Multishot cartesian turbo spin-echo diffusion imaging using iterative POCSMUSE Reconstruction.

    Science.gov (United States)

    Zhang, Zhe; Zhang, Bing; Li, Ming; Liang, Xue; Chen, Xiaodong; Liu, Renyuan; Zhang, Xin; Guo, Hua

    2017-07-01

    To report a diffusion imaging technique insensitive to off-resonance artifacts and motion-induced ghost artifacts using multishot Cartesian turbo spin-echo (TSE) acquisition and iterative POCS-based reconstruction of multiplexed sensitivity encoded magnetic resonance imaging (MRI) (POCSMUSE) for phase correction. Phase insensitive diffusion preparation was used to deal with the violation of the Carr-Purcell-Meiboom-Gill (CPMG) conditions of TSE diffusion-weighted imaging (DWI), followed by a multishot Cartesian TSE readout for data acquisition. An iterative diffusion phase correction method, iterative POCSMUSE, was developed and implemented to eliminate the ghost artifacts in multishot TSE DWI. The in vivo human brain diffusion images (from one healthy volunteer and 10 patients) using multishot Cartesian TSE were acquired at 3T and reconstructed using iterative POCSMUSE, and compared with single-shot and multishot echo-planar imaging (EPI) results. These images were evaluated by two radiologists using visual scores (considering both image quality and distortion levels) from 1 to 5. The proposed iterative POCSMUSE reconstruction was able to correct the ghost artifacts in multishot DWI. The ghost-to-signal ratio of TSE DWI using iterative POCSMUSE (0.0174 ± 0.0024) was significantly (P iterative POCSMUSE reconstruction can provide high-quality diffusion images insensitive to motion-induced ghost artifacts and off-resonance related artifacts such as chemical shifts and susceptibility-induced image distortions. 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:167-174. © 2016 International Society for Magnetic Resonance in Medicine.

  1. 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.

  2. ULTRASOUND PULSE-ECHO IMAGING USING THE SPLIT-STEP FOURIER PROPAGATOR

    Energy Technology Data Exchange (ETDEWEB)

    HUANG, LIANJIE [Los Alamos National Laboratory; QUAN, YOULI [Los Alamos National Laboratory

    2007-01-31

    Ultrasonic reflection imaging has the potential to produce higher image resolution than transmission tomography, but imaging resolution and quality still need to be further improved for early cancer detection and diagnosis. We present an ultrasound reflection image reconstruction method using the split-step Fourier propagator. It is based on recursive inward continuation of ultrasonic wavefields in the frequency-space and frequency-wavenumber domains. The inward continuation within each extrapolation interval consists of two steps. In the first step, a phase-shift term is applied to the data in the frequency-wavenumber domain for propagation in a reference medium. The second step consists of applying another phase-shift term to data in the frequency-space domain to approximately compensate for ultrasonic scattering effects of heterogeneities within the breast. We use synthetic ultrasound pulse-echo data recorded around a ring for heterogeneous, computer-generated numerical breast phantoms to study the imaging capability of the method. The phantoms are derived from an experimental breast phantom and a sound-speed tomography image of an in-vivo ultrasound breast data collected usi ng a ring array. The heterogeneous sound-speed models used for pulse-echo imaging are obtained using a computationally efficient, first-arrival-time (time-of-flight) transmission tomography method. Our studies demonstrate that reflection image reconstruction using the split-step Fourier propagator with heterogeneous sound-speed models significantly improves image quality and resolution. We also numerically verify the spatial sampling criterion of wavefields for a ring transducer array.

  3. 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

    2017-09-14

    It is highly desirable in clinical abdominal MR scans to accelerate single-shot fast spin echo (SSFSE) imaging and reduce blurring due to T2 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 2017. © 2017 International Society for Magnetic Resonance in Medicine.

  4. MR signal-fat-fraction analysis and T2*weighted imaging measure BAT reliably on humans without cold exposure

    NARCIS (Netherlands)

    Holstila, Milja; Pesola, Marko; Saari, Teemu; Koskensalo, Kalle; Raiko, Juho; Borra, Ronald J. H.; Nuutila, Pirjo; Parkkola, Riitta; Virtanen, Kirsi A.

    Objective. Brown adipose tissue (BAT) is compositionally distinct from white adipose tissue (WAT) in terms of triglyceride and water content. In adult humans, the most significant BAT depot is localized in the supraclavicular area. Our aim is to differentiate brown adipose tissue from white adipose

  5. Signal-shot echo-planner diffusion-weighted MR imaging at 3T and 1.5T for differentiation of benign vertebral fracture edema and tumor infiltration

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hee Jin; Lee, So Yeon; Rho, Myung Ho; Chung, Eun Chul; Kim, Mi Sung; Kwon, Heon Ju; Youn, In Young [Dept. of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-09-15

    To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p < 0.05). The sensitivity of the diagnostic performance was higher with an additional DWI in both 1.5T and 3T, but the sensitivities were similar with the addition of b values of 400 and 1000. The specificities of the diagnostic performances did not show significant differences (p value > 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T.

  6. Single-Shot Echo-Planar Diffusion-Weighted MR Imaging at 3T and 1.5T for Differentiation of Benign Vertebral Fracture Edema and Tumor Infiltration

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hee Jin; Lee, So Yeon; Rho, Myung Ho; Chung, Eun Chul; Kim, Mi Sung; Kwon, Heon Ju; Youn, In Young [Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181 (Korea, Republic of)

    2016-11-01

    To compare the apparent diffusion coefficient (ADC) value using single-shot echo-planar imaging sequences at 3T and 1.5T for differentiation of benign fracture edema and tumor infiltration of the vertebral body. A total of 46 spinal examinations were included in the 1.5T MRI group, and a total of 40 spinal examinations were included in the 3T MRI group. The ADC values of the lesion were measured and calculated. The diagnostic performance of the conventional MR image containing sagittal T2-weighted fat saturated image and each diffusion weighted image (DWI) with an ADC value with different b values were evaluated. The mean ADC value of the benign lesions was higher than that of the malignant lesions on 1.5T and 3T (p < 0.05). The sensitivity of the diagnostic performance was higher with an additional DWI in both 1.5T and 3T, but the sensitivities were similar with the addition of b values of 400 and 1000. The specificities of the diagnostic performances did not show significant differences (p value > 0.05). The diagnostic accuracies were higher when either of the DWIs (b values of 400 and 1000) was added to routine MR image for 1.5T and 3T. Statistical differences between 1.5T and 3T or between b values of 400 and 1000 were not seen. The ADC values of the benign lesions were significantly higher than those of the malignant lesions on 1.5T and 3T. There was no statistically significant difference in the diagnostic performances when either of the DWIs (b values of 400 and 1000) was added to the routine MR image for 1.5T and 3T.

  7. Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance

    Directory of Open Access Journals (Sweden)

    Ferreira Vanessa M

    2012-06-01

    Full Text Available Abstract Background T2w-CMR is used widely to assess myocardial edema. Quantitative T1-mapping is also sensitive to changes in free water content. We hypothesized that T1-mapping would have a higher diagnostic performance in detecting acute edema than dark-blood and bright-blood T2w-CMR. Methods We investigated 21 controls (55 ± 13 years and 21 patients (61 ± 10 years with Takotsubo cardiomyopathy or acute regional myocardial edema without infarction. CMR performed within 7 days included cine, T1-mapping using ShMOLLI, dark-blood T2-STIR, bright-blood ACUT2E and LGE imaging. We analyzed wall motion, myocardial T1 values and T2 signal intensity (SI ratio relative to both skeletal muscle and remote myocardium. Results All patients had acute cardiac symptoms, increased Troponin I (0.15-36.80 ug/L and acute wall motion abnormalities but no LGE. T1 was increased in patient segments with abnormal and normal wall motion compared to controls (1113 ± 94 ms, 1029 ± 59 ms and 944 ± 17 ms, respectively; p  Conclusions Non-contrast T1-mapping using ShMOLLI is a novel method for objectively detecting myocardial edema with a high diagnostic performance. T1-mapping may serve as a complementary technique to T2-weighted imaging for assessing myocardial edema in ischemic and non-ischemic heart disease, such as quantifying area-at-risk and diagnosing myocarditis.

  8. Carr-Purcell-Meiboom-Gill (CPMG) Imaging of Prostate Cancer: Quantitative T2 Values for Cancer Discrimination

    Science.gov (United States)

    Roebuck, Joseph R.; Haker, Steven J.; Mitsouras, Dimitris; Rybicki, Frank J.; Tempany, Clare M.; Mulkern, Robert V.

    2009-01-01

    Quantitative, apparent T2 values of suspected prostate cancer and healthy peripheral zone tissue in men with prostate cancer were measured using a Carr-Purcell-Meiboom-Gill (CPMG) imaging sequence in order to assess the cancer discrimination potential of tissue T2 values. The CPMG imaging sequence was used to image the prostates of 18 men with biopsy proven prostate cancer. Whole gland coverage with nominal voxel volumes of 0.54 × 1.1 × 4 mm3 was obtained in 10.7 minutes, resulting in data sets suitable for generating high quality images with variable T2-weighting and for evaluating quantitative T2 values on a pixel-by-pixel basis. Region-of-interest analysis of suspected healthy peripheral zone tissue and suspected cancer, identified on the basis of both T1- and T2-weighted signal intensities and available histopathology reports, yielded significantly (p < 0.0001) longer apparent T2 values in suspected healthy tissue (193 ± 49 ms) vs. suspected cancer (100 ± 26 ms), suggesting potential utility of this method as a tissue specific discrimination index for prostate cancer. We conclude that CPMG imaging of the prostate can be performed in reasonable scan times and can provide advantages over T2-weighted fast spin echo imaging alone, including quantitative T2 values for cancer discrimination as well as proton density maps without the point spread function degradation associated with short effective echo time fast spin echo (FSE) sequences. PMID:18823731

  9. Magnetic resonance imaging of acute trauma of the cervical spine: spectrum of findings

    Energy Technology Data Exchange (ETDEWEB)

    Forster, B.B.; Koopmans, R.A. [British Columbia Univ., Vancouver, BC (Canada). Faculty of Medicine

    1995-06-01

    The magnetic resonance imaging (MRI) spectrum of acute injury to the cervical spine was illustrated in this pictorial essay. The appearance of the traumatized cord was discussed, including intramedullary hemorrhage, and the causes of spinal cord compression, such as disk herniation, epidural hematoma, fracture, dislocation and underlying spinal stenosis. The ability of MRI to directly reveal the severity of cord injury and simultaneously indicate the cause of cord compression proved particularly useful in the management of incomplete injury, for which surgical intervention may prevent further deterioration. The protocol for MRI of cervical spinal trauma included sagittal T1-weighted and T2-weighted conventional spin-echo sequences. In addition, transverse T2-weighted gradient-echo images were obtained. MRI`s ability to directly reveal the extent of cord injury was said to be a powerful tool in the management of incomplete injuries where further deterioration could be prevented by timely surgical intervention. 7 refs., 12 figs.

  10. Slice-accelerated gradient-echo echo planar imaging dynamic susceptibility contrast-enhanced MRI with blipped CAIPI: effect of increasing temporal resolution.

    Science.gov (United States)

    Takamura, Tomohiro; Hori, Masaaki; Kamagata, Koji; Kumamaru, Kanako K; Irie, Ryusuke; Hagiwara, Akifumi; Hamasaki, Nozomi; Aoki, Shigeki

    2018-01-01

    To assess the influence of high temporal resolution on the perfusion measurements and image quality of perfusion maps, by applying simultaneous-multi-slice acquisition (SMS) dynamic susceptibility contrast-enhanced (DSC) magnetic resonance imaging (MRI). DSC-MRI data using SMS gradient-echo echo planar imaging sequences in 10 subjects with no intracranial abnormalities were retrospectively analyzed. Three additional data sets with temporal resolution of 1.0, 1.5, and 2.0 s were created from the raw data sets of 0.5 s. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), time to peak (TTP), and time to maximum tissue residue function (T max ) measurements were performed, as was visual perfusion map analysis. The perfusion parameter for temporal resolution of 0.5 s (reference) was compared with each synthesized perfusion parameter. CBF, MTT, and TTP values at temporal resolutions of 1.5 and 2.0 s differed significantly from the reference. The image quality of MTT, TTP, and T max maps deteriorated with decreasing temporal resolution. The temporal resolution of DSC-MRI influences perfusion parameters and SMS DSC-MRI provides better image quality for MTT, TTP, and T max maps.

  11. Gradient Spin Echo (GraSE) imaging for fast myocardial T2 mapping.

    Science.gov (United States)

    Sprinkart, Alois M; Luetkens, Julian A; Träber, Frank; Doerner, Jonas; Gieseke, Jürgen; Schnackenburg, Bernhard; Schmitz, Georg; Thomas, Daniel; Homsi, Rami; Block, Wolfgang; Schild, Hans; Naehle, Claas P

    2015-02-12

    Quantitative Cardiovascular Magnetic Resonance (CMR) techniques have gained high interest in CMR research. Myocardial T2 mapping is thought to be helpful in diagnosis of acute myocardial conditions associated with myocardial edema. In this study we aimed to establish a technique for myocardial T2 mapping based on gradient-spin-echo (GraSE) imaging. The local ethics committee approved this prospective study. Written informed consent was obtained from all subjects prior to CMR. A modified GraSE sequence allowing for myocardial T2 mapping in a single breath-hold per slice using ECG-triggered acquisition of a black blood multi-echo series was developed at 1.5 Tesla. Myocardial T2 relaxation time (T2-RT) was determined by maximum likelihood estimation from magnitude phased-array multi-echo data. Four GraSE sequence variants with varying number of acquired echoes and resolution were evaluated in-vitro and in 20 healthy volunteers. Inter-study reproducibility was assessed in a subset of five volunteers. The sequence with the best overall performance was further evaluated by assessment of intra- and inter-observer agreement in all volunteers, and then implemented into the clinical CMR protocol of five patients with acute myocardial injury (myocarditis, takotsubo cardiomyopathy and myocardial infarction). In-vitro studies revealed the need for well defined sequence settings to obtain accurate T2-RT measurements with GraSE. An optimized 6-echo GraSE sequence yielded an excellent agreement with the gold standard Carr-Purcell-Meiboom-Gill sequence. Global myocardial T2 relaxation times in healthy volunteers was 52.2 ± 2.0 ms (mean ± standard deviation). Mean difference between repeated examinations (n = 5) was -0.02 ms with 95% limits of agreement (LoA) of [-4.7; 4.7] ms. Intra-reader and inter-reader agreement was excellent with mean differences of -0.1 ms, 95% LoA = [-1.3; 1.2] ms and 0.1 ms, 95% LoA = [-1.5; 1.6] ms, respectively (n = 20). In

  12. Fast susceptibility-weighted imaging with three-dimensional short-axis propeller (SAP)-echo-planar imaging.

    Science.gov (United States)

    Holdsworth, Samantha J; Yeom, Kristen W; Moseley, Michael E; Skare, S

    2015-05-01

    Susceptibility-weighted imaging (SWI) in neuroimaging can be challenging due to long scan times of three-dimensional (3D) gradient recalled echo (GRE), while faster techniques such as 3D interleaved echo-planar imaging (iEPI) are prone to motion artifacts. Here we outline and implement a 3D short-axis propeller echo-planar imaging (SAP-EPI) trajectory as a faster, motion-correctable approach for SWI. Experiments were conducted on a 3T MRI system. The 3D SAP-EPI, 3D iEPI, and 3D GRE SWI scans were acquired on two volunteers. Controlled motion experiments were conducted to test the motion-correction capability of 3D SAP-EPI. The 3D SAP-EPI SWI data were acquired on two pediatric patients as a potential alternative to 2D GRE used clinically. The 3D GRE images had a better target resolution (0.47 × 0.94 × 2 mm, scan time = 5 min), iEPI and SAP-EPI images (resolution = 0.94 × 0.94 × 2 mm) were acquired in a faster scan time (1:52 min) with twice the brain coverage. SAP-EPI showed motion-correction capability and some immunity to undersampling from rejected data. While 3D SAP-EPI suffers from some geometric distortion, its short scan time and motion-correction capability suggest that SAP-EPI may be a useful alternative to GRE and iEPI for use in SWI, particularly in uncooperative patients. © 2014 Wiley Periodicals, Inc.

  13. Respiration impacts phase difference-based field maps in echo planar imaging.

    Science.gov (United States)

    Zeller, Mario; Kraus, Philip; Müller, Alexander; Bley, Thorsten A; Köstler, Herbert

    2014-08-01

    To investigate the influence of respiration on field maps for geometric distortion correction derived from two rapidly acquired consecutive echo planar images. Displacement maps of the brains of seven healthy volunteers were acquired under breath hold and free breathing for a 64 × 64 pixel image matrix using phase labeling for additional coordinate encoding (PLACE). The maps were transformed into undistorted gradient echo space and analyzed with regard to standard deviation and absolute deviation from an accurate reference field map derived from a multiecho reference scan. Standard deviations between PLACE field maps and absolute difference from the reference field map are a factor of about 3 higher under free breathing than under breath hold. The mean deviation decreases from 3 pixels in the slice closest to the lung to 1 pixel in the most superior slice under free breathing and from 1 to field map and thus corrupt the geometric distortion correction. The effect can be greatly reduced by acquiring the field map data under breath hold. Data acquired under free breathing can be improved with retrospective phase correction or by averaging several field maps. Copyright © 2013 Wiley Periodicals, Inc.

  14. Simultaneous Multislice Accelerated Turbo Spin Echo Magnetic Resonance Imaging: Comparison and Combination With In-Plane Parallel Imaging Acceleration for High-Resolution Magnetic Resonance Imaging of the Knee.

    Science.gov (United States)

    Fritz, Jan; Fritz, Benjamin; Zhang, Jialu; Thawait, Gaurav K; Joshi, Dharmdev H; Pan, Li; Wang, Dingxin

    2017-09-01

    We prospectively quantified the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of integrated parallel acquisition technique (PAT) and simultaneous multislice (SMS) acceleration and various combinations thereof, and we further compared two 4-fold-accelerated (PAT2-SMS2) high-resolution turbo spin echo (TSE) magnetic resonance imaging (MRI) protocols of the knee against a clinical 2-fold-accelerated (PAT2-SMS1) TSE standard. Institutional review board approval was obtained, and all subjects gave informed consent. Fourteen knee MRI examinations were obtained (8 men, 6 women; mean age, 46 years; age range, 28-62 years) using a 3 T MRI system and a TSE pulse sequence prototype that allowed for the combination of PAT and SMS acceleration. Predicted whole-body specific absorption rates were recorded for all pulse sequences. For quantitative analysis, the difference method was used to calculate SNR and CNR analysis of 6 different TSE acceleration schemes (PAT2-SMS1, PAT3-SMS1, PAT1-SMS2, PAT1-SMS3, PAT2-SMS2, and PAT2-SMS3). For qualitative analysis, sagittal intermediate-weighted and axial fat-suppressed T2-weighted MR images were obtained with PAT2-SMS1 and PAT2-SMS2 acceleration schemes using similar parameters. One faster PAT2-SMS2 acceleration scheme with decreased repetition time and longer echo train was labeled with the addition SPEED for the purpose of this report. Two readers rated the data sets for image quality, structural visibility, and overall observer satisfaction using equidistant 5-point Likert scales. Readers additionally noted the presence of cartilage defects, meniscal tears, tendons and ligament tears, and bone marrow edema pattern. Friedman and Kruskal-Wallis tests were used. P values of less than 0.01 were considered significant. All pulse sequences were successfully executed and reconstructed inline. Whole-body specific absorption rates ranged between 1.4 and 3.9 W/kg for all acquisitions and remained within mandated limits

  15. NOTE: Hybrid echo and x-ray image guidance for cardiac catheterization procedures by using a robotic arm: a feasibility study

    Science.gov (United States)

    Ma, YingLiang; Penney, Graeme P.; Bos, Dennis; Frissen, Peter; Aldo Rinaldi, C.; Razavi, Reza; Rhode, Kawal S.

    2010-07-01

    We present a feasibility study on hybrid echocardiography (echo) and x-ray image guidance for cardiac catheterization procedures. A self-tracked, remotely operated robotic arm with haptic feedback was developed that attached to a standard x-ray table. This was used to safely manipulate a three-dimensional (3D) trans-thoracic echo probe during simultaneous x-ray fluoroscopy and echo acquisitions. By a combination of calibration and tracking of the echo and x-ray systems, it was possible to register the 3D echo images with the 2D x-ray images. Visualization of the combined data was achieved by either overlaying triangulated surfaces extracted from segmented echo data onto the x-ray images or by overlaying volume rendered 3D echo data. Furthermore, in order to overcome the limited field of view of the echo probe, it was possible to create extended field of view (EFOV) 3D echo images by co-registering multiple tracked echo data to generate larger roadmaps for procedure guidance. The registration method was validated using a cross-wire phantom and showed a 2D target registration error of 3.5 mm. The clinical feasibility of the method was demonstrated during two clinical cases for patients undergoing cardiac pacing studies. The EFOV technique was demonstrated using two healthy volunteers.

  16. Readout-segmented echo-planar imaging improves the diagnostic performance of diffusion-weighted MR breast examinations at 3.0 T.

    Science.gov (United States)

    Bogner, Wolfgang; Pinker-Domenig, Katja; Bickel, Hubert; Chmelik, Marek; Weber, Michael; Helbich, Thomas H; Trattnig, Siegfried; Gruber, Stephan

    2012-04-01

    To qualitatively and quantitatively compare the diagnostic value of diffusion-weighted (DW) magnetic resonance (MR) imaging based on standard single-shot echo-planar imaging and readout-segmented echo-planar imaging in patients with breast cancer at 3.0 T. Institutional review board approval and written informed consent were obtained. Forty-seven patients with 49 histopathologically verified lesions were included in this study. In all patients, DW imaging, with single-shot echo-planar imaging and readout-segmented echo-planar imaging with comparable imaging parameters, was performed with a 3.0-T MR imager. Two independent readers visually assessed image quality and lesion conspicuity, and image properties (ie, signal-to-noise ratio, contrast, geometric distortions) were quantified. Regions of interest were drawn in all lesions (28 malignant, 21 benign) and in the normal breast parenchyma to investigate differences in apparent diffusion coefficient (ADC). Diagnostic accuracy was calculated on the basis of an ADC threshold of 1.25 × 10(-3) mm(2)/sec. Each reader found a higher diagnostic accuracy for readout-segmented (96%) than for single-shot (90%) echo-planar imaging. The area under the curve for readout-segmented echo-planar imaging (0.981) was significantly larger than for single-shot echo-planar imaging (0.867) (P = .026). There was no significant difference in the ADC obtained by using either DW imaging method. Lesion conspicuity and image quality of readout-segmented echo-planar imaging were rated superior to those of single-shot echo-planar imaging (P echo-planar imaging reduced geometric distortions by a factor of three. DW imaging based on readout-segmented echo-planar imaging provided significantly higher image quality and lesion conspicuity than single-shot echo-planar imaging by reducing geometric distortions, image blurring, and artifact level with a clinical high-field-strength MR imager. Thereby, readout-segmented echo-planar imaging reached a

  17. Advanced magnetic resonance imaging techniques for patients with hemifacial spasm.

    Science.gov (United States)

    Port, John D

    2002-01-01

    To review the underlying causes, diagnostic issues, and treatment of hemifacial spasm, with emphasis on advanced MRI techniques. Brief technical note. High-resolution T1- and T2-weighted spin-echo and/or gradient echo imaging of the posterior fossa should be performed with the use of intravenous gadolinium for maximum contrast between CSF, vessel, and nerve. Magnetic resonance angiography is often useful, and new state-of-the-art sequences provide more detail. As MRI techniques improve, diagnosis and treatment of patients with hemifacial spasm will become easier. Ophthalmologists should be aware of these new magnetic resonance techniques.

  18. Three-dimensional T1 and T2* mapping of human lung parenchyma using interleaved saturation recovery with dual echo ultrashort echo time imaging (ITSR-DUTE).

    Science.gov (United States)

    Gai, Neville D; Malayeri, Ashkan A; Bluemke, David A

    2017-04-01

    To develop and assess a new technique for three-dimensional (3D) full lung T1 and T2* mapping using a single free breathing scan during a clinically feasible time. A 3D stack of dual-echo ultrashort echo time (UTE) radial acquisition interleaved with and without a WET (water suppression enhanced through T1 effects) saturation pulse was used to map T1 and T2* simultaneously in a single scan. Correction for modulation due to multiple views per segment was derived. Bloch simulations were performed to study saturation pulse excitation profile on lung tissue. Optimization of the saturation delay time (for T1 mapping) and echo time (for T2* mapping) was performed. Monte Carlo simulation was done to predict accuracy and precision of the sequence with signal-to-noise ratio of in vivo images used in the simulation. A phantom study was carried out using the 3D interleaved saturation recovery with dual echo ultrashort echo time imaging (ITSR-DUTE) sequence and reference standard inversion recovery spin echo sequence (IR-SE) to compare accuracy of the sequence. Nine healthy volunteers were imaged and mean (SD) of T1 and T2* in lung parenchyma at 3T were estimated through manually assisted segmentation. 3D lung coverage with a resolution of 2.5 × 2.5 × 6 mm(3) was performed and nominal scan time was recorded for the scans. Repeatability was assessed in three of the volunteers. Regional differences in T1/T2* values were also assessed. The phantom study showed accuracy of T1 values to be within 2.3% of values obtained from IR-SE. Mean T1 value in lung parenchyma was 1002 ± 82 ms while T2* was 0.85 ± 0.1 ms. Scan time was ∼10 min for volunteer scans. Mean coefficient of variation (CV) across slices was 0.057 and 0.09, respectively. Regional variation along the gravitational direction and between right and left lung were not significant (P = 0.25 and P = 0.06, respectively) for T1. T2* showed significant variation (P = 0.03) along the

  19. Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging

    Science.gov (United States)

    Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

    2015-05-01

    This paper presents an 8 × 24 element, 100 μm-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 μm diameter, 220 μm long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 μm. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.

  20. Anatomical constraints on visualization of the human hippocampus using echo-planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Asano, Shuichiro; Kirino, Takaaki [Department of Neurosurgery, University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, 113-8655, Tokyo (Japan); Mihara, Ban [Department of Neurology, Mihara Memorial Hospital, 366 Ohta-machi, Isesaki-city, 372-0006, Gunma (Japan); Sugishita, Morihiro [Department of Cognitive Neuroscience, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8654, Tokyo (Japan)

    2004-07-01

    Reliable visualization of the hippocampus on echo-planar imaging (EPI) is essential in analyzing memory function using functional magnetic resonance imaging. However, the hippocampal area is notoriously prone to susceptibility artifacts caused by structures at the skull base, and avoiding such artifacts by appropriately selecting the subjects for a study is of practical importance. To elucidate factors affecting the extent of the artifacts we obtained EPI in a total of 62 hippocampi from 31 healthy volunteers and evaluated various anatomical measurements possibly associated with the quality of the images. The hippocampal head was sufficiently well demonstrated on 40 of 62 images (65%), and there were two parameters that significantly differed between the good (n=40) and poor (n=22) imaging studies: The vertical diameter (DV) of the opening of the internal acoustic meatus (IAM) and the pneumatization rate of the sphenoid sinus (RP-SS). From logistic regression analysis with the stepwise method, in addition to these two factors, the distance between the hippocampal body and IAM (Dhippo-IAM) and the distance between the hippocampal head and the middle cranial fossa at the skull base (Dhippo-base) were extracted. DV-IAM, RP-SS, and Dhippo-base were negatively correlated with the good imaging of the hippocampal head. On the other hand, Dhippo-IAM was positively correlated. These easily measurable parameters will be helpful in selecting subjects and in increasing the efficiency of hippocampal visualization in studies on human memory function. (orig.)

  1. Aspect sensitivity measurements of polar mesosphere summer echoes using coherent radar imaging

    Directory of Open Access Journals (Sweden)

    P. B. Chilson

    Full Text Available The Esrange VHF radar (ESRAD, located in northern Sweden (67.88° N, 21.10° E, has been used to investigate polar mesosphere summer echoes (PMSE. During July and August of 1998, coherent radar imaging (CRI was used to study the dynamic evolution of PMSE with high temporal and spatial resolution. A CRI analysis provides an estimate of the angular brightness distribution within the radar’s probing volume. The brightness distribution is directly related to the radar reflectivity. Consequently, these data are used to investigate the aspect sensitivity of PMSE. In addition to the CRI analysis, the full correlation analysis (FCA is used to derive estimates of the prevailing three-dimensional wind associated with the observed PMSE. It is shown that regions within the PMSE with enhanced aspect sensitivity have a correspondingly high signal-to-noise ratio (SNR. Although this relationship has been investigated in the past, the present study allows for an estimation of the aspect sensitivity independent of the assumed scattering models and avoids the complications of comparing echo strengths from vertical and off-vertical beams over large horizontal separations, as in the Doppler Beam Swinging (DBS method. Regions of enhanced aspect sensitivity were additionally shown to correlate with the wave-perturbation induced downward motions of air parcels embedded in the PMSE.

    Key words. Ionosphere (polar ionosphere Meteorology and Atmospheric Dynamics (middle atmosphere dynamics Radio Science (Interferometry

  2. Aspect sensitivity measurements of polar mesosphere summer echoes using coherent radar imaging

    Directory of Open Access Journals (Sweden)

    P. B. Chilson

    2002-02-01

    Full Text Available The Esrange VHF radar (ESRAD, located in northern Sweden (67.88° N, 21.10° E, has been used to investigate polar mesosphere summer echoes (PMSE. During July and August of 1998, coherent radar imaging (CRI was used to study the dynamic evolution of PMSE with high temporal and spatial resolution. A CRI analysis provides an estimate of the angular brightness distribution within the radar’s probing volume. The brightness distribution is directly related to the radar reflectivity. Consequently, these data are used to investigate the aspect sensitivity of PMSE. In addition to the CRI analysis, the full correlation analysis (FCA is used to derive estimates of the prevailing three-dimensional wind associated with the observed PMSE. It is shown that regions within the PMSE with enhanced aspect sensitivity have a correspondingly high signal-to-noise ratio (SNR. Although this relationship has been investigated in the past, the present study allows for an estimation of the aspect sensitivity independent of the assumed scattering models and avoids the complications of comparing echo strengths from vertical and off-vertical beams over large horizontal separations, as in the Doppler Beam Swinging (DBS method. Regions of enhanced aspect sensitivity were additionally shown to correlate with the wave-perturbation induced downward motions of air parcels embedded in the PMSE.Key words. Ionosphere (polar ionosphere Meteorology and Atmospheric Dynamics (middle atmosphere dynamics Radio Science (Interferometry

  3. Imaging of the Achilles tendon in spondyloarthritis: a comparison of ultrasound and conventional, short and ultrashort echo time MRI with and without intravenous contrast

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, R.J.; Emery, P. [University of Leeds, Chapel Allerton Hospital, Leeds Musculoskeletal Biomedical Research Centre, Leeds (United Kingdom); Grainger, A.J.; O' Connor, P.J.; Evans, R. [Chapel Allerton Hospital, Leeds Musculoskeletal Biomedical Research Centre, Leeds (United Kingdom); Coates, L.; Marzo-Ortega, H.; Helliwell, P.; McGonagle, D. [University of Leeds, Leeds Institute for Molecular Medicine, Leeds (United Kingdom); Robson, M.D. [University of Oxford, Oxford Centre for Clinical Magnetic Resonance Research, Oxford (United Kingdom)

    2011-06-15

    To compare conventional MRI, ultrashort echo time MRI and ultrasound for assessing the extent of tendon abnormalities in spondyloarthritis. 25 patients with spondyloarthritis and Achilles symptoms were studied with MRI and ultrasound. MR images of the Achilles tendon were acquired using T1-weighted spin echo, gradient echo and ultrashort echo time (UTE) sequences with echo times (TE) between 0.07 and 16 ms, before and after intravenous contrast medium. Greyscale and power Doppler ultrasound were also performed. The craniocaudal extent of imaging abnormalities measured by a consultant musculoskeletal radiologist was compared between the different techniques. Abnormalities were most extensive on spoiled gradient echo images with TE=2 ms. Contrast enhancement after intravenous gadolinium was greatest on the UTE images (TE=0.07 ms). Fewer abnormalities were demonstrated using unenhanced UTE. Abnormalities were more extensive on MRI than ultrasound. Contrast enhancement was more extensive than power Doppler signal. 3D spoiled gradient echo images with an echo time of 2 ms demonstrate more extensive tendon abnormalities than the other techniques in spondyloarthritis. Abnormalities of vascularity are best demonstrated on enhanced ultrashort echo time images. (orig.)

  4. Hepatocellular carcinoma: detection with gadolinium- and ferumoxides-enhanced MR imaging of the liver.

    Science.gov (United States)

    Pauleit, Dirk; Textor, Jochen; Bachmann, Reinald; Conrad, Rudi; Flacke, Sebastian; Layer, Günter; Kreft, Burkhard; Schild, Hans

    2002-01-01

    To test the hypothesis that the accuracy of gadolinium- and ferumoxides-enhanced magnetic resonance (MR) imaging is different in small (1.5-cm) hepatocellular carcinomas (HCCs). Forty-three consecutive patients with chronic liver disease were enrolled in this study. The imaging protocol included unenhanced breath-hold T1-weighted fast field-echo sequences, unenhanced respiratory-triggered T2-weighted turbo spin-echo (SE) sequences, dynamic gadolinium-enhanced T1-weighted three-dimensional turbo field-echo sequences, and ferumoxides-enhanced T2-weighted turbo SE sequences. Images of each sequence and two sets of sequences (ferumoxides set and gadolinium set) were reviewed by four observers. The ferumoxides set included unenhanced T1- and T2-weighted images and ferumoxides-enhanced T2-weighted turbo SE MR images. The gadolinium set included unenhanced T1- and T2-weighted images and dynamic gadolinium-enhanced three-dimensional turbo field-echo MR images. In receiver operating characteristic (ROC) curve analysis, the sensitivity and accuracy of the sequences were compared in regard to the detection of all, small, and large HCCs. Imaging performance was different with gadolinium- and ferumoxides-enhanced images in the detection of small and large HCCs. For detection of small HCCs, the sensitivity and accuracy with unenhanced and gadolinium-enhanced imaging (gadolinium set) were significantly (P =.017) superior to those with unenhanced and ferumoxides-enhanced imaging (ferumoxides set). The area under the composite ROC curves, or A(z), for the gadolinium set and the ferumoxides set was 0.97 and 0.81, respectively. For large HCC, the ferumoxides set was superior compared with the gadolinium set, but this difference was not statistically significant. Analysis of all HCCs demonstrated no significant differences for gadolinium- and ferumoxides-enhanced imaging. For the detection of early HCC, gadolinium-enhanced MR imaging is preferred to ferumoxides-enhanced MR imaging

  5. 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.

  6. Functional imaging of parotid glands: Diffusion-weighted echo-planar MRI before and after stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Habermann, C.R.; Cramer, M.C.; Gossrau, P.; Adam, G. [University Hospital Hamburg-Eppendorf (Germany). Department of Diagnostic and Interventional Radiology; Graessner, J. [Siemens AG, Hamburg (Germany). Medical Solutions; Reitmeier, F.; Jaehne, M. [University Hospital Hamburg-Eppendorf (Germany). Department of Oto-, Rhino-, Laryngology; Fiehler, J. [University Hospital Hamburg-Eppendorf (Germany). Department of Neuroradiology; Schoder, V. [University Hospital Hamburg-Eppendorf (Germany). Institute for Medical Biometry and Epidemiology

    2004-10-01

    Purpose: To investigate the feasibility of diffusion-weighted (DW) echo-planar imaging (EPI) for measuring different functional conditions of the parotid gland and to compare different measurement approaches. Materials and Methods: Parotid glands of 27 healthy volunteers were examined with a DW EPI sequence (TR 1,500 msec, TE 77 msec, field-of-view 250 x 250 mm, pixel size 2.10 x 1.95 mm, section thickness 5 mm) before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1,000 sec/mm{sup 2}. Apparent diffusion coefficient (ADC) maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed circular region of interest (ROI) containing 100-200 pixel. Additional ROIs including the entire parotid gland were placed on either side. The results of both measurements were compared, using the Student's t test based on the median ADC values for each person. A two-tailed p-value of less than.05 was determined to indicate statistical significance. To compare both measurement approaches, the Pearson's correlation coefficient (r) was calculated. Results: Diffusion-weighted echo-planar MR imaging successfully visualized the parotid gland of all volunteers. In a first step, the median ADC value per person was computed. Using ROIs of 100-200 pixels, the mean was calculated to be 1.08 x 10{sup -3} mm{sup 2}/sec{+-}0.12 x 10{sup -3} mm{sup 2}/sec for both parotid glands prior to simulation. After stimulation, the mean ADC was measured at 1.15 x 10{sup -3} mm{sup 2}/sec{+-}0.11 x 10{sup -3} mm{sup 2}/sec for both parotid glands. Evaluating the entire parotid gland, the ADC was 1.12 x 10{sup -3} mm{sup 2}/sec{+-}0.08 x 10{sup -3} mm{sup 2}/sec prior to simulation, whereas the ADC increased to 1.18 x 10{sup -3} mm{sup 2}/sec{+-}0.09 x 10{sup -3} mm{sup 2}/sec after simulation with lemon juice. For both types of measurements, the increase in ADC after

  7. Comparing consistency of R2* and T2*-weighted BOLD analysis of resting state fetal fMRI

    Science.gov (United States)

    Seshamani, Sharmishtaa; Blazejewska, Anna I.; Gatenby, Christopher; Mckown, Susan; Caucutt, Jason; Dighe, Manjiri; Studholme, Colin

    2015-03-01

    Understanding when and how resting state brain functional activity begins in the human brain is an increasing area of interest in both basic neuroscience and in the clinical evaluation of the brain during pregnancy and after premature birth. Although fMRI studies have been carried out on pregnant women since the 1990's, reliable mapping of brain function in utero is an extremely challenging problem due to the unconstrained fetal head motion. Recent studies have employed scrubbing to exclude parts of the time series and whole subjects from studies in order to control the confounds of motion. Fundamentally, even after correction of the location of signals due to motion, signal intensity variations are a fundamental limitation, due to coil sensitivity and spin history effects. An alternative technique is to use a more parametric MRI signal derived from multiple echoes that provides a level of independence from basic MRI signal variation. Here we examine the use of R2* mapping combined with slice based multi echo geometric distortion correction for in-utero studies. The challenges for R2* mapping arise from the relatively low signal strength of in-utero data. In this paper we focus on comparing activation detection in-utero using T2W and R2* approaches. We make use a subset of studies with relatively limited motion to compare the activation patterns without the additional confound of significant motion. Results at different gestational ages indicate comparable agreement in many activation patterns when limited motion is present, and the detection of some additional networks in the R2* data, not seen in the T2W results.

  8. Ultrasonic Backscatter Imaging by Shear-Wave-Induced Echo Phase Encoding of Target Locations

    Science.gov (United States)

    McAleavey, Stephen

    2011-01-01

    We present a novel method for ultrasound backscatter image formation wherein lateral resolution of the target is obtained by using traveling shear waves to encode the lateral position of targets in the phase of the received echo. We demonstrate that the phase modulation as a function of shear wavenumber can be expressed in terms of a Fourier transform of the lateral component of the target echogenicity. The inverse transform, obtained by measurements of the phase modulation over a range of shear wave spatial frequencies, yields the lateral scatterer distribution. Range data are recovered from time of flight as in conventional ultrasound, yielding a B-mode-like image. In contrast to conventional ultrasound imaging, where mechanical or electronic focusing is used and lateral resolution is determined by aperture size and wavelength, we demonstrate that lateral resolution using the proposed method is independent of the properties of the aperture. Lateral resolution of the target is achieved using a stationary, unfocused, single-element transducer. We present simulated images of targets of uniform and non-uniform shear modulus. Compounding for speckle reduction is demonstrated. Finally, we demonstrate image formation with an unfocused transducer in gelatin phantoms of uniform shear modulus. PMID:21244978

  9. Evaluation of slice accelerations using multiband echo planar imaging at 3 T.

    Science.gov (United States)

    Xu, Junqian; Moeller, Steen; Auerbach, Edward J; Strupp, John; Smith, Stephen M; Feinberg, David A; Yacoub, Essa; Uğurbil, Kâmil

    2013-12-01

    We evaluate residual aliasing among simultaneously excited and acquired slices in slice accelerated multiband (MB) echo planar imaging (EPI). No in-plane accelerations were used in order to maximize and evaluate achievable slice acceleration factors at 3 T. We propose a novel leakage (L-) factor to quantify the effects of signal leakage between simultaneously acquired slices. With a standard 32-channel receiver coil at 3 T, we demonstrate that slice acceleration factors of up to eight (MB=8) with blipped controlled aliasing in parallel imaging (CAIPI), in the absence of in-plane accelerations, can be used routinely with acceptable image quality and integrity for whole brain imaging. Spectral analyses of single-shot fMRI time series demonstrate that temporal fluctuations due to both neuronal and physiological sources were distinguishable and comparable up to slice-acceleration factors of nine (MB=9). The increased temporal efficiency could be employed to achieve, within a given acquisition period, higher spatial resolution, increased fMRI statistical power, multiple TEs, faster sampling of temporal events in a resting state fMRI time series, increased sampling of q-space in diffusion imaging, or more quiet time during a scan. © 2013 Elsevier Inc. All rights reserved.

  10. A simplified spin and gradient echo approach for brain tumor perfusion imaging.

    Science.gov (United States)

    Stokes, Ashley M; Quarles, C Chad

    2016-01-01

    In this study, we propose a simplified acquisition and analysis approach for spin and gradient echo (SAGE)-based dynamic susceptibility-contrast MRI (DSC-MRI) data that is free of contrast agent T1 leakage effects. A five-echo SAGE sequence was used to acquire DSC-MRI data in rat C6 tumors (n = 7). Nonlinear fitting of all echoes was performed to obtain T1-insensitive ΔR2* and ΔR2 time series. The simplified approach, which includes two gradient echoes and one spin echo, was also used to analytically compute T1-insensitive ΔR2* using the two gradient echoes and ΔR2 using all three echoes. The blood flow, blood volume, and vessel size values derived from each method were compared. In all cases, the five-echo and simplified SAGE ΔR2* and ΔR2 were in excellent agreement and demonstrated significant T1 leakage correction compared with the uncorrected single-echo data. The derived hemodynamic parameters for blood volume, blood flow, and vessel size were not significantly different between the two methods. The proposed simplified SAGE technique enables the acquisition of gradient and spin echo DSC-MRI data corrected for T1 leakage effects yields parameters that are in agreement with the five-echo SAGE approach and does not require nonlinear fitting to extract ΔR2* and ΔR2 time series. © 2015 Wiley Periodicals, Inc.

  11. A Simplified Spin and Gradient Echo (SAGE) Approach for Brain Tumor Perfusion Imaging

    Science.gov (United States)

    Stokes, Ashley M.; Quarles, C. Chad

    2014-01-01

    Purpose A simplified acquisition and analysis approach for spin- and gradient-echo (SAGE) based DSC-MRI data that is free of contrast agent T1 leakage effects is proposed. Methods A five-echo SAGE sequence was used to acquire DSC-MRI data in rat C6 tumors (n=7). Non-linear fitting of all echoes was performed to obtain T1-insensitive ΔR2* and ΔR2 time series. The simplified approach, which includes two gradient echoes and one spin echo, was also used to analytically compute T1-insensitive ΔR2*, using the two gradient echoes, and ΔR2, using all three echoes. The blood flow, blood volume and vessel size values derived from each method were compared. Results In all cases, the five-echo and simplified SAGE ΔR2* and ΔR2 were in excellent agreement and demonstrated significant T1-leakage correction compared to the uncorrected single-echo data. The derived hemodynamic parameters for blood volume, blood flow and vessel size were not significantly different between the two methods. Conclusions The proposed simplified SAGE technique enables the acquisition of gradient and spin echo DSC-MRI data corrected for T1 leakage effects, yields parameters that are in agreement with the five echo SAGE, and does not require non-linear fitting to extract ΔR2* and ΔR2 time series. PMID:25753958

  12. Magnetic resonance imaging assisted with fine needle aspiration biopsy in the diagnosis of fibrosarcomas of the skull in dogs.

    Science.gov (United States)

    Zhalniarovich, Y; Adamiak, Z; Przyborowska, P; Otrocka-Domagała, D

    2013-01-01

    Five canine patients were directed to low-field magnetic resonance imaging due to different neurological defects. In each case there were heterogeneous extraaxial masses covering left or right dorsal parietal and occipital lobes that were isointense to the brain on T1-weighted Spin Echo images, isointense to hypointense to the brain on T2-weighted Fast Spin Echo sequences and hypointense to the brain on Flair sequence. After MRI study fine needle aspiration biopsy of the tumors was performed. On the basis of the cytological examination fibrosarcomas with of moderate malignancy were diagnosed.

  13. Phase incremented echo train acquisition applied to magnetic resonance pore imaging

    Science.gov (United States)

    Hertel, S. A.; Galvosas, P.

    2017-02-01

    Efficient phase cycling schemes remain a challenge for NMR techniques if the pulse sequences involve a large number of rf-pulses. Especially complex is the Carr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses can range from hundreds to several thousands. Our recent implementation of Magnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in order to refocus the effect of internal gradients inherent in porous media. While the spin dynamics for spin- 1 / 2 systems in CPMG like experiments are well understood it is still not straight forward to separate the desired pathway from the spectrum of unwanted coherence pathways. In this contribution we apply Phase Incremented Echo Train Acquisition (PIETA) to MRPI. We show how PIETA offers a convenient way to implement a working phase cycling scheme and how it allows one to gain deeper insights into the amplitudes of undesired pathways.

  14. Strategically acquired gradient Echo (STAGE) imaging, part I: Creating enhanced T1 contrast and standardized susceptibility weighted imaging and quantitative susceptibility mapping.

    Science.gov (United States)

    Chen, Yongsheng; Liu, Saifeng; Wang, Yu; Kang, Yan; Mark Haacke, E

    2017-10-19

    To provide whole brain grey matter (GM) to white matter (WM) contrast enhanced T1W (T1WE) images, multi-echo quantitative susceptibility mapping (QSM), proton density (PD) weighted images, T1 maps, PD maps, susceptibility weighted imaging (SWI), and R2* maps with minimal misregistration in scanning times 3T) were used for both T1 mapping with radio frequency (RF) transmit field correction and creating enhanced GM/WM contrast (the T1WE). The proposed T1WE image was created from a combination of the proton density weighted (6°, PDW) and T1W (24°) images and corrected for RF transmit field variations. Prior to the QSM calculation, a multi-echo phase unwrapping strategy was implemented using the unwrapped short echo to unwrap the longer echo to speed up computation. R2* maps were used to mask deep grey matter and veins during the iterative QSM calculation. A weighted-average sum of susceptibility maps was generated to increase the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR). The proposed T1WE image has a significantly improved CNR both for WM to deep GM and WM to cortical GM compared to the acquired T1W image (the first echo of 24° scan) and the T1MPRAGE image. The weighted-average susceptibility maps have 80±26%, 55±22%, 108±33% SNR increases for the ten datasets compared to the single echo result of 17.5ms, and 80±36%, 59±29% and 108±37% CNR increases for the putamen, caudate nucleus, and globus pallidus, respectively. STAGE imaging offers the potential to create a standardized brain imaging protocol providing four pieces of quantitative tissue property information and multiple types of qualitative information in just 5min. Copyright © 2017. Published by Elsevier Inc.

  15. Tissue electrical property mapping from zero echo-time magnetic resonance imaging.

    Science.gov (United States)

    Lee, Seung-Kyun; Bulumulla, Selaka; Wiesinger, Florian; Sacolick, Laura; Sun, Wei; Hancu, Ileana

    2015-02-01

    The capability of magnetic resonance imaging (MRI) to produce spatially resolved estimation of tissue electrical properties (EPs) in vivo has been a subject of much recent interest. In this work we introduce a method to map tissue EPs from low-flip-angle, zero-echo-time (ZTE) imaging. It is based on a new theoretical formalism that allows calculation of EPs from the product of transmit and receive radio-frequency (RF) field maps. Compared to conventional methods requiring separation of the transmit RF field (B(1)(+)) from acquired MR images, the proposed method has such advantages as: 1) reduced theoretical error, 2) higher acquisition speed, and 3) flexibility in choice of different transmit and receive RF coils. The method is demonstrated in electrical conductivity and relative permittivity mapping in a salt water phantom, as well as in vivo measurement of brain conductivity in healthy volunteers. The phantom results show the validity and scan-time efficiency of the proposed method applied to a piece-wise homogeneous object. Quality of in vivo EP results was limited by reconstruction errors near tissue boundaries, which highlights need for image segmentation in EP mapping in a heterogeneous medium. Our results show the feasibility of rapid EP mapping from MRI without B(1)(+) mapping.

  16. Carr-Purcell-Meiboom-Gill imaging of prostate cancer: quantitative T2 values for cancer discrimination.

    Science.gov (United States)

    Roebuck, Joseph R; Haker, Steven J; Mitsouras, Dimitris; Rybicki, Frank J; Tempany, Clare M; Mulkern, Robert V

    2009-05-01

    Quantitative, apparent T(2) values of suspected prostate cancer and healthy peripheral zone tissue in men with prostate cancer were measured using a Carr-Purcell-Meiboom-Gill (CPMG) imaging sequence in order to assess the cancer discrimination potential of tissue T(2) values. The CPMG imaging sequence was used to image the prostates of 18 men with biopsy-proven prostate cancer. Whole gland coverage with nominal voxel volumes of 0.54 x 1.1 x 4 mm(3) was obtained in 10.7 min, resulting in data sets suitable for generating high-quality images with variable T(2)-weighting and for evaluating quantitative T(2) values on a pixel-by-pixel basis. Region-of-interest analysis of suspected healthy peripheral zone tissue and suspected cancer, identified on the basis of both T(1)- and T(2)-weighted signal intensities and available histopathology reports, yielded significantly (P<.0001) longer apparent T(2) values in suspected healthy tissue (193+/-49 ms) vs. suspected cancer (100+/-26 ms), suggesting potential utility of this method as a tissue specific discrimination index for prostate cancer. We conclude that CPMG imaging of the prostate can be performed in reasonable scan times and can provide advantages over T(2)-weighted fast spin echo (FSE) imaging alone, including quantitative T(2) values for cancer discrimination as well as proton density maps without the point spread function degradation associated with short effective echo time FSE sequences.

  17. Cartilaginous End Plates: Quantitative MR Imaging with Very Short Echo Times—Orientation Dependence and Correlation with Biochemical Composition

    OpenAIRE

    Fields, Aaron J.; Han, Misung; Krug, Roland; Lotz, Jeffrey C

    2014-01-01

    T2* evaluation of the cartilaginous end plate by using MR imaging with very short echo times can allow quantitative estimation of biochemical composition; however, the accuracy of the estimates depends on the orientation of the end plate in relation to the magnetic field.

  18. Carcinoma of the cervix: dynamic MR imaging.

    Science.gov (United States)

    Yamashita, Y; Takahashi, M; Sawada, T; Miyazaki, K; Okamura, H

    1992-03-01

    Dynamic magnetic resonance (MR) imaging was performed to evaluate eight normal uteri and 29 cervical carcinomas. After rapid injection of gadopentetate dimeglumine, dynamic images were obtained every 30 seconds with the spin-echo (SE) technique in the sagittal plane or the fast low-angle shot (FLASH) technique in the axial plane. In the normal uterus, initial slight enhancement of the junction between endometrium and myometrium was followed by enhancement of the uterine myometrium. Cervical carcinoma was readily distinguished from the cervical stroma and myometrium in the early dynamic phase (30-60 seconds). Tumor-cervix contrast in the early dynamic phase was significantly more marked with the dynamic SE technique than with T2-weighted or contrast material-enhanced T1-weighted imaging (P less than .01). For the evaluation of parametrial invasion, the dynamic FLASH study showed better contrast than did T2-weighted images. Among 18 patients who underwent surgery, accurate assessment of the degree of stromal invasion and tumor size was possible with dynamic MR images in 14 patients (78%), T2-weighted images in 11 (61%), and postcontrast T1-weighted images in seven (39%).

  19. Incidental ferumoxytol artifacts in clinical brain MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bowser, Bruce A.; Campeau, Norbert G.; Carr, Carrie M.; Diehn, Felix E.; McDonald, Jennifer S.; Miller, Gary M.; Kaufmann, Timothy J. [Mayo Clinic, Department of Radiology, Rochester, MN (United States)

    2016-11-15

    Ferumoxytol (Feraheme) is a parenteral therapy approved for treatment of iron deficiency anemia. The product insert for ferumoxytol states that it may affect the diagnostic ability of MRI for up to 3 months. However, the expected effects may not be commonly recognized among clinical neuroradiologists. Our purpose is to describe the artifacts we have seen at our institution during routine clinical practice. We reviewed the patients at our institution that had brain MRI performed within 90 days of receiving intravenous ferumoxytol. The imaging was reviewed for specific findings, including diffusion-weighted imaging vascular susceptibility artifact, gradient-echo echo-planar T2*-weighted vascular susceptibility artifact, SWI/SWAN vascular susceptibility artifact, hypointense vascular signal on T2-weighted images, pre-gadolinium contrast vascular enhancement on magnetization-prepared rapid acquisition gradient echo (MPRAGE) imaging, and effects on post-gadolinium contrast T1 imaging. Multiple artifacts were observed in patients having a brain MRI within 3 days of receiving intravenous ferumoxytol. These included susceptibility artifact on DWI, GRE, and SWAN/SWI imaging, pre-gadolinium contrast increased vascular signal on MPRAGE imaging, and decreased expected enhancement on post-gadolinium contrast T1-weighted imaging. Ferumoxytol can create imaging artifacts which complicate clinical interpretation when brain MRI is performed within 3 days of administration. Recognition of the constellation of artifacts produced by ferumoxytol is important in order to obviate additional unnecessary examinations and mitigate errors in interpretation. (orig.)

  20. A Study of Pulse-Echo Image Formation Using Non-Quadratic Regularization with Speckle-Based Images

    Science.gov (United States)

    Lavarello, R.; Kamalabadi, F.; O'Brien, W. D.

    Objective: B-mode imaging is a standard way of presenting results when pulse-echo data acquisition is used. Inverse approaches have been explored to a limited extent. The goals of this study are to explore the feasibility and effectiveness of regularization by: (a) evaluating the quality of the reconstruction of speckle-based images as a function of imaging parameters (i.e., bandwidth of the transducer, f/number, and distance between region of interest (ROI) and focal region), and (b) comparing the reconstructed images with those obtained by conventional imaging techniques (e.g., B-mode and synthetic aperture focusing techniques (SAFT)). Methodology: Two-dimensional pulse-echo data from a single-element focused transducer with center frequency of 6 MHz and focal distance of 19 mm were simulated using fractional bandwidths of 33%, 50% and 100%, f/numbers of 1, 2 and 3, and distances between ROI and focus of 0, 2.5 and 5 mm. A minimum scatterer density of 4 scatterers per resolution cell was used. The images were reconstructed using non-quadratic regularization. Because the desired image was known, the normalized mean squared error (MSE) was used as a quantitative indicator of reconstruction performance. The reconstructed images were also evaluated by visual inspection. Results: The best reconstructions were achieved when the ROI was at the focus, the bandwidth was 100% and the f/number was 1, for which the MSE was 25% for a 20-dB signal-to-noise ratio (SNR). The MSE increased as the bandwidth decreased, the f/number increased, and the distance between ROI and focus increased. The bandwidth was the most sensitive parameter, increasing the MSE up to 86% for a SNR of 20 dB. For all cases, parameter selection techniques such as the L-curve and generalized cross-validation (GCV) gave a close approximation to the image with the best visual appearance. Conclusion: For speckle-based images the inversion using regularization gave better results than conventional techniques

  1. Susceptibility-weighted imaging using inter-echo-variance channel combination for improved contrast at 7 tesla.

    Science.gov (United States)

    Hosseini, Zahra; Liu, Junmin; Solovey, Igor; Menon, Ravi S; Drangova, Maria

    2017-04-01

    To implement and optimize a new approach for susceptibility-weighted image (SWI) generation from multi-echo multi-channel image data and compare its performance against optimized traditional SWI pipelines. Five healthy volunteers were imaged at 7 Tesla. The inter-echo-variance (IEV) channel combination, which uses the variance of the local frequency shift at multiple echo times as a weighting factor during channel combination, was used to calculate multi-echo local phase shift maps. Linear phase masks were combined with the magnitude to generate IEV-SWI. The performance of the IEV-SWI pipeline was compared with that of two accepted SWI pipelines-channel combination followed by (i) Homodyne filtering (HPH-SWI) and (ii) unwrapping and high-pass filtering (SVD-SWI). The filtering steps of each pipeline were optimized. Contrast-to-noise ratio was used as the comparison metric. Qualitative assessment of artifact and vessel conspicuity was performed and processing time of pipelines was evaluated. The optimized IEV-SWI pipeline (σ = 7 mm) resulted in continuous vessel visibility throughout the brain. IEV-SWI had significantly higher contrast compared with HPH-SWI and SVD-SWI (P IEV-SWI pipeline processed a six-echo 16-channel dataset in under 10 min. IEV-SWI benefits from channel-by-channel processing of phase data and results in high contrast images with an optimal balance between contrast and background noise removal, thereby presenting evidence of importance of the order in which postprocessing techniques are applied for multi-channel SWI generation. 2 J. Magn. Reson. Imaging 2017;45:1113-1124. © 2016 International Society for Magnetic Resonance in Medicine.

  2. 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.

  3. Three-dimensional echo-planar cine imaging of cerebral blood supply using arterial spin labeling.

    Science.gov (United States)

    Shrestha, Manoj; Mildner, Toralf; Schlumm, Torsten; Robertson, Scott Haile; Möller, Harald

    2016-12-01

    Echo-planar imaging (EPI) with CYlindrical Center-out spatiaL Encoding (EPICYCLE) is introduced as a novel hybrid three-dimensional (3D) EPI technique. Its suitability for the tracking of a short bolus created by pseudo-continuous arterial spin labeling (pCASL) through the cerebral vasculature is demonstrated. EPICYCLE acquires two-dimensional planes of k-space along center-out trajectories. These "spokes" are rotated from shot to shot about a common axis to encode a k-space cylinder. To track a bolus of labeled blood, the same subset of evenly distributed spokes is acquired in a cine fashion after a short period of pCASL. This process is repeated for all subsets to fill the whole 3D k-space of each time frame. The passage of short pCASL boluses through the vasculature of a 3D imaging slab was successfully imaged using EPICYCLE. By choosing suitable sequence parameters, the impact of slab excitation on the bolus shape could be minimized. Parametric maps of signal amplitude, transit time, and bolus width reflected typical features of blood transport in large vessels. The EPICYCLE technique was successfully applied to track a short bolus of labeled arterial blood during its passage through the cerebral vasculature.

  4. Ultrahigh field single-refocused diffusion weighted imaging using a matched-phase adiabatic spin echo (MASE).

    Science.gov (United States)

    Dyvorne, Hadrien; O'Halloran, Rafael; Balchandani, Priti

    2016-05-01

    To improve ultrahigh field diffusion-weighted imaging (DWI) in the presence of inhomogeneous transmit B1 field by designing a novel semi-adiabatic single-refocused DWI technique. A 180° slice-selective, adiabatic radiofrequency (RF) pulse of 4 ms duration was designed using the adiabatic Shinnar-Le Roux algorithm. A matched-phase slice-selective 90° RF pulse of 8 ms duration was designed to compensate the nonlinear phase of the adiabatic 180° RF pulse. The resulting RF pulse combination, matched-phase adiabatic spin echo (MASE), was integrated into a single-shot echo planar DWI sequence. The performance of this sequence was compared with single-refocused Stejskal-Tanner (ST), twice-refocused spin echo (TRSE) and twice-refocused adiabatic spin echo (TRASE) in simulations, phantoms, and healthy volunteers at 7 Tesla (T). In regions with inhomogeneous B1 , MASE resulted in increased signal intensity compared with ST (up to 64%). Moderate increase in specific absorption rate (35-39%) was observed for adiabatic RF pulses. MASE resulted in higher signal homogeneity at 7T, leading to improved visualization of measures derived from diffusion-weighted images such as white matter tractography and track density images. Efficient adiabatic SLR pulses can be adapted to single-refocused DWI, leading to substantially improved signal uniformity when compared with conventional acquisitions. © 2015 Wiley Periodicals, Inc.

  5. 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...

  6. Model-Based Iterative Reconstruction for Radial Fast Spin-Echo MRI

    CERN Document Server

    Block, Kai Tobias; Frahm, Jens

    2016-01-01

    In radial fast spin-echo MRI, a set of overlapping spokes with an inconsistent T2 weighting is acquired, which results in an averaged image contrast when employing conventional image reconstruction techniques. This work demonstrates that the problem may be overcome with the use of a dedicated reconstruction method that further allows for T2 quantification by extracting the embedded relaxation information. Thus, the proposed reconstruction method directly yields a spin-density and relaxivity map from only a single radial data set. The method is based on an inverse formulation of the problem and involves a modeling of the received MRI signal. Because the solution is found by numerical optimization, the approach exploits all data acquired. Further, it handles multi-coil data and optionally allows for the incorporation of additional prior knowledge. Simulations and experimental results for a phantom and human brain in vivo demonstrate that the method yields spin-density and relaxivity maps that are neither affect...

  7. Low-echo sphere phantoms and methods for assessing imaging performance of medical ultrasound scanners.

    Science.gov (United States)

    Madsen, Ernest L; Song, Chihwa; Frank, Gary R

    2014-07-01

    Tissue-mimicking phantoms and software for quantifying the ability of human observers to detect small low-echo spheres as a function of depth have been developed. Detectability is related to the imager's ability to delineate the boundary of a 3-D object such as a spiculated tumor. The phantoms accommodate a broad range of transducer shapes and sizes. Three phantoms are described: one with 2-mm-diameter spheres (for higher frequencies), one with 3.2-mm-diameter spheres (for lower frequencies) and one with 4-mm-diameter spheres (for lower frequencies). The spheres are randomly distributed in each phantom. The attenuation coefficients of spheres and surroundings are nearly identical; thus, compromising shadowing or enhancement distal to spheres does not occur. Reproducibility results are given for pairs of independent data sets involving eight different combinations of scanner, transducer and console settings. The following comparison results are also reported: (i) only the selected frequency differs; (ii) transducers and scan parameters are nearly the same but manufacturers differ; (iii) ordinary B-scanning, spatial compounding and tissue harmonic imaging are addressed. The phantoms and software promise to be valuable tools for scanning system and setup comparisons and for acceptance testing. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  8. Conception and test of Echoes, a spectro-imager dedicated to the seismology of Jupiter

    Science.gov (United States)

    Soulat, L.; Schmider, F.-X.; Robbe-Dubois, S.; Appourchaux, T.; Gaulme, P.; Bresson, Y.; Gay, J.; Daban, J.-B.; Gouvret, C.

    2017-11-01

    Echoes is a project of a spaceborne Doppler Spectro-Imager (DSI) which has been proposed as payload to the JUICE mission project selected in the Cosmic Vision program of the European Space Agency (ESA). It is a Fourier transform spectrometer which measures phase shifts in the interference patterns induced by Doppler shifts of spectral lines reflected at the surface of the planet. Dedicated to the seismology of Jupiter, the instrument is designed to analyze the periodic movements induced by internal acoustic modes of the planet. It will allow the knowledge of the internal structure of Jupiter, in particular of the central region, which is essential for the comprehension of the scenario of the giant planets' formation. The optical design is based on a modified Mach-Zehnder interferometer operating in the visible domain and takes carefully into account the sensitivity of the optical path difference to the temperature. The instrument produces simultaneously four images in quadrature which allows the measurement of the phase without being contaminated by the continuum component of the incident light. We expect a noise level less than 1 cm2s-2µHz-1 in the frequency range [0.5 -10] mHz. In this paper, we present the prototype implemented at the Observatoire de la Côte d'Azur (OCA) in collaboration with Institut d'Astrophysique Spatiale (IAS) to study the real performances in laboratory and to demonstrate the capability to reach the required Technology Readiness Level 5.

  9. Pulmonary Embolism Detection with Three-dimensional Ultrashort Echo Time MR Imaging: Experimental Study in Canines

    Science.gov (United States)

    Bannas, Peter; Bell, Laura C.; Johnson, Kevin M.; Schiebler, Mark L.; François, Christopher J.; Motosugi, Utaroh; Consigny, Daniel; Reeder, Scott B.

    2016-01-01

    Purpose To demonstrate the feasibility of free-breathing three-dimensional (3D) radial ultrashort echo time (UTE) magnetic resonance (MR) imaging in the simultaneous detection of pulmonary embolism (PE) and high-quality evaluation of lung parenchyma. Materials and Methods The institutional animal care committee approved this study. A total of 12 beagles underwent MR imaging and computed tomography (CT) before and after induction of PE with autologous clots. Breath-hold 3D MR angiography and free-breathing 3D radial UTE (1.0-mm isotropic spatial resolution; echo time, 0.08 msec) were performed at 3 T. Two blinded radiologists independently marked and graded all PEs on a four-point scale (1 = low confidence, 4 = absolutely certain) on MR angiographic and UTE images. Image quality of pulmonary arteries and lung parenchyma was scored on a four-point-scale (1 = poor, 4 = excellent). Locations and ratings of emboli were compared with reference standard CT images by using an alternative free-response receiver operating characteristic curve (AFROC) method. Areas under the curve and image quality ratings were compared by using the F test and the Wilcoxon signed-rank test. Results A total of 48 emboli were detected with CT. Both readers showed higher sensitivity for PE detection with UTE (83% and 79%) than with MR angiography (75% and 71%). The AFROC area under the curve was higher for UTE than for MR angiography (0.95 vs 0.89), with a significant difference in area under the curve of 0.06 (95% confidence interval: 0.01, 0.11; P = .018). UTE image quality exceeded that of MR angiography for subsegmental arteries (3.5 ± 0.7 vs 2.9 ± 0.5, P = .002) and lung parenchyma (3.8 ± 0.5 vs 2.2 ± 0.2, P < .001). The apparent signal-to-noise ratio in pulmonary arteries and lung parenchyma was significantly higher for UTE than for MR angiography (41.0 ± 5.2 vs 24.5 ± 6.2 [P < .001] and 10.2 ± 1.8 vs 3.5 ± 0.8 [P < .001], respectively). The apparent contrast-to-noise ratio between

  10. Magnetic resonance imaging study in a normal Bengal tiger (Panthera tigris) stifle joint.

    Science.gov (United States)

    Arencibia, Alberto; Encinoso, Mario; Jáber, José R; Morales, Daniel; Blanco, Diego; Artiles, Alejandro; Vázquez, José M

    2015-08-11

    The purpose of this study was to describe the normal appearance of the bony and soft tissue structures of the stifle joint of a Bengal tiger (Panthera tigris) by low-field magnetic resonance imaging (MRI), and the use of gross anatomical dissections performed as anatomical reference. A cadaver of a mature female was imaged by MRI using specific sequences as the Spin-echo (SE) T1-weighting and Gradient-echo (GE) STIR T2-weighting sequences in sagittal, dorsal and transverse planes, with a magnet of 0.2 Tesla. The bony and articular structures were identified and labelled on anatomical dissections, as well as on the magnetic resonance (MR) images. MR images showed the bone, articular cartilage, menisci and ligaments of the normal tiger stifle. SE T1-weighted sequence provided excellent resolution of the subchondral bones of the femur, tibia and patella compared with the GE STIR T2-weighted MR images. Articular cartilage and synovial fluid were visualised with high signal intensity in GE STIR T2-weighted sequence, compared with SE T1-weighted sequence where they appeared with intermediate intensity signal. Menisci and ligaments of the stifle joint were visible with low signal intensity in both sequences. The infrapatellar fat pad was hyperintense on SE T1-weighted images and showed low signal intensity on GE STIR T2-weighted images. MRI provided adequate information of the bony and soft tissues structures of Bengal tiger stifle joints. This information can be used as initial anatomic reference for interpretation of MR stifle images and to assist in the diagnosis of diseases of this region.

  11. Detection of recurrent and primary acquired cholesteatoma with echo-planar diffusion-weighted magnetic resonance imaging.

    Science.gov (United States)

    Evlice, A; Tarkan, Ö; Kiroğlu, M; Biçakci, K; Özdemir, S; Tuncer, Ü; Çekiç, E

    2012-07-01

    To evaluate the diagnostic value of echo-planar diffusion-weighted magnetic resonance imaging in pre-operative detection of suspected primary acquired, residual and/or recurrent cholesteatoma. Fifty-eight chronic otitis media patients with suspected cholesteatoma were thus evaluated two weeks pre-operatively, and divided into group one (41 patients, no previous surgery, suspected primary acquired cholesteatoma) and group two (17 patients, previous surgery, scheduled 'second-look' or revision surgery for suspected residual or recurrent cholesteatoma). Patients' operative, histopathology and radiological findings were compared. Cholesteatoma was found in 63 per cent of group one patients and 58 per cent of group two patients at surgery. Histopathological examination of surgical specimens indicated that imaging accurately predicted the presence or absence of cholesteatoma in 90 per cent of group one (37/41; 23 true positives, 14 true negatives) and 76 per cent of group two (13/17; seven true positives, six true negatives). Three patients in both groups were false negative diagnoses and one patient in both groups was a false positive. The sensitivity, specificity, and positive and negative predictive values of echo-planar diffusion-weighted magnetic resonance imaging of cholesteatoma were respectively 88, 93, 95 and 82 per cent in group one and 70, 85, 87 and 66 per cent in group two. Echo-planar diffusion-weighted magnetic resonance imaging is a valuable technique with high sensitivity and specificity for cholesteatoma imaging.

  12. MR urography (MRU) of non-dilated ureter with diuretic administration: Static fluid 2D FSE T2-weighted versus 3D gadolinium T1-weighted GE excretory MR.

    Science.gov (United States)

    Roy, C; Ohana, M; Host, Ph; Alemann, G; Labani, A; Wattiez, A; Lang, H

    2014-01-01

    The goal of this prospective study was to compare the efficiency of two types of MRU after diuretic administration to identify the non-dilated ureter. MR pelvic examinations were performed in 126 patients after receiving furosemide. Each patient underwent in addition to their protocol for context, two types of MRU: 2D T2-weighted FSE (T2w-MRU) and 3D Gd T1-weighted GE (CE-MRU). Four segments were checked for each ureter. For the first part of the analysis, readers evaluated the whole image quality using a four points subjective scale and for the second part, they were asked to score separately each ureteral segment as present or absent. 1008 ureteral segments were checked. For the image quality, readers did not find any significant difference (3.8 ± 0.5 vs 3.6 ± 0.7, p value: 0.13) between MRU methods. The interobserver agreement was excellent with a κ correlation coefficient as high as 0.89 for T2w-MRU and 0.92 for CE-MRU, respectively. For the detection of the segments and considering the 9 rotations for the T2W MRU, there were no statistically significant differences between the two groups. T2-weighted MRU with multiple orientations and diuretic is sufficient to identify the non-dilated ureter. It offers information on ureteral peristaltism. It can be suggested that this sequence is able to detect an initial obstruction before hydronephrosis occurs.

  13. First results in rapid MR imaging of focal liver and spleen lesions using field echos and small angle excitation (gradient echo sequences)

    Energy Technology Data Exchange (ETDEWEB)

    Griebel, J.; Hess, C.F.; Kurtz, B.; Klose, U.; Kueper, K.

    1987-01-01

    15 healthy subjects and 39 patients with focal liver and spleen lesions were examined via MR tomography at 1.5 tesla. Gradient field echos at small angle excitation (< 90/sup 0/) were employed. The imaging time per layer was 10 seconds so that rapid imaging could be carried out at respiratory standstill. This enabled visualisation of liver and spleen without interference by breathing artifacts and with accurate localisation. Focal lesions can be imaged best at low flip-angle pulses (liver) or low to medium-angle pulses (spleen). The primary liver cell carcinoma is visualised as an inhomogeneous structure with similar signal intensity as the surrounding tissue. All other examined liver lesions (metastases, haemangiomas, lymphatic infiltrates, echinococcus cysts, FNH, gummae) showed greater signal intensity than the remaining organ at small angle excitation. Furthermore, contrast reversals were seen at medium-angle pulses. Contrariwise, with the exception of the light-coloured spleen infarcts, spleen lesions (lymphatic infiltrate, Boeck's disease or sarcoidosis) appeared darker at all excitation angles than the surrounding tissue.

  14. Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized 13 C imaging.

    Science.gov (United States)

    Gordon, Jeremy W; Vigneron, Daniel B; Larson, Peder E Z

    2017-02-01

    To develop symmetric echo planar imaging (EPI) and a reference scan framework for hyperpolarized 13 C metabolic imaging. Symmetric, ramp-sampled EPI with partial Fourier reconstruction was implemented on a 3T scanner. The framework for acquiring a reference scan on the 1 H channel and applied to 13 C data was described and validated in both phantoms and in vivo metabolism of [1-13 C]pyruvate. Ramp-sampled, symmetric EPI provided a substantial increase in the signal-to-noise ratio of the phantom experiments. The reference scan acquired on the 1 H channel yielded 13 C phantom images that varied in mean signal intensity Ramp-sampled, symmetric EPI with spectral-spatial excitation of a single metabolite provides a fast, robust, and clinically efficacious approach to acquire hyperpolarized 13 C dynamic molecular imaging data. The gains of this efficient sampling, combined with partial Fourier methods, enables large matrix sizes required for human studies. Magn Reson Med 77:826-832, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  15. 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.)

  16. Readout-segmented echo-planar diffusion-weighted imaging in the assessment of orbital tumors: comparison with conventional single-shot echo-planar imaging in image quality and diagnostic performance.

    Science.gov (United States)

    Xu, Xiaoquan; Wang, Yanjun; Hu, Hao; Su, Guoyi; Liu, Hu; Shi, Haibin; Wu, Feiyun

    2017-12-01

    Background Readout-segmented echo-planar imaging (RS-EPI) could improve the imaging quality of diffusion-weighted imaging (DWI) in various organs. However, whether it could improve the imaging quality and diagnostic performance for the patients with orbital tumors is still unknown. Purpose To compare the image quality and diagnostic performance of RS-EPI DWI with that of conventional single-shot EPI (SS-EPI) DWI in patients with orbital tumors. Material and Methods SS-EPI and RS-EPI DW images of 32 patients with pathologically diagnosed orbital tumors were retrospectively analyzed. Qualitative imaging parameters (imaging sharpness, geometric distortion, ghosting artifacts, and overall imaging quality) and quantitative imaging parameters (apparent diffusion coefficient [ADC], signal-to-noise ratio [SNR], contrast, and contrast-to-noise ratio [CNR]) were assessed by two independent radiologists, and compared between SS-EPI and RS-EPI DWI. Receiver operating characteristic curves were used to determine the diagnostic value of ADC in differentiating malignant from benign orbital tumors. Results RS-EPI DW imaging produced less geometric distortion and ghosting artifacts, and better imaging sharpness and overall imaging quality than SS-EPI DWI (for all, P < 0.001). Meanwhile, RS-EPI DWI produced significantly lower SNR ( P < 0.001) and ADC ( P < 0.001), and higher contrast ( P < 0.001) than SS-EPI DWI, while producing no difference in CNR ( P = 0.137). There was no significant difference on the diagnostic performance between SS-EPI and RS-EPI DWI, when using ADC as the differentiating index ( P = 0.529). Conclusion Compared with SS-EPI, RS-EPI DWI provided significantly better imaging quality and comparable diagnostic performance in differentiating malignant from benign orbital tumors.

  17. Detection of hyperacute parenchymal hemorrhage of the brain using echo-planar T2{sup *}-weighted and diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Wiesmann, M. [Dept. of Radiology, Medizinische Universitaet zu Luebeck (Germany); Mayer, T.E.; Yousry, I.; Brueckmann, H. [Dept. of Neuroradiology, Klinikum Grosshadern, Ludwig-Maximilians-Universitaet, Muenchen (Germany); Hamann, G.F. [Dept. of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-Universitaet, Muenchen (Germany)

    2001-05-01

    We investigated the usefulness of echo-planar imaging (EPI) as well as T2{sup *}-weighted and diffusion-weighted MRI (DWI) to identify hyperacute hemorrhage (within 24 h after ictus) in the brain. Seven patients were examined 3.5 to 24 h after onset of symptoms using a whole-body 1.5-T MR system. Two diffusion-weighted sequences were run to obtain isotropic and anisotropic diffusion images. Apparent diffusion coefficients (ADC) were calculated from the isotropic diffusion images. All DWI images as well as the T2*-weighted EPI images showed the hematomas as either discrete, deeply hypointense homogeneous lesions, or as lesions of mixed signal intensity containing hypointense areas. We conclude that even in the early phase after hemorrhage, sufficient amounts of paramagnetic deoxyhemoglobin are present in intracerebral hemorrhages to cause hypointensity on EPI T2{sup *}-weighted and DWI images; thus, use of ultrafast EPI allows identification of intracerebral hemorrhage. (orig.)

  18. Echoes: a new instrumental concept of spectro-imaging for Jovian seismology

    Science.gov (United States)

    Soulat, L.; Schmider, F.-X.; Robbe-Dubois, S.; Appourchaux, T.; Bresson, Y.; Daban, J.-B.; Gaulme, P.; Gay, J.; Gouvret, C.

    2012-09-01

    Echoes is a project of a space-borne instrument which has been proposed as part of the JUICE mission which is selected in the Cosmic Vision program of the European Space Agency (ESA) to perform seismic and dynamics studies of Jupiter's interior and atmosphere. Based on an original Mach-Zehnder design, the instrument aims to measure Doppler shifts of solar spectral lines, which are reflected by cloud layers of Jupiter's upper troposphere, coupled with imaging capabilities. It is specified to detect global oscillations with degree up to l = 50 and amplitude as low as 1 cm/s at the surface of Jupiter. In order to check the compliance of the instrument, and its capability to operate in representative environment (TRL5), we build a prototype to perform tests. In this paper, we present the prototype implemented at Observatoire de la Côte d'Azur in collaboration with Institut d'Astrophysique Spatiale. We describe the design of the Mach-Zehnder and the procedure of control and adjustment. We present the necessary tests and we show on simulation that the measurements will provide the required precision. In conclusion, we will explain the perspective for such a new instrument.

  19. Geometric considerations of polar mesospheric summer echoes in tilted beams using coherent radar imaging

    Science.gov (United States)

    Sommer, S.; Stober, G.; Chau, J. L.; Latteck, R.

    2014-11-01

    We present observations of polar mesospheric summer echoes (PMSE) using the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). The radar is able to resolve PMSE at high spatial and temporal resolution and to perform pulse-to-pulse beam steering. In this experiment, 81 oblique beam directions were used with off-zenith angles up to 25°. For each beam pointing direction and range gate, coherent radar imaging was applied to determine the mean backscatter location. The location of the mean scatterer in the beam volume was calculated by the deviation from the nominal off-zenith angle of the brightest pixel. It shows that in tilted beams with an off-zenith angle greater than 5°, structures appear at the altitudinal edges of the PMSE layer. Our results indicate that the mean influence of the location of the maximum depends on the tilt of the beam and on the observed area of the PMSE layer. At the upper/lower edge of the PMSE layer, the mean backscatter has a greater/smaller off-zenith angle than the nominal off-zenith angle. This effect intensifies with greater off-zenith beam pointing direction, so the beam filling factor plays an important role in the observation of PMSE layers for oblique beams.

  20. 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

  1. Single-scan z-shim method for reducing susceptibility artifacts in gradient echo myelin water imaging.

    Science.gov (United States)

    Lee, Doohee; Lee, Jingu; Lee, Jongho; Nam, Yoonho

    2018-02-25

    Myelin water imaging (MWI) reportedly corresponds closely to the myelin content in the brain. An MWI technique based on multi-echo gradient echo (mGRE) has recently been proposed as an alternative to the conventional spin-echo-based MWI. However, the mGRE signal is vulnerable to macroscopic field inhomogeneity, which makes MWI unreliable. In the present study, a z-shim-based single-scan correction method is proposed to overcome this limitation. Z-shim gradients in the slice-selection direction were added to an mGRE sequence after an echo time of 12 ms. A 3-pool model corresponding to the proposed sequence was suggested for fitting the acquired signal. The method was evaluated through a comparison with methods without a correction and with post-processing only from non-z-shimmed data. To do this, numerical simulations and in vivo experiments were conducted. The simulation and in vivo experiment results indicated that post-processing alone was not sufficient to offset the macroscopic field inhomogeneity, particularly in inferior regions of the brain. On the other hand, the proposed method compensated the field inhomogeneity in most brain areas. The estimated in vivo myelin water fraction values were in good agreement with literature values obtained by previously proposed field inhomogeneity correction method. The proposed method showed reliable myelin water fraction in most regions of the brain in vivo, including those with severe field inhomogeneity. © 2018 International Society for Magnetic Resonance in Medicine.

  2. T2 mapping of the heart with a double-inversion radial fast spin-echo method with indirect echo compensation.

    Science.gov (United States)

    Hagio, Tomoe; Huang, Chuan; Abidov, Aiden; Singh, Jaspreet; Ainapurapu, Bujji; Squire, Scott; Bruck, Denise; Altbach, Maria I

    2015-02-25

    The abnormal signal intensity in cardiac T2-weighted images is associated with various pathologies including myocardial edema. However, the assessment of pathologies based on signal intensity is affected by the acquisition parameters and the sensitivities of the receiver coils. T2 mapping has been proposed to overcome limitations of T2-weighted imaging, but most methods are limited in spatial and/or temporal resolution. Here we present and evaluate a double inversion recovery radial fast spin-echo (DIR-RADFSE) technique that yields data with high spatiotemporal resolution for cardiac T2 mapping. DIR-RADFSE data were collected at 1.5 T on phantoms and subjects with echo train length (ETL) = 16, receiver bandwidth (BW) = ±32 kHz, TR = 1RR, matrix size = 256 × 256. Since only 16 views per echo time (TE) are collected, two algorithms designed to reconstruct highly undersampled radial data were used to generate images for 16 time points: the Echo-Sharing (ES) and the CUrve Reconstruction via pca-based Linearization with Indirect Echo compensation (CURLIE) algorithm. T2 maps were generated via least-squares fitting or the Slice-resolved Extended Phase Graph (SEPG) model fitting. The CURLIE-SEPG algorithm accounts for the effect of indirect echoes. The algorithms were compared based on reproducibility, using Bland-Altman analysis on data from 7 healthy volunteers, and T2 accuracy (against a single-echo spin-echo technique) using phantoms. Both reconstruction algorithms generated in vivo images with high spatiotemporal resolution and showed good reproducibility. Mean T2 difference between repeated measures and the coefficient of repeatability were 0.58 ms and 2.97 for ES and 0.09 ms and 4.85 for CURLIE-SEPG. In vivo T2 estimates from ES were higher than those from CURLIE-SEPG. In phantoms, CURLIE-SEPG yielded more accurate T2s compared to reference values (error was 7.5-13.9% for ES and 0.6-2.1% for CURLIE-SEPG), consistent with the fact that CURLIE

  3. RARE/turbo spin echo imaging with Simultaneous Multislice Wave-CAIPI.

    Science.gov (United States)

    Gagoski, Borjan A; Bilgic, Berkin; Eichner, Cornelius; Bhat, Himanshu; Grant, P Ellen; Wald, Lawrence L; Setsompop, Kawin

    2015-03-01

    To enable highly accelerated RARE/Turbo Spin Echo (TSE) imaging using Simultaneous MultiSlice (SMS) Wave-CAIPI acquisition with reduced g-factor penalty. SMS Wave-CAIPI incurs slice shifts across simultaneously excited slices while playing sinusoidal gradient waveforms during the readout of each encoding line. This results in an efficient k-space coverage that spreads aliasing in all three dimensions to fully harness the encoding power of coil sensitivities. The novel MultiPINS radiofrequency (RF) pulses dramatically reduce the power deposition of multiband (MB) refocusing pulse, thus allowing high MB factors within the Specific Absorption Rate (SAR) limit. Wave-CAIPI acquisition with MultiPINS permits whole brain coverage with 1 mm isotropic resolution in 70 s at effective MB factor 13, with maximum and average g-factor penalties of gmax  = 1.34 and gavg  = 1.12, and without √R penalty. With blipped-CAIPI, the g-factor performance was degraded to gmax  = 3.24 and gavg  = 1.42; a 2.4-fold increase in gmax relative to Wave-CAIPI. At this MB factor, the SAR of the MultiBand and PINS pulses are 4.2 and 1.9 times that of the MultiPINS pulse, while the peak RF power are 19.4 and 3.9 times higher. Combination of the two technologies, Wave-CAIPI and MultiPINS pulse, enables highly accelerated RARE/TSE imaging with low SNR penalty at reduced SAR. © 2015 Wiley Periodicals, Inc.

  4. Accelerated 3D echo-planar imaging with compressed sensing for time-resolved hyperpolarized 13 C studies.

    Science.gov (United States)

    Geraghty, Benjamin J; Lau, Justin Y C; Chen, Albert P; Cunningham, Charles H

    2017-02-01

    To enable large field-of-view, time-resolved volumetric coverage in hyperpolarized 13 C metabolic imaging by implementing a novel data acquisition and image reconstruction method based on the compressed sensing framework. A spectral-spatial pulse for single-resonance excitation followed by a symmetric echo-planar imaging (EPI) readout was implemented for encoding a 72 × 18 cm2 field of view at 5 × 5 mm2 resolution. Random undersampling was achieved with blipped z-gradients during the ramp portion of the echo-planar imaging readout. The sequence and reconstruction were tested with phantom studies and consecutive in vivo hyperpolarized 13 C scans in rats. Retrospectively and prospectively undersampled data were compared on the basis of structural similarity in the reconstructed images and the quantification of the lactate-to-pyruvate ratio in rat kidneys. No artifacts or loss of resolution are evident in the compressed sensing reconstructed images acquired with the proposed sequence. Structural similarity analysis indicate that compressed sensing reconstructions can accurately recover spatial features in the metabolic images evaluated. A novel z-blip acquisition sequence for compressed sensing accelerated hyperpolarized 13 C 3D echo-planar imaging was developed and demonstrated. The close agreement in lactate-to-pyruvate ratios from both retrospectively and prospectively undersampled data from rats shows that metabolic information is preserved with acceleration factors up to 3-fold with the developed method. Magn Reson Med 77:538-546, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  5. Correction for Eddy Current-Induced Echo-Shifting Effect in Partial-Fourier Diffusion Tensor Imaging.

    Science.gov (United States)

    Truong, Trong-Kha; Song, Allen W; Chen, Nan-Kuei

    2015-01-01

    In most diffusion tensor imaging (DTI) studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI) sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR). However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types of artifacts in partial-Fourier DTI. Here, we present an improved DTI acquisition and reconstruction scheme, capable of generating high-quality and high-SNR DTI data without eddy current-induced artifacts. This new scheme consists of three components, respectively, addressing the three distinct types of artifacts. First, a k-space energy-anchored DTI sequence is designed to recover eddy current-induced signal loss (i.e., Type 1 artifact). Second, a multischeme partial-Fourier reconstruction is used to eliminate artificial signal elevation (i.e., Type 2 artifact) associated with the conventional partial-Fourier reconstruction. Third, a signal intensity correction is applied to remove artificial signal modulations due to eddy current-induced erroneous T2(∗) -weighting (i.e., Type 3 artifact). These systematic improvements will greatly increase the consistency and accuracy of DTI measurements, expanding the utility of DTI in translational applications where quantitative robustness is much needed.

  6. Increased speed and image quality in single-shot fast spin echo imaging via variable refocusing flip angles.

    Science.gov (United States)

    Loening, Andreas M; Saranathan, Manojkumar; Ruangwattanapaisarn, Nichanan; Litwiller, Daniel V; Shimakawa, Ann; Vasanawala, Shreyas S

    2015-12-01

    To develop and validate clinically a single-shot fast spin echo (SSFSE) sequence utilizing variable flip angle refocusing pulses to shorten acquisition times via reductions in specific absorption rate (SAR) and improve image quality. A variable refocusing flip angle SSFSE sequence (vrfSSFSE) was designed and implemented, with simulations and volunteer scans performed to determine suitable flip angle modulation parameters. With Institutional Review Board (IRB) approval/informed consent, patients referred for 3T abdominal magnetic resonance imaging (MRI) were scanned with conventional SSFSE and either half-Fourier (n = 25) or full-Fourier vrfSSFSE (n = 50). Two blinded radiologists semiquantitatively scored images on a scale from -2 to 2 for contrast, noise, sharpness, artifacts, cardiac motion-related signal loss, and the ability to evaluate the pancreas and kidneys. vrfSSFSE demonstrated significantly increased speed (∼2-fold, P parameters with full-Fourier vrfSSFSE included increased contrast, sharpness, and visualization of pancreatic and renal structures with higher bandwidth technique (mean scores 0.37, 0.83, 0.62, and 0.31, respectively, P ≤ 0.001), and decreased image noise and improved visualization of renal structures when used with an equal bandwidth technique (mean scores 0.96 and 0.35, respectively, P < 0.001). Increased cardiac motion-related signal loss with full-Fourier vrfSSFSE was seen in the pancreas but not the kidney. vrfSSFSE increases speed at 3T over conventional SSFSE via reduced SAR, and when combined with full-Fourier acquisition can improve image quality, although with some increased sensitivity to cardiac motion-related signal loss. © 2015 Wiley Periodicals, Inc.

  7. Radiology and imaging for cavernous malformations.

    Science.gov (United States)

    Wang, Kevin Y; Idowu, Oluwatoyin R; Lin, Doris D M

    2017-01-01

    Cavernous malformations are low-flow vascular malformations that are histologically characterized by the lack of mural elements of mature vascular structures and intervening parenchymal neural tissue. They are often clinically quiescent, and may grow, bleed, and regress, but can also manifest clinically as neurologic deficits or seizures in the setting of an acute hemorrhage. The low-flow nature of cavernous malformations renders them inherently occult on cerebral angiography. Magnetic resonance imaging has become the mainstay imaging modality in evaluating cavernous malformations, producing characteristic imaging features that usually provide a straightforward diagnosis. Features on magnetic resonance imaging include a reticulated pattern of mixed hyper- and hypointensity on T1- and T2-weighted imaging, with a characteristic hypointense rim best appreciated on T2-weighted imaging or gradient-echo sequences. Contrast enhancement is useful for revealing coexisting developmental venous anomalies that are frequently associated with sporadic cavernous malformations, and may further support the diagnosis. Susceptibility-weighted imaging is highly sensitive for cavernous malformations and accompanying developmental venous anomalies, and is superior to gradient-echo sequences in screening for multifocal, familial cavernous malformations. © 2017 Elsevier B.V. All rights reserved.

  8. Volumetric MRI thermometry using a three-dimensional stack-of-stars echo-planar imaging pulse sequence.

    Science.gov (United States)

    Jonathan, Sumeeth V; Grissom, William A

    2017-08-07

    To measure temperature over a large brain volume with fine spatiotemporal resolution. A three-dimensional stack-of-stars echo-planar imaging sequence combining echo-planar imaging and radial sampling with golden angle spacing was implemented at 3T for proton resonance frequency-shift temperature imaging. The sequence acquires a 188x188x43 image matrix with 1.5x1.5x2.75 mm3 spatial resolution. Temperature maps were reconstructed using sensitivity encoding (SENSE) image reconstruction followed by the image domain hybrid method, and using the k-space hybrid method. In vivo temperature maps were acquired without heating to measure temperature precision in the brain, and in a phantom during high-intensity focused ultrasound sonication. In vivo temperature standard deviation was less than 1°C at dynamic scan times down to 0.75 s. For a given frame rate, scanning at a minimum repetition time (TR) with minimum acceleration yielded the lowest standard deviation. With frame rates around 3 s, the scan was tolerant to a small number of receive coils, and temperature standard deviation was 48% higher than a standard two-dimensional Fourier transform temperature mapping scan, but provided whole-brain coverage. Phantom temperature maps with no visible aliasing were produced for dynamic scan times as short as 0.38 s. k-Space hybrid reconstructions were more tolerant to acceleration. Three-dimensional stack-of-stars echo-planar imaging temperature mapping provides volumetric brain coverage and fine spatiotemporal resolution. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Using quantitative features extracted from T2-weighted MRI to improve breast MRI computer-aided diagnosis (CAD).

    Science.gov (United States)

    Gallego-Ortiz, Cristina; Martel, Anne L

    2017-01-01

    Computer-aided diagnosis (CAD) has been proposed for breast MRI as a tool to standardize evaluation, to automate time-consuming analysis, and to aid the diagnostic decision process by radiologists. T2w MRI findings are diagnostically complementary to T1w DCE-MRI findings in the breast and prior research showed that measuring the T2w intensity of a lesion relative to a tissue of reference improves diagnostic accuracy. The diagnostic value of this information in CAD has not been yet quantified. This study proposes an automatic method of assessing relative T2w lesion intensity without the need to select a reference region. We also evaluate the effect of adding this feature to other T2w and T1w image features in the predictive performance of a breast lesion classifier for differential diagnosis of benign and malignant lesions. An automated feature of relative T2w lesion intensity was developed using a quantitative regression model. The diagnostic performance of the proposed feature in addition to T2w texture was compared to the performance of a conventional breast MRI CAD system based on T1w DCE-MRI features alone. The added contribution of T2w features to more conventional T1w-based features was investigated using classification rules extracted from the lesion classifier. After institutional review board approval that waived informed consent, we identified 627 breast lesions (245 malignant, 382 benign) diagnosed after undergoing breast MRI at our institution between 2007 and 2014. An increase in diagnostic performance in terms of area under the curve (AUC) from the receiver operating characteristic (ROC) analysis was observed with the additional T2w features and the proposed quantitative feature of relative T2w lesion intensity. AUC increased from 0.80 to 0.83 and this difference was statistically significant (adjusted p-value = 0.020).

  10. Focal treatment or observation of prostate cancer: pretreatment accuracy of transrectal ultrasound biopsy and T2-weighted MRI.

    Science.gov (United States)

    Nogueira, Lucas; Wang, Liang; Fine, Samson W; Pinochet, Rodrigo; Kurta, Jordan M; Katz, Darren; Savage, Caroline J; Cronin, Angel M; Hricak, Hedvig; Scardino, Peter T; Akin, Oguz; Coleman, Jonathan A

    2010-02-01

    To test the hypothesis that men with prostate cancer (PCA) and preoperative disease features considered favorable for focal treatment would be accurately characterized with transrectal biopsy and prostate magnetic resonance imaging (MRI) by performing a retrospective analysis of a selected cohort of such patients treated with radical prostatectomy (RP). A total of 202 patients with PCA who had preoperative MRI and low-risk biopsy criteria (no Gleason grade 4/5, 1 involved core, < 2 mm, PSA density < or = 0.10, clinical stage < or = T2a) were included in the study. Indolent RP pathology was defined as no Gleason 4/5, organ confined, tumor volume < 0.5 mL, and negative surgical margins. MRI ability to locate and determine the tumor extent was assessed. After RP, 101 men (50%) had nonindolent cancer. Multifocal and bilateral tumors were present in 81% and 68% of patients, respectively. MRI indicated extensive disease in 16 (8%). MRI sensitivity to locate PCA ranged from 2% to 20%, and specificity from 91% to 95%. On univariate analysis, MRI evidence of extracapsular extension (P = .027) and extensive disease (P = .001) were associated with nonindolent cancer. On multivariate analysis, only the latter remained as significant predictor (P = .0018). Transrectal biopsy identified men with indolent tumors favorable for focal treatment in 50% of cases. MRI findings of extracapsular extension and extensive tumor involving more than half of the gland are associated with unfavorable features, and may be useful in excluding patients from focal treatment. According to these data, endorectal MRI is not sufficient to localize small tumors for focal treatment. 2010 Elsevier Inc. All rights reserved.

  11. Using quantitative features extracted from T2-weighted MRI to improve breast MRI computer-aided diagnosis (CAD.

    Directory of Open Access Journals (Sweden)

    Cristina Gallego-Ortiz

    Full Text Available Computer-aided diagnosis (CAD has been proposed for breast MRI as a tool to standardize evaluation, to automate time-consuming analysis, and to aid the diagnostic decision process by radiologists. T2w MRI findings are diagnostically complementary to T1w DCE-MRI findings in the breast and prior research showed that measuring the T2w intensity of a lesion relative to a tissue of reference improves diagnostic accuracy. The diagnostic value of this information in CAD has not been yet quantified. This study proposes an automatic method of assessing relative T2w lesion intensity without the need to select a reference region. We also evaluate the effect of adding this feature to other T2w and T1w image features in the predictive performance of a breast lesion classifier for differential diagnosis of benign and malignant lesions. An automated feature of relative T2w lesion intensity was developed using a quantitative regression model. The diagnostic performance of the proposed feature in addition to T2w texture was compared to the performance of a conventional breast MRI CAD system based on T1w DCE-MRI features alone. The added contribution of T2w features to more conventional T1w-based features was investigated using classification rules extracted from the lesion classifier. After institutional review board approval that waived informed consent, we identified 627 breast lesions (245 malignant, 382 benign diagnosed after undergoing breast MRI at our institution between 2007 and 2014. An increase in diagnostic performance in terms of area under the curve (AUC from the receiver operating characteristic (ROC analysis was observed with the additional T2w features and the proposed quantitative feature of relative T2w lesion intensity. AUC increased from 0.80 to 0.83 and this difference was statistically significant (adjusted p-value = 0.020.

  12. ECHO virus

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001340.htm ECHO virus To use the sharing features on this page, please enable JavaScript. Enteric cytopathic human orphan (ECHO) viruses are a group of viruses that can lead ...

  13. BOLD sensitivity and SNR characteristics of parallel imaging-accelerated single-shot multi-echo EPI for fMRI.

    Science.gov (United States)

    Bhavsar, Saurabh; Zvyagintsev, Mikhail; Mathiak, Klaus

    2014-01-01

    Echo-planar imaging (EPI) is a standard procedure in functional magnetic resonance imaging (fMRI) for measuring changes in the blood oxygen level-dependent (BOLD) signal associated with neuronal activity. The images obtained from fMRI with EPI, however, exhibit signal dropouts and geometric distortions. Parallel imaging (PI), due to its short readout, accelerates image acquisition and might reduce dephasing in phase-encoding direction. The concomitant loss of signal-to-noise ratio (SNR) might be compensated through single-shot multi-echo EPI (mEPI). We systematically compared the temporal SNR and BOLD sensitivity of single echoes (TE=15, 45, and 75ms) and contrast-optimized mEPI with and without PI and mEPI-based denoising. Audio-visual stimulation under natural viewing conditions activated distributed neural networks. Heterogeneous SNR, noise gain, and sensitivity maps emerged. In single echoes, SNR and BOLD sensitivity followed the predicted dependency on echo time (TE) and were reduced under PI. However, the combination of echoes with mEPI recovered the quality parameters and increased BOLD signal changes at circumscribed fronto-polar and deep brain structures. We suggest applying PI only in combination with mEPI to reduce imaging artifacts and conserve BOLD sensitivity. © 2013.

  14. Echo intensity obtained from ultrasonography images reflecting muscle strength in elderly men

    Directory of Open Access Journals (Sweden)

    Watanabe Y

    2013-07-01

    Full Text Available Yuya Watanabe,1 Yosuke Yamada,1,2 Yoshihiro Fukumoto,3 Tatsuro Ishihara,4 Keiichi Yokoyama,1 Tsukasa Yoshida,1 Motoko Miyake,1 Emi Yamagata,5 Misaka Kimura1 1Laboratory of Sports and Health Science, Kyoto Prefectural University of Medicine, Kyoto, Japan; 2Research Fellow, Japan Society for the Promotion of Science, Tokyo, Japan; 3Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Japan; 4Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan; 5Laboratory of Gerontological Nursing, Kyoto Prefectural University of Medicine, Kyoto, Japan Background: It is well known that loss of muscle mass (quantitative change is a major change that occurs with aging. Qualitative changes in skeletal muscle, such as increased intramuscular fat, also occur as one ages. Enhanced echo intensity (EI on ultrasonography images of skeletal muscle is believed to reflect muscle quality. Recent studies evaluating the quality of skeletal muscle using computer-aided gray scale analysis showed that EI is associated with muscle strength independently of age or muscle size in middle-aged and elderly women. The aim of the present study was to investigate whether muscle quality based on EI is associated with muscle strength independently of muscle size for elderly men. Methods: A total of 184 elderly men (65–91 years living independently in Kyoto, Japan, participated in this study. The EI, muscle thickness (MT, and subcutaneous fat thickness (FT of the anterior compartment of the right thigh were determined by assessing ultrasonography images. The maximum isometric torque of knee extension at a knee angle of 90° was measured. Results: The EI showed a significant negative correlation with muscle strength (r = -0.333, P < 0.001. Multivariate regression analysis revealed that the MT and EI of the knee extensor muscle were independently associated with maximum isometric knee extension strength. Even when partial correlation analysis was performed with age

  15. Development of pulse-echo ultrasonic propagation imaging system and its delivery to Korea Air Force

    Science.gov (United States)

    Ahmed, Hasan; Hong, Seung-Chan; Lee, Jung-Ryul; Park, Jongwoon; Ihn, Jeong-Beom

    2017-04-01

    This paper proposes a full-field pulse-echo ultrasonic propagation imaging (FF-PE-UPI) system for non-destructive evaluation of structural defects. The system works by detection of bulk waves that travel through the thickness of a specimen. This is achieved by joining the laser beams for the ultrasonic wave generation and sensing. This enables accurate and clear damage assessment and defect localization in the thickness with minimum signal processing since bulk waves are less susceptible to dispersion during short propagation through the thickness. The system consists of a Qswitched laser for generating the aforementioned waves, a laser Doppler vibrometer (LDV) for sensing, optical elements to combine the generating and sensing laser beams, a dual-axis automated translation stage for raster scanning of the specimen and a digitizer to record the signals. A graphical user interface (GUI) is developed to control all the individual blocks of the system. Additionally, the software also manages signal acquisition, processing, and display. The GUI is created in C++ using the QT framework. In view of the requirements posed by the Korean Air Force(KAF), the system is designed to be compact and portable to allow for in situ inspection of a selected area of a larger structure such as radome or rudder of an aircraft. The GUI is designed with a minimalistic approach to promote usability and adaptability while masking the intricacies of actual system operation. Through the use of multithreading the software is able to show the results while a specimen is still being scanned. This is achieved by real-time and concurrent acquisition, processing, and display of ultrasonic signal of the latest scan point in the scan area.

  16. Protocol optimization of sacroiliac joint MR Imaging at 3 Tesla: Impact of coil design and motion resistant sequences on image quality.

    Science.gov (United States)

    Gondim Teixeira, P A; Bravetti, M; Hossu, G; Lecocq, S; Petit, D; Loeuille, D; Blum, A

    2017-07-21

    To evaluate the impact of coil design and motion-resistant sequences on the quality of sacroiliac magnetic resonance imaging (MRI) examination in patients with spondyloarthropathy. One hundred and twenty-one patients with suspected sacroiliitis and referred for MRI of the sacroiliac joints were retrospectively evaluated with MRI at 3-Tesla. There were 78 women and 43 men with a mean age of 36.7±11.5 (SD) years (range: 15.8-78.4 years). Conventional and motion-resistant fat-saturated fast-spin echo T2-weighted sequences were performed with two different coils. Image quality was subjectively evaluated by two independent readers (R1 and R2) using a four-point scale. Confidence in the identification of bone marrow edema pattern (BMEP) was also evaluated subjectively using a three-point scale. Phased array body coil yielded improved image quality compared to surface coil (14.1 to 30.4% for R1 and 14.6 to 25.7% for R2; Pbody coil with motion-resistant T2-weighted sequence (kappa 0.990). The smallest number of indeterminate BMEP zones was seen on MRI set acquired with the phased-array body coil and motion-resistant T2-weighted sequence. Phased array body coil and motion-resistant T2-weighted sequences perform better than surface coil and conventional T2-weighted sequences for the evaluation of sacroiliac joints, increasing confidence in the identification of BMEP. Copyright © 2017 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  17. Comparison of multi-echo dixon methods with volume interpolated breath-hold gradient magnetic resonance imaging in fat-signal fraction quantification of paravaertebral muscle

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Yeon Hwa; Kim, Hak Sun; Lee, Young Han [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); and others

    2015-10-15

    To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2{sup *} estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2{sup *}-corrected two-echo Dixon or T2{sup *}-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2{sup *}-corrected Dixon technique with two (non-T2{sup *}-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. T2{sup *}-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.

  18. Readout-segmented echo-planar imaging in diffusion-weighted MR imaging of acute infarction of the brainstem and posterior fossa: comparison of single-shot echo-planar diffusion-weighted sequences.

    Science.gov (United States)

    Byeon, Jonghyun; Kim, Jee Young; Cho, A-Hyun

    2015-01-01

    The purpose of this study was to evaluate the clinical usefulness of readout-segmented echo-planar imaging (rs-EPI) in the diagnosis of acute infarction of the brainstem and posterior fossa, by comparing its results with those of single-shot echo-planar imaging (ss-EPI) at 3-T magnetic resonance imaging. Twenty-nine patients with acute infarctions of the brainstem and posterior fossa underwent both ss-EPI and rs-EPI. Two readers independently assessed two sets of diffusion-weighted (DW) images for the qualitative comparison of image quality. Signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated for the assessment of image parameters. There were no significant differences in the conspicuity of acute infarction upon qualitative comparison; however, distinctions of anatomical structures, susceptibility artifact, the presence of uncertain high signal intensity in the brain parenchyma, and overall image quality were significantly better in rs-EPI DW images. There were no significant differences in SNR, lesion contrast, CNR, and apparent diffusion coefficient values of acute infarction and normal thalamus between rs-EPI and ss-EPI. rs-EPI DWI is a clinically useful technique for evaluating lesions in the brainstem and posterior fossa by producing high-resolution DW images with reduced susceptibility artifact. However, there are no significant differences in the conspicuity of acute infarctions in the brainstem and posterior fossa between rs-EPI and ss-EPI. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. In vivo determination of cerebral hemodynamics and bioenergetics using spin-echo magnetic resonance imaging

    Science.gov (United States)

    Oja, Joni Marcus Eric

    1999-08-01

    It is well known that the transverse relaxation time, T 2, is dependent on the oxygenation state of blood. Two biophysical mechanisms have been proposed to explain this interdependency. In the diffusion model, oxygenation effects are accounted for by water diffusion through field gradients inside and outside, of the erythrocytes, whereas in the exchange model, the oxygenation effect is thought to be due to the exchange of water between erythrocytes and plasma. Careful in vitro studies with blood have shown that the exchange model fits best to the obtained data in preference to the diffusion model. During brain activation, local increases in blood flow exceed the oxygen demand, resulting in less deoxygenated blood in the capillary and venous compartments. Due to this, blood is less paramagnetic in these activated brain regions, lengthening T2, which in turn increases the signal intensities of the corresponding voxels in the MR image. Thus the measured blood-oxygen-level-dependent (BOLD) image contrast is a complex function of many physiological parameters, such as tissue morphometry, blood volume, blood flow, oxygenation and oxygen metabolism. All of these parameters contribute to the tissue magnetization influencing the transverse relaxation rate. Until now, no exact equations have been available which would relate these hemodynamic variables to a single MRI observable parameter, namely T 2, in a manner in which absolute units can be used. A fundamental theory was developed to explain measured spin-echo BOLD effects, and it was tested in animals and humans. In animal studies, blood oxygenation was altered by regulating arterial oxygen or carbon dioxide tension. This resulted in changes in blood volume, flow and blood magnetization, which in turn was reflected in T2. Using analytical expressions derived from the theory, the transverse relaxation rate was related to the oxygen saturation and extraction and quantification of microvascular cerebral blood volume was

  20. Diffusion-prepared stimulated-echo turbo spin echo (DPsti-TSE): An eddy current-insensitive sequence for three-dimensional high-resolution and undistorted diffusion-weighted imaging.

    Science.gov (United States)

    Zhang, Qinwei; Coolen, Bram F; Versluis, Maarten J; Strijkers, Gustav J; Nederveen, Aart J

    2017-07-01

    In this study, we present a new three-dimensional (3D), diffusion-prepared turbo spin echo sequence based on a stimulated-echo read-out (DPsti-TSE) enabling high-resolution and undistorted diffusion-weighted imaging (DWI). A dephasing gradient in the diffusion preparation module and rephasing gradients in the turbo spin echo module create stimulated echoes, which prevent signal loss caused by eddy currents. Near to perfect agreement of apparent diffusion coefficient (ADC) values between DPsti-TSE and diffusion-weighted echo planar imaging (DW-EPI) was demonstrated in both phantom transient signal experiments and phantom imaging experiments. High-resolution and undistorted DPsti-TSE was demonstrated in vivo in prostate and carotid vessel wall. 3D whole-prostate DWI was achieved with four b values in only 6 min. Undistorted ADC maps of the prostate peripheral zone were obtained at low and high imaging resolutions with no change in mean ADC values [(1.60 ± 0.10) × 10-3 versus (1.60 ± 0.02) × 10-3  mm2 /s]. High-resolution 3D DWI of the carotid vessel wall was achieved in 12 min, with consistent ADC values [(1.40 ± 0.23) × 10-3  mm2 /s] across different subjects, as well as slice locations through the imaging volume. This study shows that DPsti-TSE can serve as a robust 3D diffusion-weighted sequence and is an attractive alternative to the traditional two-dimensional DW-EPI approaches. Copyright © 2017 John Wiley & Sons, Ltd.

  1. MR imaging of benign peripheral nerve sheath tumors

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, V. (Dept. of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden) Tumor Service, Karolinska Hospital, Stockholm (Sweden) Dept. of Orthopedics, Karolinska Hospital, Stockholm (Sweden)); Goeranson, H. (Dept. of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden) Tumor Service, Karolinska Hospital, Stockholm (Sweden) Dept. of Orthopedics, Karolinska Hospital, Stockholm (Sweden)); Bauer, H.C.F. (Dept. of Diagnostic Radiology, Karolinska Hospital, Stockholm (Sweden) Tumor Service, Karolinska Hospital, Stockholm (Sweden) Dept. of Orthopedics, Karolinska Hospital, Stockholm (Sweden))

    1994-05-01

    In a retrospective, nonblind review of MR imaging of 15 benign peripheral nerve neoplasms in 13 patients, the signal pattern of the tumors (including contrast-enhanced images) and stage were assessed. One lesion was subcutaneous, 9 intramuscular, 2 intermuscular and 3 extracompartmental. One lesion was located to the trunk, 5 to the upper extremity and 9 to the lower. The signal on T1-weighted spin-echo images was homogeneous isointense compared to adjacent muscle in 11 lesions and in 2 slightly hyper- and in 2 slightly hypointense. T2-weighted spin-echo images, acquired in all but one examination, showed a hyperintense signal, homogeneous in 8 and centrally inhomogeneous in 6 lesions. Postcontrast T1-weighted images of 11 lesions, showed a strong signal, with an inhomogeneous enhancement in the center of the lesion similar to that obtained in T2-weighted images. In 2 cases there were signal characteristics indicating bleeding in the tumor. In one lesion both the nonenhanced and contrast-enhanced T1-weighted images showed a hypointense signal in the tumor center suggestive of intramuscular myxoma. All lesions were well delineated without reactive edema. In all cases, anatomic tumor location was correctly assessed. Although the findings were not pathognomonic for neurinoma, MR imaging provided valuable information confirming the clinical and cytologic assessments. (orig.).

  2. K-space trajectory mapping and its application for ultrashort Echo time imaging

    Czech Academy of Sciences Publication Activity Database

    Latta, P.; Starčuk jr., Zenon; Gruwel, M. L. H.; Weber, M.H.; Tomanek, B.

    2017-01-01

    Roč. 36, February (2017), s. 68-76 ISSN 0730-725X R&D Projects: GA ČR(CZ) GA15-12607S Institutional support: RVO:68081731 Keywords : gradient imperfections * K-space deviation * trajectrory estaimation * ultrashort echo time Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.225, year: 2016

  3. Reconstruction strategy for echo planar spectroscopy and its application to partially undersampled imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Schaumburg, K; Paulson, O B

    2000-01-01

    The most commonly encountered form of echo planar spectroscopy involves oscillating gradients in one spatial dimension during readout. Data are consequently not sampled on a Cartesian grid. A fast gridding algorithm applicable to this particular situation is presented. The method is optimal, i...

  4. Diffusion-weighted imaging-guided MR spectroscopy in breast lesions using readout-segmented echo-planar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kun; Chai, Weimin; Zhan, Ying; Luo, Xianfu; Yan, Fuhua [Shanghai Jiao Tong University School of Medicine, Department of Radiology, Ruijin Hospital, Shanghai (China); Fu, Caixia [Siemens MRI Center, Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen (China); Shen, Kunwei [Shanghai Jiao Tong University School of Medicine, Comprehensive Breast Health Center, Ruijin Hospital, Shanghai (China)

    2016-06-15

    To investigate the feasibility and effectiveness of diffusion-weighted imaging (DWI)-guided magnetic resonance spectroscopy (MRS) using readout-segmented echo-planar imaging (RS-EPI) to characterise breast lesions. A total of 258 patients with 258 suspicious breast lesions larger than 1 cm in diameter were examined using DWI-guided, single-voxel MRS with RS-EPI. The mean total choline-containing compound (tCho) signal-to-noise ratio (SNR) and concentration were used for the interpretation of MRS data. T-tests, χ{sup 2}-tests, receiver operating characteristic (ROC) curve analyses and Pearson correlations were conducted for statistical analysis. Histologically, 183 lesions were malignant, and 75 lesions were benign. Both the mean tCho SNR and concentration of malignant lesions were higher than those of benign lesions (6.23 ± 3.30 AU/mL vs. 1.26 ± 1.75 AU/mL and 3.17 ± 2.03 mmol/kg vs. 0.86 ± 0.83 mmol/kg, respectively; P < 0.0001). For a tCho SNR of 2.0 AU/mL and a concentration of 1.76 mmol/kg, the corresponding areas under the ROC curves were 0.93 and 0.90, respectively. The mean tCho SNR and concentration negatively correlated with apparent diffusion coefficients calculated from RS-EPI, with correlation coefficients of -0.54 and -0.48, respectively. DWI-guided MRS using RS-EPI is feasible and accurate for characterising breast lesions. (orig.)

  5. Magnetic resonance imaging of pyomyositis in 43 cases

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Rafaela E-mail: r.soler@.teleline.es; Rodriguez, Esther; Aguilera, Cristina; Fernandez, Rosa

    2000-07-01

    Purpose: To describe the magnetic resonance imaging (MRI) findings in pyomyositis. Methods and materials: Forty-three patients with proven muscle infection (30 males, 13 females) ranging in age from 14 to 86 years (mean 42 years) were studied with MRI. The initial clinical diagnose were soft tissue infection (n=27), neoplasm (n=12), thrombophlebitis (n=3), and lymphedema (n=1). Spin-echo T1- and T2-weighted images were obtained in all cases and STIR sequence in 6. Spin-echo T1-weighted images after Gd-DTPA injection were obtained in 16 cases. The signal intensity findings, the extent of the abnormalities in the soft tissue (muscle, fascial and subcutaneous involvement), the presence of fluid collections, and the involvement of neighbouring bone and joint were reviewed retrospectively. Results: A hyperintense signal on T2-weighted and STIR images were detected in all patients. Fluid collections were seen in 21 cases as localized areas of hypointensity on the T1-weighted images, and highly hyperintense areas on the T2-weighted images. In four patients a rim of high signal intensity was seen around the fluid collection on the T1-weighted images. On contrast-enhanced T1-weighted images there was diffuse enhancement in the patients without fluid collections that was heterogeneous in seven and homogeneous in two. After Gd-DTPA all fluid collections showed a central area without enhancement and a well-defined enhancing peripheral rim. Involvement of adjacent structures included subcutaneous tissue (n=25), bone marrow (n=14), fascial planes (n=15) and joints (n=11). Conclusion: MRI is useful in the assessment of pyomyositis and in determining the location and extension. A hyperintense rim on unenhanced T1-weighted images and peripheral enhancement after Gd-DTPA are useful for identifying the number, size, and location of soft-tissue abscesses.

  6. Echo-Planar Imaging for a 9.4 Tesla Vertical-Bore Superconducting Magnet Using an Unshielded Gradient Coil.

    Science.gov (United States)

    Kodama, Nao; Kose, Katsumi

    2016-10-11

    Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (~54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach.

  7. Echo-Planar Imaging for a 9.4 Tesla Vertical-Bore Superconducting Magnet Using an Unshielded Gradient Coil

    Science.gov (United States)

    KODAMA, Nao; KOSE, Katsumi

    2016-01-01

    Echo-planar imaging (EPI) sequences were developed for a 9.4 Tesla vertical standard bore (∼54 mm) superconducting magnet using an unshielded gradient coil optimized for live mice imaging and a data correction technique with reference scans. Because EPI requires fast switching of intense magnetic field gradients, eddy currents were induced in the surrounding metallic materials, e.g., the room temperature bore, and this produced serious artifacts on the EPI images. We solved the problem using an unshielded gradient coil set of proper size (outer diameter = 39 mm, inner diameter = 32 mm) with time control of the current rise and reference scans. The obtained EPI images of a phantom and a plant sample were almost artifact-free and demonstrated the promise of our approach. PMID:27001398

  8. The Brain and Spinal Injury Center score: a novel, simple, and reproducible method for assessing the severity of acute cervical spinal cord injury with axial T2-weighted MRI findings.

    Science.gov (United States)

    Talbott, Jason F; Whetstone, William D; Readdy, William J; Ferguson, Adam R; Bresnahan, Jacqueline C; Saigal, Rajiv; Hawryluk, Gregory W J; Beattie, Michael S; Mabray, Marc C; Pan, Jonathan Z; Manley, Geoffrey T; Dhall, Sanjay S

    2015-10-01

    Previous studies that have evaluated the prognostic value of abnormal changes in signals on T2-weighted MRI scans of an injured spinal cord have focused on the longitudinal extent of this signal abnormality in the sagittal plane. Although the transverse extent of injury and the degree of spared spinal cord white matter have been shown to be important for predicting outcomes in preclinical animal models of spinal cord injury (SCI), surprisingly little is known about the prognostic value of altered T2 relaxivity in humans in the axial plane. The authors undertook a retrospective chart review of 60 patients who met the inclusion criteria of this study and presented to the authors' Level I trauma center with an acute blunt traumatic cervical SCI. Within 48 hours of admission, all patients underwent MRI examination, which included axial and sagittal T2 images. Neurological symptoms, evaluated with the grades according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS), at the time of admission and at hospital discharge were correlated with MRI findings. Five distinct patterns of intramedullary spinal cord T2 signal abnormality were defined in the axial plane at the injury epicenter. These patterns were assigned ordinal values ranging from 0 to 4, referred to as the Brain and Spinal Injury Center (BASIC) scores, which encompassed the spectrum of SCI severity. The BASIC score strongly correlated with neurological symptoms at the time of both hospital admission and discharge. It also distinguished patients initially presenting with complete injury who improved by at least one AIS grade by the time of discharge from those whose injury did not improve. The authors' proposed score was rapid to apply and showed excellent interrater reliability. The authors describe a novel 5-point ordinal MRI score for classifying acute SCIs on the basis of axial T2-weighted imaging. The proposed BASIC score stratifies the SCIs according to the extent of transverse T2

  9. Retrospective correction of B0-field-induced geometric distortions in multislice echo planar images: a 3D solution

    Science.gov (United States)

    McColl, Roderick W.; Coburn, Edward A.

    2000-04-01

    A method has been developed to utilize a 3D B0 fieldmap, with a multi-volume-of-interest segmentation map, to quantify and correct geometric distortions in echo-planar images. The purpose is to provide accurate co-registration of anatomical MRI to functional MRI time course sequences. A data structure capable of extracting and reporting the necessary information forms a central part of the solution. Images were obtained from a 1.5 Tesla scanner with an experimental y-gradient insert coil. Two 3D-gradient echo sequences supply the data needed to calculate the B0 map across the volume. Segmentation of the volume into brain/background produces the data needed for the phase unwrapping and volume(s) of interest generation, from which the global B0 variation map is obtained. Subsequent EPI acquisition yields the fMRI time- course information. Tests were carried out on a phantom and a human volunteer engaged in a motor task (finger-tapping). Strong distortions were measured, and subsequently corrected, particularly near the petrous bone/mastoid air cells and in the frontal and maxillary sinuses. Additionally, a strong eddy current resulting from the unshielded y-gradient was detected. The method facilitates geometric distortion correction through an imaging volume, containing multiple regions of interest within a slice, starting from a single starting point.

  10. Rapid estimation of cartilage T2 with reduced T1 sensitivity using double echo steady state imaging.

    Science.gov (United States)

    Heule, Rahel; Ganter, Carl; Bieri, Oliver

    2014-03-01

    In principle, double echo steady state (DESS) offers morphological and quantitative T2 imaging of cartilage within one single scan. However, accurate T2 estimation is hampered by its prominent T1 dependency in the limit of low flip angles, generally used to image cartilage morphology, as for the osteoarthritis initiative. A new postprocessing approach is introduced to overcome this T1-related bias for rapid DESS-based T2 quantification in the low flip angle regime. Based on a rough global T1 estimator and a golden section search, T2 is extracted from the ratio of the two echoes acquired with DESS. The new relaxometry method is evaluated from simulations and in vivo 3D measurements of the knee joint at 3T. A pronounced reduction in the T1-related bias of DESS-T2 estimation and increased zonal variation in T2 between deep and superficial cartilage layers are observed. The improvement becomes particularly evident in the range of low flip angles (α estimate, the reliability of DESS-T2 quantification can be considerably increased. The results emphasize the potential of DESS to fuse accurate quantitative T2 and morphological imaging of the musculoskeletal system within one single scan. Copyright © 2013 Wiley Periodicals, Inc.

  11. [Prostatic pathology imaged by magnetic resonance. 58 cases].

    Science.gov (United States)

    Gevenois, P A; Van Regemorter, G; Van Gansbeke, D; Delcour, C; Corbusier, A; Struyven, J

    1987-03-01

    Forty-eight patients with prostatic disease (benign prostatic hyperplasia (B.P.H.), carcinoma, cysts, myoma and prostatitis) and 10 normal volunteers underwent magnetic resonance imaging (M.R.I.) of the prostate. The prostatic parenchyma was best evaluated by a T2-weighted spin-echo pulse sequence. The prostate in patients with B.P.H. often had a homogeneous or more rarely a nodular appearance on T2-weighted images. In most cases, a peripheral dark rim is observed. All prostate in patients with carcinoma had an heterogeneous appearance on T2-weighted images. While most of the prostatic carcinomas appeared hypo-intense relative to adjacent prostatic parenchyma, some of the neoplasms had a high or mixed-high and low signal. The myoma showed a low-signal nodule like carcinoma. The cyst appears as a liquid tumor. The prostatitis had an homogeneous bright signal. With the used methodology, MRI can differentiate prostatic diseases in many cases. Nevertheless the technique has to be optimized to improve its accuracy.

  12. Magnetic resonance imaging in prostate disease. Review of 58 cases

    Energy Technology Data Exchange (ETDEWEB)

    Gevenois, P.A.; Van Regemorter, G.; Van Gansbeke, D.; Delcour, C.; Corbusier, A.; Struyven, J.

    1987-03-01

    Forty-eight patients with prostatic disease (benign prostatic hyperplasia (B.P.H.), carcinoma, cysts, myoma and prostatitis) and 10 normal volunteers underwent magnetic resonance imaging (M.R.I) of the prostate. The prostatic parenchyma was best evaluated by a T2-weighted spin-echo pulse sequence. The prostate in patients with B.P.H. often had an homogeneous or more rarely a nodular appearance on T2-weighted images. In most cases, a peripheral dark rim is observed. All prostate in patients with carcinoma had an heterogeneous appearance on T2-weighted images. While most of the prostatic carcinomas appeared hypointense relative to adjacent prostatic parenchyma, some of the neoplasms had a high or mixed-high and low signal. The myoma showed a low-signal nodule like carcinoma. The cyst appears as a liquid tumor. The prostatitis had an homogeneous bright signal. With the used methodology, MRI can differentiate prostatic diseases in many cases. Nevertheless the technique has to be optimalized to improve its accuracy.

  13. Accelerated three-dimensional cine phase contrast imaging using randomly undersampled echo planar imaging with compressed sensing reconstruction.

    Science.gov (United States)

    Basha, Tamer A; Akçakaya, Mehmet; Goddu, Beth; Berg, Sophie; Nezafat, Reza

    2015-01-01

    The aim of this study was to implement and evaluate an accelerated three-dimensional (3D) cine phase contrast MRI sequence by combining a randomly sampled 3D k-space acquisition sequence with an echo planar imaging (EPI) readout. An accelerated 3D cine phase contrast MRI sequence was implemented by combining EPI readout with randomly undersampled 3D k-space data suitable for compressed sensing (CS) reconstruction. The undersampled data were then reconstructed using low-dimensional structural self-learning and thresholding (LOST). 3D phase contrast MRI was acquired in 11 healthy adults using an overall acceleration of 7 (EPI factor of 3 and CS rate of 3). For comparison, a single two-dimensional (2D) cine phase contrast scan was also performed with sensitivity encoding (SENSE) rate 2 and approximately at the level of the pulmonary artery bifurcation. The stroke volume and mean velocity in both the ascending and descending aorta were measured and compared between two sequences using Bland-Altman plots. An average scan time of 3 min and 30 s, corresponding to an acceleration rate of 7, was achieved for 3D cine phase contrast scan with one direction flow encoding, voxel size of 2 × 2 × 3 mm(3) , foot-head coverage of 6 cm and temporal resolution of 30 ms. The mean velocity and stroke volume in both the ascending and descending aorta were statistically equivalent between the proposed 3D sequence and the standard 2D cine phase contrast sequence. The combination of EPI with a randomly undersampled 3D k-space sampling sequence using LOST reconstruction allows a seven-fold reduction in scan time of 3D cine phase contrast MRI without compromising blood flow quantification. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Automated Classification of Disease Patterns from Echo-cardiography Images Based on Shape Features of the Left Ventricle

    Science.gov (United States)

    Das, Shaoli; Parekh, Ranjan

    2010-10-01

    Computer assisted diagnosis using analysis of medical images is an area of active research in health informatics. This paper proposes a technique for indication of heart diseases by using information related to shapes of the left ventricle (LV). LV boundaries are tracked from echo-cardiography images taken from LV short axis view, corresponding to two disease conditions viz. dilated cardiomyopathy and hypertrophic cardiomyopathy, and discriminated from the normal condition. The LV shapes are modeled using shape histograms generated by plotting the frequency of normalized radii lengths drawn from the centroid to the periphery, against a specific number of bins. A 3-layer neural network activated by a log-sigmoid function is used to classify the shape histograms into one of the three classes. Experimentations on a dataset of 240 images show recognition accuracies of the order of 80%.

  15. Readout-segmented echo-planar imaging for diffusion-weighted imaging in the pelvis at 3T-A feasibility study.

    Science.gov (United States)

    Thian, Yee Liang; Xie, Wanying; Porter, David A; Weileng Ang, Bertrand

    2014-04-01

    Diffusion-weighted imaging (DWI) of the pelvis at 3T is prone to artifacts that diminish the image quality. Readout-segmented echo-planar imaging (RS-EPI) is a new DWI technique that can reduce the artifacts associated with standard single-shot echo-planar imaging (SS-EPI) DWI. The purpose of this study was to evaluate the feasibility and image quality of RS-EPI in pelvic DWI compared to SS-EPI on a 3T imaging system. Thirty patients underwent pelvic DWI on a 3T scanner with SS-EPI and RS-EPI techniques. Two blinded readers independently assessed each set of images for geometric distortion, image blurring, ghosting artifacts, lesion conspicuity, and overall image quality on a 7-point scale. Qualitative image scores were compared using paired Wilcoxon signed rank test. Interreader correlation was assessed by Spearman rank correlation. Geometric distortion, imaging blurring, ghosting artifacts, lesion conspicuity, and overall image quality were rated significantly better by both readers for RS-EPI technique (P parameters). There was moderate-high correlation between the readers (r = 0.649-0.752) for all parameters apart from lesion conspicuity (r = 0.351). Both readers preferred the RS-EPI set of DWI images in most of the cases (reader 1: 0.87, 95% CI 0.74-0.99; reader 2: 0.77, 95% CI 0.61-0.93). Mean difference and limits of agreement between apparent diffusion coefficient (ADC) values obtained from the two methods were 0.01 (-0.08, 0.10) × 10(-3) mm(2)/s. RS-EPI DWI images showed improved image quality compared to SS-EPI technique at 3T. RS-EPI is a feasible technique in the pelvis for producing high-resolution DWI. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

  16. Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants

    Energy Technology Data Exchange (ETDEWEB)

    Bruine, Francisca T. de; Berg-Huysmans, Annette A. van den; Buchem, Mark A. van; Grond, Jeroen van der [Leiden University Medical Center, Department of Radiology, PO Box 9600, Leiden (Netherlands); Steggerda, Sylke J.; Leijser, Lara M.; Rijken, Monique [Leiden University Medical Center, Department of Pediatrics, subdivision of Neonatology, Leiden (Netherlands); Wezel-Meijler, Gerda van [Leiden University Medical Center, Department of Pediatrics, subdivision of Neonatology, Leiden (Netherlands); Isala Hospital, Department of Neonatology, Zwolle (Netherlands)

    2014-03-15

    Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain. The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age <32 weeks) detected by T2*-W gradient echo MRI to white matter injury and neurodevelopmental outcome at 2 years. In 101 preterm infants, presence and location of hemosiderin were assessed on T2*-W gradient echo MRI performed around term-equivalent age (range: 40-60 weeks). White matter injury was defined as the presence of >6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome. In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P < 0.001) and cysts (P < 0.001) at term-equivalent age, and with a lower psychomotor development index (PDI) (P=0.02) at 2 years. After correcting for known confounders (gestational age, gender, intrauterine growth retardation and white matter injury), the correlation with PDI was no longer significant. The clinical importance of detecting small hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome. (orig.)

  17. 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 Impact factor: 2.225, year: 2016

  18. Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants.

    Science.gov (United States)

    de Bruïne, Francisca T; Steggerda, Sylke J; van den Berg-Huysmans, Annette A; Leijser, Lara M; Rijken, Monique; van Buchem, Mark A; van Wezel-Meijler, Gerda; van der Grond, Jeroen

    2014-03-01

    Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain. The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age hemosiderin were assessed on T2*-W gradient echo MRI performed around term-equivalent age (range: 40-60 weeks). White matter injury was defined as the presence of >6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome. In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome.

  19. WOLD decomposition of the backscatter echo in ultrasound images of soft tissue organs.

    Science.gov (United States)

    Cohen, F S; Georgiou, G; Halpern, E J

    1997-01-01

    Deals with a method of detecting and estimating the scatterer spacing between the regularly spaced resolvable coherent scatterers in tissue. Scatterer spacing has been successfully used in classifying tissue structure, in differentiating between normal and cirrhotic liver, and in detecting diffuse liver disease. This paper presents a WOLD decomposition of the radio frequency (RF) field into its diffused and coherent components from which maximum likelihood estimates (MLE) or minimum mean square error (MMSE) estimates of the scattering spacing are easily computed. The MLE are efficient and for relatively long record are unbiased. They result in accurate estimates in low signal-to-noise (SNR) ratios. Unfortunately, they require nonlinear minimization and knowledge of the probability density associated with the RF backscatter echo. The MMSE estimates, on the other hand, are computationally simple, yield unique closed form solutions, do not require a-priori knowledge of the probability distribution function of the backscatter echo, and result in accurate estimates in low SNR ratios. This paper also presents an unbiased decision rule to detect whether or not an RF echo exhibits any specular scattering relative to the wavelength of the interrogating ultrasonic pulse. The approach has been tried on simulations as well as on in-vivo scans of liver data, and appears to perform well.

  20. Isotropic 3D fast spin-echo imaging versus standard 2D imaging at 3.0 T of the knee - image quality and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Ristow, Oliver; Steinbach, Lynne; Sabo, Gregory; Krug, Roland; Huber, Markus; Rauscher, Isabel; Ma, Ben [University of California San Francisco, Department of Radiology, San Francisco, CA (United States); Link, Thomas M. [University of California San Francisco, Department of Radiology, San Francisco, CA (United States); University of California, Department of Radiology, San Francisco, 400 Parnassus Ave., A 367, Box 0628, San Francisco, CA (United States)

    2009-05-15

    The objective of this study was to compare a newly developed fat-saturated intermediate-weighted (IM-w) 3D fast spin-echo (FSE) sequence with standard 2D IM-w FSE sequences regarding image quality and diagnostic performance in assessing abnormal findings of the knee. MR imaging was performed at 3.0 T in 50 patients. Images were assessed independently by three radiologists. Image quality was rated significantly higher (p < 0.05) for the 2D versus the 3D FSE sequences. Sensitivity for cartilage lesions was slightly higher for the 3D sequence, but specificity was lower. Low contrast objects were better visualized with 2D sequences, while high contrast objects were better shown with the 3D sequence. Confidence scores were higher for 2D than for 3D sequences, but differences were not significant. In conclusion, isotropic 3D FSE IM-w imaging may enhance standard knee MRI by increased visualization of high contrast lesions; however, 3D FSE image quality was lower. (orig.)

  1. 3-D imaging of the CNS.

    Science.gov (United States)

    Runge, V M; Gelblum, D Y; Wood, M L

    1990-01-01

    3-D gradient echo techniques, and in particular FLASH, represent a significant advance in MR imaging strategy allowing thin section, high resolution imaging through a large region of interest. Anatomical areas of application include the brain, spine, and extremities, although the majority of work to date has been performed in the brain. Superior T1 contrast and thus sensitivity to the presence of GdDTPA is achieved with 3-D FLASH when compared to 2-D spin echo technique. There is marked arterial and venous enhancement following Gd DTPA administration on 3-D FLASH, a less common finding with 2-D spin echo. Enhancement of the falx and tentorium is also more prominent. From a single data acquisition, requiring less than 11 min of scan time, high resolution reformatted sagittal, coronal, and axial images can obtained in addition to sections in any arbitrary plane. Tissue segmentation techniques can be applied and lesions displayed in three dimensions. These results may lead to the replacement of 2-D spin echo with 3-D FLASH for high resolution T1-weighted MR imaging of the CNS, particularly in the study of mass lesions and structural anomalies. The application of similar T2-weighted gradient echo techniques may follow, however the signal-to-noise ratio which can be achieved remains a potential limitation.

  2. Appearances of diffuse excessive high signal intensity (DEHSI) on MR imaging following preterm birth

    Energy Technology Data Exchange (ETDEWEB)

    Hart, Anthony R. [Sheffield Teaching Hospital NHS Foundation Trust, Department of Neonatology, Jessop Wing, Sheffield (United Kingdom); University of Sheffield, Academic Unit of Radiology, Royal Hallamshire Hospital, Sheffield (United Kingdom); University of Sheffield, Department of Academic Radiology, Royal Hallamshire Hospital, Sheffield (United Kingdom); Smith, Michael F. [Sheffield Teaching Hospital NHS Foundation Trust, Department of Neonatology, Jessop Wing, Sheffield (United Kingdom); Rigby, Alan S. [University of Hull, Postgraduate Medical Centre, Castle Hill Hospital, East Yorkshire (United Kingdom); Wallis, Lauren I.; Whitby, Elspeth H. [University of Sheffield, Academic Unit of Radiology, Royal Hallamshire Hospital, Sheffield (United Kingdom)

    2010-08-15

    Diffuse damage to the periventricular white matter has recently been suggested to be a cause of the cognitive deficits seen following preterm birth. It is unclear whether this form of injury can be visualised on MR imaging, but one group has described diffuse excessive high signal intensity (DEHSI) as a possible form of diffuse white matter injury. This finding is dependant on window imaging and the subjective assessment of the reviewer, but little data have been published on the degree of subjectivity on its appearance among raters. To assess the subjectivity of DEHSI on conventional and ultrafast T2-weighted MR imaging following preterm birth. An observational study of 40 preterm infants who had MR imaging of the brain around term-equivalent age, including conventional fast spin-echo (FSE) and ultrafast single-shot fast spin-echo (SSFSE) T2-weighted sequences in the axial plane. Images were anonymised and scored twice by four observers for the presence of DEHSI. Inter- and intra-observer agreement were calculated. Sixty-five percent of conventional and 100% of the ultrafast images were of diagnostic quality. DEHSI was noted in between 0% and 69.2% of conventional images and 27.5-90% of the ultrafast images. Inter- and intra-observer agreement ranged from none to moderate. The visual appearances of DEHSI on conventional FSE and ultrafast SSFSE T2-W images are highly subjective, limiting its clinical application. (orig.)

  3. Interim heterogeneity changes measured using entropy texture features on T2-weighted MRI at 3.0 T are associated with pathological response to neoadjuvant chemotherapy in primary breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Shelley; Lerski, Richard [Ninewells Hospital and Medical School, Department of Medical Physics, Dundee (United Kingdom); Purdie, Colin [Ninewells Hospital and Medical School, Department of Pathology, Dundee (United Kingdom); Michie, Caroline [Ninewells Hospital and Medical School, Department of Oncology, Dundee (United Kingdom); Evans, Andrew; Vinnicombe, Sarah [University of Dundee, Division of Imaging and Technology, Ninewells Hospital and Medical School, Dundee (United Kingdom); Johnston, Marilyn [Ninewells Hospital and Medical School, Department of Clinical Radiology, Dundee (United Kingdom); Thompson, Alastair M. [University of Texas MD Anderson Cancer Centre, Department of Breast Surgical Oncology, Houston, TX (United States)

    2017-11-15

    To investigate whether interim changes in hetereogeneity (measured using entropy features) on MRI were associated with pathological residual cancer burden (RCB) at final surgery in patients receiving neoadjuvant chemotherapy (NAC) for primary breast cancer. This was a retrospective study of 88 consenting women (age: 30-79 years). Scanning was performed on a 3.0 T MRI scanner prior to NAC (baseline) and after 2-3 cycles of treatment (interim). Entropy was derived from the grey-level co-occurrence matrix, on slice-matched baseline/interim T2-weighted images. Response, assessed using RCB score on surgically resected specimens, was compared statistically with entropy/heterogeneity changes and ROC analysis performed. Association of pCR within each tumour immunophenotype was evaluated. Mean entropy percent differences between examinations, by response category, were: pCR: 32.8%, RCB-I: 10.5%, RCB-II: 9.7% and RCB-III: 3.0%. Association of ultimate pCR with coarse entropy changes between baseline/interim MRI across all lesions yielded 85.2% accuracy (area under ROC curve: 0.845). Excellent sensitivity/specificity was obtained for pCR prediction within each immunophenotype: ER+: 100%/100%; HER2+: 83.3%/95.7%, TNBC: 87.5%/80.0%. Lesion T2 heterogeneity changes are associated with response to NAC using RCB scores, particularly for pCR, and can be useful across all immunophenotypes with good diagnostic accuracy. (orig.)

  4. Magnetic resonance fingerprinting using echo-planar imaging: Joint quantification of T1 and T2∗ relaxation times.

    Science.gov (United States)

    Rieger, Benedikt; Zimmer, Fabian; Zapp, Jascha; Weingärtner, Sebastian; Schad, Lothar R

    2017-11-01

    To develop an implementation of the magnetic resonance fingerprinting (MRF) paradigm for quantitative imaging using echo-planar imaging (EPI) for simultaneous assessment of T1 and T2∗. The proposed MRF method (MRF-EPI) is based on the acquisition of 160 gradient-spoiled EPI images with rapid, parallel-imaging accelerated, Cartesian readout and a measurement time of 10 s per slice. Contrast variation is induced using an initial inversion pulse, and varying the flip angles, echo times, and repetition times throughout the sequence. Joint quantification of T1 and T2∗ is performed using dictionary matching with integrated B1+ correction. The quantification accuracy of the method was validated in phantom scans and in vivo in 6 healthy subjects. Joint T1 and T2∗ parameter maps acquired with MRF-EPI in phantoms are in good agreement with reference measurements, showing deviations under 5% and 4% for T1 and T2∗, respectively. In vivo baseline images were visually free of artifacts. In vivo relaxation times are in good agreement with gold-standard techniques (deviation T1 : 4 ± 2%, T2∗: 4 ± 5%). The visual quality was comparable to the in vivo gold standard, despite substantially shortened scan times. The proposed MRF-EPI method provides fast and accurate T1 and T2∗ quantification. This approach offers a rapid supplement to the non-Cartesian MRF portfolio, with potentially increased usability and robustness. Magn Reson Med 78:1724-1733, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  5. Cartilaginous End Plates: Quantitative MR Imaging with Very Short Echo Times—Orientation Dependence and Correlation with Biochemical Composition

    Science.gov (United States)

    Han, Misung; Krug, Roland; Lotz, Jeffrey C.

    2015-01-01

    Purpose To measure the T2* of the human cartilaginous end plate by using magnetic resonance (MR) imaging with very short echo times and to determine the effect of the orientation of the end plate on T2* and on relationships between T2* and biochemical composition. Materials and Methods This study was exempt from institutional review board approval, and informed consent was not required. Thirty-four samples of three cadaveric lumbar spines (from subjects who died at ages 51, 57, and 66 years) containing cartilaginous end plates and subchondral bone were prepared. Samples were imaged with a 3-T imager for T2* quantification by using a three-dimensional very short echo time sequence (repetition time msec/echo times msec, 30/0.075, 2, 5, 12, 18). Samples were imaged with the end plate at three orientations with respect to the constant magnetic induction field: 0°, 54.7°, and 90°. After imaging, the cartilage was assayed for its water, glycosaminoglycan, and collagen content. Pearson correlations were used to investigate the effect of orientation on the relationships between T2* and biochemical composition. Results T2* was significantly longer when measured at an orientation of 54.7° (21.8 msec ± 2.8 [± standard error of the mean]) than at 0° (10.0 msec ± 0.7, P < .001) or 90° (9.9 msec ± 0.4, P < .001). At 54.7°, T2* was highly correlated with glycosaminoglycan content (r = 0.85, P < .001), the collagen-to-glycosaminoglycan ratio (r = −0.79, P < .001), and water content (r = 0.62, P = .02); at 0° and 90°, there were no significant differences in these relationships, with a minimum P value of .19. Conclusion T2* evaluation can allow noninvasive estimation of the degeneration of the cartilaginous end plate; however, the accuracy of T2*-based estimates of biochemical composition depends on the orientation of the end plate. © RSNA, 2014 PMID:25302832

  6. Parotid fat contents in healthy subjects evaluated with iterative decomposition with echo asymmetry and least squares fat-water separation.

    Science.gov (United States)

    Chang, Hing-Chiu; Juan, Chun-Jung; Chiu, Hui-Chu; Liu, Yi-Jui; Cheng, Cheng-Chieh; Chiu, Su-Chin; Chen, Cheng-Yu; Huang, Guo-Shu; Chung, Hsiao-Wen

    2013-06-01

    To evaluate the effectiveness of three fat measurement methods for parotid glands in healthy subjects, with or without metallic dental implants. The institutional review board approved this study, with informed consent obtained from 114 volunteers undergoing magnetic resonance (MR) imaging at 1.5 T. Fat-saturated (FS) and non-fat-saturated (NFS) fast spin-echo T1-weighted imaging (T1 method), FS and NFS T2-weighted periodically rotated overlapping parallel lines with enhanced reconstruction fast spin-echo imaging (T2 method), and gradient-echo imaging with fat-water separation using iterative decomposition with echo asymmetry and least squares (IDEAL) method were used to derive parotid fat contents. Two raters examined the homogeneity of fat saturation to determine whether parotid fat quantification was successful, with the success rate in the 114 subjects recorded for each protocol. In subjects whose fat quantification was successful with all three imaging methods, linear regression was used to analyze the correlation between any pair of the three parotid fat content measurement methods. Success rates in parotid fat measurements by using T1, T2, and IDEAL methods were 87.7% (100 of 114), 87.7% (100 of 114), and 100% (114 of 114), respectively. The means of measured parotid fat contents revealed significant differences (P measurement methods. The parotid fat contents measured with the three methods were significantly correlated with each other between any pair of combinations. The IDEAL method provided a high success rate for parotid fat measurements, even in subjects with metallic dental implants.

  7. Reconstruction strategy for echo planar spectroscopy and its application to partially undersampled imaging

    DEFF Research Database (Denmark)

    Hanson, L G; Schaumburg, K; Paulson, O B

    2000-01-01

    The most commonly encountered form of echo planar spectroscopy involves oscillating gradients in one spatial dimension during readout. Data are consequently not sampled on a Cartesian grid. A fast gridding algorithm applicable to this particular situation is presented. The method is optimal, i...... or fewer interleaves per acquisition. The method is of particular interest when large bandwidths are needed (e.g., for high field scanning) and for scanners with limited gradient performance. The unavoidable artifacts resulting from undersampling are demonstrated to be acceptable for spectroscopy with long...

  8. 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

    2017-12-05

    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.

  9. On the relationship between aspect sensitivity, wave activity, andmultiple scattering centers of mesosphere summer echoes: a case study using coherent radar imaging

    Directory of Open Access Journals (Sweden)

    J.-S. Chen

    2004-03-01

    Full Text Available A mesosphere-summer-echo layer, observed by the OSWIN VHF radar (54.1°N, 11.8°E with vertical and 7° oblique radar beams, was examined using the method of coherent radar imaging (CRI. We disclosed the echo events having multiple scattering centers (MSC in the radar volume by means of the high angular resolution of the CRI technique and found that the MSC events occurred more frequently in the upper portion of the echo layer. More examinations showed that the characteristics were different between the upper and lower portions of the layer. For example, the differences in echo power between vertical and oblique beams changed mostly from positive to negative along the increase of altitude, and strong turbulent echoes were seen in the upper portion of the layer. These observations indicate that the aspect sensitivity of the echoes became less and less with the increase of altitude. Moreover, the scattering centers of the echoes were close to zenith for the lower portion of the layer but were usually several degrees from the zenith for the upper portion of the layer. Observable wave-like variation in the scattering center was also seen in the upper part of the layer. Based on these features, we drew some conclusions for this case study: (a the MSC events might result from the slanted layer/anisotropic structure tilted by short-wave activities, (b the tilt angle of the layer structure could be 6°–10°, causing the echo power received by the 7° oblique beam was larger than or comparable to that received by the vertical beam, and (c short-wave activities not only tilted the layer structure, but also induced isotropic irregularities.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics. Radio science (interferometry; instruments and techniques

  10. Multi-echo EPI of human fear conditioning reveals improved BOLD detection in ventromedial prefrontal cortex.

    Science.gov (United States)

    Fernandez, Brice; Leuchs, Laura; Sämann, Philipp G; Czisch, Michael; Spoormaker, Victor I

    2017-08-01

    Standard T2(*) weighted functional magnetic resonance imaging (fMRI) performed with echo-planar imaging (EPI) suffers from signal loss in the ventromedial prefrontal cortex (vmPFC) due to macroscopic field inhomogeneity. However, this region is of special interest to affective neuroscience and psychiatry. The Multi-echo EPI (MEPI) approach has several advantages over EPI but its performance against EPI in the vmPFC has not yet been examined in a study with sufficient statistical power using a task specifically eliciting activity in this region. We used a fear conditioning task with MEPI to compare the performance of MEPI and EPI in vmPFC and control regions in 32 healthy young subjects. We analyzed activity associated with short (12ms), standard (29ms) and long (46ms) echo times, and a voxel-wise combination of these three echo times. Behavioral data revealed successful differentiation of the conditioned versus safety stimulus; activity in the vmPFC was shown by the contrast "safety stimulus > conditioned stimulus" as in previous research and proved significantly stronger with the combined MEPI than standard single-echo EPI. Then, we aimed to demonstrate that the additional cluster extent (ventral extension) detected in the vmPFC with MEPI reflects activation in a relevant cluster (i.e., not just non-neuronal noise). To do this, we used resting state data from the same subjects to show that the time-course of this region was both connected to bilateral amygdala and the default mode network. Overall, we demonstrate that MEPI (by means of the weighted sum combination approach) outperforms standard EPI in vmPFC; MEPI performs always at least as good as the best echo time for a given brain region but provides all necessary echo times for an optimal BOLD sensitivity for the whole brain. This is relevant for affective neuroscience and psychiatry given the critical role of the vmPFC in emotion regulation. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Multiple-echo diffusion tensor acquisition technique (MEDITATE) on a 3T clinical scanner.

    Science.gov (United States)

    Baete, Steven H; Cho, Gene; Sigmund, Eric E

    2013-11-01

    This article describes the concepts and implementation of an MRI method, the multiple-echo diffusion tensor acquisition technique (MEDITATE), which is capable of acquiring apparent diffusion tensor maps in two scans on a 3T clinical scanner. In each MEDITATE scan, a set of RF pulses generates multiple echoes, the amplitudes of which are diffusion weighted in both magnitude and direction by a pattern of diffusion gradients. As a result, two scans acquired with different diffusion weighting strengths suffice for accurate estimation of diffusion tensor imaging (DTI) parameters. The MEDITATE variation presented here expands previous MEDITATE approaches to adapt to the clinical scanner platform, such as exploiting longitudinal magnetization storage to reduce T2 weighting. Fully segmented multi-shot Cartesian encoding is used for image encoding. MEDITATE was tested on isotropic (agar gel), anisotropic diffusion phantoms (asparagus) and in vivo skeletal muscle in healthy volunteers with cardiac gating. Comparisons of accuracy were performed with standard twice-refocused spin echo (TRSE) DTI in each case and good quantitative agreement was found between diffusion eigenvalues, mean diffusivity and fractional anisotropy derived from TRSE DTI and from the MEDITATE sequence. Orientation patterns were correctly reproduced in both isotropic and anisotropic phantoms, and approximately for in vivo imaging. This illustrates that the MEDITATE method of compressed diffusion encoding is feasible on the clinical scanner platform. With future development and employment of appropriate view-sharing image encoding, this technique may be used in clinical applications requiring time-sensitive acquisition of DTI parameters such as dynamical DTI in muscle. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Proton MR spectroscopic imaging of basal ganglia and thalamus in neurofibromatosis type 1: correlation with T2 hyperintensities

    Energy Technology Data Exchange (ETDEWEB)

    Barbier, Charlotte; Barantin, Laurent [CHRU and Tours University, Department of Neuroradiology, Tours (France); Chabernaud, Camille [CHRU and Tours University et INSERM U930, Department of Pediatric Neurology, Tours (France); Bertrand, Philippe [CHRU and Tours University, Department of Radiology, Tours (France); Sembely, Catherine; Sirinelli, Dominique [CHRU and Tours University, Department of Pediatric Radiology, Tours (France); Castelnau, Pierre [CHRU and Tours University et INSERM U930, Department of Pediatric Neurology, Tours (France); CHRU and Tours University et INSERM U930, Tours (France); Neurologie Pediatrique and INSERM U930, Hopital d' Enfants Gatien de Clocheville, Tours cedex 09 (France); Cottier, Jean-Philippe [CHRU and Tours University, Department of Neuroradiology, Tours (France); CHRU and Tours University et INSERM U930, Tours (France)

    2011-02-15

    Neurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called ''unidentified bright objects'' (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images. Magnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO- group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained. Patients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO. Multivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions. (orig.)

  13. 3D printed phantoms mimicking cortical bone for the assessment of ultrashort echo time magnetic resonance imaging.

    Science.gov (United States)

    Rai, Robba; Manton, David; Jameson, Michael G; Josan, Sonal; Barton, Michael B; Holloway, Lois C; Liney, Gary P

    2018-02-01

    Human cortical bone has a rapid T2∗ decay, and it can be visualized using ultrashort echo time (UTE) techniques in magnetic resonance imaging (MRI). These sequences operate at the limits of gradient and transmit-receive signal performance. Development of multicompartment anthropomorphic phantoms that can mimic human cortical bone can assist with quality assurance and optimization of UTE sequences. The aims of this study were to (a) characterize the MRI signal properties of a photopolymer resin that can be 3D printed, (b) develop multicompartment phantoms based on the resin, and (c) demonstrate the feasibility of using these phantoms to mimic human anatomy in the assessment of UTE sequences. A photopolymer resin (Prismlab China Ltd, Shanghai, China) was imaged on a 3 Tesla MRI system (Siemens Skyra) to characterize its MRI properties with emphasis on T2∗ signal and longevity. Two anthropomorphic phantoms, using the 3D printed resin to simulate skeletal anatomy, were developed and imaged using UTE sequences. A skull phantom was developed and used to assess the feasibility of using the resin to develop a complex model with realistic morphological human characteristics. A tibia model was also developed to assess the suitability of the resin at mimicking a simple multicompartment anatomical model and imaged using a three-dimensional UTE sequence (PETRA). Image quality measurements of signal-to-noise ratio (SNR) and contrast factor were calculated and these were compared to in vivo values. The T2∗ and T1 (mean ± standard deviation) of the photopolymer resin was found to be 411 ± 19 μs and 74.39 ± 13.88 ms, respectively, and demonstrated no statistically significant change during 4 months of monitoring. The resin had a similar T2∗ decay to human cortical bone; however, had lower T1 properties. The bone water concentration of the resin was 59% relative to an external water reference phantom, and this was higher than in vivo values reported for human cortical

  14. Graffiti echoes

    National Research Council Canada - National Science Library

    Purcell, John

    2014-01-01

      Graffiti and street art are a kind of "voice" of the city. From the street-tagged neighborhoods to the grand billboards high in the air, graffiti seems to always echo what is happening in Los Angeles...

  15. Improved in vivo detection of cortical lesions in multiple sclerosis using double inversion recovery MR imaging at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Birgit; Traeber, Frank; Willinek, Winfried A.; Schild, Hans H. [University Hospital of Bonn, Department of Radiology, Bonn (Germany); Schmidt, Stephan [Neurologische Gemeinschaftspraxis Bonn, Bonn (Germany); Lukas, Carsten [University of Bochum, Department of Diagnostic and Interventional Radiology, St. Josef Hospital, Bochum (Germany); VU University Medical Center, Department of Radiology, MS Center Amsterdam, Amsterdam (Netherlands); Gieseke, Juergen [University Hospital of Bonn, Department of Radiology, Bonn (Germany); Philips Medical Systems, Hamburg (Germany); Knol, Dirk L. [VU University Medical Center, Department of Epidemiology and Biostatistics, Amsterdam (Netherlands); Geurts, Jeroen J.G. [VU University Medical Center, Department of Radiology, MS Center Amsterdam, Amsterdam (Netherlands); VU University Medical Center, Department of Pathology, Amsterdam (Netherlands); Barkhof, Frederik; Wattjes, Mike P. [VU University Medical Center, Department of Radiology, MS Center Amsterdam, Amsterdam (Netherlands)

    2010-07-15

    To investigate the impact of a higher magnetic field strength of 3 Tesla (T) on the detection rate of cortical lesions in multiple sclerosis (MS) patients, in particular using a dedicated double inversion recovery (DIR) pulse sequence. Thirty-four patients with clinically isolated syndromes or definite MS were included. All patients underwent magnetic resonance imaging (MRI) at 1.5 T and 3 T, including T2-weighted turbo spin echo (TSE), fluid-attenuated inversion recovery (FLAIR) and DIR sequences. All images were analysed for focal lesions categorised according to their anatomical location. The total number of detected lesions was higher at 3 T across all pulse sequences. We observed significantly higher numbers of lesions involving the cortex at 3 T using a DIR sequence. DIR at 3 T showed 192% more pure intracortical (p < 0.001) and 30% more mixed grey matter-white matter lesions (p = 0.008). No significant increase in cortical lesions could be detected on the FLAIR and T2-weighted images. Using the T2-weighted and FLAIR sequences, significantly more lesions could be detected at 3 T in the infratentorial, periventricular and juxtacortical white matter. DIR brain MR imaging at 3 T substantially improves the sensitivity of the detection of cortical lesions compared with the standard magnetic field strength of 1.5 T. (orig.)

  16. Dobutamine stress tagging and gradient-echo imaging for detection of coronary heart disease at 3 T.

    Science.gov (United States)

    Thomas, D; Meyer, C; Strach, K; Naehle, C P; Mazraeh, J; Gampert, T; Schild, H H; Sommer, T

    2011-01-01

    The purpose of this study was to evaluate the feasibility and diagnostic accuracy of a combined spoiled gradient-echo (sGRE) and tagged gradient-echo (SPAMM-GRE) protocol for detection of coronary artery disease (CAD) during high-dose dobutamine stress at 3 T. The study protocol was approved by the local ethics committee. For stress testing, a standard high-dose dobutamine protocol was employed. Image quality at the highest stress level and diagnostic accuracy of the sGRE and SPAMM-GRE sequences were compared. The final study population consisted of 37 patients. The mean image quality score was 2.6±0.6 for the sGRE sequence and 2.4±0.6 for the SPAMM-GRE sequence (p>0.05). Sensitivity, specificity and diagnostic accuracy were 0.81, 0.86, 0.84 and 0.88, 0.86, 0.86 for the sGRE and SPAMM-GRE, respectively. In three cases with new wall motion abnormalities (WMAs), detected by sGRE and SPAMM-GRE, WMAs were detected at a lower stress level by tagging. The combined sGRE and SPAMM-GRE high-dose dobutamine protocol at 3 T is feasible and delivers good diagnostic accuracy. Tagging increases the sensitivity of high-dose dobutamine stress testing for detection of CAD and may allow for detection of new WMAs at lower stress levels compared with sGRE alone.

  17. 3D spatially encoded and accelerated TE-averaged echo planar spectroscopic imaging in healthy human brain.

    Science.gov (United States)

    Iqbal, Zohaib; Wilson, Neil E; Thomas, M Albert

    2016-03-01

    Several different pathologies, including many neurodegenerative disorders, affect the energy metabolism of the brain. Glutamate, a neurotransmitter in the brain, can be used as a biomarker to monitor these metabolic processes. One method that is capable of quantifying glutamate concentration reliably in several regions of the brain is TE-averaged (1) H spectroscopic imaging. However, this type of method requires the acquisition of multiple TE lines, resulting in long scan durations. The goal of this experiment was to use non-uniform sampling, compressed sensing reconstruction and an echo planar readout gradient to reduce the scan time by a factor of eight to acquire TE-averaged spectra in three spatial dimensions. Simulation of glutamate and glutamine showed that the 2.2-2.4 ppm spectral region contained 95% glutamate signal using the TE-averaged method. Peak integration of this spectral range and home-developed, prior-knowledge-based fitting were used for quantitation. Gray matter brain phantom measurements were acquired on a Siemens 3 T Trio scanner. Non-uniform sampling was applied retrospectively to these phantom measurements and quantitative results of glutamate with respect to creatine 3.0 (Glu/Cr) ratios showed a coefficient of variance of 16% for peak integration and 9% for peak fitting using eight-fold acceleration. In vivo scans of the human brain were acquired as well and five different brain regions were quantified using the prior-knowledge-based algorithm. Glu/Cr ratios from these regions agreed with previously reported results in the literature. The method described here, called accelerated TE-averaged echo planar spectroscopic imaging (TEA-EPSI), is a significant methodological advancement and may be a useful tool for categorizing glutamate changes in pathologies where affected brain regions are not known a priori. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Dynamic pelvic floor imaging: MRI techniques and imaging parameters.

    Science.gov (United States)

    Reiner, Caecilia S; Weishaupt, Dominik

    2013-10-01

    Magnetic resonance imaging (MRI) is an excellent tool to understand the complex anatomy of the pelvic floor and to assess pelvic floor disorders. MRI enables static and dynamic imaging of the pelvic floor. Using static T2-weighted sequences the morphology of the pelvic floor can be visualized in great detail. A rapid half-Fourier T2-weighted, balanced steady state free precession, or gradient-recalled echo sequence are used to obtain sagittal images while the patient is at rest, during pelvic squeeze, during pelvic strain and to document the evacuation process. On these images the radiologist identifies the pubococcygeal line (PCL) (which represents the level of the pelvic floor). In normal findings, the base of the anterior and the middle compartment are above the PCL at rest, and the pelvic floor elevates during contraction. During straining the pelvic floor muscles should relax and the pelvic floor descends normally less than 3 cm below the PCL. Pelvic floor MRI based on the static and dynamic MRI sequences allows for the detection and characterization of a vast array of morphologic and functional pelvic floor disorders. In this review, we focus on technical aspects of static and dynamic pelvic floor MRI.

  19. A SEmi-Adiabatic matched-phase spin echo (SEAMS) PINS pulse-pair for B1 -insensitive simultaneous multislice imaging.

    Science.gov (United States)

    Feldman, Rebecca E; Islam, Haisam M; Xu, Junqian; Balchandani, Priti

    2016-02-01

    Simultaneous multislice (SMS) imaging is a powerful technique that can reduce image acquisition time for anatomical, functional, and diffusion weighted magnetic resonance imaging. At higher magnetic fields, such as 7 Tesla, increased radiofrequency (RF) field inhomogeneity, power deposition, and changes in relaxation parameters make SMS spin echo imaging challenging. We designed an adiabatic 180° Power Independent of Number of Slices (PINS) pulse and a matched-phase 90° PINS pulse to generate a SEmi-Adiabatic Matched-phase Spin echo (SEAMS) PINS sequence to address these issues. We used the adiabatic Shinnar Le-Roux (SLR) algorithm to generate a 180° pulse. The SLR polynomials for the 180° pulse were then used to create a matched-phase 90° pulse. The pulses were sub-sampled to produce a SEAMS PINS pulse-pair and the performance of this pulse-pair was validated in phantoms and in vivo. Simulations as well as phantom and in vivo results, demonstrate multislice capability and improved B1 -insensitivity of the SEAMS PINS pulse-pair when operating at RF amplitudes of up to 40% above adiabatic threshold. The SEAMS PINS approach presented here achieves multislice spin echo profiles with improved B1 -insensitivity when compared with a conventional spin echo. © 2015 Wiley Periodicals, Inc.

  20. Magnetic resonance imaging of the brain in congenital rubella virus and cytomegalovirus infections

    Energy Technology Data Exchange (ETDEWEB)

    Sugita, K.; Ando, M.; Makino, M.; Takanashi, J.; Fujimoto, N.; Niimi, H. (Chiba Univ. School of Medicine (Japan). Dept. of Pediatrics)

    1991-06-01

    Two children with congenital rubella virus and six with cytomegalovirus (CMV) infections, were examined by magnetic resonance (MR) and CT. Cranial MR imaging (MRI) with T2-weighted spin-echo (SE) and inversion recovery (IR) sequences demonstrated the following: Periventricular hyperintensity (4), subcortical hyperintensity (5), delayed myelination (4), oligo/pachygyria (2), cerebellar hypoplasia (2). This study showed that the more-disabled children had more marked abnormal MRI findings. MRI was more effective in the detection of parenchymal lesion than was CT, although intraventricular calcification was better visualized with CT. (orig.).

  1. MR urography (MRU of non-dilated ureter with diuretic administration: Static fluid 2D FSE T2-weighted versus 3D gadolinium T1-weighted GE excretory MR

    Directory of Open Access Journals (Sweden)

    C. Roy

    2014-01-01

    Conclusion: T2-weighted MRU with multiple orientations and diuretic is sufficient to identify the non-dilated ureter. It offers information on ureteral peristaltism. It can be suggested that this sequence is able to detect an initial obstruction before hydronephrosis occurs.

  2. Echo-lucency of computerized ultrasound images of carotid atherosclerotic plaques are associated with increased levels of triglyceride-rich lipoproteins as well as increased plaque lipid content

    DEFF Research Database (Denmark)

    Grønholdt, Marie-Louise Moes; Nordestgaard, Børge G.; Weibe, Brit M.

    1998-01-01

    Background-Echo-lucency of carotid atherosclerotic plaques on computerized ultrasound B-mode images has been associated with a high incidence of brain infarcts as evaluated on CT scans. We tested the hypotheses that triglyceride-rich lipoproteins in the fasting and postprandial state predict...... computer processed to yield a measure of echogenicity (gray-scale level). Lipoproteins were measured before and hourly ibr 4 hours after a standardized fatty meal, A subgroup of 58 patients underwent endarterectomy. On linear regression analysis, echu-lucency (low gray-scale level) was associated......-rich lipoproteins predict echo-lucency of carotid plaques, which is associated with increased plaque Lipid content, Because echo-lucency has been associated with a high incidence of brain infarcts on CT scans, triglyceride-rich lipoproteins may predict a plaque type particularly vulnerable to rupture....

  3. Relationship between the trochlear groove angle and patellar cartilage morphology defined by 3D spoiled gradient-echo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Yuko; Tokuda, Osamu; Matsunaga, Naofumi [Yamaguchi University Graduate School of Medicine, Department of Radiology, Yamaguchi (Japan); Fukuda, Kouji [Shunan Memorial Hospital, Division of Radiological Technology, Yamaguchi (Japan); Shiraishi, Gen; Motomura, Tetsuhisa [Shunan Memorial Hospital, Department of Orthopedics Surgery, Yamaguchi (Japan); Kimura, Motoichi [Customer Application Gr., GE Healthcare MR Sales and Marketing Department, Osaka (Japan)

    2012-05-15

    To examine whether the femoral trochlear groove angle (TGA) is a determinant of the patellar cartilage volume and patellar cartilage damage. Patellar cartilage was evaluated by MR imaging in 66 patients (22 males and 44 females) with knee pain. Fat-suppressed 3D spoiled gradient-echo images were used to calculate the cartilage volume and to grade the cartilage damage. The proximal and distal TGAs were measured from axial PD-weighted FSE MR images with fat suppression. For every increase in the TGA at the distal femur, the patellar cartilage volume was significantly increased by 6.07 x 10{sup -3} cm{sup 3} (95% CI: 1.27 x 10{sup -3}, 10.9 x 10{sup -3}) after adjustment for age, gender, and patellar bone volume (P < 0.05). The MR grade of medial patellar cartilage damage progressed as the distal TGA became narrower, although there was no significant correlation between the distal TGA and the MR grading of patellar cartilage damage. A more flattened distal TGA was associated with increased patellar cartilage volume. However, there was no association between TGA and patellar cartilage defects. (orig.)

  4. A comparative quantitative analysis of magnetic susceptibility artifacts in echo planar and PROPELLER diffusion-weighted images

    Science.gov (United States)

    Cho, Jae-Hwan; Lee, Hae-Kag; Yang, Han-Joon; Lee, Gui-Won; Park, Yong-Soon; Chung, Woon-Kwan

    2013-01-01

    In this study, the authors investigated whether periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging (DWI) can remove magnetic susceptibility artifacts and compared apparent diffusion coefficient (ADC) values for PROPELLER DWI and the common echo planar (EP) DWI. Twenty patients that underwent brain MRI with a metal dental implant were selected. A 3.0T MR scanner was then used to obtain EP DWI, PROPELLER DWI, and corresponding apparent diffusion coefficient (ADC) maps for a b-value of 0 and 1,000 s/mm2. The frequencies of magnetic susceptibility artifacts in four parts of the brain (bilateral temporal lobes, pons, and orbit) were selected. In the ADC maps, we measured the ADC values of both sides of the temporal lobe and the pons. According to the study results, the frequency of magnetic susceptibility artifacts in PROPELLER DW images was lower than it was in EP DW images. In ADC maps, the ADC values of the bilateral temporal lobes and the pons were all higher in PROPELLER ADC maps than in EP ADC maps. Our findings show that when a high-field MRI machine is used, magnetic susceptibility artifacts can distort anatomical structures and produce high-intensity signals. Furthermore, our findings suggest that in many cases, PROPELLER DWI would be helpful in terms of achieving a correct diagnosis.

  5. Defect visualization of aircraft UHF antenna radome using full-field pulse-echo ultrasonic propagation imaging system

    Science.gov (United States)

    Shin, H. J.; Hong, S. C.; Lee, J. R.; Kim, J. H.

    2016-10-01

    Most of aircraft antennas usually have various types of radome made of composite materials for protecting antenna structures. However, these antenna radome structures, which are installed on the outside of airplane, are easy to be damaged by external forces such as drag, foreign object, bird strike and others. In this study, full-field pulse-echo ultrasonic propagation imaging (PE UPI) system is proposed as the non-destructive inspection technique to visualize manufacturing defects in composite antenna radome. Based on the results of the sample case study, it is shown that the ultrasonic wave propagation imaging (UWPI) that is generated by the proposed full-field PE UPI system is able to highlight the intact internal condition of antenna structure and its defect area. Additional damage visualization techniques like ultrasonic energy mapping (UEM), variable time window amplitude map (VTWAM) and also ultrasonic spectral imaging (USI) algorithms are applied to improve the reliability of the damage visualization. It can be concluded that the proposed PE UPI system is an effective non-destructive inspection technique for the composite radome structures.

  6. Diffusion-weighted imaging of the sellar region: A comparison study of BLADE and single-shot echo planar imaging sequences

    Energy Technology Data Exchange (ETDEWEB)

    Yiping, Lu [Department of Radiology, Huashan Hospital, Fudan University, 12 Wulumuqi Rd. Middle, Shanghai 200040 (China); Hui, Liu [MR Collaboration NE Asia, Siemens Healthcare, Siemens Ltd., China, Shanghai 201318 (China); Kun, Zhou [MR PLM APPL, Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen 518057 (China); Daoying, Geng, E-mail: GengdaoyingGDY@163.com [Department of Radiology, Huashan Hospital, Fudan University, 12 Wulumuqi Rd. Middle, Shanghai 200040 (China); Bo, Yin, E-mail: yinbo7@163.com [Department of Radiology, Huashan Hospital, Fudan University, 12 Wulumuqi Rd. Middle, Shanghai 200040 (China)

    2014-07-15

    Purpose: The purpose of this study is to compare BLADE diffusion-weighted imaging (DWI) with single-shot echo planar imaging (EPI) DWI on the aspects of feasibility of imaging the sellar region and image quality. Methods: A total of 3 healthy volunteers and 52 patients with suspected lesions in the sellar region were included in this prospective intra-individual study. All exams were performed at 3.0 T with a BLADE DWI sequence and a standard single-shot EP-DWI sequence. Phantom measurements were performed to measure the objective signal-to-noise ratio (SNR). Two radiologists rated the image quality according to the visualisation of the internal carotid arteries, optic chiasm, pituitary stalk, pituitary gland and lesion, and the overall image quality. One radiologist measured lesion sizes for detecting their relationship with the image score. Results: The SNR in BLADE DWI sequence showed no significant difference from the single-shot EPI sequence (P > 0.05). All of the assessed regions received higher scores in BLADE DWI images than single-shot EP-DWI.

  7. Diffusion-weighted 3D multislab echo planar imaging for high signal-to-noise ratio efficiency and isotropic image resolution.

    Science.gov (United States)

    Engström, Mathias; Skare, Stefan

    2013-12-01

    To acquire isotropic high-resolution, signal-to-noise ratio (SNR) efficient, 3D encoded diffusion-weighted MRI data. Multiple Fourier encoded slabs were combined into one full volume, using a generalized autocalibrating partially parallel acquisitions (GRAPPA) accelerated diffusion-weighted 3D multislab echo planar imaging (EPI) sequence with 2D phase navigation and in-plane motion correction. Reconstructed data with 1.5-mm(3) nominal resolution is presented and shown under the influence of motion and with variable slab thicknesses. The SNR efficiency between diffusion-weighted 3D multislab EPI and DW 2D ss-EPI is compared. Finally, a 1.3-mm(3) full brain scan with 45 diffusion directions is presented. Diffusion-weighted 3D multislab EPI has been presented as an alternative sequence for high-resolution and high-SNR full brain coverage diffusion studies. Compared with the gold standard 2D diffusion-weighted single-shot Echo Planar Imaging, the SNR efficiency is significantly higher. Copyright © 2012 Wiley Periodicals, Inc.

  8. High-resolution morphologic and ultrashort time-to-echo quantitative magnetic resonance imaging of the temporomandibular joint

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Won C.; Chang, Eric Y.; Biswas, Reni; Statum, Sheronda; Chung, Christine B. [Veterans Administration San Diego Healthcare System, Department of Radiology, San Diego, CA (United States); University of California, San Diego, School of Medicine, Department of Radiology, San Diego, CA (United States); Tafur, Monica; Du, Jiang; Healey, Robert [University of California, San Diego, School of Medicine, Department of Radiology, San Diego, CA (United States); Kwack, Kyu-Sung [Ajou University Medical Center, Department of Radiology, Wonchon-dong, Yeongtong-gu, Gyeonggi-do, Suwon (Korea, Republic of)

    2016-03-15

    To implement high-resolution morphologic and quantitative magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) using ultrashort time-to-echo (UTE) techniques in cadavers and volunteers. This study was approved by the institutional review board. TMJs of cadavers and volunteers were imaged on a 3-T MR system. High-resolution morphologic and quantitative sequences using conventional and UTE techniques were performed in cadaveric TMJs. Morphologic and UTE quantitative sequences were performed in asymptomatic and symptomatic volunteers. Morphologic evaluation demonstrated the TMJ structures in open- and closed-mouth position. UTE techniques facilitated the visualization of the disc and fibrocartilage. Quantitative UTE MRI was successfully performed ex vivo and in vivo, reflecting the degree of degeneration. There was a difference in the mean UTE T2* values between asymptomatic and symptomatic volunteers. MRI evaluation of the TMJ using UTE techniques allows characterization of the internal structure and quantification of the MR properties of the disc. Quantitative UTE MRI can be performed in vivo with short scan times. (orig.)

  9. 7 Tesla magnetic resonance imaging to detect cortical pathology in multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Bing Yao

    Full Text Available Neocortical lesions (NLs are an important pathological component of multiple sclerosis (MS, but their visualization by magnetic resonance imaging (MRI remains challenging.We aimed at assessing the sensitivity of multi echo gradient echo (ME-GRE T2*-weighted MRI at 7.0 Tesla in depicting NLs compared to myelin and iron staining.Samples from two MS patients were imaged post mortem using a whole body 7 T MRI scanner with a 24-channel receive-only array. Isotropic 200 micron resolution images with varying T2* weighting were reconstructed from the ME-GRE data and converted into R2* maps. Immunohistochemical staining for myelin (proteolipid protein, PLP and diaminobenzidine-enhanced Turnbull blue staining for iron were performed.Prospective and retrospective sensitivities of MRI for the detection of NLs were 48% and 67% respectively. We observed MRI maps detecting only a small portion of 20 subpial NLs extending over large cortical areas on PLP stainings. No MRI signal changes suggestive of iron accumulation in NLs were observed. Conversely, R2* maps indicated iron loss in NLs, which was confirmed by histological quantification.High-resolution post mortem imaging using R2* and magnitude maps permits detection of focal NLs. However, disclosing extensive subpial demyelination with MRI remains challenging.

  10. 7 Tesla Magnetic Resonance Imaging to Detect Cortical Pathology in Multiple Sclerosis

    Science.gov (United States)

    van Gelderen, Peter; Merkle, Hellmuth; Chen, Christina; Lassmann, Hans; Duyn, Jeff H.; Bagnato, Francesca

    2014-01-01

    Background Neocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS), but their visualization by magnetic resonance imaging (MRI) remains challenging. Objectives We aimed at assessing the sensitivity of multi echo gradient echo (ME-GRE) T2*-weighted MRI at 7.0 Tesla in depicting NLs compared to myelin and iron staining. Methods Samples from two MS patients were imaged post mortem using a whole body 7T MRI scanner with a 24-channel receive-only array. Isotropic 200 micron resolution images with varying T2* weighting were reconstructed from the ME-GRE data and converted into R2* maps. Immunohistochemical staining for myelin (proteolipid protein, PLP) and diaminobenzidine-enhanced Turnbull blue staining for iron were performed. Results Prospective and retrospective sensitivities of MRI for the detection of NLs were 48% and 67% respectively. We observed MRI maps detecting only a small portion of 20 subpial NLs extending over large cortical areas on PLP stainings. No MRI signal changes suggestive of iron accumulation in NLs were observed. Conversely, R2* maps indicated iron loss in NLs, which was confirmed by histological quantification. Conclusions High-resolution post mortem imaging using R2* and magnitude maps permits detection of focal NLs. However, disclosing extensive subpial demyelination with MRI remains challenging. PMID:25303286

  11. Qualitative and Quantitative Assessment of Isotropic Ankle Magnetic Resonance Imaging: Three-Dimensional Isotropic Intermediate-Weighted Turbo Spin Echo versus Three-Dimensional Isotropic Fast Field Echo Sequences

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun; Su; Yoon, Young Cheol; Kwon, Jong Won [Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul (Korea, Republic of); Choe, Bong Keun [Kyung Hee University School of Medicine, Seoul (Korea, Republic of)

    2012-07-15

    To compare the image quality of volume isotropic turbo spin echo acquisition (VISTA) imaging method with that of the three-dimensional (3D) isotropic fast field echo (FFE) imaging method applied for ankle joint imaging. MR imaging of the ankles of 10 healthy volunteers was performed with VISTA and 3D FFE sequences by using a 3.0 T machine. Two radiologists retrospectively assessed the tissue contrast between fluid and cartilage (F-C), and fluid and the Achilles tendon (F-T) with use of a 4-point scale. For a quantitative analysis, signal-to-noise ratio (SNR) was obtained by imaging phantom, and the contrast ratios (CRs) were calculated between F-T and F-C. Statistical analyses for differences in grades of tissue contrast and CRs were performed. VISTA had significantly superior grades in tissue contrast of F-T (p = 0.001). Results of 3D FFE had superior grades in tissue contrast of F-C, but these result were not statistically significant (p 0.157). VISTA had significantly superior CRs in F-T (p = 0.002), and 3D FFE had superior CRs in F-C (p = 0.003). The SNR of VISTA was higher than that of 3D FFE (49.24 vs. 15.94). VISTA demonstrates superior tissue contrast between fluid and the Achiles tendon in terms of quantitative and qualitative analysis, while 3D FFE shows superior tissue contrast between fluid and cartilage in terms of quantitative analysis.

  12. In vivo carbon-edited detection with proton echo-planar spectroscopic imaging (ICED PEPSI) : [3,4-(CH2)-C-13] glutamate/glutamine tomography in rat brain

    NARCIS (Netherlands)

    Hyder, F; Renken, R; Rothman, DL

    1999-01-01

    A method for in vivo carbon-edited detection with proton echo-planar spectroscopic imaging (ICED PEPSI) is described. This method is composed of an echo-planar based acquisition implemented with C-13-H-1 J editing spectroscopy and is intended for high temporal and spatial resolution in vivo

  13. Dynamic multi-coil technique (DYNAMITE) shimming for echo-planar imaging of the human brain at 7 Tesla.

    Science.gov (United States)

    Juchem, Christoph; Umesh Rudrapatna, S; Nixon, Terence W; de Graaf, Robin A

    2015-01-15

    Gradient-echo echo-planar imaging (EPI) is the primary method of choice in functional MRI and other methods relying on fast MRI to image brain activation and connectivity. However, the high susceptibility of EPI towards B0 magnetic field inhomogeneity poses serious challenges. Conventional magnetic field shimming with low-order spherical harmonic (SH) functions is capable of compensating shallow field distortions, but performs poorly for global brain shimming or on specific areas with strong susceptibility-induced B0 distortions such as the prefrontal cortex (PFC). Excellent B0 homogeneity has been demonstrated recently in the human brain at 7 Tesla with the DYNAmic Multi-coIl TEchnique (DYNAMITE) for magnetic field shimming (J Magn Reson (2011) 212:280-288). Here, we report the benefits of DYNAMITE shimming for multi-slice EPI and T2* mapping. A standard deviation of 13Hz was achieved for the residual B0 distribution in the human brain at 7 Tesla with DYNAMITE shimming and was 60% lower compared to conventional shimming that employs static zero through third order SH shapes. The residual field inhomogeneity with SH shimming led to an average 8mm shift at acquisition parameters commonly used for fMRI and was reduced to 1.5-3mm with DYNAMITE shimming. T2* values obtained from the prefrontal and temporal cortices with DYNAMITE shimming were 10-50% longer than those measured with SH shimming. The reduction of the confounding macroscopic B0 field gradients with DYNAMITE shimming thereby promises improved access to the relevant microscopic T2* effects. The combination of high spatial resolution and DYNAMITE shimming allows largely artifact-free EPI and T2* mapping throughout the brain, including prefrontal and temporal lobe areas. DYNAMITE shimming is expected to critically benefit a wide range of MRI applications that rely on excellent B0 magnetic field conditions including EPI-based fMRI to study various cognitive processes and assessing large-scale brain connectivity

  14. Dynamic Multi-Coil Technique (DYNAMITE) Shimming for Echo-Planar Imaging of the Human Brain at 7 Tesla

    Science.gov (United States)

    Juchem, Christoph; Rudrapatna, S. Umesh; Nixon, Terence W.; de Graaf, Robin A.

    2014-01-01

    Gradient-echo echo-planar imaging (EPI) is the primary method of choice in functional MRI and other methods relying on fast MRI to image brain activation and connectivity. However, the high susceptibility of EPI towards B0 magnetic field inhomogeneity poses serious challenges. Conventional magnetic field shimming with low-order spherical harmonic (SH) functions is capable of compensating shallow field distortions, but performs poorly for global brain shimming or on specific areas with strong susceptibility-induced B0 distortions such as the prefrontal cortex (PFC). Excellent B0 homogeneity has been demonstrated recently in the human brain at 7 Tesla with the DYNAmic Multi-coIl TEchnique (DYNAMITE) for magnetic field shimming (Juchem et al., J Magn Reson (2011) 212:280-288). Here, we report the benefits of DYNAMITE shimming for multi-slice EPI and T2* mapping. A standard deviation of 13 Hz was achieved for the residual B0 distribution in the human brain at 7 Tesla with DYNAMITE shimming and was 60% lower compared to conventional shimming that employs static zero through third order SH shapes. The residual field inhomogeneity with SH shimming led to an average 8 mm shift at