Leptomeningeal high signal intensity (ivy sign) on fluid-attenuated inversion-recovery (FLAIR) MR images in moyamoya disease

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Fujiwara, Hirokazu [Department of Diagnostic Radiology, School of Medicine, Keio University, Tokyo 1608582 (Japan)]. E-mail: hirokazu_fujiwara@ybb.ne.jp; Momoshima, Suketaka [Department of Diagnostic Radiology, School of Medicine, Keio University, Tokyo 1608582 (Japan); Kuribayashi, Sachio [Department of Diagnostic Radiology, School of Medicine, Keio University, Tokyo 1608582 (Japan)

2005-08-01

Purpose: There are a few reports on leptomeningeal high signal intensity (LMHI: ivy sign) on fluid-attenuated inversion-recovery (FLAIR) images in moyamoya disease, but the feature of this finding has not been completely understood. The purpose of this study was to characterize LMHI on FLAIR images in moyamoya disease and to assess usefulness of this finding in the diagnosis of moyamoya disease in conventional MR imaging. Material and methods: MR imaging of 28 patients with moyamoya disease was retrospectively reviewed. The grade of LMHI on FLAIR images was classified as 'absent,' 'minimal,' 'moderate' and 'marked.' Fifty-four hemispheres of 28 patients (2 patients had unilateral disease) were assessed for the frequency of visualization and distribution of LMHI. The correlations between LMHI on FLAIR images, moyamoya vessels on T1- and T2-weighted images and MR angiography findings were also analyzed. Results: Moderate and marked LMHI was seen in 31 out of 54 hemispheres (57%). LMHI was seen more prominently in the frontal and parietal lobes than in the temporal and occipital lobes. Although there was a tendency for LMHI on FLAIR images to be prominent in groups with moderate and marked moyamoya vessels on T1- and T2-weighted images, there was no significant correlation. More prominent LMHI was observed in the hemispheres in which cortical branches of the middle cerebral arteries were poorly visualized on MR angiography. Conclusion: Leptomeningeal high signal intensity (ivy sign) on FLAIR images is predominantly seen in the frontal and parietal lobes. Because this sign can be seen in patients with unremarkable moyamoya vessels, LMHI is a useful sign in conventional MR imaging for the diagnosis of moyamoya disease.

All that glitters is not gold: Increased Signal in the Subarachnoid Space on Fluid-Attenuated Inversion Recovery Imaging after gadolinium injection

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Juliana Avila Duarte

2016-08-01

Full Text Available A 61-year-old woman arrived at the emergency department of the Hospital Nossa Senhora das Graças, Canoas, southern Brazil, with suspected ischemic stroke. After clinical and laboratory examination, the clinical diagnosis of ischemic stroke was made, without fulfilling criteria for thrombolysis. The patient had no history of renal failure. Three days later, she performed a magnetic resonance imaging (MRI examination that confirmed the suspected diagnosis. This examination was performed without sedation or supplemental oxygen. Brain MRI was performed after gadolinium injection, using fluid-attenuated inversion recovery (FLAIR imaging, T1-weighted image, diffusion-weighted imaging, and T2-weighted image sequences that revealed signs of subacute watershed stroke in the left cerebral hemisphere (Figures 1, 2 and 3. There was a hyperintense cerebrospinal fluid (CSF in the subarachnoid space (SAS on FLAIR imaging, a finding that has been reported in many  pathologic conditions1 such as superior sagittal thrombosis, subarachnoid hemorrhage², meningitis,  meningeal carcinomatosis,  next to tumors, status epilepticus and stroke.3-7 It has also been reported in otherwise healthy patients undergoing anesthesia with supplemental oxygen.8 The exact mechanism by which CSF diffuses into the SAS in patients with or without renal insufficiency is not completely explained. Some authores have suggested that in patients with renal failure, the gadolinium may shift across an osmotic gradient at the circumventricular organs in the setting of proctracted elevation of plasma concentrations.9 We believe that the cause of this imaging phenomenon of hyperintense signal of the CSF in the SAS which has already been noted in patients with compromised cerebral perfusion, including cases of acute ischemic stroke, was due to the recent stroke.10-11 Keywords: Flair hyperintensity, MRI, stroke, Gadolinium

Experimental acute intracerebral hemorrhage: Value of MR sequences for a safe diagnosis at 1.5 and 0.5 T

International Nuclear Information System (INIS)

Kueker, W.; Thron, A.; Thiex, R.; Rohde, I.; Rohde, V.

2000-01-01

To determine the detectability of intracerebral hematomas with MR imaging at 1.5 T and 0.5 T with fluid attenuated inversion recovery turbo spin-echo (FLAIR) and gradient-echo sequences. Material and Methods: Twenty-seven intracerebral hematomas were created in 25 piglets by injection of venous blood into the brain through a burr hole. All were imaged with T2*-weighted gradient echo sequences (fast field echo, FFE), T2-weighted fluid attenuated inversion recovery turbo spin-echo sequences (FLAIR), T2-weighted turbo spin-echo (TSE) and T1-weighted spin-echo sequences. Follow-up was performed on the 2nd, 4th and 10th postoperative days. Ten animals were additionally investigated with similar sequences at 0.5 T. Histologic correlation was obtained in all cases. Results: T2* FFE sequences detected all acute intracerebral hematomas and demonstrated the size correctly at 1.5 T and 0.5 T. The conspicuity was better at 1.5 T. FLAIR sequences were unreliable in the hyperacute phase at 1.5 T. However, subarachnoid and intraventricular extension was best appreciated with FLAIR images. T2 TSE images were incapable of detecting para ventricular and subarachnoid hemorrhages, but clearly demonstrated intracerebral blood in other locations. T1-weighted images were insensitive to hemorrhage in the acute state but very useful in subacute and chronic hematomas. Conclusion: The safe and reliable diagnosis of intracerebral hemorrhage is probably possible with MR imaging at 1.5 T and 0.5 T even of hematomas less than 90 min old, but requires the application of at least FLAIR, T2* FFE and T1 sequences and is therefore time consuming

The effect of magnetisation transfer contrast on cerebrospinal fluid on motion artefacts on fluid-attenuated inversion-recovery images

International Nuclear Information System (INIS)

Aprile, I.; Principi, M.; Ottaviano, P.; Scapeccia, M.

2003-01-01

We assessed possible advantages of the use of fluid-attenuated inversion-recovery (FLAIR) sequences with magnetisation-transfer contrast (MTC) over conventional FLAIR images. We carried out cranial MRI at 1 tesla on 50 patients with both sequences. In nine patients with multiple sclerosis (MS) we performed a quantitative comparison of the two sequences, looking at the contrast-to-noise ratio between lesions and normal white matter and counting the number of lesions shown using each method. A qualitative comparison on all patients consisted of the analysis of the appearance of the normal parenchyma, of any lesions, and of artefacts, with particular reference to cerebrospinal fluid (CSF) motion artefacts. The quantitative analysis showed no meaningful difference between the two sequences. The cerebral parenchyma and lesions appeared substantially the same with both techniques. With FLAIR MTC there was a clear, and consistent reduction in CSF motion artefacts. FLAIR MTC sequences can usefully be used in place of the conventional sequence at 1 tesla. (orig.)

Evaluation of the Subscapularis Tendon Tears on 3T Magnetic Resonance Arthrography: Comparison of Diagnostic Performance of T1-Weighted Spectral Presaturation with Inversion-Recovery and T2-Weighted Turbo Spin-Echo Sequences.

Science.gov (United States)

Lee, Hoseok; Ahn, Joong Mo; Kang, Yusuhn; Oh, Joo Han; Lee, Eugene; Lee, Joon Woo; Kang, Heung Sik

2018-01-01

To compare the T1-weighted spectral presaturation with inversion-recovery sequences (T1 SPIR) with T2-weighted turbo spin-echo sequences (T2 TSE) on 3T magnetic resonance arthrography (MRA) in the evaluation of the subscapularis (SSC) tendon tear with arthroscopic findings as the reference standard. This retrospective study included 120 consecutive patients who had undergone MRA within 3 months between April and December 2015. Two musculoskeletal radiologists blinded to the arthroscopic results evaluated T1 SPIR and T2 TSE images in separate sessions for the integrity of the SSC tendon, examining normal/articular-surface partial-thickness tear (PTTa)/full-thickness tear (FTT). Diagnostic performance of T1 SPIR and T2 TSE was calculated with arthroscopic results as the reference standard, and sensitivity, specificity, and accuracy were compared using the McNemar test. Interobserver agreement was measured with kappa (κ) statistics. There were 74 SSC tendon tears (36 PTTa and 38 FTT) confirmed by arthroscopy. Significant differences were found in the sensitivity and accuracy between T1 SPIR and T2 TSE using the McNemar test, with respective rates of 95.9-94.6% vs. 71.6-75.7% and 90.8-91.7% vs. 79.2-83.3% for detecting tear; 55.3% vs. 31.6-34.2% and 85.8% vs. 78.3-79.2%, respectively, for FTT; and 91.7-97.2% vs. 58.3-61.1% and 89% vs. 78-79.3%, respectively, for PTTa. Interobserver agreement for T1 SPIR was almost perfect for T1 SPIR (κ = 0.839) and substantial for T2 TSE (κ = 0.769). T1-weighted spectral presaturation with inversion-recovery sequences is more sensitive and accurate compared to T2 TSE in detecting SSC tendon tear on 3T MRA.

Three-dimensional fluid-attenuated inversion recovery sequence for visualisation of subthalamic nucleus for deep brain stimulation in Parkinson's disease

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Heo, Young Jin [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology, Research Institute of Radiology, Seoul (Korea, Republic of); Inje University, Department of Radiology, Busan Paik Hospital, Busan (Korea, Republic of); Kim, Sang Joon; Kim, Ho Sung; Choi, Choong Gon; Jung, Seung Chai [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology, Research Institute of Radiology, Seoul (Korea, Republic of); Lee, Jung Kyo [University of Ulsan College of Medicine, Asan Medical Center, Department of Neurosurgery, Seoul (Korea, Republic of); Lee, Chong Sik; Chung, Sun J. [University of Ulsan College of Medicine, Asan Medical Center, Department of Neurology, Seoul (Korea, Republic of); Cho, So Hyun [Department of Radiology, Busan (Korea, Republic of); Lee, Gyoung Ro [Philips HealthCare Korea, Seoul (Korea, Republic of)

2015-09-15

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson's disease (PD). However, targeting the STN is difficult due to its relatively small size and variable location. The purpose of this study was to assess which of the following sequences obtained with the 3.0 T MR system can accurately delineate the STN: coronal 3D fluid-attenuated inversion recovery (FLAIR), 2D T2*-weighted fast-field echo (T2*-FFE) and 2D T2-weighted turbo spin-echo (TSE) sequences. We included 20 consecutive patients with PD who underwent 3.0 T MR for DBS targeting. 3D FLAIR, 2D T2*-FFE and T2-TSE images were obtained for all study patients. Image quality and demarcation of the STN were analysed using 4-point scales, and contrast ratio (CR) of the STN and normal white matter was calculated. The Friedman test was used to compare the three sequences. In qualitative analysis, the 2D T2*-FFE image showed more artefacts than 3D FLAIR or 2D T2-TSE, but the difference did not reach statistical significance. 3D FLAIR images showed significantly superior demarcation of the STN compared with 2D T2*-FFE and T2-TSE images (P < 0.001, respectively). The CR of 3D FLAIR was significantly higher than that of 2D T2*-FFE or T2-TSE images in multiple comparison correction (P < 0.001), but there was no significant difference in the CR between 2D T2*-FFE and T2-TSE images. Coronal 3D FLAIR images showed the most accurate demarcation of the STN for DBS targeting among coronal 3D FLAIR, 2D T2*-FFE and T2-TSE images. (orig.)

Three-dimensional fluid-attenuated inversion recovery sequence for visualisation of subthalamic nucleus for deep brain stimulation in Parkinson's disease

International Nuclear Information System (INIS)

Heo, Young Jin; Kim, Sang Joon; Kim, Ho Sung; Choi, Choong Gon; Jung, Seung Chai; Lee, Jung Kyo; Lee, Chong Sik; Chung, Sun J.; Cho, So Hyun; Lee, Gyoung Ro

2015-01-01

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson's disease (PD). However, targeting the STN is difficult due to its relatively small size and variable location. The purpose of this study was to assess which of the following sequences obtained with the 3.0 T MR system can accurately delineate the STN: coronal 3D fluid-attenuated inversion recovery (FLAIR), 2D T2*-weighted fast-field echo (T2*-FFE) and 2D T2-weighted turbo spin-echo (TSE) sequences. We included 20 consecutive patients with PD who underwent 3.0 T MR for DBS targeting. 3D FLAIR, 2D T2*-FFE and T2-TSE images were obtained for all study patients. Image quality and demarcation of the STN were analysed using 4-point scales, and contrast ratio (CR) of the STN and normal white matter was calculated. The Friedman test was used to compare the three sequences. In qualitative analysis, the 2D T2*-FFE image showed more artefacts than 3D FLAIR or 2D T2-TSE, but the difference did not reach statistical significance. 3D FLAIR images showed significantly superior demarcation of the STN compared with 2D T2*-FFE and T2-TSE images (P < 0.001, respectively). The CR of 3D FLAIR was significantly higher than that of 2D T2*-FFE or T2-TSE images in multiple comparison correction (P < 0.001), but there was no significant difference in the CR between 2D T2*-FFE and T2-TSE images. Coronal 3D FLAIR images showed the most accurate demarcation of the STN for DBS targeting among coronal 3D FLAIR, 2D T2*-FFE and T2-TSE images. (orig.)

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

International Nuclear Information System (INIS)

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

1997-01-01

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

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

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

1999-07-01

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

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

International Nuclear Information System (INIS)

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

1999-01-01

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

Efficacy of the fluid attenuated inversion recovery (FLAIR) sequence of MRI as a preoperative diagnosis of hippocampal sclerosis

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Morioka, Takato; Nishio, Shunji; Mihara, Futoshi; Muraishi, Mitsuteru; Hisada, Kei; Hasuo, Kanehiro; Fukui, Masashi

1998-01-01

A newly advanced MRI pulse sequence, the FLAIR (fluid attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no-signal intensity area. There have been only a few reports on the FLAIR pulse sequence of temporal lobe epilepsy (TLE) as yet. We examined 9 cases of intractable TLE by FLAIR images and analyzed the advantages and disadvantages of the FLAIR pulse sequence for decision making on temporal lobectomy. All patients underwent anterior temporal lobectomy with hippocampectomy, and the diagnoses were confirmed histologically after surgery. Abnormally high T2 signals (HT2S) were more conspicuous with the FLAIR sequence than with any of the conventional sequences. Tilted axial plane, orientated along to the long axis of the hippocampal body, clearly demonstrated hippocampal atrophy (HA). Selection of a FLAIR sequence into the routine MR examination of patients with TLE is recommended. (author)

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.

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

International Nuclear Information System (INIS)

Fellner, Franz A.; Fellner, Claudia; Aichner, Franz T.; Moelzer, Guenther

2005-01-01

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 μs, 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

Influence of fluid-attenuated inversion-recovery on stroke apparent diffusion coefficient measurements and its clinical application

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Ni Jianming [Medical Imaging Department, Wuxi Second Hospital Affiliated Nanjing Medical University, 68 Zhong Shan Road, Wuxi, Jiangsu Province 214002 (China); Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China); Mogensen, Monique A. [Department of Radiology, Division of Neuroradiology, University of Southern California, Los Angeles, CA (United States); Chen Zengai [Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China); Shuang Chen; Shen Tianzhen [Radiology Department, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Urumqi Middle Road, Shanghai 200040 (China); Huang Gang, E-mail: huang2802@163.co [Nuclear Medicine Department, Renji Hospital, Medical School of Jiaotong University, Dongfang Road 1630, Shanghai 200127 (China)

2010-08-15

Background and purpose: The application of a fluid-attenuated inversion-recovery pulse with a conventional diffusion-weighted MRI sequence (FLAIR DWI) decreases the partial volume effects from cerebrospinal fluid on apparent diffusion coefficient (ADC) measurements. For this reason, FLAIR DWI may be more useful in the evaluation of ischemic stroke, but few studies have looked at the effect of FLAIR on ADC measurements in this setting. This study quantitatively compares FLAIR DWI and conventional DWI in ischemic stroke of varying ages to assess the potential advantages of this technique. Methods: We respectively analyzed 139 DWI studies in patients with ischemic stroke with and without FLAIR at varying time points ranging from hyperacute to chronic. ADC values were measured in each lesion, as well as in the contralateral normal side. Comparisons were made between the ADC values obtained from the DWI sequences with and without FLAIR for both the lesion and the normal contralateral side. Results: The ADC measurements within the ischemic lesion were very similar on FLAIR DWI and conventional DWI for lesions less than 14 days old (p > 0.05), but were significantly decreased on FLAIR DWI for lesions between 15 and 30 days old and in lesions >31 days old (chronic stage) (p < 0.01). The contralateral ADC values were all significantly decreased on the FLAIR DWI sequence compared with conventional DWI (p < 0.01). Conclusions: The application of an inversion pulse does not significantly affect the ADC values for early stage ischemic stroke (less than 14 days from symptom onset), but results in a more accurate relative ADC measurement by reducing the cerebrospinal fluid partial volume effects of the normal contralateral side. In addition, combined with the conventional DWI, FLAIR DWI may be helpful in determining the age of ischemic lesions.

DWI-ASPECTS (Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Scores) and DWI-FLAIR (Diffusion-Weighted Imaging-Fluid Attenuated Inversion Recovery) Mismatch in Thrombectomy Candidates: An Intrarater and Interrater Agreement Study.

Science.gov (United States)

Fahed, Robert; Lecler, Augustin; Sabben, Candice; Khoury, Naim; Ducroux, Célina; Chalumeau, Vanessa; Botta, Daniele; Kalsoum, Erwah; Boisseau, William; Duron, Loïc; Cabral, Dominique; Koskas, Patricia; Benaïssa, Azzedine; Koulakian, Hasmik; Obadia, Michael; Maïer, Benjamin; Weisenburger-Lile, David; Lapergue, Bertrand; Wang, Adrien; Redjem, Hocine; Ciccio, Gabriele; Smajda, Stanislas; Desilles, Jean-Philippe; Mazighi, Mikaël; Ben Maacha, Malek; Akkari, Inès; Zuber, Kevin; Blanc, Raphaël; Raymond, Jean; Piotin, Michel

2018-01-01

We aimed to study the intrarater and interrater agreement of clinicians attributing DWI-ASPECTS (Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Scores) and DWI-FLAIR (Diffusion-Weighted Imaging-Fluid Attenuated Inversion Recovery) mismatch in patients with acute ischemic stroke referred for mechanical thrombectomy. Eighteen raters independently scored anonymized magnetic resonance imaging scans of 30 participants from a multicentre thrombectomy trial, in 2 different reading sessions. Agreement was measured using Fleiss κ and Cohen κ statistics. Interrater agreement for DWI-ASPECTS was slight (κ=0.17 [0.14-0.21]). Four raters (22.2%) had a substantial (or higher) intrarater agreement. Dichotomization of the DWI-ASPECTS (0-5 versus 6-10 or 0-6 versus 7-10) increased the interrater agreement to a substantial level (κ=0.62 [0.48-0.75] and 0.68 [0.55-0.79], respectively) and more raters reached a substantial (or higher) intrarater agreement (17/18 raters [94.4%]). Interrater agreement for DWI-FLAIR mismatch was moderate (κ=0.43 [0.33-0.57]); 11 raters (61.1%) reached a substantial (or higher) intrarater agreement. Agreement between clinicians assessing DWI-ASPECTS and DWI-FLAIR mismatch may not be sufficient to make repeatable clinical decisions in mechanical thrombectomy. The dichotomization of the DWI-ASPECTS (0-5 versus 0-6 or 0-6 versus 7-10) improved interrater and intrarater agreement, however, its relevance for patients selection for mechanical thrombectomy needs to be validated in a randomized trial. © 2017 American Heart Association, Inc.

Flair MR imaging in the Detection of subarachnoid hemorrhage : comparison with CT and T1-weighted MR imaging

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Min, Soo Hyun; Kim, Soo Youn; Lee, Ghi Jai; Shim, Jae Chan; Oh, Tae Kyung; Kim, Ho Kyun [College of Medicine, Jnje University, Seoul (Korea, Republic of)

2000-03-01

To compare the findings of fluid-attenuated inversion recovery (FLAIR) MR imaging in the detection of subarachnoid hemorrhage (SAH), with those of precontrast CT and T1-weighted MR imaging. In 13 patients (14 cases) with SAH, FLAIR MR images were retrospectively analyzed and compared with CT (10 patients, 11 cases) and T1-weighted MR images (9 cases). SAH was confirmed on the basis of high density along the subarachnoid space, as seen on precontrast CT, or lumbar puncture. MR imaging was performed on a 1.0T unit. FLAIR MR and CT images were obtained during the acute stage(less than 3 days after ictus) in 10 and 9 cases, respectively, during the subacute stage (4-14 days after ictus) in two cases and one, respectively, and during the chronic stage (more than 15 days after ictus) in two cases and one, respectively. CT was performed before FLAIR MR imaging, and the interval between CT and FLAIR ranged from 24 hours (6 cases) to 2-3 (2 cases) or 4-7 days (3 cases). In each study, the conspicuity of visualization of SAH was graded as excellent, good, fair, or negative at five locations (sylvian fissure, cortical sulci, anterior basal cistern, posterior basal cistern, and perimesencephalic cistern). In all cases, subarachnoid hemorrhages were demonstrated as high signal intensity areas on FLAIR images. The detection rates for SAH on CT and T1-weighted MR images were 100% (11/11) and 89% (8/9), respectively. FLAIR was superior to T1-weighted imaging in the detection of SAH at all sites except the anterior basal cistern (p less than 0.05) and superior to CT in the detection of SAH at the cortical sulci (p less than 0.05). On FLAIR MR images, subarachnoid hemorrhages at all stages are demonstrated as high signal intensity areas; the FLAIR MR sequence is thus considered useful in the detection of SAH. In particular FLAIR is more sensitive than CT for the detection of SAH in the cortical sulci. (author)

Application of variable threshold intensity to segmentation for white matter hyperintensities in fluid attenuated inversion recovery magnetic resonance images

International Nuclear Information System (INIS)

Yoo, Byung Il; Han, Ji Won; Oh, San Yeo Wool; Kim, Tae Hui; Lee, Jung Jae; Lee, Eun Young; MacFall, James R.; Payne, Martha E.; Kim, Jae Hyoung; Kim, Ki Woong

2014-01-01

White matter hyperintensities (WMHs) are regions of abnormally high intensity on T2-weighted or fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Accurate and reproducible automatic segmentation of WMHs is important since WMHs are often seen in the elderly and are associated with various geriatric and psychiatric disorders. We developed a fully automated monospectral segmentation method for WMHs using FLAIR MRIs. Through this method, we introduce an optimal threshold intensity (I O ) for segmenting WMHs, which varies with WMHs volume (V WMH ), and we establish the I O -V WMH relationship. Our method showed accurate validations in volumetric and spatial agreements of automatically segmented WMHs compared with manually segmented WMHs for 32 confirmatory images. Bland-Altman values of volumetric agreement were 0.96 ± 8.311 ml (bias and 95 % confidence interval), and the similarity index of spatial agreement was 0.762 ± 0.127 (mean ± standard deviation). Furthermore, similar validation accuracies were obtained in the images acquired from different scanners. The proposed segmentation method uses only FLAIR MRIs, has the potential to be accurate with images obtained from different scanners, and can be implemented with a fully automated procedure. In our study, validation results were obtained with FLAIR MRIs from only two scanner types. The design of the method may allow its use in large multicenter studies with correct efficiency. (orig.)

Application of variable threshold intensity to segmentation for white matter hyperintensities in fluid attenuated inversion recovery magnetic resonance images

Energy Technology Data Exchange (ETDEWEB)

Yoo, Byung Il; Han, Ji Won; Oh, San Yeo Wool; Kim, Tae Hui [Seoul National University Bundang Hospital, Department of Neuropsychiatry, Seongnam, Gyeonggi-do (Korea, Republic of); Lee, Jung Jae; Lee, Eun Young [Kyungbook National University Chilgok Hospital, Department of Psychiatry, Buk-gu, Daegu (Korea, Republic of); MacFall, James R. [Duke University Medical Center, Neuropsychiatric Imaging Research Laboratory, Durham, NC (United States); Duke University Medical Center, Department of Radiology, Durham, NC (United States); Payne, Martha E. [Duke University Medical Center, Neuropsychiatric Imaging Research Laboratory, Durham, NC (United States); Duke University Medical Center, Department of Psychiatry and Behavioral Sciences, Durham, NC (United States); Kim, Jae Hyoung [Seoul National University Bundang Hospital, Department of Radiology, Seongnam, Gyeonggi-do (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Jongno-gu, Seoul (Korea, Republic of); Kim, Ki Woong [Seoul National University Bundang Hospital, Department of Neuropsychiatry, Seongnam, Gyeonggi-do (Korea, Republic of); Seoul National University College of Medicine, Department of Psychiatry, Jongno-gu, Seoul (Korea, Republic of); Seoul National University College of Natural Sciences, Department of Brain and Cognitive Science, Gwanak-gu, Seoul (Korea, Republic of)

2014-04-15

White matter hyperintensities (WMHs) are regions of abnormally high intensity on T2-weighted or fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). Accurate and reproducible automatic segmentation of WMHs is important since WMHs are often seen in the elderly and are associated with various geriatric and psychiatric disorders. We developed a fully automated monospectral segmentation method for WMHs using FLAIR MRIs. Through this method, we introduce an optimal threshold intensity (I{sub O}) for segmenting WMHs, which varies with WMHs volume (V{sub WMH}), and we establish the I{sub O} -V{sub WMH} relationship. Our method showed accurate validations in volumetric and spatial agreements of automatically segmented WMHs compared with manually segmented WMHs for 32 confirmatory images. Bland-Altman values of volumetric agreement were 0.96 ± 8.311 ml (bias and 95 % confidence interval), and the similarity index of spatial agreement was 0.762 ± 0.127 (mean ± standard deviation). Furthermore, similar validation accuracies were obtained in the images acquired from different scanners. The proposed segmentation method uses only FLAIR MRIs, has the potential to be accurate with images obtained from different scanners, and can be implemented with a fully automated procedure. In our study, validation results were obtained with FLAIR MRIs from only two scanner types. The design of the method may allow its use in large multicenter studies with correct efficiency. (orig.)

Basic evaluation of the new pulse sequence for simultaneous acquisition of T1- and T2-weighted images

International Nuclear Information System (INIS)

Kurose, Atsunari; Takahashi, Tohru; Ohishi, Tae; Ishikawa, Akihiro

2006-01-01

A novel pulse sequence that enables simultaneous acquisition of T1-weighted (T1W) and T2-weighted (T2W) images is presented. In this new technique, the inversion recovery (IR) pulse of conventional fast inversion recovery (Fast IR) is replaced with a pulse train that consists of a fast spin echo (FSE) and 180(y)+90(x) for driven inversion (DI). By using a shorter T1 and independent k-space ordering, the first part of the sequence provides T2W images and the second part provides T1W images, thereby enabling simultaneous acquisition in a single scan time comparable to that of Fast IR. Signal simulation also was conducted, and this was compared with conventional scanning techniques using normal volunteers. In the human studies, both T1W and T2W images showed the same image quality as conventional images, suggesting the potential for this technique to replace the combination of Fast IR and T2W FSE for scan-time reduction. (author)

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

International Nuclear Information System (INIS)

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

2000-01-01

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

Improving attenuation tomography by novel inversions for t* and Q: application to Parkfield, California and Okmok volcano, Alaska

Science.gov (United States)

Pesicek, J. D.; Bennington, N. L.; Thurber, C. H.; Zhang, H.

2011-12-01

Standard methods for mapping variations in seismic attenuation (Q) structure using local earthquake data involve a two-step process. First, values of the whole path attenuation operator t* are determined from earthquake data recorded on a seismic array by inverting observed spectra for source and attenuation parameters. Then, these t* data are used to invert tomographically for frequency-independent Q models. The observed earthquake amplitude spectra depend on both source parameters and site effects. However, quantification of site effects is often neglected. Bennington et al. [2008] determined site response jointly with source parameters for small groups of events and then computed each station's site response as the average over all groups. Building on this work, we have adapted the method to model all events simultaneously to more accurately determine site response from the earthquake spectra. This in turn allows us to more accurately determine t*. However, resolution analysis of the results shows that some parameters are not well resolved in the joint inversion. Thus, an alternating inversion scheme is tested and adapted to alleviate poor resolution and parameter trade-offs. The new scheme produces better fits to the earthquake spectra than previous methods, and the resulting t* data should allow for more accurate determination of the Q structure. Because the equation relating t* to Q is nonlinear, the typical approach to determining Q is to solve for changes to a starting model iteratively, similar to methods commonly used in travel time tomography. However, if we instead solve for the inverse of Q, the equation becomes linear and the solution no longer depends on the starting model. This simple modification may allow us to more accurately determine Q. We test these new t* and Q methods using earthquake data from Parkfield, California and Okmok volcano, Alaska. We present the results for real and synthetic data and compare and contrast these results to more

Influence of crosstalk on the fast fluid attenuated inversion recovery pulse sequence

International Nuclear Information System (INIS)

Urata, Tohru; Nonoshita, Koji; Miyazaki, Takayuki; Arima, Akira

2000-01-01

The influence of crosstalk on the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence was studied. On multislice fast FLAIR images, the water null point was shortened in comparison with that on single slice images owing to the crosstalk received from adjacent slices. That influence became greater with decreases in the slice gap and increases in the number of slices. The timing of crosstalk in each slice varied according to excitation order. The process of recovery of longitudinal magnetization changed according to differences in timing; thus, it was possible that the water null point changed in each slice. In brain images with thinner slice gaps, the signal intensity of CSF is increased by the effect of crosstalk. In order to eliminate changes in the water null point caused by crosstalk on fast FLAIR, the multislice sequence requires a sequence with interleaving based on the premise that slice gaps are set for more than 100% of slice thickness. (author)

Influence of crosstalk on the fast fluid attenuated inversion recovery pulse sequence

Energy Technology Data Exchange (ETDEWEB)

Urata, Tohru; Nonoshita, Koji; Miyazaki, Takayuki; Arima, Akira [Funabashi Municipal Medical Center, Chiba (Japan)

2000-04-01

The influence of crosstalk on the fast fluid attenuated inversion recovery (fast FLAIR) pulse sequence was studied. On multislice fast FLAIR images, the water null point was shortened in comparison with that on single slice images owing to the crosstalk received from adjacent slices. That influence became greater with decreases in the slice gap and increases in the number of slices. The timing of crosstalk in each slice varied according to excitation order. The process of recovery of longitudinal magnetization changed according to differences in timing; thus, it was possible that the water null point changed in each slice. In brain images with thinner slice gaps, the signal intensity of CSF is increased by the effect of crosstalk. In order to eliminate changes in the water null point caused by crosstalk on fast FLAIR, the multislice sequence requires a sequence with interleaving based on the premise that slice gaps are set for more than 100% of slice thickness. (author)

Ivy Sign on Fluid-Attenuated Inversion Recovery Images in Moyamoya Disease: Correlation with Clinical Severity and Old Brain Lesions

OpenAIRE

Seo, Kwon-Duk; Suh, Sang Hyun; Kim, Yong Bae; Kim, Ji Hwa; Ahn, Sung Jun; Kim, Dong-Seok; Lee, Kyung-Yul

2015-01-01

Purpose Leptomeningeal collateral, in moyamoya disease (MMD), appears as an ivy sign on fluid-attenuated inversion-recovery (FLAIR) images. There has been little investigation into the relationship between presentation of ivy signs and old brain lesions. We aimed to evaluate clinical significance of ivy signs and whether they correlate with old brain lesions and the severity of clinical symptoms in patients with MMD. Materials and Methods FLAIR images of 83 patients were reviewed. Each cerebr...

Fat-suppressed MRI of musculoskeletal infection: fast T2-weighted techniques versus gadolinium-enhanced T1-weighted images

International Nuclear Information System (INIS)

Miller, T.T.; Randolph, D.A. Jr.; Staron, R.B.; Feldman, F.; Cushin, S.

1997-01-01

Purpose. To investigate gadolinium's role in imaging musculoskeletal infection by comparing the conspicuity and extent of inflammatory changes demonstrated on gadolinium-enhanced fat-suppressed T1-weighted images versus fat-suppressed fast T2-weighted sequences. Design. Eighteen patients with infection were imaged in a 1.5-T unit, using frequency-selective and/or inversion recovery fat-suppressed fast T2-weighted images (T2WI) and gadolinium-enhanced frequency-selective fat-suppressed T1-weighted images (T1WI). Thirty-four imaging planes with both a fat-suppressed gadolinium-enhanced T1-weighted sequence and a fat-suppressed T2-weighted sequence were obtained. Comparison of the extent and conspicuity of signal intensity changes was made for both bone and soft tissue in each plane. Results. In bone, inflammatory change was equal in extent and conspicuity on fat-suppressed T2WI and fat-suppressed T1WI with gadolinium in 19 planes, more extensive or conspicuous on T2WI in three planes, and less so on T2WI in two planes. Marrow was normal on all three sequences in 10 cases. In soft tissue, inflammatory change was seen equally well in 20 instances, more extensively or conspicuously on the T2WI in 11 instances, and less so on T2WI in 2 instances. One case had no soft tissue involvement on any of the sequences. Five abscesses and three joint effusions were present, all more conspicuously delineated from surrounding inflammatory change on the fat-saturated T1WI with gadolinium. The average imaging time for the fat-saturated T1WI with gadolinium was 6.75 min, while that of the T2-weighted sequences was 5.75 min. Conclusion. Routine use of gadolinium is not warranted. Instead, gadolinium should be reserved for clinically suspected infection in or around a joint, and in cases refractory to medical or surgical treatment due to possible abscess formation. (orig.)

A study on CT attenuation and MR signal intensity of protein solution

International Nuclear Information System (INIS)

Kim, Joung Hae; Choi, Dae Seob; Kim, Soon; Lee, Hyeon Kyeong; Oh, Hyeon Hee; Kim, Seung Hyeon; Lee, Sung Woo; Chang, Kee Hyun; Chung, Jun Ho

2001-01-01

To correlate CT attenuation and MR signal intensity with concentration of protein solution. CT and MR examinations of a phantom containing bovine serum albumin solutions of various concentrations ranging from 0 to 55% were performed. CT Hounsfield units(HUs), MR signal intensities, and apparent diffusion coefficients (ADCs) of each albumin solution were measured, and CT HUs and MR signal intensities of the solutions were compared with those of cerebrospinal fluid (CSF), white matter, and cortical gray matter. CT HU increased gradually with increasing albumin concentration. On T1-weighted images(T1WI), signal intensity increased with increasing albumin concentrations of up to 35% but then decreased. On T2-weighted images(T2Wl), gradually decreasing signal intensity and increasing albumin concentration were observed Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images (DWls) showed that signal intensity peaked at a concentration of 10% and then gradually decreased. The ADC of the solution gradually decreased as concentration increased. Compared with those of normal brain structures, the CT HUs of solutions at concentrations of over 20% were higher than those of white and gray matter. At T1WI, the signal intensities of 10-45% solutions were similar to or higher than that of the gray matter. At T2Wl, the signal intensities of solutions above 25, 35, and 40% were lower than those of CSF, gray matter, and white matter, respectively. FLAIR images showed that the signal intensities of 5-35% solutions were higher than that of gray matter. The CT attenuation of albumin solution increased gradually with increasing concentration. MR signal intensities peaked at 35% concentration on T1WI and at 10% on FLAIR and DW images, respectively, and then gradually decreased. T2Wl and ADC map images showed gradually decreasing signal intensity and ADC as albumin concentration increased

Evaluation of Possible Prognostic Factors of Fulminant Acute Disseminated Encephalomyelitis (ADEM) on Magnetic Resonance Imaging with Fluid-Attenuated Inversion Recovery (FLAIR) and Diffusion-Weighted Imaging

Energy Technology Data Exchange (ETDEWEB)

Donmez, F.Y.; Aslan, H.; Coskun, M. (Dept. of Radiology, Faculty of Medicine, Baskent Univ., Ankara (Turkey))

2009-04-15

Background: Acute disseminated encephalomyelitis (ADEM) may be a rapidly progressive disease with different clinical outcomes. Purpose: To investigate the radiological findings of fulminant ADEM on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) images, and to correlate these findings with clinical outcome. Material and Methods: Initial and follow-up magnetic resonance imaging (MRI) scans in eight patients were retrospectively evaluated for distribution of lesions on FLAIR images and presence of hemorrhage or contrast enhancement. DWI of the patients was evaluated as to cytotoxic versus vasogenic edema. The clinical records were analyzed, and MRI results and clinical outcome were correlated. Results: Four of the eight patients died, three had full recovery, and one had residual cortical blindness. The distribution of the hyperintense lesions on FLAIR sequence was as follows: frontal (37.5%), parietal (50%), temporal (37.5%), occipital (62.5%), basal ganglia (50%), pons (37.5%), mesencephalon (37.5%), and cerebellum (50%). Three of the patients who died had brainstem involvement. Two patients had a cytotoxic edema, one of whom died, and the other developed cortical blindness. Six patients had vasogenic edema: three of these patients had a rapid progression to coma and died; three of them recovered. Conclusion: DWI is not always helpful for evaluating the evolution or predicting the outcome of ADEM. However, extension of the lesions, particularly brainstem involvement, may have an influence on the prognosis.

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

International Nuclear Information System (INIS)

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

1997-01-01

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

Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners.

Science.gov (United States)

Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

2014-01-01

We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (μ-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The μ-maps generated with this "Atlas-T1w-DUTE" approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT μ-maps were considered to the "silver standard"; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The μ-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based μ-maps across all subjects were higher than those for DUTE-based μ-maps; the atlas-based μ-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally.

Fluid-Attenuated Inversion Recovery Hypointensity of the Pulvinar Nucleus of Patients with Alzheimer Disease: Its Possible Association with Iron Accumulation as Evidenced by the T2 Map

International Nuclear Information System (INIS)

Moon, Won Jin; Roh, Hong Gee; Choi, Jin Woo; Kim, Hee Jin; Han, Seol Heui

2012-01-01

We hypothesized that prominent pulvinar hypointensity in brain MRI represents the disease process due to iron accumulation in Alzheimer disease (AD). We aimed to determine whether or not the pulvinar signal intensity (SI) on the fluid-attenuated inversion recovery (FLAIR) sequences at 3.0T MRI differs between AD patients and normal subjects, and also whether the pulvinar SI is correlated with the T2 map, an imaging marker for tissue iron, and a cognitive scale. Twenty one consecutive patients with AD and 21 age-matched control subjects were prospectively included in this study. The pulvinar SI was assessed on the FLAIR image. We measured the relative SI ratio of the pulvinar to the corpus callosum. The T2 values were calculated from the T2 relaxometry map. The differences between the two groups were analyzed, by using a Student t test. The correlation between the measurements was assessed by the Pearson's correlation test. As compared to the normal white matter, the FLAIR signal intensity of the pulvinar nucleus was significantly more hypointense in the AD patients than in the control subjects (p < 0.01). The pulvinar T2 was shorter in the AD patients than in the control subjects (51.5 ± 4.95 ms vs. 56.5 ± 5.49 ms, respectively, p = 0.003). The pulvinar SI ratio was strongly correlated with the pulvinar T2 (r = 0.745, p < 0.001). When controlling for age, only the pulvinar-to-CC SI ratio was positively correlated with that of the Mini-Mental State Examination (MMSE) score (r = 0.303, p < 0.050). Conversely, the pulvinar T2 was not correlated with the MMSE score (r = 0.277, p = 0.080). The FLAIR hypointensity of the pulvinar nucleus represents an abnormal iron accumulation in AD and may be used as an adjunctive finding for evaluating AD.

Conventional and Diffusion-Weighted MRI in the Evaluation of Methanol Poisoning. A case report

International Nuclear Information System (INIS)

Server, A.; Nakstad, P.Hj.; Dullerud, R.; Haakonsen, M.; Hovda, K.E.; Jacobsen, D.

2003-01-01

Cerebral lesions were studied in 2 methanol-poisoned patients using conventional magnetic resonance imaging (MRI). In 1 patient, diffusion-weighted MRI (DWI) was also performed. In this patient, conventional MRI showed symmetrical, bilateral increased signal in the lentiform nuclei, involving predominantly putamina, but also extending into the corona radiata, centrum semiovale and subcortical white matter. DWI showed decreased diffusion, which most probably reflects cytotoxic edema. In the other patient, fluid attenuated-inversion recovery (FLAIR) and T2-weighted images showed hyperintensity in the putamina, characteristic of post-necrotic changes

Bilateral Pulvinar Signal Intensity Decrease on T2-Weighted Images in Patients with Aspartylglucosaminuria

International Nuclear Information System (INIS)

Autti, T.; Loennqvist, T.; Joensuu, R.

2008-01-01

Background: Aspartylglucosaminuria (AGU) is an autosomal recessive lysosomal disease caused by deficiency of aspartylglucosaminidase. A thalamic T2 signal intensity decrease is associated with lysosomal diseases. Purpose: To investigate thalamic signal intensity in AGU by performing a retrospective review of brain magnetic resonance (MR) imaging studies of AGU patients. Material and Methods: A total of 25 MR examinations were available for 11 patients aged between 3 and 32 years (four patients underwent bone marrow transplantation). Of these, 13 examinations were performed after bone marrow transplantation. Five patients had from two to six examinations, and six patients had one examination each. In every patient, the diagnosis of AGU was confirmed by blood and urine tests. Eighteen examinations were performed with a 1.0T imager including dual spin-echo T2 and proton density (PD) axial and coronal images, and 10 examinations also included T1-weighted images. Seven examinations were performed with a 1.5T imager including turbo spin-echo axial and coronal T2-weighted images and axial fluid-attenuated inversion recovery (FLAIR) images; three examinations included T1-weighted three-dimensional magnetization-prepared rapid acquisition gradient-echo (3D MPRAGE) images. The signal intensity of the thalamus and pulvinar in every sequence was compared to that of the putamina. Results: In AGU, thalamic alterations were first detectable on T2-weighted images (25 examinations in 11 patients) from the age of 3 years 6 months, showing decreased signal intensity in 21 of 24 examinations. T1-weighted images (13 examinations) showed slightly increased thalamic signal intensity in five out of seven examinations from the age of 7 years, and PD images (19 examinations) showed decreased signal intensity from the age of 16 years (three examinations). The pulvinar showed decreased signal intensity on spin-echo T2-weighted images for 14 of 18 examinations or on FLAIR sequences for seven

Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis

NARCIS (Netherlands)

Moraal, Bastiaan; Roosendaal, Stefan; Pouwels, Petra; Vrenken, Hugo; Schijndel, van Ronald; Meier, Dominik; Guttmann, Charles; Geurts, Jeroen; Barkhof, Frederik

2008-01-01

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion- recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting

Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis

NARCIS (Netherlands)

Moraal, B.; Roosendaal, S.D.; Pouwels, P.J.W.; Vrenken, H.; van Schijndel, R.A.; Meier, D.S.; Guttmann, C.R.G.; Geurts, J.J.G.; Barkhof, F.

2008-01-01

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion-recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting multiple

Diffusion-weighted MR imaging in biopsy-proven Creutzfeldt-Jakob disease

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyo Cheol; Chang, Kee Hyun; Song In Chan; Lee, Sang Hyun; Kwon, Bae Ju; Han, Moon Hee; Kim, Sang Yun [Seoul National University College of Medicine, Seoul (Korea, Republic of)

2001-12-01

To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluidattenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.

Diffusion-weighted MR imaging in biopsy-proven Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Kim, Hyo Cheol; Chang, Kee Hyun; Song In Chan; Lee, Sang Hyun; Kwon, Bae Ju; Han, Moon Hee; Kim, Sang Yun

2001-01-01

To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluidattenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia

Phase sensitive reconstruction of T1-weighted inversion recovery in the evaluation of the cervical cord lesions in multiple Sclerosis; is it similarly eligible in 1.5 T magnet fields?

Science.gov (United States)

Shayganfar, A; Sarrami, A H; Fathi, S; Shaygannejad, V; Shamsian, S

2018-04-22

In primary studies with 3 T Magnets, phase sensitive reconstruction of T1-weighted inversion recovery (PSIR) have showed ability to depict the cervical multiple sclerosis (MS) lesions some of which may not be detected by short tau inversion recovery (STIR). Regarding to more availability of 1.5 T MRI, this study was designed to evaluate the eligibility of PSIR in 1.5 T for detection of spinal cord MS lesions. In a study between September 2016 till March 2017 the patients with proven diagnosis of MS enrolled to the study. The standard protocol (sagittal STIR and T2W FSE and axial T2W FSE) as well as sagittal PSIR sequences were performed using a 1.5 T magnet. The images were studied and the lesions were localized and recorded as sharp or faint on each sequence. Of 25 patients (22 females and 3 males, with mean age of 33.5 ± 9.8 years and mean disease duration of 5.4 ± 3.9 years) 69 lesions in STIR, 53 lesions in T2W FSE, 47 lesions in Magnitude reconstruction of PSIR (Magnitude), and 30 lesions in phase sensitive (real) reconstruction PSIR were detected. A Wilcoxon signed-rank test showed STIR has a statistically significant higher detection rate of the plaques rather than other three sequences. (STIR and T2W FSE, Z = -4.000, p definition of the plaques rather than other three sequences. This study shows that in the setting of a 1.5 T magnet field, STIR significantly has a superiority over both of the PSIR reconstructions (i.e. real and magnitude) for the detection as well as the boundary definition of the cervical cord lesions of MS. These results have a good relevance to clinical practice by using MRI scanners and sequences routinely available, however, it is discrepant with other reports performed by 3 T Magnet fields. Copyright © 2018 Elsevier B.V. All rights reserved.

Diagnostic value of three-dimensional fluid-attenuated inversion recovery MR imaging after intratympanic administration of contrast media in Meniere's disease

International Nuclear Information System (INIS)

Shi Honglu; Zhang Daogong; Wang Guangbin; Fan Zhaomin; Bai Xue; Guo Lijun; Man Xiaoni

2012-01-01

Objective: After intratympanic gadolinium administration through the tympanic membrane, three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) was performed to evaluate endolymphatic visualization and its diagnostic value in Meniere's disease. Methods: Twenty-four hours after intratympanic gadolinium administration through the tympanic membrane, 19 patients with unilateral Meniere's disease diagnosed clinically underwent 3D-FLAIR and 3D-Balance-FFE imaging at 3.0 T MR scanner. The enhanced imaging of perilymphatic space in bilateral cochlea, vestibular and (or) canal were observed. Scala tympani and scala vestibule of bilateral cochlear basal turn were scored respectively. The enhanced range of bilateral vestibule and the signal intensity ratio (SIR) between the vestibule and the brain stem were measured. Wilcoxon tests and paired t tests were used. Results: The gadolinium appeared in almost all parts of the perilymph in cochlea,vestibular and (or) canal, so the endolymphatic space was clearly visualized on 3D-FLAIR imaging. The score of scala vestibuli between the affected side (3 cases scored 2, 9 cases scored 1, 7 cases scored 0) and the healthy side (15 cases scored 2, 2 cases scored 1, 2 cases scored 0) were significantly different (U=3.090, P<0.05). The area of enhanced vestibular were (5.77 ± 2.33) mm 2 and (8.11 ± 3.32) mm 2 for the affected side and the healthy side, which were significantly different (U=3.090, P<0.05 and t=2.638, P<0.05). Conclusions: According to 3D-Balance-FFE MRI and the enhancement of perilymphatic space, 3D-FLAIR MRI with intratympanic gadolinium injection through the tympanic membrane can be used to show the border between the perilymph and the endolymph and confirm endolymphatic hydrops, thus providing radiographic evidence for the diagnosis of Meniere's disease. (authors)

Comparison of post-contrast 3D-T1-MPRAGE, 3D-T1-SPACE and 3D-T2-FLAIR MR images in evaluation of meningeal abnormalities at 3-T MRI.

Science.gov (United States)

Jeevanandham, Balaji; Kalyanpur, Tejas; Gupta, Prashant; Cherian, Mathew

2017-06-01

This study was to assess the usefulness of newer three-dimensional (3D)-T 1 sampling perfection with application optimized contrast using different flip-angle evolutions (SPACE) and 3D-T 2 fluid-attenuated inversion recovery (FLAIR) sequences in evaluation of meningeal abnormalities. 78 patients who presented with high suspicion of meningeal abnormalities were evaluated using post-contrast 3D-T 2 -FLAIR, 3D-T 1 magnetization-prepared rapid gradient-echo (MPRAGE) and 3D-T 1 -SPACE sequences. The images were evaluated independently by two radiologists for cortical gyral, sulcal space, basal cisterns and dural enhancement. The diagnoses were confirmed by further investigations including histopathology. Post-contrast 3D-T 1 -SPACE and 3D-T 2 -FLAIR images yielded significantly more information than MPRAGE images (p evaluation of meningeal abnormalities and when used in combination have the maximum sensitivity for leptomeningeal abnormalities. The negative-predictive value is nearly 100%, where no leptomeningeal abnormality was detected on these sequences. Advances in knowledge: Post-contrast 3D-T 1 -SPACE and 3D-T 2 -FLAIR images are more useful than 3D-T 1 -MPRAGE images in evaluation of meningeal abnormalities.

Revisiting the relationship of three-dimensional fluid attenuation inversion recovery imaging and hearing outcomes in adults with idiopathic unilateral sudden sensorineural hearing loss

Energy Technology Data Exchange (ETDEWEB)

Liao, Wen-Huei [School of Medicine, National Yang Ming University, Taipei, 11221, Taiwan (China); Department of Otolaryngology, Taipei Veterans General Hospital, Taipei, 11217, Taiwan (China); Wu, Hsiu-Mei [School of Medicine, National Yang Ming University, Taipei, 11221, Taiwan (China); Department of Radiology, Taipei Veterans General Hospital, Taipei, 11217, Taiwan (China); Wu, Hung-Yi [Department of Radiology, Taipei Veterans General Hospital, Taipei, 11217, Taiwan (China); Tu, Tzong-Yang; Shiao, An-Suey [School of Medicine, National Yang Ming University, Taipei, 11221, Taiwan (China); Department of Otolaryngology, Taipei Veterans General Hospital, Taipei, 11217, Taiwan (China); Castillo, Mauricio [Department of Radiology, University of North Carolina, Chapel Hill, NC, 27599-7510 (United States); Hung, Sheng-Che, E-mail: hsz829@gmail.com [School of Medicine, National Yang Ming University, Taipei, 11221, Taiwan (China); Department of Radiology, Taipei Veterans General Hospital, Taipei, 11217, Taiwan (China); Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, 11221, Taiwan (China)

2016-12-15

Background and purpose: Three-dimensional fluid attenuation inversion recovery (3D FLAIR) may demonstrate high signal in the inner ears of patients with idiopathic sudden sensorineural hearing loss (ISSNHL), but the correlations of this finding with outcomes are still controversial. Here we compared 4 3D MRI sequences with the outcomes of patients with ISSNHL. Materials and methods: 77 adult patients with ISSNHL underwent MRI with pre contrast FLAIR, fast imaging employing steady-state acquisition images (FIESTA-C), post contrast T1WI and post contrast FLAIR. The extent and degree of high signal in both cochleas were evaluated in all patients, and asymmetry ratios between the affected ears and the normal ones were calculated. The relationships among MRI findings, including extent and asymmetry of abnormal cochlear high signals, degree of FLAIR enhancement, and clinical information, including age, vestibular symptoms, baseline hearing loss, and final hearing outcomes were analyzed. Results: 54 patients (28 men; age, 52.1 ± 15.5 years) were included in our study. Asymmetric cochlear signal intensities were more frequently observed in pre contrast and post contrast FLAIR (79.6% and 68.5%) than in FIESTA-C (61.1%) and T1WI (51.9%) (p < 0.001). Age, baseline hearing loss, extent of high signal and asymmetry ratios of pre contrast and post contrast FLAIR were all correlated with final hearing outcomes. In multivariate analysis, age and the extent of high signals were the most significant predictors of final hearing outcomes. Conclusion: 3D FLAIR provides a higher sensitivity in detecting the asymmetric cochlear signal abnormality. The more asymmetric FLAIR signals and presence of high signals beyond cochlea indicated a poorer prognosis.

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

International Nuclear Information System (INIS)

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

1997-01-01

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

Predictors of short-term outcome in patients with acute middle cerebral artery occlusion: unsuitability of fluid-attenuated inversion recovery vascular hyperintensity scores

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Chan-chan Li

2018-01-01

Full Text Available Fluid-attenuated inversion recovery (FLAIR vascular hyperintensity (FVH is used to assess leptomeningeal collateral circulation, but clinical outcomes of patients with FVH can be very different. The aim of the present study was to assess a FVH score and explore its relationship with clinical outcomes. Patients with acute ischemic stroke due to middle cerebral artery M1 occlusion underwent magnetic resonance imaging and were followed up at 10 days (National Institutes of Health Stroke Scale and 90 days (modified Rankin Scale to determine short-term clinical outcomes. Effective collateral circulation indirectly improved recovery of neurological function and short-term clinical outcome by extending the size of the pial penumbra and reducing infarct lesions. FVH score showed no correlation with 90-day functional clinical outcome and was not sufficient as an independent predictor of short-term clinical outcome.

Signal alteration of the cochlear perilymph on 3 different sequences after intratympanic Gd-DTPA administration at 3 tesla. Comparison of 3D-FLAIR, 3D-T1-weighted imaging, and 3D-CISS

International Nuclear Information System (INIS)

Yamazaki, Masahiro; Naganawa, Shinji; Kawai, Hisashi; Nihashi, Takashi; Nakashima, Tsutomu

2010-01-01

Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging after intratympanic gadolinium injection is useful for pathophysiologic and morphologic analysis of the inner ear. However, statistical analysis of differences in inner ear signal intensity among 3D-FLAIR and other sequences has not been reported. We evaluated the signal intensity of cochlear fluid on each of 3D-FLAIR, 3D-T 1 -weighted imaging (T 1 WI), and 3D-constructive interference in the steady state (CISS) to clarify the differences in contrast effect among these 3 sequences using intratympanic gadolinium injection. Twenty-one patients underwent 3D-FLAIR, 3D-T 1 WI, and 3D-CISS imaging at 3 tesla 24 hours after intratympanic injection of gadolinium. We determined regions of interest of the cochleae (C) and medulla oblongata (M) on each image, evaluated the signal intensity ratio between C and M (CM ratio), and determined the ratio of cochlear signal intensity of the injected side to that of the non-injected side (contrast value). The CM ratio of the injected side (3.00±1.31, range, 0.53 to 4.88, on 3D-FLAIR; 0.83±0.30, range, 0.36 to 1.58 on 3D-T 1 WI) was significantly higher than that of the non-injected side (0.52±0.14, range, 0.30 to 0.76 on 3D-FLAIR; 0.49±0.11, range, 0.30 to 0.71 on 3D-T 1 WI) on 3D-FLAIR and 3D-T 1 WI (P 1 WI (1.73±0.60 range, 0.98 to 3.09) (P<0.001). The 3D-FLAIR sequence is the most sensitive for observing alteration in inner ear fluid signal after intratympanic gadolinium injection. Our results warrant use of 3D-FLAIR as a sensitive imaging technique to clarify the pathological and morphological mechanisms of disorders of the inner ear. (author)

Inversion recovery RARE: Clinical application of T2-weighted CSF-suppressed rapid sequence

International Nuclear Information System (INIS)

Goetz, G.F.; Hennig, J.; Ziyeh, S.

1995-01-01

Inversion-Recovery RARE is a strongly T 2 -weighted fast sequence in which the CSF appears dark. This sequence was used in more than 100 patients. Retrospective analysis of 80 patients with cerebrovascular and inflammatory disease was carried out. The IR-RARE sequence proved to be particularly suitable for identifying small lesions in the neighbourhood of the subarachnoid space. We illustrate the typical contrast provided by this sequence, and describe its characteristics, exemplifying the advantages it offers for the diagnosis of multiple sclerosis, cerebral microangiopathy and brain infarction. (orig.) [de

Diffusion-weighted echo-planar MRI of lacunar infarcts

International Nuclear Information System (INIS)

Noguchi, K.; Nagayoshi, T.; Watanabe, N.; Kanazawa, T.; Toyoshima, S.; Morijiri, M.; Shojaku, H.; Shimizu, M.; Seto, H.

1998-01-01

We studied 35 patients with lacunar infarcts, using diffusion-weighted echo-planar imaging (DW-EPI) at 1.5 T. The relative apparent diffusion coefficient ratio (ADCR) of each lesion was calculated and lesion conspicuity on DW-EPI was compared to that on images aquired with fast fluid-attenuated inversion recovery and T2-weighted fast spin-echo sequences. Acute small infarcts (within 3 days) were identified with DW-EPI as an area of decreased ADCR (range 0.33-0.87; mean 0.67) and high signal, subacute small infarcts (4-30 days) as a high-signal or isointense areas of decreased or nearly normal ADCR (0.54-0.98; 0.73), and chronic small infarcts (> 30 days) as low- or high-signal areas of nearly normal or increased ADCR (0.97-1.92; 1.32). In three patients, small infarcts of the brain stem in the hyperacute phase (within 6 h) were seen only with DW-EPI. In five patients, fresh small infarcts adjacent to multiple old infarcts could be distinguished only with DW-EPI. (orig.)

Comparison between FLAIR images and T2-weighted fast spin-echo images of cerebral territory and lacunar infarction

International Nuclear Information System (INIS)

Paeng, Mi Hye; Choi, Hye-Young; Lim, Soo Mee; Lee, Jung Sik

2003-01-01

To assess the significance of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in the diagnosis of intracranial infarctions and to find out differential points between central lacunar infarctions and perivascular spaces. We consecutively selected 25 cases of territorial infarction in 20 patients, 37 cases of central infarction in 40 patients, and 30 patients with perivascular space. Signal intensity and lesion conspicuity were analyzed and compared between FLAIR and FSE T2-weighted images, and differences in signal intensity between central infarction and perivascular spaces were determined. Lesion conspicuity for FLAIR was better than for T2-weighted images in 12 and 15, worse in 4 and 24, and similar in 9 and 16 of territorial and central infarctions, respectively. In nine cases of territorial and one case of central infarction, there was associated hemorrhage. At FLAIR imaging, perivascular spaces showed a fine round low signal without a peripheral high signal rim in 17 patients but no demonstrable signals in 15. Differential diagnosis of perivascular spaces and central infarction was thus not difficult. FLAIR MRI was useful in the diagnosis of infarctions and in differentiating between central small lacular infarctions and perivascular spaces

Cerebrospinal Fluid Enhancement on Fluid Attenuated Inversion Recovery Images After Carotid Artery Stenting with Neuroprotective Balloon Occlusions: Hemodynamic Instability and Blood–Brain Barrier Disruption

International Nuclear Information System (INIS)

Ogami, Ryo; Nakahara, Toshinori; Hamasaki, Osamu; Araki, Hayato; Kurisu, Kaoru

2011-01-01

Purpose: A rare complication of carotid artery stenting (CAS), prolonged reversible neurological symptoms with delayed cerebrospinal fluid (CSF) space enhancement on fluid attenuated inversion recovery (FLAIR) images, is associated with blood–brain barrier (BBB) disruption. We prospectively identified patients who showed CSF space enhancement on FLAIR images. Methods: Nineteen patients—5 acute-phase and 14 scheduled—underwent 21 CAS procedures. Balloon catheters were navigated across stenoses, angioplasty was performed using a neuroprotective balloon, and stents were placed with after dilation under distal balloon protection. CSF space hyperintensity or obscuration on FLAIR after versus before CAS indicated CSF space enhancement. Correlations with clinical factors were examined. Results: CSF space was enhanced on FLAIR in 12 (57.1%) cases. Postprocedural CSF space enhancement was significantly related to age, stenosis rate, acute-stage procedure, and total occlusion time. All acute-stage CAS patients showed delayed enhancement. Only age was associated with delayed CSF space enhancement in scheduled CAS patients. Conclusions: Ischemic intolerance for severe carotid artery stenosis and temporary neuroprotective balloon occlusion, causing reperfusion injury, seem to be the main factors that underlie BBB disruption with delayed CSF space enhancement shortly after CAS, rather than sudden poststenting hemodynamic change. Our results suggest that factors related to hemodynamic instability or ischemic intolerance seem to be associated with post-CAS BBB vulnerability. Patients at risk for hemodynamic instability or with ischemic intolerance, which decrease BBB integrity, require careful management to prevent intracranial hemorrhagic and other post-CAS complications.

T1-weighted MRI for the detection of coronary artery plaque haemorrhage

International Nuclear Information System (INIS)

Oei, May Lin; Ozgun, Murat; Seifarth, Harald; Bunck, Alexander; Fischbach, Roman; Heindel, Walter; Maintz, David; Orwat, Stefan; Botnar, Rene

2010-01-01

Hyperintense areas in atherosclerotic plaques on pre-contrast T1-weighted MRI have been shown to correlate with intraplaque haemorrhage. We evaluated the presence of T1 hyperintensity in coronary artery plaques in coronary artery disease (CAD) patients and correlated results with multi-detector computed tomography (MDCT) findings. Fifteen patients with CAD were included. Plaques detected by MDCT were categorised based on their Hounsfield number. T1-weighted inversion recovery (IR) MRI prepared coronary MRI for the detection of plaque and steady-state free-precession coronary MR-angiography for anatomical correlation was performed. After registration of MDCT and MRI, regions of interest were defined on MDCT-visible plaques and in corresponding vessel segments acquired with MRI. MDCT density and MR signal measurement were performed in each plaque. Forty-three plaques were identified with MDCT. With IR-MRI 5/43 (12%) plaques were hyperintense, 2 of which were non-calcified and 3 mixed. Average signal-to-noise and contrast-to-noise ratios of hyperintense plaques were 15.7 and 9.1, compared with 5.6 and 1.2 for hypointense plaques. Hyperintense plaques exhibited a significantly lower CT density than hypointense plaques (63.6 vs. 140.8). There was no correlation of plaque signal intensity with degree of stenosis. T1-weighted IR-MRI may be useful for non-invasive detection and characterisation of intraplaque haemorrhage in coronary artery plaques. (orig.)

Constructing inverse probability weights for continuous exposures: a comparison of methods.

Science.gov (United States)

Naimi, Ashley I; Moodie, Erica E M; Auger, Nathalie; Kaufman, Jay S

2014-03-01

Inverse probability-weighted marginal structural models with binary exposures are common in epidemiology. Constructing inverse probability weights for a continuous exposure can be complicated by the presence of outliers, and the need to identify a parametric form for the exposure and account for nonconstant exposure variance. We explored the performance of various methods to construct inverse probability weights for continuous exposures using Monte Carlo simulation. We generated two continuous exposures and binary outcomes using data sampled from a large empirical cohort. The first exposure followed a normal distribution with homoscedastic variance. The second exposure followed a contaminated Poisson distribution, with heteroscedastic variance equal to the conditional mean. We assessed six methods to construct inverse probability weights using: a normal distribution, a normal distribution with heteroscedastic variance, a truncated normal distribution with heteroscedastic variance, a gamma distribution, a t distribution (1, 3, and 5 degrees of freedom), and a quantile binning approach (based on 10, 15, and 20 exposure categories). We estimated the marginal odds ratio for a single-unit increase in each simulated exposure in a regression model weighted by the inverse probability weights constructed using each approach, and then computed the bias and mean squared error for each method. For the homoscedastic exposure, the standard normal, gamma, and quantile binning approaches performed best. For the heteroscedastic exposure, the quantile binning, gamma, and heteroscedastic normal approaches performed best. Our results suggest that the quantile binning approach is a simple and versatile way to construct inverse probability weights for continuous exposures.

Arterial hyperintensity on BLADE fluid-attenuated inversion recovery images (FLAIR) in hyperacute territorial infarction: comparison with conventional FLAIR

Energy Technology Data Exchange (ETDEWEB)

Kwag, Eujean; Lim, Soo Mee; Park, Ji Eun; Chae, In Hye [Ewha Womans University School of Medicine, Department of Radiology, Mokdong Hospital, Seoul (Korea, Republic of)

2014-09-15

To evaluate the utility of BLADE fluid-attenuated inversion recovery images (FLAIR) magnetic resonance (MR) imaging compared to conventional FLAIR for the detection of arterial hyperintensity (AH) in hyperacute territorial infarction. We retrospectively analysed MR images of patients with hyperacute (<6 h) territorial infarction over a 9-month study period. Special attention was paid to the presence or absence of AH in the frontal, parietal and temporal lobes and the number of AHs in the sylvian fissure. We also evaluated the presence of three kinds of artefacts on BLADE FLAIR and conventional FLAIR images. AH was seen in 41 (91 %) patients with conventional FLAIR and 45 (100 %) patients with BLADE FLAIR images. More instances of AH were detected in the frontal, parietal and temporal lobes and within the sylvian fissure using BLADE FLAIR. Motion artefacts, pulsation artefacts from the sigmoid sinus and incomplete cerebrospinal fluid (CSF) nulling that reduced image quality were observed more frequently on conventional FLAIR images than on BLADE FLAIR images. BLADE FLAIR sequences are more sensitive than conventional FLAIR for the detection of AH in hyperacute territorial infarctions and provide better image quality by reducing artefacts. They may be used in place of conventional FLAIR for patients with hyperacute stroke. (orig.)

Nonlinear inversion of borehole-radar tomography data to reconstruct velocity and attenuation distribution in earth materials

Science.gov (United States)

Zhou, C.; Liu, L.; Lane, J.W.

2001-01-01

A nonlinear tomographic inversion method that uses first-arrival travel-time and amplitude-spectra information from cross-hole radar measurements was developed to simultaneously reconstruct electromagnetic velocity and attenuation distribution in earth materials. Inversion methods were developed to analyze single cross-hole tomography surveys and differential tomography surveys. Assuming the earth behaves as a linear system, the inversion methods do not require estimation of source radiation pattern, receiver coupling, or geometrical spreading. The data analysis and tomographic inversion algorithm were applied to synthetic test data and to cross-hole radar field data provided by the US Geological Survey (USGS). The cross-hole radar field data were acquired at the USGS fractured-rock field research site at Mirror Lake near Thornton, New Hampshire, before and after injection of a saline tracer, to monitor the transport of electrically conductive fluids in the image plane. Results from the synthetic data test demonstrate the algorithm computational efficiency and indicate that the method robustly can reconstruct electromagnetic (EM) wave velocity and attenuation distribution in earth materials. The field test results outline zones of velocity and attenuation anomalies consistent with the finding of previous investigators; however, the tomograms appear to be quite smooth. Further work is needed to effectively find the optimal smoothness criterion in applying the Tikhonov regularization in the nonlinear inversion algorithms for cross-hole radar tomography. ?? 2001 Elsevier Science B.V. All rights reserved.

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

The reliability of magnetic resonance imaging in traumatic brain injury lesion detection

NARCIS (Netherlands)

Geurts, B.H.J.; Andriessen, T.M.J.C.; Goraj, B.M.; Vos, P.E.

2012-01-01

Objective: This study compares inter-rater-reliability, lesion detection and clinical relevance of T2-weighted imaging (T2WI), Fluid Attenuated Inversion Recovery (FLAIR), T2*-gradient recalled echo (T2*-GRE) and Susceptibility Weighted Imaging (SWI) in Traumatic Brain Injury (TBI). Methods: Three

Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections.

Science.gov (United States)

Schmid-Tannwald, C; Schmid-Tannwald, C M; Morelli, J N; Neumann, R; Reiser, M F; Nikolaou, K; Rist, C

2014-07-01

To evaluate the role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the differentiation of hepatic abscesses from non-infected fluid collections. In this retrospective study, 22 hepatic abscesses and 27 non-infected hepatic fluid collections were examined in 27 patients who underwent abdominal MRI including DW-MRI. Two independent observers reviewed T2-weighted + DW-MRI and T2-weighted + contrast-enhanced T1-weighted (CET1W) images in two sessions. Detection rates and confidence levels were calculated and compared using McNemar's and Wilcoxon's signed rank tests, respectively. Apparent diffusion coefficient (ADC) values of abscesses and non-infected fluid collections were compared using the t-test. Receiver operating characteristic (ROC) curves were constructed. There was no statistically significant difference in the accuracy of detecting abscesses using T2-weighted + DW-MRI (both observers: 21/22, 95.5%) versus T2-weighted + CET1W images (observer 1: 21/22, 95.5%; observer 2: 22/22, 100%; p collections (0.83 ± 0.24 versus 2.25 ± 0.61 × 10(-3) mm(2)/s; p collections at a threshold ADC value of 1.36 × 10(-3) mm(2)/s. DW-MRI allows qualitative and quantitative differentiation of abscesses from non-infected fluid collections in the liver. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Abnormal hyperintensity within the subarachnoid space evaluated by fluid-attenuated inversion-recovery MR imaging: a spectrum of central nervous system diseases

International Nuclear Information System (INIS)

Maeda, M.; Sakuma, H.; Takeda, K.; Yagishita, A.; Yamamoto, T.

2003-01-01

A variety of central nervous system (CNS) diseases are associated with abnormal hyperintensity within the subarachnoid space (SAS) by fluid-attenuated inversion-recovery (FLAIR) MR imaging. Careful attention to the SAS can provide additional useful information that may not be available with conventional MR sequences. The purpose of this article is to provide a pictorial essay about CNS diseases and FLAIR images with abnormal hyperintensity within the SAS. We present several CNS diseases including subarachnoid hemorrhage, meningitis, leptomeningeal metastases, acute infarction, and severe arterial occlusive diseases such as moya-moya disease. We also review miscellaneous diseases or normal conditions that may exhibit cerebrospinal fluid hyperintensity on FLAIR images. Although the detection of abnormal hyperintensity suggests the underlying CNS diseases and narrows differential diagnoses, FLAIR imaging sometimes presents artifactual hyperintensity within the SAS that can cause the misinterpretation of normal SAS as pathologic conditions; therefore, radiologists should be familiar with such artifactual conditions as well as pathologic conditions shown as hyperintensity by FLAIR images. This knowledge is helpful in establishing the correct diagnosis. (orig.)

Radiation protection clothing in X-ray diagnostics. Comparison of attenuation equivalents in narrow beam and inverse broad-beam geometry

International Nuclear Information System (INIS)

Pichler, Thomas; Schoepf, T.; Ennemoser, O.

2011-01-01

Purpose: Standard DIN EN 61 331-1 for attenuation measurements in the narrow and broad beam as well as DIN 6857-1 for the determination of shielding properties in the inverse broad-beam geometry are available for testing the attenuation of protection clothing. The attenuation measurements in the narrow beam don't consider scattered radiation and fluorescence due to the arrangement. This leads to the fact that the protective effect of lead-free materials will be misestimated when compared to lead. Therefore, the differences in attenuation equivalents, determined by both test methods for topical radiation protection aprons, were examined. Materials and Methods: The attenuations in inverse broad-beam geometry according to DIN 6857-1 and in the narrow beam according to DIN EN 61 331-1 were measured using commercially available aprons. They were made of lead, lead-reduced and lead-free materials. For determination of the attenuation equivalents, certificated lead-foils with high purity and a precise thickness of 0.1 to 1.25 mm were used. Results: The measurements in the narrow beam according to DIN EN 61 331-1 showed that nearly all aprons reach the required lead equivalent at mid-range tube voltages of 100 kV. At higher and lower tube voltages, the requirements of DIN EN 61 331-3 were largely not met. In contrast, the testing of the same aprons in inverse broad-beam geometry according to DIN 6857-1 showed that only a few aprons meet the requirements for being classified in the nominal protection class. Conclusion: The measurements suggest that testing method DIN 6857-1 has yet to prevail and that manufacturers are just beginning to develop the appropriate protective materials. (orig.)

MR imaging findings of diffuse axonal injury: comparison of T2-weighted gradient images and T1- and T2-weighted spin-echo images

Energy Technology Data Exchange (ETDEWEB)

Park, Seo Young; Lee, Ghi Jai; Kim, Jeong Seok; Shim, Jae Chan; Kim, Ho Kyun [Inje Univ. College of Medicine, Seoul (Korea, Republic of)

1998-10-01

To compare T2-weighted images with spin-echo T1- and turbo spin-echo (TSE) T2-weighted images in patients with diffuse axonal injury(DAI). Using a 1.0T MR unit, SE T1-, TSE T2-, and and FLASH T2-weighted images were obtained from 69 patients with a history of head trauma. In 18MR images of 17 patients with imaging findings of DAI, T2-weighted images were retrospectively compared with SE T1- and TSE T2-weighted images. The interval between trauma and MR scan varied from 5 days to 24(mean, 11) months. Focusing on the number of lesions, and their location and signal intensity, as weel as associated findings, three images were simultaueously evaluated. In 18 MR images of 17 patients with MR imaging findings of DAI, 21 lesions were detected on T1-weighted images, 28 on TSE T2-weighted images, and 70 on T2-weighted images;the last of these revealed all lesions detected on the other two. Most lesions were hypointense on T1-weighted images(17/21), hyperintense on TSE T2-weighted (21/28), and hypointense on T2-weighted (63/70). Common locations for DAI were the frontal lobe (n=3D35) and corpus callosum (n=3D22). Associated brain injuries were cortical contusion (n=3D5), brainstem injury (n=3D3), deep gray matter injury (n=3D2), and subdural hematoma(n=3D1). In patients with DAI. T2-weighted images can detect more lesions and associated petechial hemorrhage than can TSE T2-weighted images. This modality is thus useful for the evaluation of patients with head trauma.=20.

Regional Fluid-Attenuated Inversion Recovery (FLAIR at 7 Tesla correlates with Amyloid beta in Hippocampus and Brainstem of cognitively normal elderly subjects.

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Simon J Schreiner

2014-09-01

Full Text Available Background: Accumulation of amyloid beta (Aβ may occur during healthy aging and is a risk factor for Alzheimer Disease (AD. While individual Aβ-accumulation can be measured non-invasively using Pittsburgh compound-B positron-emission-tomography (PiB-PET, Fluid-Attenuated Inversion Recovery (FLAIR is a Magnetic Resonance Imaging (MRI sequence, capable of indicating heterogeneous age-related brain pathologies associated with tissue-edema. In the current study cognitively normal elderly subjects were investigated for regional correlation of PiB- and FLAIR- intensity. Methods: 14 healthy elderly subjects without known history of cognitive impairment received 11C-PiB-PET for estimation of regional Aβ-load. In addition, whole brain T1-MPRAGE and FLAIR-MRI sequences were acquired at high field strength of 7 Tesla (7T. Volume-normalized intensities of brain regions were assessed by applying an automated subcortical segmentation algorithm for spatial definition of brain structures. Statistical dependence between FLAIR- and PiB-PET intensities was tested using Spearman's rank correlation coefficient (rho, followed by Holm-Bonferroni correction for multiple testing. Results: Neuropsychological testing revealed normal cognitive performance levels in all participants. Mean regional PiB-PET and FLAIR intensities were normally distributed and independent. Significant correlation between volume-normalized PiB-PET signals and FLAIR intensities resulted for Hippocampus (right:rho=0.86; left:rho=0.84, Brainstem (rho=0.85 and left Basal Ganglia vessel region (rho=0.82. Conclusions: Our finding of a significant relationship between PiB- and FLAIR-intensity mainly observable in the Hippocampus and Brainstem, indicates regional Aβ associated tissue-edema in cognitively normal elderly subjects. Further studies including clinical populations are necessary to clarify the relevance of our findings for estimating individual risk for age-related neurodegenerative

Regional Fluid-Attenuated Inversion Recovery (FLAIR) at 7 Tesla correlates with amyloid beta in hippocampus and brainstem of cognitively normal elderly subjects

Science.gov (United States)

Schreiner, Simon J.; Liu, Xinyang; Gietl, Anton F.; Wyss, Michael; Steininger, Stefanie C.; Gruber, Esmeralda; Treyer, Valerie; Meier, Irene B.; Kälin, Andrea M.; Leh, Sandra E.; Buck, Alfred; Nitsch, Roger M.; Pruessmann, Klaas P.; Hock, Christoph; Unschuld, Paul G.

2014-01-01

Background: Accumulation of amyloid beta (Aβ) may occur during healthy aging and is a risk factor for Alzheimer Disease (AD). While individual Aβ-accumulation can be measured non-invasively using Pittsburgh Compund-B positron emission tomography (PiB-PET), Fluid-attenuated inversion recovery (FLAIR) is a Magnetic Resonance Imaging (MRI) sequence, capable of indicating heterogeneous age-related brain pathologies associated with tissue-edema. In the current study cognitively normal elderly subjects were investigated for regional correlation of PiB- and FLAIR intensity. Methods: Fourteen healthy elderly subjects without known history of cognitive impairment received 11C-PiB-PET for estimation of regional Aβ-load. In addition, whole brain T1-MPRAGE and FLAIR-MRI sequences were acquired at high field strength of 7 Tesla (7T). Volume-normalized intensities of brain regions were assessed by applying an automated subcortical segmentation algorithm for spatial definition of brain structures. Statistical dependence between FLAIR- and PiB-PET intensities was tested using Spearman's rank correlation coefficient (rho), followed by Holm–Bonferroni correction for multiple testing. Results: Neuropsychological testing revealed normal cognitive performance levels in all participants. Mean regional PiB-PET and FLAIR intensities were normally distributed and independent. Significant correlation between volume-normalized PiB-PET signals and FLAIR intensities resulted for Hippocampus (right: rho = 0.86; left: rho = 0.84), Brainstem (rho = 0.85) and left Basal Ganglia vessel region (rho = 0.82). Conclusions: Our finding of a significant relationship between PiB- and FLAIR intensity mainly observable in the Hippocampus and Brainstem, indicates regional Aβ associated tissue-edema in cognitively normal elderly subjects. Further studies including clinical populations are necessary to clarify the relevance of our findings for estimating individual risk for age-related neurodegenerative

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T.

Science.gov (United States)

Schwindt, W; Kugel, H; Bachmann, R; Kloska, S; Allkemper, T; Maintz, D; Pfleiderer, B; Tombach, B; Heindel, W

2003-09-01

The increasing availability of high-field (3 T) MR scanners requires adapting and optimizing clinical imaging protocols to exploit the theoretically higher signal-to-noise ratio (SNR) of the higher field strength. Our aim was to establish reliable and stable protocols meeting the clinical demands for imaging the neurocranium at 3 T. Two hundred patients with a broad range of indications received an examination of the neurocranium with an appropriate assortment of imaging techniques at 3 T. Several imaging parameters were optimized. Keeping scan times comparable to those at 1.5 T we increased spatial resolution. Contrast-enhanced and non-enhanced T1-weighted imaging was best applying gradient-echo and inversion recovery (rather than spin-echo) techniques, respectively. For fluid-attenuated inversion recovery (FLAIR) imaging a TE of 120 ms yielded optimum contrast-to-noise ratio (CNR). High-resolution isotropic 3D data sets were acquired within reasonable scan times. Some artifacts were pronounced, but generally imaging profited from the higher SNR. We present a set of optimized examination protocols for neuroimaging at 3 T, which proved to be reliable in a clinical routine setting.

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T

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Schwindt, W.; Kugel, H.; Bachmann, R.; Kloska, S.; Allkemper, T.; Maintz, D.; Pfleiderer, B.; Tombach, B.; Heindel, W. [Institut fuer Klinische Radiologie, Universitaetsklinikum Muenster, Albert-Schweitzer-Strasse 33, 48129, Muenster (Germany)

2003-09-01

The increasing availability of high-field (3 T) MR scanners requires adapting and optimizing clinical imaging protocols to exploit the theoretically higher signal-to-noise ratio (SNR) of the higher field strength. Our aim was to establish reliable and stable protocols meeting the clinical demands for imaging the neurocranium at 3 T. Two hundred patients with a broad range of indications received an examination of the neurocranium with an appropriate assortment of imaging techniques at 3 T. Several imaging parameters were optimized. Keeping scan times comparable to those at 1.5 T we increased spatial resolution. Contrast-enhanced and non-enhanced T1-weighted imaging was best applying gradient-echo and inversion recovery (rather than spin-echo) techniques, respectively. For fluid-attenuated inversion recovery (FLAIR) imaging a TE of 120 ms yielded optimum contrast-to-noise ratio (CNR). High-resolution isotropic 3D data sets were acquired within reasonable scan times. Some artifacts were pronounced, but generally imaging profited from the higher SNR. We present a set of optimized examination protocols for neuroimaging at 3 T, which proved to be reliable in a clinical routine setting. (orig.)

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T

International Nuclear Information System (INIS)

Schwindt, W.; Kugel, H.; Bachmann, R.; Kloska, S.; Allkemper, T.; Maintz, D.; Pfleiderer, B.; Tombach, B.; Heindel, W.

2003-01-01

The increasing availability of high-field (3 T) MR scanners requires adapting and optimizing clinical imaging protocols to exploit the theoretically higher signal-to-noise ratio (SNR) of the higher field strength. Our aim was to establish reliable and stable protocols meeting the clinical demands for imaging the neurocranium at 3 T. Two hundred patients with a broad range of indications received an examination of the neurocranium with an appropriate assortment of imaging techniques at 3 T. Several imaging parameters were optimized. Keeping scan times comparable to those at 1.5 T we increased spatial resolution. Contrast-enhanced and non-enhanced T1-weighted imaging was best applying gradient-echo and inversion recovery (rather than spin-echo) techniques, respectively. For fluid-attenuated inversion recovery (FLAIR) imaging a TE of 120 ms yielded optimum contrast-to-noise ratio (CNR). High-resolution isotropic 3D data sets were acquired within reasonable scan times. Some artifacts were pronounced, but generally imaging profited from the higher SNR. We present a set of optimized examination protocols for neuroimaging at 3 T, which proved to be reliable in a clinical routine setting. (orig.)

Disruption of the leptomeningeal blood barrier in neuromyelitis optica spectrum disorder

DEFF Research Database (Denmark)

Asgari, Nasrin; Flanagan, Eoin P.; Fujihara, Kazuo

2017-01-01

with leptomeningeal enhancement (LME) were collected from 5 centers. External neuroradiologists, blinded to the clinical details, evaluated MRIs. Results: LME was demonstrated on postcontrast T1-weighted and fluid-attenuated inversion recovery images as a sign of leptomeningeal blood-barrier disruption and transient...

Elastic wave attenuation in rocks containing fluids

International Nuclear Information System (INIS)

Berryman, J.G.

1986-01-01

The low-frequency limit of Biot's theory of fluid-saturated porous media predicts that the coefficients for viscous attenuation of shear waves and of the fast compressional wave are proportional to the fluid permeability. Although the observed attenuation is generally in qualitative agreement with the theory, the magnitude of the observed attenuation coefficient in rocks is often more than an order of magnitude higher than expected. This apparent dilemma can be resolved without invoking other attenuation mechanisms if the intrinsic permeability of the rock is inhomogeneous and varies widely in magnitude. A simple calculation of the overall behavior of a layered porous material using local-flow Biot theory shows that the effective permeability for attenuation is the mean of the constituent permeabilities while the effective permeability for fluid flow is the harmonic mean. When the range of variation in the local permeability is one or more orders of magnitude, this difference in averaging method can easily explain some of the observed discrepancies

MR imaging pulse sequence rationale: SD-, T1-, and T2-weighted images

International Nuclear Information System (INIS)

Sax, S.; Weathers, S.W.; Schneiders, N.J.; Horowitz, B.L.; Mawad, M.E.; Sandlin, M.E.; Blackwell, R.; Bryan, R.N.

1986-01-01

Over 500 patients have been examined with a pulse sequence designed to provide spin-density (SD)-weighted images (TR=3 sec, TE=35 msec), T1-weighted images (TR=0.3 sec, TE=35msec), and T2-weighted images (TR=3 sec, TE=105 msec) from which calculated ''synthesized'' images and SD, T1, and T2 calculated images could be obtained. Each image contributes unique information. SD-weighted images optimally display anatomy and often best highlight pathology. T1-weighted images are critical in assessing cerebral hemorrhages. T2-weighted images best display most lesions, but yield incomplete information in 35% of cases. All three types of ''weighted'' images are necessary to optimally display anatomy and fully characterize a lesion. Computerized calculations and simulations suggest that no other combination of pulse sequences yields equal information for a given examination time

[Contrastive analysis of artifacts produced by metal dental crowns in 3.0 T magnetic resonance imaging with six sequences].

Science.gov (United States)

Lan, Gao; Yunmin, Lian; Pu, Wang; Haili, Huai

2016-06-01

This study aimed to observe and evaluate six 3.0 T sequences of metallic artifacts produced by metal dental crowns. Dental crowns fabricated with four different materials (Co-Gr, Ni-Gr, Ti alloy and pure Ti) were evaluated. A mature crossbreed dog was used as the experimental animal, and crowns were fabricated for its upper right second premolar. Each crown was examined through head MRI (3.0 T) with six sequences, namely, T₁ weighted-imaging of spin echo (T₁W/SE), T₂ weighted-imaging of inversion recovery (T₂W/IR), T₂ star gradient echo (T₂*/GRE), T2 weighted-imaging of fast spin echo (T₂W/FSE), T₁ weighted-imaging of fluid attenuate inversion recovery (T₂W/FLAIR), and T₂ weighted-imaging of propeller (T₂W/PROP). The largest area and layers of artifacts were assessed and compared. The artifact in the T₂*/GRE sequence was significantly wider than those in the other sequences (P 0.05). T₂*/GRE exhibit the strongest influence on the artifact, whereas the five other sequences contribute equally to artifact generation.

Magnetic resonance characteristics and susceptibility weighted imaging of the brain in gadolinium encephalopathy.

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Samardzic, Dejan; Thamburaj, Krishnamoorthy

2015-01-01

To report the brain imaging features on magnetic resonance imaging (MRI) in inadvertent intrathecal gadolinium administration. A 67-year-old female with gadolinium encephalopathy from inadvertent high dose intrathecal gadolinium administration during an epidural steroid injection was studied with multisequence 3T MRI. T1-weighted imaging shows pseudo-T2 appearance with diffusion of gadolinium into the brain parenchyma, olivary bodies, and membranous labyrinth. Nulling of cerebrospinal fluid (CSF) signal is absent on fluid attenuation recovery (FLAIR). Susceptibility-weighted imaging (SWI) demonstrates features similar to subarachnoid hemorrhage. CT may demonstrate a pseudo-cerebral edema pattern given the high attenuation characteristics of gadolinium. Intrathecal gadolinium demonstrates characteristic imaging features on MRI of the brain and may mimic subarachnoid hemorrhage on susceptibility-weighted imaging. Identifying high dose gadolinium within the CSF spaces on MRI is essential to avoid diagnostic and therapeutic errors. Copyright © 2013 by the American Society of Neuroimaging.

Temporal pole signal abnormality on MR imaging in temporal lobe epilepsy with hippocampal sclerosis: a fluid-attenuated inversion-recovery study.

Science.gov (United States)

Carrete, Henrique; Abdala, Nitamar; Lin, Kátia; Caboclo, Luís Otávio; Centeno, Ricardo Silva; Sakamoto, Américo Ceiki; Szjenfeld, Jacob; Nogueira, Roberto Gomes; Yacubian, Elza Márcia Targas

2007-09-01

To determine the frequency and regional involvement of temporal pole signal abnormality (TPA) in patients with hippocampal sclerosis (HS) using fluid-attenuated inversion-recovery (FLAIR) MR imaging, and to correlate this feature with history. Coronal FLAIR images of the temporal pole were assessed in 120 patients with HS and in 30 normal subjects, to evaluate gray-white matter demarcation. Ninety (75%) of 120 patients had associated TPA. The HS side made difference regarding the presence of TPA, with a left side prevalence (p=0.04, chi2 test). The anteromedial zone of temporal pole was affected in 27 (30%) out of 90 patients. In 63 (70%) patients the lateral zone were also affected. Patients with TPA were younger at seizure onset (p=0.018), but without association with duration of epilepsy. Our FLAIR study show temporal pole signal abnormality in 3/4 of patients with HS, mainly seen on the anteromedial region, with a larger prevalence when the left hippocampus was involved.

Temporal pole signal abnormality on MR imaging in temporal lobe epilepsy with hippocampal sclerosis: a fluid-attenuated inversion-recovery study

International Nuclear Information System (INIS)

Carrete Junior, Henrique; Abdala, Nitamar; Szjenfeld, Jacob; Nogueira, Roberto Gomes; Lin, Katia; Caboclo, Luis Otavio; Centeno, Ricardo Silva; Sakamoto, Americo Ceiki; Yacubian, Elza Marcia Targas

2007-01-01

Objective: To determine the frequency and regional involvement of temporal pole signal abnormality (TPA) in patients with hippocampal sclerosis (HS) using fluid-attenuated inversion-recovery (FLAIR) MR imaging, and to correlate this feature with history. Method: Coronal FLAIR images of the temporal pole were assessed in 120 patients with HS and in 30 normal subjects, to evaluate gray-white matter demarcation. Results: Ninety (75%) of 120 patients had associated TPA. The HS side made difference regarding the presence of TPA, with a left side prevalence (p=0.04, χ 2 test). The anteromedial zone of temporal pole was affected in 27 (30%) out of 90 patients. In 63 (70%) patients the lateral zone were also affected. Patients with TPA were younger at seizure onset (p=0.018), but without association with duration of epilepsy. Conclusion: Our FLAIR study show temporal pole signal abnormality in 3/4 of patients with HS, mainly seen on the anteromedial region, with a larger prevalence when the left hippocampus was involved. (author)

Magnetic resonance imaging of pelvic entheses - a systematic comparison between short tau inversion recovery (STIR) and T1-weighted, contrast-enhanced, fat-saturated sequences

International Nuclear Information System (INIS)

Klang, Eyal; Aharoni, Dvora; Rimon, Uri; Eshed, Iris; Hermann, Kay-Geert; Herman, Amir; Shazar, Nachshon

2014-01-01

To assess the contribution of contrast material in detecting and evaluating enthesitis of pelvic entheses by MRI. Sixty-seven hip or pelvic 1.5-T MRIs (30:37 male:female, mean age: 53 years) were retrospectively evaluated for the presence of hamstring and gluteus medius (GM) enthesitis by two readers (a resident and an experienced radiologist). Short tau inversion recovery (STIR) and T1-weighted pre- and post-contrast (T1+Gd) images were evaluated by each reader at two sessions. A consensus reading of two senior radiologists was regarded as the gold standard. Clinical data was retrieved from patients' referral form and medical files. Cohen's kappa was used for intra- and inter-observer agreement calculation. Diagnostic properties were calculated against the gold standard reading. A total of 228 entheses were evaluated. Gold standard analysis diagnosed 83 (36 %) enthesitis lesions. Intra-reader reliability for the experienced reader was significantly (p = 0.0001) higher in the T1+Gd images compared to the STIR images (hamstring: k = 0.84/0.45, GM: k = 0.84/0.47). Sensitivity and specificity increased from 0.74/0.8 to 0.87/0.9 in the STIR images and T1+Gd sequences. Intra-reader reliability for the inexperienced reader was lower (p > 0.05). Evidence showing that contrast material improves the reliability, sensitivity, and specificity of detecting enthesitis supports its use in this setting. (orig.)

Quantitative T1 and T2* carotid atherosclerotic plaque imaging using a three-dimensional multi-echo phase-sensitive inversion recovery sequence: a feasibility study.

Science.gov (United States)

Fujiwara, Yasuhiro; Maruyama, Hirotoshi; Toyomaru, Kanako; Nishizaka, Yuri; Fukamatsu, Masahiro

2018-06-01

Magnetic resonance imaging (MRI) is widely used to detect carotid atherosclerotic plaques. Although it is important to evaluate vulnerable carotid plaques containing lipids and intra-plaque hemorrhages (IPHs) using T 1 -weighted images, the image contrast changes depending on the imaging settings. Moreover, to distinguish between a thrombus and a hemorrhage, it is useful to evaluate the iron content of the plaque using both T 1 -weighted and T 2 *-weighted images. Therefore, a quantitative evaluation of carotid atherosclerotic plaques using T 1 and T 2 * values may be necessary for the accurate evaluation of plaque components. The purpose of this study was to determine whether the multi-echo phase-sensitive inversion recovery (mPSIR) sequence can improve T 1 contrast while simultaneously providing accurate T 1 and T 2 * values of an IPH. T 1 and T 2 * values measured using mPSIR were compared to values from conventional methods in phantom and in vivo studies. In the phantom study, the T 1 and T 2 * values estimated using mPSIR were linearly correlated with those of conventional methods. In the in vivo study, mPSIR demonstrated higher T 1 contrast between the IPH phantom and sternocleidomastoid muscle than the conventional method. Moreover, the T 1 and T 2 * values of the blood vessel wall and sternocleidomastoid muscle estimated using mPSIR were correlated with values measured by conventional methods and with values reported previously. The mPSIR sequence improved T 1 contrast while simultaneously providing accurate T 1 and T 2 * values of the neck region. Although further study is required to evaluate the clinical utility, mPSIR may improve carotid atherosclerotic plaque detection and provide detailed information about plaque components.

T1- Thresholds in Black Holes Increase Clinical-Radiological Correlation in Multiple Sclerosis Patients.

Science.gov (United States)

Thaler, Christian; Faizy, Tobias; Sedlacik, Jan; Holst, Brigitte; Stellmann, Jan-Patrick; Young, Kim Lea; Heesen, Christoph; Fiehler, Jens; Siemonsen, Susanne

2015-01-01

Magnetic Resonance Imaging (MRI) is an established tool in diagnosing and evaluating disease activity in Multiple Sclerosis (MS). While clinical-radiological correlations are limited in general, hypointense T1 lesions (also known as Black Holes (BH)) have shown some promising results. The definition of BHs is very heterogeneous and depends on subjective visual evaluation. We aimed to improve clinical-radiological correlations by defining BHs using T1 relaxation time (T1-RT) thresholds to achieve best possible correlation between BH lesion volume and clinical disability. 40 patients with mainly relapsing-remitting MS underwent MRI including 3-dimensional fluid attenuated inversion recovery (FLAIR), magnetization-prepared rapid gradient echo (MPRAGE) before and after Gadolinium (GD) injection and double inversion-contrast magnetization-prepared rapid gradient echo (MP2RAGE) sequences. BHs (BHvis) were marked by two raters on native T1-weighted (T1w)-MPRAGE, contrast-enhancing lesions (CE lesions) on T1w-MPRAGE after GD and FLAIR lesions (total-FLAIR lesions) were detected separately. BHvis and total-FLAIR lesion maps were registered to MP2RAGE images, and the mean T1-RT were calculated for all lesion ROIs. Mean T1 values of the cortex (CTX) were calculated for each patient. Subsequently, Spearman rank correlations between clinical scores (Expanded Disability Status Scale and Multiple Sclerosis Functional Composite) and lesion volume were determined for different T1-RT thresholds. Significant differences in T1-RT were obtained between all different lesion types with highest T1 values in visually marked BHs (BHvis: 1453.3±213.4 ms, total-FLAIR lesions: 1394.33±187.38 ms, CTX: 1305.6±35.8 ms; p1500 ms (Expanded Disability Status Scale vs. lesion volume: rBHvis = 0.442 and rtotal-FLAIR = 0.497, p<0.05; Multiple Sclerosis Functional Composite vs. lesion volume: rBHvis = -0.53 and rtotal-FLAIR = -0.627, p<0.05). Clinical-radiological correlations in MS patients are

3D-Flair sequence at 3T in cochlear otosclerosis

International Nuclear Information System (INIS)

Lombardo, Francesco; De Cori, Sara; Aghakhanyan, Gayane; Montanaro, Domenico; De Marchi, Daniele; Frijia, Francesca; Canapicchi, Raffaello; Fortunato, Susanna; Forli, Francesca; Berrettini, Stefano; Chiappino, Dante

2016-01-01

To assess the capability of three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequences in detecting signal alterations of the endolabyrinthine fluid in patients with otosclerosis. 3D-FLAIR before and after (-/+) gadolinium (Gd) administration was added to the standard MR protocol and acquired in 13 patients with a clinical/audiological diagnosis of severe/profound hearing loss in otosclerosis who were candidates for cochlear implantation and in 11 control subjects using 3-T magnetic resonance imaging (MRI) equipment. The MRI signal of the fluid-filled cochlea was assessed both visually and calculating the signal intensity ratio (SIR = signal intensity cochlea/brainstem). We revealed no endocochlear signal abnormalities on T1-weighted -/+ Gd images for either group, while on 3D-FLAIR we found bilateral hyperintensity with enhancement after Gd administration in eight patients and bilateral hyperintensity without enhancement in one patient. No endocochlear signal abnormalities were detected in other patients or the control group. Using 3-T MRI equipment, the 3D-FLAIR -/+ Gd sequence is able to detect the blood-labyrinth barrier (BLB) breakdown responsible for alterations of the endolabyrinthine fluid in patients with cochlear otosclerosis. We believe that 3D-FLAIR +/- Gd is an excellent imaging modality to assess the intra-cochlear damage in otosclerosis patients. (orig.)

3D-Flair sequence at 3T in cochlear otosclerosis

Energy Technology Data Exchange (ETDEWEB)

Lombardo, Francesco; De Cori, Sara; Aghakhanyan, Gayane; Montanaro, Domenico; De Marchi, Daniele; Frijia, Francesca; Canapicchi, Raffaello [Fondazione CNR Regione Toscana ' ' G. Monasterio' ' , Neuroradiology Unit, Pisa (Italy); Fortunato, Susanna; Forli, Francesca; Berrettini, Stefano [University of Pisa, ENT Audiology Phoniatry Unit, Department of Neuroscience, Pisa (Italy); Chiappino, Dante [Fondazione CNR Regione Toscana ' ' G. Monasterio' ' , Department of Radiology, Massa (Italy)

2016-10-15

To assess the capability of three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequences in detecting signal alterations of the endolabyrinthine fluid in patients with otosclerosis. 3D-FLAIR before and after (-/+) gadolinium (Gd) administration was added to the standard MR protocol and acquired in 13 patients with a clinical/audiological diagnosis of severe/profound hearing loss in otosclerosis who were candidates for cochlear implantation and in 11 control subjects using 3-T magnetic resonance imaging (MRI) equipment. The MRI signal of the fluid-filled cochlea was assessed both visually and calculating the signal intensity ratio (SIR = signal intensity cochlea/brainstem). We revealed no endocochlear signal abnormalities on T1-weighted -/+ Gd images for either group, while on 3D-FLAIR we found bilateral hyperintensity with enhancement after Gd administration in eight patients and bilateral hyperintensity without enhancement in one patient. No endocochlear signal abnormalities were detected in other patients or the control group. Using 3-T MRI equipment, the 3D-FLAIR -/+ Gd sequence is able to detect the blood-labyrinth barrier (BLB) breakdown responsible for alterations of the endolabyrinthine fluid in patients with cochlear otosclerosis. We believe that 3D-FLAIR +/- Gd is an excellent imaging modality to assess the intra-cochlear damage in otosclerosis patients. (orig.)

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

International Nuclear Information System (INIS)

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

1997-01-01

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

Evaluation of neonatal brain myelination using the T1- and T2-weighted MRI ratio.

Science.gov (United States)

Soun, Jennifer E; Liu, Michael Z; Cauley, Keith A; Grinband, Jack

2017-09-01

To validate the T1- and T2-weighted (T1w/T2w) MRI ratio technique in evaluating myelin in the neonatal brain. T1w and T2w MR images of 10 term neonates with normal-appearing brain parenchyma were obtained from a single 1.5 Tesla MRI and retrospectively analyzed. T1w/T2w ratio images were created with a postprocessing pipeline and qualitatively compared with standard clinical sequences (T1w, T2w, and apparent diffusion coefficient [ADC]). Quantitative assessment was also performed to assess the ratio technique in detecting areas of known myelination (e.g., posterior limb of the internal capsule) and very low myelination (e.g., optic radiations) using linear regression analysis and the Michelson Contrast equation, a measure of luminance contrast intensity. The ratio image provided qualitative improvements in the ability to visualize regional variation in myelin content of neonates. Linear regression analysis demonstrated a significant inverse relationship between the ratio intensity values and ADC values in the posterior limb of the internal capsule and the optic radiations (R 2  = 0.96 and P ratio images were 1.6 times higher than T1w, 2.6 times higher than T2w, and 1.8 times higher than ADC (all P ratio improved visualization of the corticospinal tract, one of the earliest myelinated pathways. The T1w/T2w ratio accentuates contrast between myelinated and less myelinated structures and may enhance our diagnostic ability to detect myelination patterns in the neonatal brain. 2 Technical Efficacy: Stage2 J. MAGN. RESON. IMAGING 2017;46:690-696. © 2016 International Society for Magnetic Resonance in Medicine.

Comparison of a T1-weighted inversion-recovery-, gradient-echo- and spin-echo sequence for imaging of the brain at 3.0 Tesla

International Nuclear Information System (INIS)

Stehling, C.; Niederstadt, T.; Kraemer, S.; Kugel, H.; Schwindt, W.; Heindel, W.; Bachmann, R.

2005-01-01

Purpose: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). Materials and Methods: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. Results: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the based ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p<0.001), but the CNR of the basal ganglia was not significantly different. Conclusion: For unenhanced T1w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T. (orig.)

Multi-resolution inversion algorithm for the attenuated radon transform

KAUST Repository

Barbano, Paolo Emilio

2011-09-01

We present a FAST implementation of the Inverse Attenuated Radon Transform which incorporates accurate collimator response, as well as artifact rejection due to statistical noise and data corruption. This new reconstruction procedure is performed by combining a memory-efficient implementation of the analytical inversion formula (AIF [1], [2]) with a wavelet-based version of a recently discovered regularization technique [3]. The paper introduces all the main aspects of the new AIF, as well numerical experiments on real and simulated data. Those display a substantial improvement in reconstruction quality when compared to linear or iterative algorithms. © 2011 IEEE.

Role of T2 weighted magnetic resonance image in chronic phase of head injured patients

International Nuclear Information System (INIS)

Uzura, Masahiko; Taguchi, Yoshio; Watanabe, Hiroyuki; Chiba, Syunmei; Matsuzawa, Motoshi

2002-01-01

In neuroimaging studies of head injury, addition of echo planar imaging (EPI) T2-weighted images (WI) to routine MR images has been useful in demonstrating small hemorrhagic lesions as magnetic susceptibility artifacts (MSAs). MSAs are often found in the acute or subacute phases of head injured patients with diffuse axonal injury. We studied MSAs in follow-up MR images of patients with diffuse brain injury and discuss the role of EPI T2-WI in patients with chronic phase of head injured patients. This series consisted of 20 patients with diffuse brain injury diagnosed clinically. Their head CT findings were classified into Diffuse Injury I or II according to the CT classification of Marshall et al. All patients underwent long-term follow-up MR examinations. MR findings in chronic phase were divided into three categories in terms of MSAs: group A, MSAs remaining even after disappearance of small traumatic lesions in both T2-WI and fluid attenuated inversion recovery (FLAIR) images (11 cases); group B, MSA (s) that disappeared in association with disappearance of small traumatic lesions (4 cases); and group C, MSAs that remained but could not be differentiated from non-traumatic lesions such as hemorrhagic lacunae or cavernoma (5 cases). Adding EPI T2-WI to routine MR images can provide useful information in visualizing old traumatic lesions of the brain in patients with diffuse brain injury even if no neuroimaging studies in acute or subacute phase. (author)

Comparison of MR sequences in early cerebral infarction at 0.5 T

International Nuclear Information System (INIS)

Saatci, I.; Baskan, O.; Cekirge, H.S.; Besim, A.

2000-01-01

To compare the diagnostic values of fluid-attenuated inversion recovery (FLAIR) and gradient spin-echo (GRASE) with those of conventional spin-echo (SE) and fast SE T2-weighted sequences in the evaluation of acute cerebrovascular lesions at 0.5 T. Material and Methods: Twenty-two consecutive patients with the clinical diagnosis of acute cerebrovascular accident were examined by MR imaging within the first 48 h of ictus. MR examination included 5-mm axial conventional SE and turbo SE (TSE) T2-weighted, dual-echo GRASE and FLAIR sequences. The patients also had pre- and postcontrast T1-weighted axial images. Two examiners evaluated the images and scored the conspicuity of the acute lesions. Results: Regardless of location, FLAIR provided the best lesion conspicuity in the detection of acute infarcts, followed by the GRASE sequence. In the posterior fossa, TSE and SE demonstrated the lesions better than GRASE and FLAIR techniques. In the detection of hemorrhagic elements within the ischemic region, TSE demonstrated statistically significant superiority over other sequences. Conclusion: In the detection of acute ischemic lesions in locations other than the posterior fossa, FLAIR provided the best lesion conspicuity among four T2-weighted sequences, including SE, TSE, GRASE and FLAIR. However, for the posterior fossa examination, preference of SE or TSE T2-weighted sequences is suggested

Comparison of MR sequences in early cerebral infarction at 0.5 T

Energy Technology Data Exchange (ETDEWEB)

Saatci, I.; Baskan, O.; Cekirge, H.S.; Besim, A. [Hacettepe Univ. Hospital, Ankara (Turkey). Radiology Dept.

2000-11-01

To compare the diagnostic values of fluid-attenuated inversion recovery (FLAIR) and gradient spin-echo (GRASE) with those of conventional spin-echo (SE) and fast SE T2-weighted sequences in the evaluation of acute cerebrovascular lesions at 0.5 T. Material and Methods: Twenty-two consecutive patients with the clinical diagnosis of acute cerebrovascular accident were examined by MR imaging within the first 48 h of ictus. MR examination included 5-mm axial conventional SE and turbo SE (TSE) T2-weighted, dual-echo GRASE and FLAIR sequences. The patients also had pre- and postcontrast T1-weighted axial images. Two examiners evaluated the images and scored the conspicuity of the acute lesions. Results: Regardless of location, FLAIR provided the best lesion conspicuity in the detection of acute infarcts, followed by the GRASE sequence. In the posterior fossa, TSE and SE demonstrated the lesions better than GRASE and FLAIR techniques. In the detection of hemorrhagic elements within the ischemic region, TSE demonstrated statistically significant superiority over other sequences. Conclusion: In the detection of acute ischemic lesions in locations other than the posterior fossa, FLAIR provided the best lesion conspicuity among four T2-weighted sequences, including SE, TSE, GRASE and FLAIR. However, for the posterior fossa examination, preference of SE or TSE T2-weighted sequences is suggested.

Gadoxate-enhanced T1-weighted MR cholangiography: comparison of 1.5 T and 3.0 T

Energy Technology Data Exchange (ETDEWEB)

Koelblinger, C.; Schima, W.; Weber, M.; Mang, T.; Nemec, S.; Kulinna-Cosentini, C.; Bastati, N.; Ba-Ssalamah, A. [Universitaetsklinik fuer Radiodiagnostik, Medizinische Univ. Wien (Austria)

2009-06-15

Purpose: to qualitatively and quantitatively compare gadoxate-enhanced T1-weighted MR cholangiography at magnetic field strengths of 1.5 T and 3.0 T. Materials and methods: a total of 40 patients with a non-dilated biliary system were retrospectively included in the study. T1-weighted MR cholangiography 20 min after IV administration of 0.025 mmol/kg gadoxate (Primovist trademark) was performed in 20 patients at 1.5 T and in another 20 patients at 3.0 T. Contrast-to-noise ratios (CNR) of the biliary system (common bile duct - CBD, right hepatic duct - RHD, left hepatic duct - LHD) compared to the periductal tissue were measured. Two radiologists also qualitatively assessed the visibility of the intrahepatic and extrahepatic biliary system using a six-point rating scale. The Mann-Whitney U-test and Pearson's correlation coefficient were used for statistical analysis. Results: the CNRs of the intrahepatic and extrahepatic hepatic bile ducts were significantly higher at 3.0 T. Qualitative analysis showed a significant superiority for 3.0 T in the delineation of the intrahepatic biliary system (RHD, LHD, segmental ducts). (orig.)

Assessment of Silent T1-weighted head imaging at 7 T

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Costagli, Mauro; Tiberi, Gianluigi; Tosetti, Michela [Imago7 Foundation, Pisa (Italy); IRCCS Stella Maris, Laboratory of Medical Physics and Biotechnologies for Magnetic Resonance, Pisa (Italy); Symms, Mark R. [GE Applied Science Laboratory, Pisa (Italy); Angeli, Lorenzo [University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Pisa (Italy); Kelley, Douglas A.C. [GE Healthcare Technologies, San Francisco, CA (United States); Biagi, Laura [IRCCS Stella Maris, Laboratory of Medical Physics and Biotechnologies for Magnetic Resonance, Pisa (Italy); Farnetani, Andrea [University of Ferrara, Engineering Department, Ferrara (Italy); Materiacustica s.r.l., Ferrara (Italy); Rua, Catarina [University of Pisa, Department of Physics, Pisa (Italy); Donatelli, Graziella [Azienda Ospedaliero-Universitaria Pisana (AOUP), Neuroradiology Unit, Department of Diagnostic and Interventional Radiology, Pisa (Italy); Cosottini, Mirco [Imago7 Foundation, Pisa (Italy); University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Pisa (Italy)

2016-06-15

This study aimed to assess the performance of a ''Silent'' zero time of echo (ZTE) sequence for T1-weighted brain imaging using a 7 T MRI system. The Silent sequence was evaluated qualitatively by two neuroradiologists, as well as quantitatively in terms of tissue contrast, homogeneity, signal-to-noise ratio (SNR) and acoustic noise. It was compared to conventional T1-weighted imaging (FSPGR). Adequacy for automated segmentation was evaluated in comparison with FSPGR acquired at 7 T and 1.5 T. Specific absorption rate (SAR) was also measured. Tissue contrast and homogeneity in Silent were remarkable in deep brain structures and in the occipital and temporal lobes. Mean tissue contrast was significantly (p < 0.002) higher in Silent (0.25) than in FSPGR (0.11), which favoured automated tissue segmentation. On the other hand, Silent images had lower SNR with respect to conventional imaging: average SNR of FSPGR was 2.66 times that of Silent. Silent images were affected by artefacts related to projection reconstruction, which nevertheless did not compromise the depiction of brain tissues. Silent acquisition was 35 dB(A) quieter than FSPGR and less than 2.5 dB(A) louder than ambient noise. Six-minute average SAR was <2 W/kg. The ZTE Silent sequence provides high-contrast T1-weighted imaging with low acoustic noise at 7 T. (orig.)

Unfocused beam patterns in nonattenuating and attenuating fluids

International Nuclear Information System (INIS)

Goldstein, Albert

2004-01-01

The most important aspect of an ultrasound measuring system is knowledge of the transducer beam pattern. At all depths accurate single integral equations have been derived for the full beam pattern of steady state unfocused circular flat piston sources radiating into nonattenuating and attenuating fluids. The axial depth of the beginning of the unattenuated beam pattern far field is found to be at 6.41Y 0 . The unattenuated single integral equations are identical to a Jinc function directivity term at this and deeper depths. For attenuating fluids values of α and z are found that permit the attenuated axial pressure to be represented by a plane wave multiplicative exponential attenuation factor. This knowledge will aid in the experimental design of highly accurate attenuation measurements. Accurate single integral equations for the attenuated full beam pattern are derived using complex Bessel functions

Role of three-dimensional fluid-attenuated inversion recovery (3D FLAIR) and proton density magnetic resonance imaging for the detection and evaluation of lesion extent of focal cortical dysplasia in patients with refractory epilepsy

International Nuclear Information System (INIS)

Saini, Jitender; Kesavadas, Chandrasekharan; Thomas, Bejoy; Singh, Atampreet; Rathore, Chathurbhuj; Radhakrishnan, Ashalatha; Radhakrishnan, Kurupath; Bahuleyan, Biji

2010-01-01

Background: Focal cortical dysplasia (FCD) is often associated with epilepsy. Identification of FCD can be difficult due to subtle magnetic resonance imaging (MRI) changes. Though fluid-attenuated inversion recovery (FLAIR) sequence detects the majority of these lesions, smaller lesions may go unnoticed while larger lesions may be poorly delineated. Purpose: To determine the ability of a specialized epilepsy protocol in visualizing and delineating the extent of FCD. Material and Methods: We compared the imaging findings in nine patients with cortical malformation who underwent routine epilepsy MR imaging as well as a specialized epilepsy protocol. All imaging was done on a 1.5T MR unit. The specialized epilepsy protocol included 3D FLAIR in the sagittal plane as well as proton density (PD) and high-resolution T2-weighted (T2W) images in the transverse plane. Results: In all nine patients, the specialized protocol identified lesion anatomy better. In three patients in whom routine MRI was normal, the specialized epilepsy protocol including 3D FLAIR helped in identifying the lesions. One of these patients underwent surgery, and histo-pathology revealed a cortical dysplasia. In one patient, lesion characterization was improved, while in the remaining patients the extent of the FCD was more clearly demonstrated in the 3D FLAIR and PD images. Statistical analysis of images for cortical thickness, cortical signal intensity, adjacent white matter abnormalities, and gray-white matter junction showed significant statistical difference in the ability of 3D FLAIR to assess these aspects over conventional images. PD images were also found superior to the routine epilepsy protocol in assessment of cortical signal, adjacent white matter, and gray-white matter junction. Conclusion: Specialized MRI sequences and techniques should be performed whenever there is a high suspicion of cortical dysplasia, especially when they remain occult on conventional MR protocols. These techniques

Anterior temporal lobe white matter abnormal signal (ATLAS) as an indicator of seizure focus laterality in temporal lobe epilepsy: comparison of double inversion recovery, FLAIR and T2W MR imaging

Energy Technology Data Exchange (ETDEWEB)

Morimoto, Emiko; Kanagaki, Mitsunori; Okada, Tomohisa; Yamamoto, Akira; Togashi, Kaori [Kyoto University Graduate School of Medicine, Department of Diagnostic Imaging and Nuclear Medicine, Kyoto (Japan); Mori, Nobuyuki [Tenri Hospital, Department of Radiology, Tenri, Nara (Japan); Matsumoto, Riki; Ikeda, Akio; Takahashi, Ryosuke [Kyoto University Graduate School of Medicine, Department of Neurology, Kyoto (Japan); Mikuni, Nobuhiro [Sapporo Medical University, Department of Neurosurgery, Sapporo, Hokkaido (Japan); Kunieda, Takeharu; Miyamoto, Susumu [Kyoto University Graduate School of Medicine, Department of Neurosurgery, Kyoto (Japan); Paul, Dominik [Siemens AG Healthcare Sector, Erlangen (Germany)

2013-01-15

To investigate the diagnostic capability of anterior temporal lobe white matter abnormal signal (ATLAS) for determining seizure focus laterality in temporal lobe epilepsy (TLE) by comparing different MR sequences. This prospective study was approved by the institutional review board and written informed consent was obtained. Three 3D sequences (double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI)) and two 2D sequences (FLAIR and T2WI) were acquired at 3 T. Signal changes in the anterior temporal white matter of 21 normal volunteers were evaluated. ATLAS laterality was evaluated in 21 TLE patients. Agreement of independent evaluations by two neuroradiologists was assessed using {kappa} statistics. Differences in concordance between ATLAS laterality and clinically defined seizure focus laterality were analysed using McNemar's test with multiple comparisons. Pre-amygdala high signals (PAHS) were detected in all volunteers only on 3D-DIR. Inter-evaluator agreement was moderate to almost perfect for each sequence. Correct diagnosis of seizure laterality was significantly more frequent on 3D-DIR than on any other sequences (P {<=} 0.031 for each evaluator). The most sensitive sequence for detecting ATLAS laterality was 3D-DIR. ATLAS laterality on 3D-DIR can be a good indicator for determining seizure focus localization in TLE. (orig.)

Anterior temporal lobe white matter abnormal signal (ATLAS) as an indicator of seizure focus laterality in temporal lobe epilepsy: comparison of double inversion recovery, FLAIR and T2W MR imaging

International Nuclear Information System (INIS)

Morimoto, Emiko; Kanagaki, Mitsunori; Okada, Tomohisa; Yamamoto, Akira; Togashi, Kaori; Mori, Nobuyuki; Matsumoto, Riki; Ikeda, Akio; Takahashi, Ryosuke; Mikuni, Nobuhiro; Kunieda, Takeharu; Miyamoto, Susumu; Paul, Dominik

2013-01-01

To investigate the diagnostic capability of anterior temporal lobe white matter abnormal signal (ATLAS) for determining seizure focus laterality in temporal lobe epilepsy (TLE) by comparing different MR sequences. This prospective study was approved by the institutional review board and written informed consent was obtained. Three 3D sequences (double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI)) and two 2D sequences (FLAIR and T2WI) were acquired at 3 T. Signal changes in the anterior temporal white matter of 21 normal volunteers were evaluated. ATLAS laterality was evaluated in 21 TLE patients. Agreement of independent evaluations by two neuroradiologists was assessed using κ statistics. Differences in concordance between ATLAS laterality and clinically defined seizure focus laterality were analysed using McNemar's test with multiple comparisons. Pre-amygdala high signals (PAHS) were detected in all volunteers only on 3D-DIR. Inter-evaluator agreement was moderate to almost perfect for each sequence. Correct diagnosis of seizure laterality was significantly more frequent on 3D-DIR than on any other sequences (P ≤ 0.031 for each evaluator). The most sensitive sequence for detecting ATLAS laterality was 3D-DIR. ATLAS laterality on 3D-DIR can be a good indicator for determining seizure focus localization in TLE. (orig.)

Difference between T1 and T2 weighted MR images in avascular necrosis of the femoral head

International Nuclear Information System (INIS)

Kokubo, Takashi; Yoshikawa, Koki; Itai, Yuzo; Iio, Masahiro; Takatori, Yoshio; Kamogawa, Morihide; Ninomiya, Setsuo

1990-01-01

T 1 and T 2 weighted MR images were compared in 32 hips with avascular necrosis, and the difference between them was discussed. In 27 of 32 hips, abnormal low intensity area in the affected femoral head is smaller in T 2 weighted images than in T 1 weighted images. The area of low intensity on T 1 weighted image and high on T 2 weighted image might be granuloma in reactive tissue and surrounding hyperemia. The difference between T 1 and T 2 weighted images must be taken into consideration especially in determination of the border of affected bone. (author)

Evaluation of bone marrow by opposed phase T1-weighted images and enhanced MR imaging

International Nuclear Information System (INIS)

Amano, Yasuo; Tanabe, Yoshihiro; Miyashita, Tsuguhiro; Hayashi, Hiromitsu; Horiuchi, Junichi; Nomura, Takeo; Kumazaki, Tatsuo

1994-01-01

We investigated bone marrow in a control group, cases of aplastic anemia and post-irradiation patients by examining T1-weighted (T1W1), short T1 inversion recovery (STIR), opposed phase T1W1 (op-T1W1) and Gd-DTPA enhanced op-T1W1 images obtained by 0.5 T MRI. Bone marrow was classified into four types based on MR findings. Normal marrow showed low intensity on op-T1W1 and STIR images without enhancement (I). Fatty marrow, which showed high intensity on T1W1 and op-T1W1 images was observed in aplastic anemia and post-irradiation patients (II). Hematopoietic marrow (III) showed low intensity on op-T1W1 and enhanced, while active hematopoietic marrow (IV) revealed high intensity on both STIR and op-T1W1 images and was enhanced following Gd-DTPA infusion. Aplastic anemia of moderate grade included types II, III and IV. Enhanced MR was needed to differentiate between types I and III since both types showed low intensity on op-T1W1 images. Furthermore, type IV was considered as hyperplastic compared with type III. Enhanced MR and op-T1W1 images were useful in evaluating hematopoiesis of bone marrow. (author)

Evaluation of bone marrow by opposed phase T1-weighted images and enhanced MR imaging

Energy Technology Data Exchange (ETDEWEB)

Amano, Yasuo; Tanabe, Yoshihiro; Miyashita, Tsuguhiro; Hayashi, Hiromitsu; Horiuchi, Junichi; Nomura, Takeo; Kumazaki, Tatsuo (Nippon Medical School, Tokyo (Japan))

1994-09-01

We investigated bone marrow in a control group, cases of aplastic anemia and post-irradiation patients by examining T1-weighted (T1W1), short T1 inversion recovery (STIR), opposed phase T1W1 (op-T1W1) and Gd-DTPA enhanced op-T1W1 images obtained by 0.5 T MRI. Bone marrow was classified into four types based on MR findings. Normal marrow showed low intensity on op-T1W1 and STIR images without enhancement (I). Fatty marrow, which showed high intensity on T1W1 and op-T1W1 images was observed in aplastic anemia and post-irradiation patients (II). Hematopoietic marrow (III) showed low intensity on op-T1W1 and enhanced, while active hematopoietic marrow (IV) revealed high intensity on both STIR and op-T1W1 images and was enhanced following Gd-DTPA infusion. Aplastic anemia of moderate grade included types II, III and IV. Enhanced MR was needed to differentiate between types I and III since both types showed low intensity on op-T1W1 images. Furthermore, type IV was considered as hyperplastic compared with type III. Enhanced MR and op-T1W1 images were useful in evaluating hematopoiesis of bone marrow. (author).

Breast MRI at 7 Tesla with a bilateral coil and T1-weighted acquisition with robust fat suppression: image evaluation and comparison with 3 Tesla.

Science.gov (United States)

Brown, Ryan; Storey, Pippa; Geppert, Christian; McGorty, KellyAnne; Leite, Ana Paula Klautau; Babb, James; Sodickson, Daniel K; Wiggins, Graham C; Moy, Linda

2013-11-01

To evaluate the image quality of T1-weighted fat-suppressed breast MRI at 7 T and to compare 7-T and 3-T images. Seventeen subjects were imaged using a 7-T bilateral transmit-receive coil and 3D gradient echo sequence with adiabatic inversion-based fat suppression (FS). Images were graded on a five-point scale and quantitatively assessed through signal-to-noise ratio (SNR), fibroglandular/fat contrast and signal uniformity measurements. Image scores at 7 and 3 T were similar on standard-resolution images (1.1 × 1.1 × 1.1-1.6 mm(3)), indicating that high-quality breast imaging with clinical parameters can be performed at 7 T. The 7-T SNR advantage was underscored on 0.6-mm isotropic images, where image quality was significantly greater than at 3 T (4.2 versus 3.1, P ≤ 0.0001). Fibroglandular/fat contrast was more than two times higher at 7 T than at 3 T, owing to effective adiabatic inversion-based FS and the inherent 7-T signal advantage. Signal uniformity was comparable at 7 and 3 T (P coil and adiabatic inversion-based FS technique produce image quality that is as good as or better than at 3 T. • High image quality bilateral breast MRI is achievable with clinical parameters at 7 T. • 7-T high-resolution imaging improves delineation of subtle soft tissue structures. • Adiabatic-based fat suppression provides excellent fibroglandular/fat contrast at 7 T. • 7- and 3-T 3D T1-weighted gradient-echo images have similar signal uniformity. • The 7-T dual solenoid coil enables bilateral imaging without compromising uniformity.

Diffusion-weighted imaging in the diagnosis of enterovirus 71 encephalitis

International Nuclear Information System (INIS)

Lian, Zhou-yang; Huang, Biao; Liang, Chang-hong; He, Shaoru; Guo, Yuxiong

2012-01-01

Background. In the early phase of viral encephalitis, conventional MRI may appear normal. Diffusion-weighted imaging (DWI) is a sensitive tool for detecting early changes in cellular function in the central nervous system. Purpose. To investigate the usefulness of DWI in the diagnosis of enterovirus 71 (EV71) encephalitis, and to determine whether DWI is superior to conventional MR sequences. Material and Methods. MRI scans in 26 patients were retrospectively evaluated for distribution of lesions on T1-weighted images (T1WI), T2-weighted images (T2WI), fluid-attenuated inversion recovery (FLAIR), and DWI. Contrast-to-noise ratios (CNRs) were calculated for all regions on each sequence and differences in the four MRI sequences were assessed using CNRs. Apparent diffusion coefficient (ADC) values were measured for all regions to look for true restriction of diffusion. Results. Fifteen out of 26 cases showed positive findings on MR imaging. The brain stem was involved in 11 patients, cortex and subcortical white matter in four patients. DWI was more sensitive in detecting the abnormalities (89.7%) compared to T2WI (48.7%), FLAIR (41.0%), and T1WI (35.9%), and the positive ratio of DWI was significantly higher compared to other sequences. Furthermore, no significant difference was found between T2WI and FLAIR (P 0.649). The corresponding mean CNRs were 8.73 ± 2.57, 83.59 ± 29.28, 24.22 ± 6.22, and 132.27 ± 78.32 on T1WI, T2WI, FLAIR, and DWI, respectively. The absolute values of CNRs of lesions on DWI were significantly greater than those on other sequences. Conclusion. DWI appears to be more sensitive in detecting EV71 encephalitis than conventional MRI sequences. This capability may improve the accuracy in diagnosing EV71 encephalitis, especially at the early stage

Diffusion-weighted imaging in the diagnosis of enterovirus 71 encephalitis

Energy Technology Data Exchange (ETDEWEB)

Lian, Zhou-yang; Huang, Biao; Liang, Chang-hong (Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China)), Email: cjr.huangbiao@vip.163.com; He, Shaoru; Guo, Yuxiong (Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China))

2012-03-15

Background. In the early phase of viral encephalitis, conventional MRI may appear normal. Diffusion-weighted imaging (DWI) is a sensitive tool for detecting early changes in cellular function in the central nervous system. Purpose. To investigate the usefulness of DWI in the diagnosis of enterovirus 71 (EV71) encephalitis, and to determine whether DWI is superior to conventional MR sequences. Material and Methods. MRI scans in 26 patients were retrospectively evaluated for distribution of lesions on T1-weighted images (T1WI), T2-weighted images (T2WI), fluid-attenuated inversion recovery (FLAIR), and DWI. Contrast-to-noise ratios (CNRs) were calculated for all regions on each sequence and differences in the four MRI sequences were assessed using CNRs. Apparent diffusion coefficient (ADC) values were measured for all regions to look for true restriction of diffusion. Results. Fifteen out of 26 cases showed positive findings on MR imaging. The brain stem was involved in 11 patients, cortex and subcortical white matter in four patients. DWI was more sensitive in detecting the abnormalities (89.7%) compared to T2WI (48.7%), FLAIR (41.0%), and T1WI (35.9%), and the positive ratio of DWI was significantly higher compared to other sequences. Furthermore, no significant difference was found between T2WI and FLAIR (P 0.649). The corresponding mean CNRs were 8.73 +- 2.57, 83.59 +- 29.28, 24.22 +- 6.22, and 132.27 +- 78.32 on T1WI, T2WI, FLAIR, and DWI, respectively. The absolute values of CNRs of lesions on DWI were significantly greater than those on other sequences. Conclusion. DWI appears to be more sensitive in detecting EV71 encephalitis than conventional MRI sequences. This capability may improve the accuracy in diagnosing EV71 encephalitis, especially at the early stage

Gadolinium-enhanced T{sub 1}-weighted MR urography versus T{sub 2}-weighted (HASTE) MR urography in children; Kontrastangehobene T{sub 1}-gewichtete MR-Urographie versus T{sub 2}-gewichtete (HASTE) MR-Urographie im Kindesalter

Energy Technology Data Exchange (ETDEWEB)

Staatz, G.; Nolte-Ernsting, C.C.A.; Haage, P.; Tacke, J.; Guenther, R.W. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik; Rohrmann, D. [Technische Hochschule Aachen (Germany). Urologische Klinik; Stollbrink, C. [Technische Hochschule Aachen (Germany). Kinderklinik

2001-11-01

Purpose: To evaluate gadolinium-enhanced T{sub 1}-weighted excretory MR urography (EMRU) versus T{sub 2}-weighted (HASTE) MR urography in children with upper urinary tract abnormalities. Patients and Methods: In a prospective study 63 children, aged from 3 weeks to 15 years, underwent MR urography in a 1.5-T scanner. Before and after an intravenous injection of 0.05 mg/kg body weight of furosemide, respiratory-triggered HASTE images were obtained for T{sub 2}-weighted MR urography. EMRU was performed subsequent to i.v. gadolinium injection with respiratory-gated, coronal 3D-gradient-echo sequences. Results: Compared to T{sub 2}-weighted (HASTE) MR urography, gadolinium-enhanced MR urography revealed a superior diagnostic accuracy in non-dilated collecting systems (horseshoe kidneys, ectopic kidneys, duplex systems, single ectopic ureters, ureteroceles). EMRU and T{sub 2}-weighted (HASTE) MRU turned out to be equivalent in the assessment of obstructed but normal functioning upper urinary tracts (UPJ obstructions, megaureters). Non-functioning dilated collecting systems and multicystic dysplastic kidneys were best visualized with use of T{sub 2}-weighted (HASTE) MR urography. Conclusion: Respiratory-gated gadolinium-enhanced T{sub 1}-weighted MRU allows accurate evaluation of most upper urinary tract abnormalities. T{sub 2}-weighted (HASTE) MRU complements GMRU in the evaluation of non-functioning renal units and cystic disease of the kidneys. (orig.) [German] Ziel: Vergleich der kontrastangehobenen T{sub 1}-gewichteten MR-Urographie mit der T{sub 2}-gewichteten (HASTE) MR-Urographie bei Kindern mit Anomalien des oberen Harntraktes. Methoden: In einer prospektiven Studie wurde bei 63 Kindern (3 Wo. - 15J.) eine MR-Urographie (MRU) in einem 1,5-Tesla-Magneten durchgefuehrt. Die T{sub 2}-gewichtete MRU erfolgte vor und nach intravenoeser Injektion von 0,05 mg/kg KG Furosemid mit atemgetriggerten HASTE-Sequenzen. Fuer die T{sub 1}-gewichtete MRU wurden nach

Abnormalities on diffusion-weighted magnetic resonance imaging in patients with transient ischemic attack

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Nakamura, Tomomi; Shibagaki, Yasuro [Ushiku Aiwa General Hospital, Ibaraki (Japan); Uchiyama, Shinichiro; Iwata, Makoto [Tokyo Women' s Medical Coll. (Japan)

2003-03-01

We studied abnormalities on diffusion-weighted magnetic resonance imaging (DWI) in patients with transient ischemic attack (TIA). Out of 18 consecutive TIA patients, 9 patients had relevant focal abnormalities on DWI. Among TIA patients, six patients were associated with atrial fibrillation (Af), and all of these patients had focal abnormalities on DWI as well. TIA patients with Af had significantly more frequent focal abnormalities on DWI than those without Af (p=0.009; Fisher's exact probability test). In addition, the duration of TIA symptoms was not related to the presence of focal abnormalities on DWI. These results indicate that embolic mechanism may cause focal abnormalities on DWI. DWI was more sensitive to detect responsible ischemic lesions in these patients than T2-weighted image or fluid-attenuated inversion recovery image. (author)

Abnormalities on diffusion-weighted magnetic resonance imaging in patients with transient ischemic attack

International Nuclear Information System (INIS)

Nakamura, Tomomi; Shibagaki, Yasuro; Uchiyama, Shinichiro; Iwata, Makoto

2003-01-01

We studied abnormalities on diffusion-weighted magnetic resonance imaging (DWI) in patients with transient ischemic attack (TIA). Out of 18 consecutive TIA patients, 9 patients had relevant focal abnormalities on DWI. Among TIA patients, six patients were associated with atrial fibrillation (Af), and all of these patients had focal abnormalities on DWI as well. TIA patients with Af had significantly more frequent focal abnormalities on DWI than those without Af (p=0.009; Fisher's exact probability test). In addition, the duration of TIA symptoms was not related to the presence of focal abnormalities on DWI. These results indicate that embolic mechanism may cause focal abnormalities on DWI. DWI was more sensitive to detect responsible ischemic lesions in these patients than T2-weighted image or fluid-attenuated inversion recovery image. (author)

MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

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Radlbauer, Rudolf, E-mail: rudolf.radlbauer@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Lomoschitz, Friedrich, E-mail: friedrich.lomoschitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Salomonowitz, Erich, E-mail: erich.salomonowitz@stpoelten.lknoe.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Eberhardt, Knut E., E-mail: info@mrt-kompetenzzentrum.d [MRT Competence Center Schloss Werneck, Balthasar-Neumann-Platz 2, 97440 Werneck (Germany); Stadlbauer, Andreas, E-mail: andi@nmr.a [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, 3100 St. Poelten (Austria); Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany)

2010-08-15

The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

MR imaging of the knee: Improvement of signal and contrast efficiency of T1-weighted turbo spin echo sequences by applying a driven equilibrium (DRIVE) pulse

International Nuclear Information System (INIS)

Radlbauer, Rudolf; Lomoschitz, Friedrich; Salomonowitz, Erich; Eberhardt, Knut E.; Stadlbauer, Andreas

2010-01-01

The purpose of this study was to assess the effect of a driven equilibrium (DRIVE) pulse incorporated in a standard T1-weighted turbo spin echo (TSE) sequence as used in our routine MRI protocol for examination of pathologies of the knee. Sixteen consecutive patients with knee disorders were examined using the routine MRI protocol, including T1-weighted TSE-sequences with and without a DRIVE pulse. Signal-to-noise ratios (SNRs) and contrast-to-noise ratio (CNR) of anatomical structures and pathologies were calculated and compared for both sequences. The differences in diagnostic value of the T1-weighted images with and without DRIVE pulse were assessed. SNR was significantly higher on images acquired with DRIVE pulse for fluid, effusion, cartilage and bone. Differences in the SNR of meniscus and muscle between the two sequences were not statistically significant. CNR was significantly increased between muscle and effusion, fluid and cartilage, fluid and meniscus, cartilage and meniscus, bone and cartilage on images acquired using the DRIVE pulse. Diagnostic value of the T1-weighted images was found to be improved for delineation of anatomic structures and for diagnosing a variety of pathologies when a DRIVE pulse is incorporated in the sequence. Incorporation of a DRIVE pulse into a standard T1-weighted TSE-sequence leads to significant increase of SNR and CNR of both, anatomical structures and pathologies, and consequently to an increase in diagnostic value within the same acquisition time.

Viscoacoustic wave-equation traveltime inversion with correct and incorrect attenuation profiles

KAUST Repository

Yu, Han

2017-08-17

A visco-acoustic wave-equation traveltime inversion method is presented that inverts for a shallow subsurface velocity distribution with correct and incorrect attenuation profiles. Similar to the classical wave equation traveltime inversion, this method applies the misfit functional that minimizes the first break differences between the observed and predicted data. Although, WT can partly avoid the cycle skipping problem, an initial velocity model approaches to the right or wrong velocity models under different setups of the attenuation profiles. However, with a Q model far away from the real model, the inverted tomogram is obviously different from the true velocity model while a small change of the Q model does not improve the inversion quality in a strong manner if low frequency information is not lost.

Multi-resolution inversion algorithm for the attenuated radon transform

KAUST Repository

Barbano, Paolo Emilio; Fokas, Athanasios S.

2011-01-01

We present a FAST implementation of the Inverse Attenuated Radon Transform which incorporates accurate collimator response, as well as artifact rejection due to statistical noise and data corruption. This new reconstruction procedure is performed

Cerebral and meningeal manifestations of AIDS: comparison of plain T2-weighted images and Gd-DTPA enhanced T1-weighted images in 105 patients

International Nuclear Information System (INIS)

Jochens, R.; Henkes, H.; Steinkamp, H.J.; Terstegge, K.; Hosten, N.; Ruf, B.; Schoerner, W.

1994-01-01

The purpose of the present study was to evaluate the potential of T1-weighted Gd-DTPA enhanced MR imaging in the diagnosis of cerebral manifestations of AIDS. 105 patients with AIDS were imaged with plain T2-weighted images as well as with Gd-DTPA enhanced T1-weighted pulse sequences. Our study revealed comparable sensitivities in the detection of morphological changes as shown on plain T2-weighted images and Gd-DTPA enhanced T1-weighted images in 55% of patients (normal and pathologic findings). Plain T2-weighted images were superior in 28.5% and provided significantly better results in 8.5% of patients. Gd-DTPA enhanced T1-weighted images were superior in only 5% cases and revealed significantly better results in 3%. As a result, T2-weighted plain images were superior in approximately 40% of patients concerning detection of morphologic changes. In almost 10% of patients with parechymal and meningeal lesions, Gd-DTPA enhanced T1-weighted images, however, were superior or even significantly better compared to T2-weighted plain images. The detection of morphologic changes in MR imaging can be further increased with Gd-DTPA. With regard to differential diagnosis and diesease activity, plain T2-weighted images and Gd-DTPA enhanced T1-weighted images revealed comparable results in 42% of patients (normal and pathologic findings). T2-weighted plain images were superior in 2% of cases whereas Gd-DTPA enhanced T1-weighted images were superior in as much as 56% of patient. MR imaging enhanced with Gd-DTPA yielded additional information on disease activity in 73% of patients with pathologic findings in the cerebral parechyma and the meninges. The surplus of information also refers to the etiology of cerebral pathology and differential diagnosis. Because of the frequency of cerebral manifestations in AIDS, early diagnosis for initiation of therapy and follow-up studies to monitor therapy are crucial. (orig./MG) [de

7T MRI in focal epilepsy with unrevealing conventional field strength imaging.

Science.gov (United States)

De Ciantis, Alessio; Barba, Carmen; Tassi, Laura; Cosottini, Mirco; Tosetti, Michela; Costagli, Mauro; Bramerio, Manuela; Bartolini, Emanuele; Biagi, Laura; Cossu, Massimo; Pelliccia, Veronica; Symms, Mark R; Guerrini, Renzo

2016-03-01

To assess the diagnostic yield of 7T magnetic resonance imaging (MRI) in detecting and characterizing structural lesions in patients with intractable focal epilepsy and unrevealing conventional (1.5 or 3T) MRI. We conducted an observational clinical imaging study on 21 patients (17 adults and 4 children) with intractable focal epilepsy, exhibiting clinical and electroencephalographic features consistent with a single seizure-onset zone (SOZ) and unrevealing conventional MRI. Patients were enrolled at two tertiary epilepsy surgery centers and imaged at 7T, including whole brain (three-dimensional [3D] T1 -weighted [T1W] fast-spoiled gradient echo (FSPGR), 3D susceptibility-weighted angiography [SWAN], 3D fluid-attenuated inversion recovery [FLAIR]) and targeted imaging (2D T2*-weighted dual-echo gradient-recalled echo [GRE] and 2D gray-white matter tissue border enhancement [TBE] fast spin echo inversion recovery [FSE-IR]). MRI studies at 1.5 or 3T deemed unrevealing at the referral center were reviewed by three experts in epilepsy imaging. Reviewers were provided information regarding the suspected localization of the SOZ. The same team subsequently reviewed 7T images. Agreement in imaging interpretation was reached through consensus-based discussions based on visual identification of structural abnormalities and their likely correlation with clinical and electrographic data. 7T MRI revealed structural lesions in 6 (29%) of 21 patients. The diagnostic gain in detection was obtained using GRE and FLAIR images. Four of the six patients with abnormal 7T underwent epilepsy surgery. Histopathology revealed focal cortical dysplasia (FCD) in all. In the remaining 15 patients (71%), 7T MRI remained unrevealing; 4 of the patients underwent epilepsy surgery and histopathologic evaluation revealed gliosis. 7T MRI improves detection of epileptogenic FCD that is not visible at conventional field strengths. A dedicated protocol including whole brain FLAIR and GRE images at 7T

Estimation of gadolinium-induced T1-shortening with measurement of simple signal intensity ratio between the cochlea and brain parenchyma on 3D-FLAIR. Correlation with T1 measurement by TI scout sequence

International Nuclear Information System (INIS)

Naganawa, Shinji; Ishihara, Shunichi; Iwano, Shingo; Kawai, Hisashi; Sone, Michihiko; Nakashima, Tsutomu

2010-01-01

The purpose of this study was to T 1 -shortening of labyrinthine fluid on 3-dimensional fluid-attenuated inversion recovery (3D-FLAIR) has been reported in many inner ear disorders. Although semi-quantitative assessment by simple signal intensity ratio between cochlear fluid and brain tissue has been tried, its feasibility using a multi-channel phased-array head coil with an inherently inhomogenous sensitivity distribution has not been fully evaluated. We evaluated the feasibility of measuring simple signal intensity ratio by correlating rapid T 1 measurements using an inversion time (TI) scout sequence. We evaluated 10 patients with Meniere's disease and 4 patients with sudden deafness. Nine of the patients with Meniere's disease received a unilateral intratympanic injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA); the tenth patient received bilateral injections. The 4 patients with sudden deafness received a double-dose intravenous injection. Magnetic resonance (MR) images were obtained 24 hours after intratympanic injections and 4 hours after intravenous injections at 3 tesla using a 32-channel head coil. We measured the ratio (CM ratio) between the signal intensity of the perilymph in the cochlea (C) and that of the medulla oblongata (M) and correlated it with the null-point inversion time (TI null ) obtained with the TI scout sequence. The TI scout consisted of 85 images obtained with TI values between 132.5 and 3087.5 ms at increments of 37.5 ms. The correlation coefficient between TI null and the natural logarithm of the CM ratio was -0.88 (P<0.01). There was significant negative linear correlation. Measurement of the simple signal intensity ratio between the cochlea and the medulla can be used for semi-quantitative analysis of 3D-FLAIR. The results of this study may facilitate clinical research of inner-ear disease using 3D-FLAIR. (author)

Assessment of T2- and T1-weighted MRI brain lesion load in patients with subcortical vascular encephalopathy

International Nuclear Information System (INIS)

Gass, A.; Oster, M.; Cohen, S.; Daffertshofer, M.; Schwartz, A.; Hennerici, M.G.

1998-01-01

Previous cross-sectional studies in patients with subcortical vascular encephalopathy (SVE) have shown little or no correlation between brain lesion load and clinical disability, which could be due to the low specificity of T2-weighted MRI. Recent studies have indicated that T1-weighted MRI may be more specific than T2-weighted MRI for severe tissue destruction. We studied 37 patients with a diagnosis of SVE and 11 normal controls with standardised T1- and T2-weighted MRI. All patients underwent detailed clinical assessment including a neuropsychological test battery and computerised gait analysis. Both the T2- and T1-weighted total MRI lesion loads different between patients and controls different, particularly T1. The ratio of T2-/T1-weighted lesion load was lower in controls than in patients. There was no overall correlation of T1- or T2-weighted lesion load with clinical disability, but group comparison of patients with severe and mild clinical deficits showed different lesion loads. We suggest that T1- and T2-weighted MRI lesion loads demonstrate relevant structural abnormality in patients with SVE. (orig.)

Three-dimensional isotropic T2-weighted cervical MRI at 3 T: Comparison with two-dimensional T2-weighted sequences

International Nuclear Information System (INIS)

Kwon, J.W.; Yoon, Y.C.; Choi, S.-H.

2012-01-01

Aim: To compare three-dimensional (3D) isotropic T2-weighted magnetic resonance imaging (MRI) sequences and reformation with two-dimensional (2D) T2-weighted sequences regarding image quality of the cervical spine at 3 T. Materials and methods: A phantom study was performed using a water-filled cylinder. The signal-to-noise and image homogeneity were evaluated. Fourteen (n = 14) volunteers were examined at 3 T using 3D isotropic T2-weighted sagittal and conventional 2D T2-weighted sagittal, axial, and oblique sagittal MRI. Multiplanar reformation (MPR) of the 3D T2-weighted sagittal dataset was performed simultaneously with image evaluation. In addition to artefact assessment, the visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen’s kappa and Wilcoxon signed rank test were used for the statistical analysis. Result: The 3D isotropic T2-weighted sequence resulted in the highest signal-to-noise ratio (SNR) and lowest non-uniformity (NU) among the sequences in the phantom study. Quantitative evaluation revealed lower NU values of the cerebrospinal fluid (CSF) and muscles in 2D T2-weighted sagittal sequences compared to the 3D volume isotropic turbo spin-echo acquisition (VISTA) sequence. The other NU values revealed no statistically significant difference between the 2D turbo spin-echo (TSE) and 3D VISTA sequences (0.059 < p < 0.959). 3D VISTA images showed significantly fewer CSF flow artefacts (p < 0.001) and better delineated intradural nerve rootlets (p = 0.001) and neural foramina (p = 0.016) compared to 2D sequences. Conclusion: A 3D T2 weighted sequence is superior to conventional 2D sequences for the delineation of intradural nerve rootlets and neural foramina and is less affected by CSF flow artefacts.

Rapid T1 quantification based on 3D phase sensitive inversion recovery

Directory of Open Access Journals (Sweden)

Warntjes Marcel JB

2010-08-01

Full Text Available Abstract Background In Contrast Enhanced Magnetic Resonance Imaging fibrotic myocardium can be distinguished from healthy tissue using the difference in the longitudinal T1 relaxation after administration of Gadolinium, the so-called Late Gd Enhancement. The purpose of this work was to measure the myocardial absolute T1 post-Gd from a single breath-hold 3D Phase Sensitivity Inversion Recovery sequence (PSIR. Equations were derived to take the acquisition and saturation effects on the magnetization into account. Methods The accuracy of the method was investigated on phantoms and using simulations. The method was applied to a group of patients with suspected myocardial infarction where the absolute difference in relaxation of healthy and fibrotic myocardium was measured at about 15 minutes post-contrast. The evolution of the absolute R1 relaxation rate (1/T1 over time after contrast injection was followed for one patient and compared to T1 mapping using Look-Locker. Based on the T1 maps synthetic LGE images were reconstructed and compared to the conventional LGE images. Results The fitting algorithm is robust against variation in acquisition flip angle, the inversion delay time and cardiac arrhythmia. The observed relaxation rate of the myocardium is 1.2 s-1, increasing to 6 - 7 s-1 after contrast injection and decreasing to 2 - 2.5 s-1 for healthy myocardium and to 3.5 - 4 s-1 for fibrotic myocardium. Synthesized images based on the T1 maps correspond very well to actual LGE images. Conclusions The method provides a robust quantification of post-Gd T1 relaxation for a complete cardiac volume within a single breath-hold.

Contributions of an adiabatic initial inversion pulse and K-space Re-ordered by inversion-time at each slice position (KRISP) to control of CSF artifacts and visualization of the brain in FLAIR magnetic resonance imaging

International Nuclear Information System (INIS)

Curati, Walter L.; Oatridge, Angela; Herlihy, Amy H.; Hajnal, Joseph V.; Puri, Basant K.; Bydder, Graeme M.

2001-01-01

AIM: The aim of this study was to compare the performance of three fluid attenuated inversion recovery (FLAIR) pulse sequences for control of cerebrospinal fluid (CSF) and blood flow artifacts in imaging of the brain. The first of these sequences had an initial sinc inversion pulse which was followed by conventional k-space mapping. The second had an initial sinc inversion pulse followed by k-space re-ordered by inversion time at each slice position (KRISP) and the third had an adiabatic initial inversion pulse followed by KRISP. MATERIALS AND METHODS: Ten patients with established disease were studied with all three pulse sequences. Seven were also studied with the adiabatic KRISP sequence after contrast enhancement. Their images were evaluated for patient motion artifact, CSF and blood flow artifact as well as conspicuity of the cortex, meninges, ventricular system, brainstem and cerebellum. The conspicuity of lesions and the degree of enhancement were also evaluated. RESULTS: Both the sinc and adiabatic KRISP FLAIR sequences showed better control of CSF and blood flow artifacts than the conventional FLAIR sequence. In addition the adiabatic KRISP FLAIR sequence showed better control of CSF artifact at the inferior aspect of the posterior fossa. The lesion conspicuity was similar for each of the FLAIR sequences as was the degree of contrast enhancement to that shown with a T 1 weighted spin echo sequence. CONCLUSION: The KRISP FLAIR sequence controls high signal artifacts from CSF flow and blood flow and the adiabatic pulse controls high signal artifacts due to inadequate inversion of the CSF magnetization at the periphery of the head transmitter coil. The KRISP FLAIR sequence also improves cortical and meningeal definition as a result of an edge enhancement effect. The effects are synergistic and can be usefully combined in a single pulse sequence. Curati, W.L. et al. (2001)

Breast MRI at 7 Tesla with a bilateral coil and T1-weighted acquisition with robust fat suppression: image evaluation and comparison with 3 Tesla

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Brown, Ryan; Storey, Pippa; McGorty, KellyAnne; Klautau Leite, Ana Paula; Babb, James; Sodickson, Daniel K.; Wiggins, Graham C.; Moy, Linda [New York University Langone Medical Center, Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York, NY (United States); Geppert, Christian [Siemens Medical Solutions USA Inc., New York, NY (United States)

2013-11-15

To evaluate the image quality of T1-weighted fat-suppressed breast MRI at 7 T and to compare 7-T and 3-T images. Seventeen subjects were imaged using a 7-T bilateral transmit-receive coil and 3D gradient echo sequence with adiabatic inversion-based fat suppression (FS). Images were graded on a five-point scale and quantitatively assessed through signal-to-noise ratio (SNR), fibroglandular/fat contrast and signal uniformity measurements. Image scores at 7 and 3 T were similar on standard-resolution images (1.1 x 1.1 x 1.1-1.6 mm{sup 3}), indicating that high-quality breast imaging with clinical parameters can be performed at 7 T. The 7-T SNR advantage was underscored on 0.6-mm isotropic images, where image quality was significantly greater than at 3 T (4.2 versus 3.1, P {<=} 0.0001). Fibroglandular/fat contrast was more than two times higher at 7 T than at 3 T, owing to effective adiabatic inversion-based FS and the inherent 7-T signal advantage. Signal uniformity was comparable at 7 and 3 T (P < 0.05). Similar 7-T image quality was observed in all subjects, indicating robustness against anatomical variation. The 7-T bilateral transmit-receive coil and adiabatic inversion-based FS technique produce image quality that is as good as or better than at 3 T. (orig.)

Breast MRI at 7 Tesla with a bilateral coil and T1-weighted acquisition with robust fat suppression: image evaluation and comparison with 3 Tesla

International Nuclear Information System (INIS)

Brown, Ryan; Storey, Pippa; McGorty, KellyAnne; Klautau Leite, Ana Paula; Babb, James; Sodickson, Daniel K.; Wiggins, Graham C.; Moy, Linda; Geppert, Christian

2013-01-01

To evaluate the image quality of T1-weighted fat-suppressed breast MRI at 7 T and to compare 7-T and 3-T images. Seventeen subjects were imaged using a 7-T bilateral transmit-receive coil and 3D gradient echo sequence with adiabatic inversion-based fat suppression (FS). Images were graded on a five-point scale and quantitatively assessed through signal-to-noise ratio (SNR), fibroglandular/fat contrast and signal uniformity measurements. Image scores at 7 and 3 T were similar on standard-resolution images (1.1 x 1.1 x 1.1-1.6 mm 3 ), indicating that high-quality breast imaging with clinical parameters can be performed at 7 T. The 7-T SNR advantage was underscored on 0.6-mm isotropic images, where image quality was significantly greater than at 3 T (4.2 versus 3.1, P ≤ 0.0001). Fibroglandular/fat contrast was more than two times higher at 7 T than at 3 T, owing to effective adiabatic inversion-based FS and the inherent 7-T signal advantage. Signal uniformity was comparable at 7 and 3 T (P < 0.05). Similar 7-T image quality was observed in all subjects, indicating robustness against anatomical variation. The 7-T bilateral transmit-receive coil and adiabatic inversion-based FS technique produce image quality that is as good as or better than at 3 T. (orig.)

An efficient sequence for fetal brain imaging at 3T with enhanced T1 contrast and motion robustness.

Science.gov (United States)

Ferrazzi, Giulio; Price, Anthony N; Teixeira, Rui Pedro A G; Cordero-Grande, Lucilio; Hutter, Jana; Gomes, Ana; Padormo, Francesco; Hughes, Emer; Schneider, Torben; Rutherford, Mary; Kuklisova Murgasova, Maria; Hajnal, Joseph V

2018-07-01

Ultrafast single-shot T 2 -weighted images are common practice in fetal MR exams. However, there is limited experience with fetal T 1 -weighted acquisitions. This study aims at establishing a robust framework that allows fetal T 1 -weighted scans to be routinely acquired in utero at 3T. A 2D gradient echo sequence with an adiabatic inversion was optimized to be robust to fetal motion and maternal breathing optimizing grey/white matter contrast at the same time. This was combined with slice to volume registration and super resolution methods to produce volumetric reconstructions. The sequence was tested on 22 fetuses. Optimized grey/white matter contrast and robustness to fetal motion and maternal breathing were achieved. Signal from cerebrospinal fluid (CSF) and amniotic fluid was nulled and 0.75 mm isotropic anatomical reconstructions of the fetal brain were obtained using slice-to-volume registration and super resolution techniques. Total acquisition time for a single stack was 56 s, all acquired during free breathing. Enhanced sensitivity to normal anatomy and pathology with respect to established methods is demonstrated. A direct comparison with a 3D spoiled gradient echo sequence and a controlled motion experiment run on an adult volunteer are also shown. This paper describes a robust framework to perform T 1 -weighted acquisitions and reconstructions of the fetal brain in utero. Magn Reson Med 80:137-146, 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 Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic

Diagnostic performance of dark-blood T2-weighted CMR for evaluation of acute myocardial injury.

Science.gov (United States)

Srichai, Monvadi B; Lim, Ruth P; Lath, Narayan; Babb, James; Axel, Leon; Kim, Daniel

2013-01-01

We compared the image quality and diagnostic performance of 2 fat-suppression methods for black-blood T2-weighted fast spin-echo (FSE), which are as follows: (a) short T1 inversion recovery (STIR; FSE-STIR) and (b) spectral adiabatic inversion recovery (SPAIR; FSE-SPAIR), for detection of acute myocardial injury. Edema-sensitive T2-weighted FSE cardiac magnetic resonance (CMR) imaging is useful in detecting acute myocardial injury but may experience reduced myocardial signal and signal dropout. The SPAIR pulse aims to eliminate artifacts associated with the STIR pulse. A total of 65 consecutive patients referred for CMR evaluation of myocardial structure and function underwent FSE-STIR and FSE-SPAIR, in addition to cine and late gadolinium enhancement (LGE) CMR. T2-weighted FSE images were independently evaluated by 2 readers for image quality and artifacts (Likert scale of 1-5; best-worst) and presence of increased myocardial signal suggestive of edema. In addition, clinical CMR interpretation, incorporating all CMR sequences available, was recorded for comparison. Diagnostic performance of each T2-weighted sequence was measured using recent (T2, and wall motion. There was a statistically significant difference in sensitivity between the clinical interpretation and each of the T2-weighted sequences but not between each T2-weighted sequence. Although FSE-SPAIR demonstrated significantly improved image quality and decreased artifacts, isolated interpretations of each T2-weighted technique demonstrated high specificity but overall low sensitivity for the detection of myocardial injury, with no difference in accuracy between the techniques. However, real-world interpretation in combination with cine and LGE CMR methods significantly improves the overall sensitivity and diagnostic performance.

Fast T1-weighted imaging using GRASE sequence for the female pelvis

International Nuclear Information System (INIS)

Dohke, Masako; Watanabe, Yuji; Kumashiro, Masayuki; Amoh, Yoshiki; Ishimori, Takayoshi; Oda, Kazushige; Okumura, Akira; Koike, Shinji; Dodo, Yoshihiro

1998-01-01

GRASE sequence, a combination of TSE and gradient echo, has been developed as a fast T 2 -weighted imaging technique. We have modified the GRASE sequence to be used for fast T 1 -weighted imaging of the female pelvis. In this article, we compared image quality and incidence of artifacts between T 1 -weighted GRASE images and conventional T 1 -weighted SE images. In a phantom study, signal-to-noise ratio was inferior in the GRASE images relative to corresponding on SE images. Susceptibility and chemical shift artifacts seen in GRASE images were seen with almost equal incidence in SE and TSE images. In a clinical study, we compared GRASE images with SE images in six patients with endometrial cysts and four patients with dermoid cysts. The overall image quality obtained with GRASE sequence was satisfactory in all patients and was almost identical with that obtained with SE sequence. GRASE images demonstrated endometrial cysts and dermoid cysts as clearly as did SE images. T 1 -weighted GRASE imaging, however, has a relatively long TE (35 ms) for T 1 -weighted images, which makes the signal intensity of urine and uterine endometrium with long T 2 values higher than in SE images. In conclusion, GRASE sequence can be used for fast T 1 -weighted imaging of the female pelvis because of short imaging time. (author)

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

International Nuclear Information System (INIS)

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

2009-01-01

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

Biologically aggressive regions within glioblastoma identified by spin-lock contrast T1 relaxation in the rotating frame (T1ρ MRI

Directory of Open Access Journals (Sweden)

Ramon Francisco Barajas, Jr., MD

2017-12-01

Full Text Available Spin-lattice relaxation in the rotating frame magnetic resonance imaging allows for the quantitative assessment of spin-lock contrast within tissues. We describe the utility of spin-lattice relaxation in the rotating frame metrics in characterizing glioblastoma biological heterogeneity. A 84-year-old man presented to our institution with a right frontal temporal mass. Prior tissue sampling from a peripheral nonenhancing lesion was nondiagnostic. Stereotactic image-guided tissue sampling of the nonenhancing T2-fluid-attenuated inversion recovery hyperintense region involving the anterior cingulate gyrus with elevated spin-lattice relaxation in the rotating frame metrics provided a pathologic diagnosis of glioblastoma. This case illustrates the utility of spin-lattice relaxation in the rotating frame magnetic resonance imaging in identifying biologically aggressive regions within glioblastoma.

L-2-hydroxyglutaric Aciduria in Two Female Yorkshire Terriers

NARCIS (Netherlands)

Sanchez-Masian, D.F.; Artuch, R.; Mascort, J.; Jakobs, C.A.J.M.; Salomons, G.S.; Zamora, A.; Casado, M.; Fernandez, M.; Recio, A.; Lujan, A.

2012-01-01

Two female Yorkshire terrier puppies were presented with generalized tonic-clonic seizures and ataxia. MRI revealed bilaterally symmetrical, diffuse regions of gray matter hyperintensity on T2-weighted and fluid-attenuated inversion recovery sequences. Urinary organic acids were quantified by gas

Difference between T sub 1 and T sub 2 weighted MR images in avascular necrosis of the femoral head

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Kokubo, Takashi; Yoshikawa, Koki; Itai, Yuzo; Iio, Masahiro; Takatori, Yoshio; Kamogawa, Morihide; Ninomiya, Setsuo [Tokyo Univ. (Japan). Faculty of Medicine

1990-01-01

T{sub 1} and T{sub 2} weighted MR images were compared in 32 hips with avascular necrosis, and the difference between them was discussed. In 27 of 32 hips, abnormal low intensity area in the affected femoral head is smaller in T{sub 2} weighted images than in T{sub 1} weighted images. The area of low intensity on T{sub 1} weighted image and high on T{sub 2} weighted image might be granuloma in reactive tissue and surrounding hyperemia. The difference between T{sub 1} and T{sub 2} weighted images must be taken into consideration especially in determination of the border of affected bone. (author).

The value of qualitative and quantitative assessment of lesion to cerebral cortex signal ratio on double inversion recovery sequence in the differentiation of demyelinating plaques from non-specific T2 hyperintensities

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Hamcan, Salih; Battal, Bilal; Akgun, Veysel; Sari, Sebahattin; Tasar, Mustafa [Gulhane Military Medical School, Department of Radiology, Etlik, Ankara (Turkey); Oz, Oguzhan; Tasdemir, Serdar [Gulhane Military Medical School, Department of Neurology, Ankara (Turkey); Bozkurt, Yalcin [Golcuk Military Hospital, Department of Radiology, Kocaeli (Turkey)

2017-02-15

To assess the usefulness of the visual assessment and to determine diagnostic value of the lesion-to-cerebral cortex signal ratio (LCSR) measurement in the differentiation of demyelinating plaques and non-specific T2 hyperintensities on double inversion recovery (DIR) sequence. DIR and fluid-attenuated inversion recovery (FLAIR) sequences of 25 clinically diagnosed multiple sclerosis (MS) patients and 25 non-MS patients with non-specific T2-hyperintense lesions were evaluated visually and LCSRs were measured by two observers independently. On DIR sequence, the calculated mean LCSR ± SD for demyelinating plaques and non-specific T2-hyperintense lesions were 1.60 ± 0.26 and 0.75 ± 0.19 for observer1, and 1.61 ± 0.27 and 0.74 ± 0.19 for observer2. LCSRs of demyelinating plaques were significantly higher than other non-specific T2-hyperintense lesions on DIR sequence. By using the visual assessment demyelinating plaques were differentiated from non-specific T2-hyperintensities with 92.8 % sensitivity, 97.5 % specificity and 95.1 % accuracy for observer1 and 92.8 % sensitivity, 95 % specificity and 93.9 % accuracy for observer2. Visual assessment and LCSR measurement on DIR sequence seems to be useful for differentiating demyelinating MS plaques from supratentorial non-specific T2 hyperintensities. This feature can be used for diagnosis of MS particularly in patients with only supratentorial T2-hyperintense lesions who are categorized as radiologically possible MS. (orig.)

A new hybrid-FBP inversion algorithm with inverse distance backprojection weight for CT reconstruction

Energy Technology Data Exchange (ETDEWEB)

Narasimhadhan, A.V.; Rajgopal, Kasi

2011-07-01

This paper presents a new hybrid filtered backprojection (FBP) algorithm for fan-beam and cone-beam scan. The hybrid reconstruction kernel is the sum of the ramp and Hilbert filters. We modify the redundancy weighting function to reduce the inverse square distance weighting in the backprojection to inverse distance weight. The modified weight also eliminates the derivative associated with the Hilbert filter kernel. Thus, the proposed reconstruction algorithm has the advantages of the inverse distance weight in the backprojection. We evaluate the performance of the new algorithm in terms of the magnitude level and uniformity in noise for the fan-beam geometry. The computer simulations show that the spatial resolution is nearly identical to the standard fan-beam ramp filtered algorithm while the noise is spatially uniform and the noise variance is reduced. (orig.)

Magnetic resonance imaging at 3.0 tesla detects more lesions in acute optic neuritis than at 1.5 tesla

DEFF Research Database (Denmark)

Nielsen, Kirsten; Rostrup, Egill; Frederiksen, Jette L

2006-01-01

OBJECTIVE:: We sought to assess whether magnetic resonance imaging (MRI) at 3.0 T detects more brain lesions in acute optic neuritis (ON) than MRI at 1.5 T. MATERIALS AND METHODS:: Twenty-eight patients with acute ON were scanned at both field-strengths using fast-fluid-attenuated inversion recov...

Ivy Sign on Fluid-Attenuated Inversion Recovery Images in Moyamoya Disease: Correlation with Clinical Severity and Old Brain Lesions.

Science.gov (United States)

Seo, Kwon-Duk; Suh, Sang Hyun; Kim, Yong Bae; Kim, Ji Hwa; Ahn, Sung Jun; Kim, Dong-Seok; Lee, Kyung-Yul

2015-09-01

Leptomeningeal collateral, in moyamoya disease (MMD), appears as an ivy sign on fluid-attenuated inversion-recovery (FLAIR) images. There has been little investigation into the relationship between presentation of ivy signs and old brain lesions. We aimed to evaluate clinical significance of ivy signs and whether they correlate with old brain lesions and the severity of clinical symptoms in patients with MMD. FLAIR images of 83 patients were reviewed. Each cerebral hemisphere was divided into 4 regions and each region was scored based on the prominence of the ivy sign. Total ivy score (TIS) was defined as the sum of the scores from the eight regions and dominant hemispheric ivy sign (DHI) was determined by comparing the ivy scores from each hemisphere. According to the degree of ischemic symptoms, patients were classified into four subgroups: 1) nonspecific symptoms without motor weakness, 2) single transient ischemic attack (TIA), 3) recurrent TIA, or 4) complete stroke. TIS was significantly different as follows: 4.86±2.55 in patients with nonspecific symptoms, 5.89±3.10 in patients with single TIA, 9.60±3.98 in patients with recurrent TIA and 8.37±3.39 in patients with complete stroke (p=0.003). TIS associated with old lesions was significantly higher than those not associated with old lesions (9.35±4.22 vs. 7.49±3.37, p=0.032). We found a significant correlation between DHI and motor symptoms (p=0.001). Because TIS has a strong tendency with severity of ischemic motor symptom and the presence of old lesions, the ivy sign may be useful in predicting severity of disease progression.

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

International Nuclear Information System (INIS)

Ma, J; Son, J; Arun, B; Hazle, J; Hwang, K; Madewell, J; Yang, W; Dogan, B; Wang, K; Bayram, E

2016-01-01

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

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

High-resolution T1-weighted 3D real IR imaging of the temporal bone using triple-dose contrast material

Energy Technology Data Exchange (ETDEWEB)

Naganawa, Shinji; Koshikawa, Tokiko; Nakamura, Tatsuya; Fukatsu, Hiroshi; Ishigaki, Takeo [Department of Radiology, Nagoya University School of Medicine, 65 Tsurumai-cho, Shouwa-ku, 466-8550, Nagoya (Japan); Aoki, Ikuo [Medical System Company, Toshiba Corporation, Tokyo (Japan)

2003-12-01

The small structures in the temporal bone are surrounded by bone and air. The objectives of this study were (a) to compare contrast-enhanced T1-weighted images acquired by fast spin-echo-based three-dimensional real inversion recovery (3D rIR) against those acquired by gradient echo-based 3D SPGR in the visualization of the enhancement of small structures in the temporal bone, and (b) to determine whether either 3D rIR or 3D SPGR is useful for visualizing enhancement of the cochlear lymph fluid. Seven healthy men (age range 27-46 years) volunteered to participate in this study. All MR imaging was performed using a dedicated bilateral quadrature surface phased-array coil for temporal bone imaging at 1.5 T (Visart EX, Toshiba, Tokyo, Japan). The 3D rIR images (TR/TE/TI: 1800 ms/10 ms/500 ms) and flow-compensated 3D SPGR images (TR/TE/FA: 23 ms/10 ms/25 ) were obtained with a reconstructed voxel size of 0.6 x 0.7 x 0.8 mm{sup 3}. Images were acquired before and 1, 90, 180, and 270 min after the administration of triple-dose Gd-DTPA-BMA (0.3 mmol/kg). In post-contrast MR images, the degree of enhancement of the cochlear aqueduct, endolymphatic sac, subarcuate artery, geniculate ganglion of the facial nerve, and cochlear lymph fluid space was assessed by two radiologists. The degree of enhancement was scored as follows: 0 (no enhancement); 1 (slight enhancement); 2 (intermediate between 1 and 3); and 3 (enhancement similar to that of vessels). Enhancement scores for the endolymphatic sac, subarcuate artery, and geniculate ganglion were higher in 3D rIR than in 3D SPGR. Washout of enhancement in the endolymphatic sac appeared to be delayed compared with that in the subarcuate artery, suggesting that the enhancement in the endolymphatic sac may have been due in part to non-vascular tissue enhancement. Enhancement of the cochlear lymph space was not observed in any of the subjects in 3D rIR and 3D SPGR. The 3D rIR sequence may be more sensitive than the 3D SPGR sequence in

Musculoskeletal MRI at 3.0 T and 7.0 T: A comparison of relaxation times and image contrast

International Nuclear Information System (INIS)

Jordan, Caroline D.; Saranathan, Manojkumar; Bangerter, Neal K.; Hargreaves, Brian A.; Gold, Garry E.

2013-01-01

Objective: The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T. Materials and methods: We measured the T 1 and T 2 relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T 1 relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T 2 relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T 1 and T 2 measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency. Results: The T 1 relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T 2 relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T 2 -weighted FSE, and 3D-FSE-Cube. Conclusion: The T 1 and T 2 changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols

Acoustic Velocity and Attenuation in Magnetorhelogical fluids based on an effective density fluid model

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Shen Min

2016-01-01

Full Text Available Magnetrohelogical fluids (MRFs represent a class of smart materials whose rheological properties change in response to the magnetic field, which resulting in the drastic change of the acoustic impedance. This paper presents an acoustic propagation model that approximates a fluid-saturated porous medium as a fluid with a bulk modulus and effective density (EDFM to study the acoustic propagation in the MRF materials under magnetic field. The effective density fluid model derived from the Biot’s theory. Some minor changes to the theory had to be applied, modeling both fluid-like and solid-like state of the MRF material. The attenuation and velocity variation of the MRF are numerical calculated. The calculated results show that for the MRF material the attenuation and velocity predicted with this effective density fluid model are close agreement with the previous predictions by Biot’s theory. We demonstrate that for the MRF material acoustic prediction the effective density fluid model is an accurate alternative to full Biot’s theory and is much simpler to implement.

Analytical inversion formula for uniformly attenuated fan-beam projections

International Nuclear Information System (INIS)

Weng, Y.; Zeng, G.L.; Gullberg, G.T.

1997-01-01

In deriving algorithms to reconstruct single photon emission computed tomography (SPECT) projection data, it is important that the algorithm compensates for photon attenuation in order to obtain quantitative reconstruction results. A convolution backprojection algorithm was derived by Tretiak and Metz to reconstruct two-dimensional (2-D) transaxial slices from uniformly attenuated parallel-beam projections. Using transformation of coordinates, this algorithm can be modified to obtain a formulation useful to reconstruct uniformly attenuated fan-beam projections. Unlike that for parallel-beam projections, this formulation does not produce a filtered backprojection reconstruction algorithm but instead has a formulation that is an inverse integral operator with a spatially varying kernel. This algorithm thus requires more computation time than does the filtered backprojection reconstruction algorithm for the uniformly attenuated parallel-beam case. However, the fan-beam reconstructions demonstrate the same image quality as that of parallel-beam reconstructions

Lumbosacral lipoma : gadolinium-enhanced fat saturation T1 weighted MR image is necessary?

International Nuclear Information System (INIS)

Yoon, Man Won; Kim, Hyun Chul; Chung, Tae Woong; Seo, Jeong Jin; Chung, Gwang Woo; Kim, Yun Hyeon; Kim, Jae Kyu; Park, Jin Gyoon; Kang, Heoung Keun

1999-01-01

To evaluate the usefulness of contrast-enhanced fat saturation T1-weighted imaging for the evaluation of spinal lipoma, compared with clinical symptoms and surgical findings. Ten patients with lipomyelomeningocele, confirmed by surgery, were included in this study. In all cases, conventional spin echo T1-and T2-weighted MR imaging, and contrast-enhanced fat saturation T1-weighted imaging was performed to evaluate clinical symptoms, the position of the conus medullaris, the presence of cord tethering, and associated anomalies, and to compare the relative usefulness of the techniques. All ten patients were suffering from lipomyelomeningocele without filum terminale fibrolipoma or intradural lipoma. All cases were associated with cord tethering. As associated anomalies, there were seven cases of syringomyelia without hydrocephalus or anorectal anomaly. To evaluate the position of the spinal conus and the presence of cord tethering, conventional T1-weighted imaging was more useful than the contrast-enhanced fat saturation equivalent. In patients with early-stage spinal lipoma, MRI is useful for evaluation of the causes and position of cord tethering and associated anomalies Our results suggest that contrast-enhanced fat saturation T1-weighted images do not provide additional information concerning spinal lipoma, and that for the diagnosis of this condition, conventional T1 and T2-weighted images are more useful than those obtained by contrast-enhanced fat saturation T1-weighted imaging

Diffusion-weighted MR neurography of the brachial and lumbosacral plexus: 3.0 T versus 1.5 T imaging

International Nuclear Information System (INIS)

Mürtz, P.; Kaschner, M.; Lakghomi, A.; Gieseke, J.; Willinek, W.A.; Schild, H.H.; Thomas, D.

2015-01-01

Highlights: •DW MRN of brachial and lumbosacral plexus at 1.5 T and at 3.0 T was compared. •For lumbosacral plexus, nerve conspicuity on MIP images was superior at 3.0 T, also visible length and mean sharpness of the nerves. •For brachial plexus, nerve conspicuity at 3.0 T was rather inferior, nerve length was not significantly different, mean sharpness was superior at 3.0 T. -- Abstract: Purpose: To compare intraindividually the nerve conspicuity of the brachial and lumbosacral plexus on diffusion-weighted (DW) MR neurography (MRN) at two different field strengths. Materials and methods: 16 healthy volunteers were investigated at 3.0 T and 1.5 T applying optimized variants of a DW spin-echo echo-planar imaging sequence with short TI inversion recovery fat suppression. Full-volume (FV) and curved sub-volume (CSV) maximum intensity projection (MIP) images were reconstructed and nerve conspicuity was visually assessed. Moreover, visible length and sharpness of the nerves were quantitatively analyzed. Results: On FV MIP images, nerve conspicuity at 3.0 T compared to 1.5 T was worse for brachial plexus (P = 0.00228), but better for lumbosacral plexus (P = 0.00666). On CSV MIP images, nerve conspicuity did not differ significantly for brachial plexus, but was better at 3.0 T for lumbosacral plexus (P = 0.00091). The visible length of the analyzed nerves did not differ significantly with the exception of some lumbosacral nerves, which were significantly longer at 3.0 T. The sharpness of all investigated nerves was significantly higher at 3.0 T by about 40–60% for cervical and 97–169% for lumbosacral nerves. Conclusion: DW MRN imaging at 3.0 T compared to 1.5 T is superior for lumbosacral plexus, but not for brachial plexus

Diffusion-weighted MR neurography of the brachial and lumbosacral plexus: 3.0 T versus 1.5 T imaging

Energy Technology Data Exchange (ETDEWEB)

Mürtz, P., E-mail: petra.muertz@ukb.uni-bonn.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Kaschner, M., E-mail: Marius.Kaschner@med.uni-duesseldorf.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Lakghomi, A., E-mail: Asadeh.Lakghomi@ukb.uni-bonn.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Gieseke, J., E-mail: juergen.gieseke@ukb.uni-bonn.de [Philips Healthcare, Lübeckertordamm 5, 20099 Hamburg (Germany); Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Willinek, W.A., E-mail: winfried.willinek@ukb.uni-bonn.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Schild, H.H., E-mail: hans.schild@ukb.uni-bonn.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Thomas, D., E-mail: daniel.thomas@ukb.uni-bonn.de [Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany)

2015-04-15

Highlights: •DW MRN of brachial and lumbosacral plexus at 1.5 T and at 3.0 T was compared. •For lumbosacral plexus, nerve conspicuity on MIP images was superior at 3.0 T, also visible length and mean sharpness of the nerves. •For brachial plexus, nerve conspicuity at 3.0 T was rather inferior, nerve length was not significantly different, mean sharpness was superior at 3.0 T. -- Abstract: Purpose: To compare intraindividually the nerve conspicuity of the brachial and lumbosacral plexus on diffusion-weighted (DW) MR neurography (MRN) at two different field strengths. Materials and methods: 16 healthy volunteers were investigated at 3.0 T and 1.5 T applying optimized variants of a DW spin-echo echo-planar imaging sequence with short TI inversion recovery fat suppression. Full-volume (FV) and curved sub-volume (CSV) maximum intensity projection (MIP) images were reconstructed and nerve conspicuity was visually assessed. Moreover, visible length and sharpness of the nerves were quantitatively analyzed. Results: On FV MIP images, nerve conspicuity at 3.0 T compared to 1.5 T was worse for brachial plexus (P = 0.00228), but better for lumbosacral plexus (P = 0.00666). On CSV MIP images, nerve conspicuity did not differ significantly for brachial plexus, but was better at 3.0 T for lumbosacral plexus (P = 0.00091). The visible length of the analyzed nerves did not differ significantly with the exception of some lumbosacral nerves, which were significantly longer at 3.0 T. The sharpness of all investigated nerves was significantly higher at 3.0 T by about 40–60% for cervical and 97–169% for lumbosacral nerves. Conclusion: DW MRN imaging at 3.0 T compared to 1.5 T is superior for lumbosacral plexus, but not for brachial plexus.

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

Science.gov (United States)

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

2018-04-02

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

Pre- and postcontrast FLAIR MR imaging in the diagnosis of intracranial meningeal pathology

International Nuclear Information System (INIS)

Tsuchiya, Kazuhiro; Katase, Shichiro; Yoshino, Ayako; Hachiya, Junichi

2000-01-01

Few reports address the use of fluid-attenuated inversion-recovery (FLAIR) images of the brain in the diagnosis of extraaxial lesions. Our purpose was to assess the value of FLAIR images, including postcontrast ones, in the diagnosis of intracranial meningeal diseases. We reviewed precontrast (n=24) and postcontrast (n=20) FLAIR images obtained from 25 patients with infectious meningitis (n=13), carcinomatous meningitis or dissemination of primary brain tumor (n=7), dural metastasis (n=3), and others (n=2) in comparison with fast spin-echo T2-weighted and postcontrast T1-weighted images. In lesion detectability, precontrast FLAIR images were significantly superior to fast spin-echo T2-weighted images but inferior to postcontrast T1-weighted images. There was no significant difference between postcontrast T1-weighted and FLAIR images. Precontrast FLAIR images can substitute for conventional fast spin-echo T2-weighted images. Postcontrast FLAIR images have diagnostic potential equivalent to conventional postcontrast T1-weighted images. (author)

Measurement of brain oxygenation changes using dynamic T1-weighted imaging

DEFF Research Database (Denmark)

Haddock, Bryan; Larsson, Henrik B W; Hansen, Adam E

2013-01-01

Magnetic resonance imaging (MRI) has proven useful in evaluating oxygenation in several types of tissue and blood. This study evaluates brain tissue oxygenation changes between normoxia and hyperoxia in healthy subjects using dynamic T1 and T2*-weighted imaging sequences. The change in FiO2 induced...... by hyperoxia caused a significant decrease in T1. A model to determine changes in tissue oxygen tension from the T1-weighted MRI signal is presented based on previous findings that T1 is sensitive to oxygen tension whereas T2* is sensitive to blood saturation. The two sequences produce results with different...... regional and temporal dynamics. These differences combined with results from simulations of the T1 signal intensities, indicate an increase in extravascular oxygen tension during hyperoxia. This study concludes that T1 and T2* responses to FiO2 serve as independent biomarkers of oxygen physiology...

Magnetic resonance separation imaging using a divided inversion recovery technique (DIRT).

Science.gov (United States)

Goldfarb, James W

2010-04-01

The divided inversion recovery technique is an MRI separation method based on tissue T(1) relaxation differences. When tissue T(1) relaxation times are longer than the time between inversion pulses in a segmented inversion recovery pulse sequence, longitudinal magnetization does not pass through the null point. Prior to additional inversion pulses, longitudinal magnetization may have an opposite polarity. Spatial displacement of tissues in inversion recovery balanced steady-state free-precession imaging has been shown to be due to this magnetization phase change resulting from incomplete magnetization recovery. In this paper, it is shown how this phase change can be used to provide image separation. A pulse sequence parameter, the time between inversion pulses (T180), can be adjusted to provide water-fat or fluid separation. Example water-fat and fluid separation images of the head, heart, and abdomen are presented. The water-fat separation performance was investigated by comparing image intensities in short-axis divided inversion recovery technique images of the heart. Fat, blood, and fluid signal was suppressed to the background noise level. Additionally, the separation performance was not affected by main magnetic field inhomogeneities.

MRI in seven cases of tacrolimus (FK-506) encephalopathy: utility of FLAIR and diffusion-weighted imaging

Energy Technology Data Exchange (ETDEWEB)

Furukawa, M. [Dept. of Radiology, Yamaguchi University School of Medicine, Ube (Japan); Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan); Terae, S.; Chu, B.C.; Kaneko, K.; Kamada, H.; Miyasaka, K. [Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan)

2001-08-01

We assessed the utility of fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted (DWI) images in investigation of tacrolimus (FK-506) encephalopathy, and to see whether we could predict its cause from clinical and imaging data. In seven patients with presumed FK-506 toxicity the areas involved on MRI were similar to those in cyclosporin A (CsA) toxicity. The abnormal signal was most evident on FLAIR in all cases. In three of four patients who underwent DWI, no diffusion abnormalities were detected; in the remaining patient, increased diffusion was seen in the deep white matter bilaterally on the apparent diffusion coefficient map, consistent with the findings on T2-weighted spin-echo and FLAIR images. Five of the six patients for whom we had clinical data showed sudden changes in electrolyte or fluid equilibrium due to diarrhoea, a polyuria or oliguria one day before or on the day of onset of the central nervous system disturbances. We speculate that FK-506 encephalopathy is triggered by the disturbance of the electrolyte and/or fluid equilibrium, given a certain serum level of FK-506. (orig.)

MRI in seven cases of tacrolimus (FK-506) encephalopathy: utility of FLAIR and diffusion-weighted imaging

International Nuclear Information System (INIS)

Furukawa, M.; Terae, S.; Chu, B.C.; Kaneko, K.; Kamada, H.; Miyasaka, K.

2001-01-01

We assessed the utility of fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted (DWI) images in investigation of tacrolimus (FK-506) encephalopathy, and to see whether we could predict its cause from clinical and imaging data. In seven patients with presumed FK-506 toxicity the areas involved on MRI were similar to those in cyclosporin A (CsA) toxicity. The abnormal signal was most evident on FLAIR in all cases. In three of four patients who underwent DWI, no diffusion abnormalities were detected; in the remaining patient, increased diffusion was seen in the deep white matter bilaterally on the apparent diffusion coefficient map, consistent with the findings on T2-weighted spin-echo and FLAIR images. Five of the six patients for whom we had clinical data showed sudden changes in electrolyte or fluid equilibrium due to diarrhoea, a polyuria or oliguria one day before or on the day of onset of the central nervous system disturbances. We speculate that FK-506 encephalopathy is triggered by the disturbance of the electrolyte and/or fluid equilibrium, given a certain serum level of FK-506. (orig.)

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

International Nuclear Information System (INIS)

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

2002-01-01

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

Calculation of null points in SPAIR, FLAIR, and STIR. Part 2. Application to pelvic diffusion-weighted imaging with SPAIR at 3T

International Nuclear Information System (INIS)

Kita, Miho; Kawano, Kazuhiro; Kometani, Katsuya; Kondo, Toshihiko; Shimamoto, Kazuhiro; Tanaka, Humihiro; Oda, Hideyuki; Kojima, Akihiro; Sato, Morio

2013-01-01

Diffusion-weighted imaging (DWI) requires adequate fat suppression because of its sensitivity to chemical shift artifacts, especially at 3 Tesla (T). We investigated the utility of calculating the inversion time of the null point (TI null ) in pelvic DWI with spectral attenuated inversion recovery (SPAIR) at 3 T for obtaining adequate fat suppression. Thirteen volunteers underwent pelvic SPAIR-DWI using various SPAIR inversion delay times (TI) at 5-ms intervals in the range of the calculated TI null ±25 ms. The degree of fat suppression was evaluated into 3 grades and was compared among the various SPAIR-TIs with the calculated TI null . In 65 cases of prostatic disease, we evaluated the ratio of adequate fat suppression obtained using the calculated TI null . We obtained adequate fat suppression in all 13 volunteers and in 61 (94%) of the 65 patients using the calculated TI null . Fat suppression was best when the calculated TI null was used (P null (P null increased. In conclusion, this method of calculating the TI null may be useful for obtaining adequate fat suppression for pelvic SPAIR-DWI at 3T. (author)

Value of diffusion-weighted MR imaging in the diagnosis of Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Xu Quangang; Wu Weiping; Huang Dehui; Zhang Jiatang; Lang Senyang; Pu Chuanqiang

2005-01-01

Objective: To assess the diagnosis value of diffusion- weighted imaging (DWI) in Creutzfeldt-Jakob disease (CJD). Methods: 8 cases of sporadic CJD who underwent MRI were reported. 4 cases were definite, 3 cases were probable and 1 case was possible. The sensitivity of DWI and conventional MRI were compared. Results: T 1 WI and T 2 WI revealed no abnormal signals except nonspecific diffuse brain atrophy in 4 cases, whereas DWI detected hyperintense abnormalities in all cases. 2 cases showed linear lesions only in the cerebral cortex, and 6 cases showed lesions in both the cerebral cortex and the striatum. The lesions were symmetric in 5 cases, but were asymmetric in the other 3 cases. Although fluid- attenuated inversion recovery (FLAIR) imaging also showed cortical hyperintensity in 1 case, the high signal changes were more evident and extensive on DWI. Conclusions: The hyperintense changes in the cerebral cortices and/or striata on DWI are considered characteristic of CJD. DWI is more sensitive than conventional MRI in depicting lesions of CJD and may be an essential tool for the early diagnosis of this disease. (authors)

Intra-individual comparison of image contrast in SPIO-enhanced liver MRI at 1.5T and 3.0T

International Nuclear Information System (INIS)

Falkenhausen, Marcus von; Meyer, Carsten; Lutterbey, Goetz; Morakkabati, Nuschin; Bloemer, Renate; Willinek, Winfried A.; Kuhl, Christiane K.; Schild, Hans H.; Walter, Oliver; Gieseke, Juergen

2007-01-01

The purpose of the study was to examine if the higher susceptibility at 3.0 Tesla (T) compared to 1.5 T will affect the contrast in MR imaging of the liver after application of superparamagnetic iron oxide particles (SPIO). The study was approved by our institutional review board and informed consent was obtained. Seventeen healthy volunteers were examined in a prospective, intra-individual comparative study within one day on a 1.5 T and a 3.0 T MRI system. T2 weighted TSE sequences were acquired after bolus injection of a SPIO contrast agent. Image contrast and signal to noise ratio (SNR) were compared between the field strengths. Image contrast was calculated between the liver tissue and the kidneys / spleen / muscles and fluids. The students'T-test was used for statistical analysis. No influence of the higher field strength could be observed on image contrast except for the liver / muscle contrast. This was due to a distinct SNR increase of the muscle tissue at 3.0 T as a result of their relaxation properties. The higher susceptibility at 3.0 T compared to 1.5 T does not translate into a stronger signal attenuation of the SPIO enhanced liver parenchyma. (orig.)

Intra-individual comparison of image contrast in SPIO-enhanced liver MRI at 1.5T and 3.0T

Energy Technology Data Exchange (ETDEWEB)

Falkenhausen, Marcus von; Meyer, Carsten; Lutterbey, Goetz; Morakkabati, Nuschin; Bloemer, Renate; Willinek, Winfried A.; Kuhl, Christiane K.; Schild, Hans H. [University of Bonn, Department of Radiology, Bonn (Germany); Walter, Oliver [Leibniz-Institute for Science Education, Kiel (Germany); Gieseke, Juergen [University of Bonn, Department of Radiology, Bonn (Germany); Philips Medical Systems, Hamburg (Germany)

2007-05-15

The purpose of the study was to examine if the higher susceptibility at 3.0 Tesla (T) compared to 1.5 T will affect the contrast in MR imaging of the liver after application of superparamagnetic iron oxide particles (SPIO). The study was approved by our institutional review board and informed consent was obtained. Seventeen healthy volunteers were examined in a prospective, intra-individual comparative study within one day on a 1.5 T and a 3.0 T MRI system. T2 weighted TSE sequences were acquired after bolus injection of a SPIO contrast agent. Image contrast and signal to noise ratio (SNR) were compared between the field strengths. Image contrast was calculated between the liver tissue and the kidneys / spleen / muscles and fluids. The students'T-test was used for statistical analysis. No influence of the higher field strength could be observed on image contrast except for the liver / muscle contrast. This was due to a distinct SNR increase of the muscle tissue at 3.0 T as a result of their relaxation properties. The higher susceptibility at 3.0 T compared to 1.5 T does not translate into a stronger signal attenuation of the SPIO enhanced liver parenchyma. (orig.)

MR urography (MRU) of non-dilated ureter with diuretic administration: Static fluid 2D FSE T2-weighted versus 3D gadolinium T1-weighted GE excretory MR

International Nuclear Information System (INIS)

Roy, C.; Ohana, M.; Host, Ph.; Alemann, G.; Labani, A.; Wattiez, A.; Lang, H.

2014-01-01

•T2w-MRU with multiple orientations and diuretic is sufficient to identify non-dilated ureter.•T2w-MRU offers information on ureteral contractions and could be proposed to detect initial obstruction before hydronephrosis occurs (for instance in cases of endometriosis).•T2w-MRU could also be used to evaluate potential renal donors or in patients unable to receive gadolinium.•CE-MRU rapidly produces an overdistended bladder with a risk of false positive diagnosis of mild obstruction.•CE-MRU is less convenient for patients. T2w-MRU with multiple orientations and diuretic is sufficient to identify non-dilated ureter. T2w-MRU offers information on ureteral contractions and could be proposed to detect initial obstruction before hydronephrosis occurs (for instance in cases of endometriosis). T2w-MRU could also be used to evaluate potential renal donors or in patients unable to receive gadolinium. CE-MRU rapidly produces an overdistended bladder with a risk of false positive diagnosis of mild obstruction. CE-MRU is less convenient for patients. 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

ipw: An R Package for Inverse Probability Weighting

Directory of Open Access Journals (Sweden)

Ronald B. Geskus

2011-10-01

Full Text Available We describe the R package ipw for estimating inverse probability weights. We show how to use the package to fit marginal structural models through inverse probability weighting, to estimate causal effects. Our package can be used with data from a point treatment situation as well as with a time-varying exposure and time-varying confounders. It can be used with binomial, categorical, ordinal and continuous exposure variables.

On the sound attenuation in fluid due to the thermal diffusion and viscous dissipation

Energy Technology Data Exchange (ETDEWEB)

Hu, Hanping, E-mail: hphu@ustc.edu.cn; Wang, Yandong; Wang, Dongdong

2015-09-11

We review the sound attenuation in fluid due to the thermal diffusion and viscous dissipation and derive the formula of the sound attenuation coefficient in fluid by solving a fully thermally–mechanically coupled equation set. Problem occurring in Stokes–Kirchhoff relation, the well-known and widely used classical formula for sound attenuation coefficient, is therefore found and pointed out. The reason for its generation is analyzed and verified. An improved formula to replace Stokes–Kirchhoff relation is suggested and the typical case for the error in calculating sound pressure level (SPL) of attenuated sound wave in fluid between the two formulas is also given. - Highlights: • Problem with Stokes–Kirchhoff relation. • Generation reason of defect in Stokes–Kirchhoff relation. • An improved formula for sound attenuation coefficient in fluid. • Typical cases of the calculation error by Stokes–Kirchhoff relation.

Tumour nuclear oestrogen receptor beta 1 correlates inversely with parathyroid tumour weight.

Science.gov (United States)

Haglund, Felix; Rosin, Gustaf; Nilsson, Inga-Lena; Juhlin, C Christofer; Pernow, Ylva; Norenstedt, Sophie; Dinets, Andrii; Larsson, Catharina; Hartman, Johan; Höög, Anders

2015-03-01

Primary hyperparathyroidism (PHPT) is a common endocrinopathy, frequently caused by a parathyroid adenoma, rarely by a parathyroid carcinoma that lacks effective oncological treatment. As the majority of cases are present in postmenopausal women, oestrogen signalling has been implicated in the tumourigenesis. Oestrogen receptor beta 1 (ERB1) and ERB2 have been recently identified in parathyroid adenomas, the former inducing genes coupled to tumour apoptosis. We applied immunohistochemistry and slide digitalisation to quantify nuclear ERB1 and ERB2 in 172 parathyroid adenomas, atypical adenomas and carcinomas, and ten normal parathyroid glands. All the normal parathyroid glands expressed ERB1 and ERB2. The majority of tumours expressed ERB1 (70.6%) at varying intensities, and ERB2 (96.5%) at strong intensities. Parathyroid carcinomas expressed ERB1 in three out of six cases and ERB2 in five out of six cases. The intensity of tumour nuclear ERB1 staining significantly correlated inversely with tumour weight (P=0.011), and patients whose tumours were classified as ERB1-negative had significantly greater tumour weight as well as higher serum calcium (P=0.002) and parathyroid hormone levels (P=0.003). Additionally, tumour nuclear ERB1 was not expressed differentially with respect to sex or age of the patient. Levels of tumour nuclear ERB2 did not correlate with clinical characteristics. In conclusion, decreased ERB1 immunoreactivity is associated with increased tumour weight in parathyroid adenomas. Given the previously reported correlation with tumour-suppressive signalling, selective oestrogen receptor modulation (SERMs) may play a role in the treatment of parathyroid carcinomas. Future studies of SERMs and oestrogen treatment in PHPT should consider tumour weight as a potential factor in pharmacological responsiveness. © 2015 The authors.

Equilibrium cluster fluids: Pair interactions via inverse design

OpenAIRE

Jadrich, Ryan B.; Bollinger, Jonathan A.; Lindquist, Beth A.; Truskett, Thomas M.

2015-01-01

Inverse methods of statistical mechanics are becoming productive tools in the design of materials with specific microstructures or properties. While initial studies have focused on solid-state design targets (e.g, assembly of colloidal superlattices), one can alternatively design fluid states with desired morphologies. This work addresses the latter and demonstrates how a simple iterative Boltzmann inversion strategy can be used to determine the isotropic pair potential that reproduces the ra...

Changes in Wetting Hysteresis During Bioremediation: Changes in fluid flow behavior monitored with low-frequency seismic attenuation

Science.gov (United States)

Wempe, W.; Spetzler, H.; Kittleson, C.; Pursley, J.

2003-12-01

We observed significant reduction in wetting hysteresis with time while a diesel-contaminated quartz crystal was dipped in and out of an oil-reducing bacteria solution. This wetting hysteresis is significantly greater than the wetting hysteresis when the diesel-contaminated quartz crystal is dipped in and out of (1) water, (2) diesel and (3) the bacterial food solution that does not contain bacteria. The reduction in wetting hysteresis of the bacteria solution on the quartz surface results from a reduction in the advancing contact angle formed at the air-liquid-quartz contact with time; the receding contact angle remains the same with time. Our results suggest that the bacteria solution moves across the quartz surface with less resistance after bioremediation has begun. These results imply that bioremediation may influence fluid flow behavior with time. For many fluid-solid systems there is a difference between the contact angle while a contact line advances and recedes across a solid surface; this difference is known as wetting hysteresis. Changes in wetting hysteresis can occur from changes in surface tension or the surface topography. Low contact angle values indicate that the liquid spreads or wets well, while high values indicate poor wetting or non-wetting. Contact angles are estimated in the lab by measuring the weight of the meniscus formed at the air-liquid-quartz interface and by knowing the fluid surface tension. In the lab, we have been able to use low-frequency seismic attenuation data to detect changes in the wetting characteristics of glass plates and of Berea sandstone. The accepted seismic attenuation mechanism is related to the loss of seismic energy due to the hysteresis of meniscus movement (wetting hysteresis) when a pore containing two fluids is stressed at very low frequencies (bioremediation progress using seismic attenuation data. We are measuring low-frequency seismic attenuation in the lab while flowing bacteria solution through Berea

White matter hyperintensities segmentation: a new semi-automated method

Directory of Open Access Journals (Sweden)

Mariangela eIorio

2013-12-01

Full Text Available White matter hyperintensities (WMH are brain areas of increased signal on T2-weighted or fluid attenuated inverse recovery magnetic resonance imaging (MRI scans. In this study we present a new semi-automated method to measure WMH load that is based on the segmentation of the intensity histogram of fluid-attenuated inversion recovery images. Thirty patients with Mild Cognitive Impairment with variable WMH load were enrolled. The semi-automated WMH segmentation included: removal of non-brain tissue, spatial normalization, removal of cerebellum and brain stem, spatial filtering, thresholding to segment probable WMH, manual editing for correction of false positives and negatives, generation of WMH map and volumetric estimation of the WMH load. Accuracy was quantitatively evaluated by comparing semi-automated and manual WMH segmentations performed by two independent raters. Differences between the two procedures were assessed using Student’s t tests and similarity was evaluated using linear regression model and Dice Similarity Coefficient (DSC. The volumes of the manual and semi-automated segmentations did not statistically differ (t-value= -1.79, DF=29, p= 0.839 for rater 1; t-value= 1.113, DF=29, p= 0.2749 for rater 2, were highly correlated (R²= 0.921, F (1,29 =155,54, p

MR imaging of hematopoietic regions in bone marrow of aplastic anemia. Diagnostic usefulness of opposed phase T1-weighted images

Energy Technology Data Exchange (ETDEWEB)

Amano, Yasuo; Tanabe, Yoshihiro; Amano, Maki; Kumazaki, Tatsuo [Nippon Medical School, Tokyo (Japan)

1996-01-01

The signal intensity of hematopoietic regions in the marrow of aplastic anemia were investigated on opposed phase T1-weighted images (op-T1WI) with a 0.5-Tesla MR unit. Hematopoietic regions were classified into two groups: low intensity hematopoietic areas (LH) isointense to normal marrow and high intensity hematopoietic regions (HH) with higher intensity than normal marrow on op-T1WI. The signal intensity of LH was significantly lower than that of HH on STIR. LH converted into HH with improvement of laboratory data after therapy, whereas HH decreased with impairment of data. HH were hyperintense to cerebrospinal fluid on op-T1WI. These results indicated that the signal intensity of hematopoietic regions on op-T1WI reflected the cellularity in these regions and that aplastic anemia included hypercellular regions relative to normal marrow. (author).

Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences.

Science.gov (United States)

Finkenstaedt, Tim; Del Grande, Filippo; Bolog, Nicolae; Ulrich, Nils; Tok, Sina; Kolokythas, Orpheus; Steurer, Johann; Andreisek, Gustav; Winklhofer, Sebastian

2018-02-01

 To assess the performance of fat-suppressed fluid-sensitive MRI sequences compared to T1-weighted (T1w) / T2w sequences for the detection of Modic 1 end-plate changes on lumbar spine MRI.  Sagittal T1w, T2w, and fat-suppressed fluid-sensitive MRI images of 100 consecutive patients (consequently 500 vertebral segments; 52 female, mean age 74 ± 7.4 years; 48 male, mean age 71 ± 6.3 years) were retrospectively evaluated. We recorded the presence (yes/no) and extension (i. e., Likert-scale of height, volume, and end-plate extension) of Modic I changes in T1w/T2w sequences and compared the results to fat-suppressed fluid-sensitive sequences (McNemar/Wilcoxon-signed-rank test).  Fat-suppressed fluid-sensitive sequences revealed significantly more Modic I changes compared to T1w/T2w sequences (156 vs. 93 segments, respectively; p definition of Modic I changes is not fully applicable anymore.. · Fat-suppressed fluid-sensitive MRI sequences revealed more/greater extent of Modic I changes.. · Finkenstaedt T, Del Grande F, Bolog N et al. Modic Type 1 Changes: Detection Performance of Fat-Suppressed Fluid-Sensitive MRI Sequences. Fortschr Röntgenstr 2018; 190: 152 - 160. © Georg Thieme Verlag KG Stuttgart · New York.

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

Science.gov (United States)

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

2009-06-01

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

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

International Nuclear Information System (INIS)

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

1994-01-01

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

From capture to simulation: connecting forward and inverse problems in fluids

KAUST Repository

Gregson, James; Ihrke, Ivo; Thuerey, Nils; Heidrich, Wolfgang

2014-01-01

We explore the connection between fluid capture, simulation and proximal methods, a class of algorithms commonly used for inverse problems in image processing and computer vision. Our key finding is that the proximal operator constraining fluid velocities to be divergence-free is directly equivalent to the pressure-projection methods commonly used in incompressible flow solvers. This observation lets us treat the inverse problem of fluid tracking as a constrained flow problem all while working in an efficient, modular framework. In addition it lets us tightly couple fluid simulation into flow tracking, providing a global prior that significantly increases tracking accuracy and temporal coherence as compared to previous techniques. We demonstrate how we can use these improved results for a variety of applications, such as re-simulation, detail enhancement, and domain modification. We furthermore give an outlook of the applications beyond fluid tracking that our proximal operator framework could enable by exploring the connection of deblurring and fluid guiding.

From capture to simulation: connecting forward and inverse problems in fluids

KAUST Repository

Gregson, James

2014-07-27

We explore the connection between fluid capture, simulation and proximal methods, a class of algorithms commonly used for inverse problems in image processing and computer vision. Our key finding is that the proximal operator constraining fluid velocities to be divergence-free is directly equivalent to the pressure-projection methods commonly used in incompressible flow solvers. This observation lets us treat the inverse problem of fluid tracking as a constrained flow problem all while working in an efficient, modular framework. In addition it lets us tightly couple fluid simulation into flow tracking, providing a global prior that significantly increases tracking accuracy and temporal coherence as compared to previous techniques. We demonstrate how we can use these improved results for a variety of applications, such as re-simulation, detail enhancement, and domain modification. We furthermore give an outlook of the applications beyond fluid tracking that our proximal operator framework could enable by exploring the connection of deblurring and fluid guiding.

Contrast-enhanced turbo spin-echo(TSE) T1-weighted imaging: improved contrast of enhancing lesions

International Nuclear Information System (INIS)

Choi, Sung Wook; Lee, Ghi Jai; Shim, Jae Chan; Lee, Young Ju; Jeong, Se Hyung; Kim, Ho kyun

1997-01-01

The purpose of this study was to evaluate the effect of contrast improvement of enhancing brain lesions by inherent magnetization transfer effect in turbo spin-echo(TSE)T1-weighted MR imaging. Twenty-six enhancing lesions of 19 patients were included in this study. Using a 1.0T superconductive MR unit, contrast-enhanced SE T1-weighted images(TR=3D600 msec, TE=3D12 msec, NEX=3D2, acquistition time=3D4min 27sec) and contrast-enhanced TSE T1-weighted images(TR=3D600 msec, TE=3D12, acquistition time=3D1min 44sec) were obtained. Signal intensities at enhancing lesions and adjacent white matter were measured in the same regions of both images. Signal-to-noise ratio(SNR) of enhancing lesions and adjacent white matter, and con-trast-to-noise ratio(CNR) and lesion-to-background contrast (LBC) of enhancing lesions were calculated and statistically analysed using the paired t-test. On contrast-enhanced TSE T1-weighted images, SNR of enhancing lesions and adjacent white matter decreased by 18%(p<0.01) and 32%(p<0.01), respectively, compared to contrast-enhanced SE T1-weighted images. CNR and LBC of enhancing lesions increased by 16%(p<0.05) and 66%(p<0.01), respectively. Due to the proposed inherent magnetization transfer effects in TSE imaging, con-trast-enhanced T1-weighted TSE images demonstrated a statistically significant improvement in CNR and LBC, compared to conventional contrast-enhanced T1-weighted SE images, and scan time was much shorter

Spin-echo and STIR MR imaging of sports-related muscle injuries at 1.5 T

International Nuclear Information System (INIS)

Greco, A.; McNamara, M.T.; Escher, R.M.B.; Trifilio, G.; Parienti, J.

1990-01-01

This paper assesses the value of T2-weighted and short T1 inversion recovery (Stir 1,800,170,27) sequences in the MR diagnosis and follow-up of muscle strain injuries. Fifty-six athletes with clinically diagnosed traumatic muscular damage were studied at 1.5 T with SE T1-weighted, double T2-weighted, and STIR techniques. Images were evaluated in order to detect the presence of muscle tear with associated edema, muscle hemorrhage (focal or diffuse), and perimuscular hemorrhage. The relative conspicuity of muscle injuries on T2-weighted and STIR images was assessed. All acute and subacute muscle injuries were detected on both SE T2-weighted and STIR images, muscle edema and subacute hemorrhage appearing hyperintense to normal muscle. Acute hemorrhage could appear hypointense on T2-weighted images but was always hyperintense on STIR images

CT and MRI findings of cyclosporine-related encephalopathy and hypertensive encephalopathy

International Nuclear Information System (INIS)

Yamamoto, Akira; Hayakawa, Katsumi; Houjyou, Makoto

2002-01-01

We present the MRI and CT findings of one child with cyclosporine-related encephalopathy, and one child with hypertensive encephalopathy following cyclosporine-related encephalopathy. The imaging findings were shown well on T2-weighted and fluid-attenuated inversion recovery (FLAIR) MR images. Cyclosporine-related encephalopathy was distributed predominantly in the posterior white matter. Hypertensive encephalopathy showed similar changes of CT attenuation, but with wider distribution. These two disorders seem to have the same pathogenesis. (orig.)

Visco-acoustic wave-equation traveltime inversion and its sensitivity to attenuation errors

KAUST Repository

Yu, Han

2018-02-23

A visco-acoustic wave-equation traveltime inversion method is presented that inverts for the shallow subsurface velocity distribution. Similar to the classical wave equation traveltime inversion, this method finds the velocity model that minimizes the squared sum of the traveltime residuals. Even though, wave-equation traveltime inversion can partly avoid the cycle skipping problem, a good initial velocity model is required for the inversion to converge to a reasonable tomogram with different attenuation profiles. When Q model is far away from the real model, the final tomogram is very sensitive to the starting velocity model. Nevertheless, a minor or moderate perturbation of the Q model from the true one does not strongly affect the inversion if the low wavenumber information of the initial velocity model is mostly correct. These claims are validated with numerical tests on both the synthetic and field data sets.

Visco-acoustic wave-equation traveltime inversion and its sensitivity to attenuation errors

Science.gov (United States)

Yu, Han; Chen, Yuqing; Hanafy, Sherif M.; Huang, Jiangping

2018-04-01

A visco-acoustic wave-equation traveltime inversion method is presented that inverts for the shallow subsurface velocity distribution. Similar to the classical wave equation traveltime inversion, this method finds the velocity model that minimizes the squared sum of the traveltime residuals. Even though, wave-equation traveltime inversion can partly avoid the cycle skipping problem, a good initial velocity model is required for the inversion to converge to a reasonable tomogram with different attenuation profiles. When Q model is far away from the real model, the final tomogram is very sensitive to the starting velocity model. Nevertheless, a minor or moderate perturbation of the Q model from the true one does not strongly affect the inversion if the low wavenumber information of the initial velocity model is mostly correct. These claims are validated with numerical tests on both the synthetic and field data sets.

Modic type 1 changes. Detection performance of fat-suppressed fluid-sensitive MRI sequences

Energy Technology Data Exchange (ETDEWEB)

Finkenstaedt, Tim; Andreisek, Gustav [University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; Del Grande, Filippo [Ospedale Regionale di Lugano (Switzerland). Inst. of Diagnostic and Interventional Radiology; Bolog, Nicolae [Phoenix Diagnostic Clinic, Bucharest (Romania); Ulrich, Nils; Tok, Sina [Schulthess Clinic, Zurich (Switzerland). Dept. of Neurosurgery; Kolokythas, Orpheus [Kantonsspital Winterthur (Switzerland). Inst. for Radiology and Nuclear Medicine; Steurer, Johann [University Hospital Zurich (Switzerland). Horten Center for Patient Oriented Research and Knowledge Transfer; Winklhofer, Sebastian [University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; University Hospital Zurich (Switzerland). Dept. of Neuroradiology; Collaboration: LSOS Study Group

2018-02-15

To assess the performance of fat-suppressed fluid-sensitive MRI sequences compared to T1-weighted (T1w) / T2w sequences for the detection of Modic 1 end-plate changes on lumbar spine MRI. Sagittal T1w, T2w, and fat-suppressed fluid-sensitive MRI images of 100 consecutive patients (consequently 500 vertebral segments; 52 female, mean age 74 ± 7.4 years; 48 male, mean age 71 ± 6.3 years) were retrospectively evaluated. We recorded the presence (yes/no) and extension (i.e., Likert-scale of height, volume, and end-plate extension) of Modic I changes in T1w/T2w sequences and compared the results to fat-suppressed fluid-sensitive sequences (McNemar/Wilcoxon-signed-rank test). Fat-suppressed fluid-sensitive sequences revealed significantly more Modic I changes compared to T1w/T2w sequences (156 vs. 93 segments, respectively; p < 0.001). The extension of Modic I changes in fat-suppressed fluid-sensitive sequences was significantly larger compared to T1w/T2w sequences (height: 2.53 ± 0.82 vs. 2.27 ± 0.79, volume: 2.35 ± 0.76 vs. 2.1 ± 0.65, end-plate: 2.46 ± 0.76 vs. 2.19 ± 0.81), (p < 0.05). Modic I changes that were only visible in fat-suppressed fluid-sensitive sequences but not in T1w/T2w sequences were significantly smaller compared to Modic I changes that were also visible in T1w/T2w sequences (p < 0.05). In conclusion, fat-suppressed fluid-sensitive MRI sequences revealed significantly more Modic I end-plate changes and demonstrated a greater extent compared to standard T1w/T2w imaging.

Contrast-enhanced flair imaging in the evaluation of infectious leptomeningeal diseases

International Nuclear Information System (INIS)

Parmar, Hemant; Sitoh, Y.-Y.; Anand, Pooja; Chua, Violet; Hui, Francis

2006-01-01

Purpose: The purpose of our study was to compare contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images with contrast-enhanced T1 weighted images for infectious leptomeningitis. Materials and methods: We studied twenty-four patients with a clinical suspicion of infectious meningitis with unenhanced FLAIR, contrast-enhanced T1 weighted and contrast-enhanced FLAIR MR sequences. Twelve patients had cytologic and biochemical diagnosis of meningitis on cerebrospinal fluid (CSF) examination obtained 48 h before or after the MR study. Sequences were considered positive if abnormal signal was seen in the subarachnoid space (cistern or sulci) or along pial surface. Results: Twenty-seven examinations in 24 patients were performed. Of the 12 patients (thirteen studies) in whom cytology was positive, unenhanced FLAIR images were positive in six cases (sensitivity 46%), contrast-enhanced FLAIR images were positive in 11 (sensitivity 85%), and contrast-enhanced T1 weighted MR images were positive in 11 patients (sensitivity 85%). Of the 12 patients (14 studies) in whom cerebrospinal fluid study was negative, unenhanced FLAIR images were negative in 13, contrast-enhanced FLAIR images were negative in 11, and contrast-enhanced T1 weighted MR images were negative in eight. Thus, the specificity of unenhanced FLAIR, contrast-enhanced FLAIR and contrast-enhanced T1 weighted images was 93, 79 and 57%, respectively. Conclusion: Our results suggest that post-contrast FLAIR images have similar sensitivity but a higher specificity compared to contrast-enhanced T1 weighted images for detection of leptomeningeal enhancement. It can be a useful adjunct to post-contrast T1 weighted images in evaluation of infectious leptomeningitis

Contrast-enhanced flair imaging in the evaluation of infectious leptomeningeal diseases

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Parmar, Hemant [Department of Neuroradiology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433 (Singapore) and Department of Diagnostic Imaging, Hospital for Sick Children, Toronto (Canada)]. E-mail: parurad@hotmail.com; Sitoh, Y.-Y. [Department of Neuroradiology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433 (Singapore); Anand, Pooja [Department of Neurology, National Neuroscience Institute, 11 Jalan Tan Tock Seng (Singapore); Chua, Violet [Department of Neuroradiology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433 (Singapore); Hui, Francis [Department of Neuroradiology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433 (Singapore)

2006-04-15

Purpose: The purpose of our study was to compare contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images with contrast-enhanced T1 weighted images for infectious leptomeningitis. Materials and methods: We studied twenty-four patients with a clinical suspicion of infectious meningitis with unenhanced FLAIR, contrast-enhanced T1 weighted and contrast-enhanced FLAIR MR sequences. Twelve patients had cytologic and biochemical diagnosis of meningitis on cerebrospinal fluid (CSF) examination obtained 48 h before or after the MR study. Sequences were considered positive if abnormal signal was seen in the subarachnoid space (cistern or sulci) or along pial surface. Results: Twenty-seven examinations in 24 patients were performed. Of the 12 patients (thirteen studies) in whom cytology was positive, unenhanced FLAIR images were positive in six cases (sensitivity 46%), contrast-enhanced FLAIR images were positive in 11 (sensitivity 85%), and contrast-enhanced T1 weighted MR images were positive in 11 patients (sensitivity 85%). Of the 12 patients (14 studies) in whom cerebrospinal fluid study was negative, unenhanced FLAIR images were negative in 13, contrast-enhanced FLAIR images were negative in 11, and contrast-enhanced T1 weighted MR images were negative in eight. Thus, the specificity of unenhanced FLAIR, contrast-enhanced FLAIR and contrast-enhanced T1 weighted images was 93, 79 and 57%, respectively. Conclusion: Our results suggest that post-contrast FLAIR images have similar sensitivity but a higher specificity compared to contrast-enhanced T1 weighted images for detection of leptomeningeal enhancement. It can be a useful adjunct to post-contrast T1 weighted images in evaluation of infectious leptomeningitis.

Fluid-fluid level on MR image: significance in Musculoskeletal diseases

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Chung, Hye Won; Lee, Kyung Won [Seoul Naitonal University, Seoul (Korea, Republic of). Coll. of Medicine; Song, Chi Sung [Seoul City Boramae Hospital, Seoul (Korea, Republic of); Han, Sang Wook; Kang, Heung Sik [Seoul Naitonal University, Seoul (Korea, Republic of). Coll. of Medicine

1998-01-01

To evaluate the frequency, number and signal intensity of fluid-fluid levels of musculoskeletal diseases on MR images, and to determine the usefulness of this information for the differentiation of musculoskeletal diseases. MR images revealed fluid-fluid levels in the following diseases : giant cell tumor(6), telangiectatic osteosarcoma(4), aneurysmal bone cyst(3), synovial sarcoma(3), chondroblastoma(2), soft tissue tuberculous abscess(2), hematoma(2), hemangioma (1), neurilemmoma(1), metastasis(1), malignant fibrous histiocytoma(1), bursitis(1), pyogenic abscess(1), and epidermoid inclusion cyst(1). Fourteen benign tumors and ten malignant, three abscesses, and the epidermoid inclusion cyst showed only one fluid-fluid level in a unilocular cyst. On T1-weighted images, the signal intensities of fluid varied, but on T2-weighted images, superior layers were in most cases more hyperintense than inferior layers. Because fluid-fluid layers are a nonspecific finding, it is difficult to specifically diagnose each disease according to the number of fluid-fluid levels or signal intensity of fluid. In spite of the nonspecificity of fluid-fluid levels, they were frequently seen in cases of giant cell tumor, telangiectatic osteosarcoma, aneurysmal bone cycle, and synovial sarcoma. Nontumorous diseases such abscesses and hematomas also demonstrated this finding. (author). 11 refs., 1 tab., 4 figs.

Fluid-fluid level on MR image: significance in Musculoskeletal diseases

International Nuclear Information System (INIS)

Chung, Hye Won; Lee, Kyung Won; Han, Sang Wook; Kang, Heung Sik

1998-01-01

To evaluate the frequency, number and signal intensity of fluid-fluid levels of musculoskeletal diseases on MR images, and to determine the usefulness of this information for the differentiation of musculoskeletal diseases. MR images revealed fluid-fluid levels in the following diseases : giant cell tumor(6), telangiectatic osteosarcoma(4), aneurysmal bone cyst(3), synovial sarcoma(3), chondroblastoma(2), soft tissue tuberculous abscess(2), hematoma(2), hemangioma (1), neurilemmoma(1), metastasis(1), malignant fibrous histiocytoma(1), bursitis(1), pyogenic abscess(1), and epidermoid inclusion cyst(1). Fourteen benign tumors and ten malignant, three abscesses, and the epidermoid inclusion cyst showed only one fluid-fluid level in a unilocular cyst. On T1-weighted images, the signal intensities of fluid varied, but on T2-weighted images, superior layers were in most cases more hyperintense than inferior layers. Because fluid-fluid layers are a nonspecific finding, it is difficult to specifically diagnose each disease according to the number of fluid-fluid levels or signal intensity of fluid. In spite of the nonspecificity of fluid-fluid levels, they were frequently seen in cases of giant cell tumor, telangiectatic osteosarcoma, aneurysmal bone cycle, and synovial sarcoma. Nontumorous diseases such abscesses and hematomas also demonstrated this finding. (author). 11 refs., 1 tab., 4 figs

MRI detection of hypointense brain lesions in patients with multiple sclerosis: T1 spin-echo vs. gradient-echo

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Dupuy, Sheena L.; Tauhid, Shahamat; Kim, Gloria; Chu, Renxin; Tummala, Subhash [Departments of Neurology, Brigham and Women' s Hospital, Laboratory for Neuroimaging Research, Partners MS Center, Harvard Medical School, Boston, MA (United States); Hurwitz, Shelley [Departments of Medicine, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States); Bakshi, Rohit, E-mail: rbakshi@bwh.harvard.edu [Departments of Neurology, Brigham and Women' s Hospital, Laboratory for Neuroimaging Research, Partners MS Center, Harvard Medical School, Boston, MA (United States); Departments of Radiology, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States)

2015-08-15

Highlights: • Compared T1SE and T1GE in detecting hypointense brain lesions in MS patients. • T1GE detected a higher cerebral lesion volume and number than T1SE. • T1SE correlated significantly with disability, while T1GE did not. • Hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. - Abstract: Objective: Compare T1 spin-echo (T1SE) and T1 gradient-echo (T1GE) sequences in detecting hypointense brain lesions in multiple sclerosis (MS). Background: Chronic hypointense lesions on T1SE MRI scans are a surrogate of severe demyelination and axonal loss in MS. The role of T1GE images in the detection of such lesions has not been clarified. Design/methods: In 45 patients with MS [Expanded Disability Status Scale (EDSS) score (mean ± SD) 3.5 ± 2.0; 37 relapsing-remitting (RR); 8 secondary progressive (SP)], cerebral T1SE, T1GE, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images were acquired on a 1.5 T MRI scanner. Images were re-sampled to axial 5 mm slices before directly comparing lesion detectability using Jim (v.7, Xinapse Systems). Statistical methods included Wilcoxon signed rank tests to compare sequences and Spearman correlations to test associations. Results: Considering the entire cohort, T1GE detected a higher lesion volume (5.90 ± 6.21 vs. 4.17 ± 4.84 ml, p < 0.0001) and higher lesion number (27.82 ± 20.66 vs. 25.20 ± 20.43, p < 0.05) than T1SE. Lesion volume differences persisted when considering RR and SP patients separately (both p < 0.01). A higher lesion number by T1GE was seen only in the RR group (p < 0.05). When comparing correlations between lesion volume and overall neurologic disability (EDSS score), T1SE correlated with EDSS (Spearman r = 0.29, p < 0.05) while T1GE (r = 0.23, p = 0.13) and FLAIR (r = 0.24, p = 0.12) did not. Conclusion: Our data suggest that hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. Based on these results, we hypothesize that T1GE

MRI detection of hypointense brain lesions in patients with multiple sclerosis: T1 spin-echo vs. gradient-echo

International Nuclear Information System (INIS)

Dupuy, Sheena L.; Tauhid, Shahamat; Kim, Gloria; Chu, Renxin; Tummala, Subhash; Hurwitz, Shelley; Bakshi, Rohit

2015-01-01

Highlights: • Compared T1SE and T1GE in detecting hypointense brain lesions in MS patients. • T1GE detected a higher cerebral lesion volume and number than T1SE. • T1SE correlated significantly with disability, while T1GE did not. • Hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. - Abstract: Objective: Compare T1 spin-echo (T1SE) and T1 gradient-echo (T1GE) sequences in detecting hypointense brain lesions in multiple sclerosis (MS). Background: Chronic hypointense lesions on T1SE MRI scans are a surrogate of severe demyelination and axonal loss in MS. The role of T1GE images in the detection of such lesions has not been clarified. Design/methods: In 45 patients with MS [Expanded Disability Status Scale (EDSS) score (mean ± SD) 3.5 ± 2.0; 37 relapsing-remitting (RR); 8 secondary progressive (SP)], cerebral T1SE, T1GE, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images were acquired on a 1.5 T MRI scanner. Images were re-sampled to axial 5 mm slices before directly comparing lesion detectability using Jim (v.7, Xinapse Systems). Statistical methods included Wilcoxon signed rank tests to compare sequences and Spearman correlations to test associations. Results: Considering the entire cohort, T1GE detected a higher lesion volume (5.90 ± 6.21 vs. 4.17 ± 4.84 ml, p < 0.0001) and higher lesion number (27.82 ± 20.66 vs. 25.20 ± 20.43, p < 0.05) than T1SE. Lesion volume differences persisted when considering RR and SP patients separately (both p < 0.01). A higher lesion number by T1GE was seen only in the RR group (p < 0.05). When comparing correlations between lesion volume and overall neurologic disability (EDSS score), T1SE correlated with EDSS (Spearman r = 0.29, p < 0.05) while T1GE (r = 0.23, p = 0.13) and FLAIR (r = 0.24, p = 0.12) did not. Conclusion: Our data suggest that hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. Based on these results, we hypothesize that T1GE

Metastatic spinal tumor. Assessment with fat-saturation T1-weighted MR imaging

International Nuclear Information System (INIS)

Kasai, Toshifumi; Sugimura, Kazuro; Uchida, Nobue; Kawamitsu, Hideaki; Komatsu, Akio; Okui, Shouji; Kimino, Katsuji.

1994-01-01

The purpose of this study was to compare conventional T1-weighted imaging (T1-WI) and chemical shift fat-saturation T1-weighted imaging (fat-sat T1-WI) by a diagnosis of the bone metastases. Thirty-two patients (143 vertebrae) with non-neoplastic lesions (normal group) and 32 patients (82 vertebrae) with spinal metastases (metastatic group) were evaluated using both images. The signal intensity (SI) distribution of both groups regarding T1-WI provided various patterns, and the SI measurements were not significantly different between the two groups ; however, the metastases which were mixed, showed a low SI. Regarding fat-sat T1-WI, all non-neoplastic lesions had a low-intensity homogeneous appearance ; however, the metastases were mixed to a high SI. The SI measurement data of the metastatic group was significantly higher than that of the normal group. In conclusion, fat-sat T1-WI was useful for evaluating the vertebral metastases. When fat-sat T1-WI demonstrated a mixed to high SI in patients suspected of having vertebral metastasis, Gd-DTPA enhancement was thought to be the problem. (author)

Comparison of different magnetic resonance cholangiography techniques in living liver donors including Gd-EOB-DTPA enhanced T1-weighted sequences.

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Sonja Kinner

Full Text Available Preoperative evaluation of potential living liver donors (PLLDs includes the assessment of the biliary anatomy to avoid postoperative complications. Aim of this study was to compare T2-weighted (T2w and Gd-EOB-DTPA enhanced T1-weighted (T1w magnetic resonance cholangiography (MRC techniques in the evaluation of PLLDs.30 PLLDs underwent MRC on a 1.5 T Magnetom Avanto (Siemens, Erlangen, Germany using (A 2D T2w HASTE (Half Fourier Acquisition Single Shot Turbo Spin Echo fat saturated (fs in axial plane, (B 2D T2w HASTE fs thick slices in coronal plane, (C free breathing 3D T2w TSE (turbo spin echo RESTORE (high-resolution navigator corrected plus (D maximum intensity projections (MIPs, (E T2w SPACE (sampling perfection with application optimized contrasts using different flip angle evolutions plus (F MIPs and (G T2w TSE BLADE as well as Gd-EOB-DTPA T1w images without (G and with (H inversion recovery. Contrast enhanced CT cholangiography served as reference imaging modality. Two independent reviewers evaluated the biliary tract anatomy on a 5-point scale subjectively and objectively. Data sets were compared using a Mann-Whitney-U-test. Kappa values were also calculated.Source images and maximum intensity projections of 3D T2w TSE sequences (RESTORE and SPACE proved to be best for subjective and objective evaluation directly followed by 2D HASTE sequences. Interobserver variabilities were good to excellent (k = 0.622-0.804.3D T2w sequences are essential for preoperative biliary tract evaluation in potential living liver donors. Furthermore, our results underline the value of different MRCP sequence types for the evaluation of the biliary anatomy in PLLDs including Gd-EOB-DTPA enhanced T1w MRC.

Fat Attenuation at CT in Anorexia Nervosa

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Gill, Corey M.; Torriani, Martin; Murphy, Rachel; Harris, Tamara B.; Miller, Karen K.; Klibanski, Anne

2016-01-01

Purpose To investigate the composition, cross-sectional area (CSA), and hormonal correlates of different fat depots in women with anorexia nervosa (AN) and control subjects with normal weights to find out whether patients with AN have lower fat CSA but higher attenuation than did control subjects and whether these changes may be mediated by gonadal steroids, cortisol, and thyroid hormones. Materials and Methods This study was institutional review board approved and HIPAA compliant. Written informed consent was obtained. Forty premenopausal women with AN and 40 normal-weight women of comparable age (mean age ± standard deviation, 26 years ± 5) were studied. All individuals underwent computed tomography of the abdomen and thigh with a calibration phantom. Abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), thigh SAT, and thigh intermuscular adipose tissue CSA and attenuation were quantified. Serum estradiol, thyroid hormones, and urinary free cortisol levels were assessed. Variables were compared by using analysis of variance. Associations were examined by using linear regression analysis. Results Women with AN had higher fat attenuation than did control subjects (−100.1 to −46.7 HU vs −117.6 to −61.8 HU, P < .0001), despite lower fat CSA (2.0–62.8 cm2 vs 5.5–185.9 cm2, P < .0001). VAT attenuation but not CSA was inversely associated with lowest prior lifetime body mass index in AN (r = −0.71, P = .006). Serum estradiol levels were inversely associated with fat attenuation (r = −0.34 to −0.61, P = .03 to <.0001) and were positively associated with fat CSA of all compartments (r = 0.42–0.64, P = .007 to <.0001). Thyroxine levels and urinary free cortisol levels were positively associated with thigh SAT attenuation (r = 0.64 [P = .006] and r = 0.68 [P = .0004], respectively) and were inversely associated with abdominal SAT and VAT CSA (r = −0.44 to −0.58, P = .04 to .02). Conclusion Women with AN have differences in fat

Extracting Low-Frequency Information from Time Attenuation in Elastic Waveform Inversion

Science.gov (United States)

Guo, Xuebao; Liu, Hong; Shi, Ying; Wang, Weihong

2017-03-01

Low-frequency information is crucial for recovering background velocity, but the lack of low-frequency information in field data makes inversion impractical without accurate initial models. Laplace-Fourier domain waveform inversion can recover a smooth model from real data without low-frequency information, which can be used for subsequent inversion as an ideal starting model. In general, it also starts with low frequencies and includes higher frequencies at later inversion stages, while the difference is that its ultralow frequency information comes from the Laplace-Fourier domain. Meanwhile, a direct implementation of the Laplace-transformed wavefield using frequency domain inversion is also very convenient. However, because broad frequency bands are often used in the pure time domain waveform inversion, it is difficult to extract the wavefields dominated by low frequencies in this case. In this paper, low-frequency components are constructed by introducing time attenuation into the recorded residuals, and the rest of the method is identical to the traditional time domain inversion. Time windowing and frequency filtering are also applied to mitigate the ambiguity of the inverse problem. Therefore, we can start at low frequencies and to move to higher frequencies. The experiment shows that the proposed method can achieve a good inversion result in the presence of a linear initial model and records without low-frequency information.

T1 weighted brain images at 7 Tesla unbiased for Proton Density, T2* contrast and RF coil receive B1 sensitivity with simultaneous vessel visualization.

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Van de Moortele, Pierre-François; Auerbach, Edwards J; Olman, Cheryl; Yacoub, Essa; Uğurbil, Kâmil; Moeller, Steen

2009-06-01

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as "intensity field bias". Such inhomogeneities mostly originate from heterogeneous RF coil B(1) profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T(1)-weighted (T(1)w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T(1) weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T(1) contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B(1) variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B(1) profiles become more heterogeneous. Another characteristic of T(1)w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T(2)(*) contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T(1)w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T(2)(*) contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 T, provide higher T(1) contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help in identifying small brain structures and that T(2)(*) induced artifacts can be removed from the images. The resulting unbiased T(1)w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T(1)w structural images. In addition

Quantitative Gd-DOTA uptake from cerebrospinal fluid into rat brain using 3D VFA-SPGR at 9.4T.

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Lee, Hedok; Mortensen, Kristian; Sanggaard, Simon; Koch, Palle; Brunner, Hans; Quistorff, Bjørn; Nedergaard, Maiken; Benveniste, Helene

2018-03-01

We propose a quantitative technique to assess solute uptake into the brain parenchyma based on dynamic contrast-enhanced MRI (DCE-MRI). With this approach, a small molecular weight paramagnetic contrast agent (Gd-DOTA) is infused in the cerebral spinal fluid (CSF) and whole brain gadolinium concentration maps are derived. We implemented a 3D variable flip angle spoiled gradient echo (VFA-SPGR) longitudinal relaxation time (T1) technique, the accuracy of which was cross-validated by way of inversion recovery rapid acquisition with relaxation enhancement (IR-RARE) using phantoms. Normal Wistar rats underwent Gd-DOTA infusion into CSF via the cisterna magna and continuous MRI for approximately 130 min using T1-weighted imaging. Dynamic Gd-DOTA concentration maps were calculated and parenchymal uptake was estimated. In the phantom study, T1 discrepancies between the VFA-SPGR and IR-RARE sequences were approximately 6% with a transmit coil inhomogeneity correction. In the in vivo study, contrast transport profiles indicated maximal parenchymal retention of approximately 19% relative to the total amount delivered into the cisterna magna. Imaging strategies for accurate 3D contrast concentration mapping at 9.4T were developed and whole brain dynamic concentration maps were derived to study solute transport via the glymphatic system. The newly developed approach will enable future quantitative studies of the glymphatic system in health and disease states. Magn Reson Med 79:1568-1578, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

High-speed imaging at 3 tesla. A technical and clinical review with an emphasis on whole-brain 3D imaging

International Nuclear Information System (INIS)

Naganawa, Shinji; Kawai, Hisashi; Fukatsu, Hiroshi; Ishigaki, Takeo; Komada, Tomomi

2005-01-01

Improvements to the inherently high specific-absorption rate (SAR) of high-speed imaging at 3T are necessary in order to render this method clinically feasible. Various efforts have been undertaken to improve the associated hardware and software. In this review, we focus on whole-brain isotropic 3D imaging with a turbo spin-echo sequence with variable flip-angle echo trains (3D-TSE-VFL) and present its technical and clinical features. This sequence can be used to acquire images of various contrasts including T 2 -weighted, fat-suppressed T 2 -weighted, fluid-attenuated inversion recovery (FLAIR), fat-suppressed FLAIR, and STIR (short tau inversion recovery). Various aspects of 3D-TSE-VFL are discussed, including CSF (cerebrospinal fluid) and metal artifacts, STIR contrast, small-part visualization other than brain, and the possibility of serial subtraction. Some images from clinical cases are presented. (author)

Postcontrast T1-weighted brain magnetic resonance imaging in pediatric patients: comparison between postcontrast fat-suppression imaging and conventional T1-weighted or magnetization transfer imaging

International Nuclear Information System (INIS)

Lee, Choong Wook; Goo, Hyun Woo

2004-01-01

We wished to assess the merits and weaknesses of postcontrast fat-suppression (FS) brain MR imaging in children for the evaluation of various enhancing lesions as compared with postcontrast conventional T1-weighted or magnetization transfer (MT) imaging. We reviewed the records of those patients with enhancing lesions on brain MR imaging who had undergone both FS imaging and one of the conventional T1-weighted or MT imaging as a post-contrast T1-weighted brain MR imaging. Thirty-one patients (21 male, 10 female; mean age, 8.7 years) with 38 enhancing lesions (18 intra-axial, 16 extra-axial and 4 orbital locations) were included in this study. There were 27 pairs of FS and conventional imagings, and 13 pairs of FS and MT imagings available for evaluation. Two radiologists visually assessed by consensus the lesions' conspicuity, and they also looked for the presence of flow or susceptibility artifacts in a total of 40 pairs of MR imagings. For 19 measurable lesions (14 pairs of FS and conventional T1-weighted imagings, 5 pairs of FS and MT imagings), the contrast ratios between the lesion and the normal brain ([SIlesion-SIwater]/[SInormal brain-SIwater]) were calculated and compared. Compared with conventional imaging, the lesion conspicuity on FS imaging was better in 10 cases (7 extra-axial lesions, 2 orbital lesions and 1 fat-containing intra-axial lesion), equal in 16 cases, and worse in one case. Compared with MT imaging, the lesion conspicuity on FS imaging was better in 3 cases (2 extra-axial lesions and 1 intra-axial lesion), equal in 8 cases, and worse in 2 cases. Image quality of FS imaging was compromised by flow or susceptibility artifacts for 7 patients. The contrast ratios for FS imaging were not significantly different from those for conventional imaging (2.2±0.7 vs. 2.2±0.6, respectively, p=0.914) and they were significantly lower than those for MT imaging (2.4±0.8 vs. 4.5±1.5, respectively, p=0.018). Postcontrast FS brain MR imaging appears to be

T1 weighted Brain Images at 7 Tesla Unbiased for Proton Density, T2* contrast and RF Coil Receive B1 Sensitivity with Simultaneous Vessel Visualization

Science.gov (United States)

Van de Moortele, Pierre-François; Auerbach, Edwards J.; Olman, Cheryl; Yacoub, Essa; Uğurbil, Kâmil; Moeller, Steen

2009-01-01

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as “intensity field bias”. Such inhomogeneities mostly originate from heterogeneous RF coil B1 profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T1-weighted (T1w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T1 weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T1 contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B1 variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B1 profiles become more heterogeneous. Another characteristic of T1w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T2* contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T1w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T2* contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 Tesla, provide higher T1 contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help identifying small brain structures and that T2* induced artifacts can be removed from the images. The resulting unbiased T1w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T1w structural images. In addition, we introduce a simple technique

Peritoneal fluid causing inferior attenuation on SPECT thallium-201 myocardial imaging in women

International Nuclear Information System (INIS)

Rab, S.T.; Alazraki, N.P.; Guertler-Krawczynska, E.

1988-01-01

On SPECT thallium images, myocardial left ventricular (LV) anterior wall attenuation due to breast tissue is common in women. In contrast, in men, inferior wall counts are normally decreased compared to anterior counts. The purpose of this report is to describe cases of inferior wall attenuation of counts in women caused by peritoneal fluid, not myocardial disease. Twelve consecutive SPECT thallium myocardial studies performed in women on peritoneal dialysis, being evaluated for kidney transplant, were included in this study. For all studies, 3.5 mCi 201Tl were injected intravenously. Thirty-two images were acquired over 180 degrees (45 degrees RAO progressing to 45 degrees LPO) at 40 sec per stop. SPECT images were reviewed in short axis, horizontal long and vertical long axes. Data were also displayed in bullseye format with quantitative comparison to gender-matched normal files. Ten of 12 female patients studied had inferior wall defects on images, confirmed by bullseye display. All patients had approximately 2 liters of peritoneal fluid. Review of planar rotational views showed diaphragm elevation and fluid margin attenuations affecting left ventricular inferior wall. Thus, peritoneal fluid is a cause of inferior attenuation on 201Tl cardiac imaging

Inverse optimization of objective function weights for treatment planning using clinical dose-volume histograms

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Babier, Aaron; Boutilier, Justin J.; Sharpe, Michael B.; McNiven, Andrea L.; Chan, Timothy C. Y.

2018-05-01

We developed and evaluated a novel inverse optimization (IO) model to estimate objective function weights from clinical dose-volume histograms (DVHs). These weights were used to solve a treatment planning problem to generate ‘inverse plans’ that had similar DVHs to the original clinical DVHs. Our methodology was applied to 217 clinical head and neck cancer treatment plans that were previously delivered at Princess Margaret Cancer Centre in Canada. Inverse plan DVHs were compared to the clinical DVHs using objective function values, dose-volume differences, and frequency of clinical planning criteria satisfaction. Median differences between the clinical and inverse DVHs were within 1.1 Gy. For most structures, the difference in clinical planning criteria satisfaction between the clinical and inverse plans was at most 1.4%. For structures where the two plans differed by more than 1.4% in planning criteria satisfaction, the difference in average criterion violation was less than 0.5 Gy. Overall, the inverse plans were very similar to the clinical plans. Compared with a previous inverse optimization method from the literature, our new inverse plans typically satisfied the same or more clinical criteria, and had consistently lower fluence heterogeneity. Overall, this paper demonstrates that DVHs, which are essentially summary statistics, provide sufficient information to estimate objective function weights that result in high quality treatment plans. However, as with any summary statistic that compresses three-dimensional dose information, care must be taken to avoid generating plans with undesirable features such as hotspots; our computational results suggest that such undesirable spatial features were uncommon. Our IO-based approach can be integrated into the current clinical planning paradigm to better initialize the planning process and improve planning efficiency. It could also be embedded in a knowledge-based planning or adaptive radiation therapy framework to

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

International Nuclear Information System (INIS)

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

1991-01-01

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

Diagnosis of acute subarachnoid hemorrhage at 1.5 Tesla using proton-density weighted FSE and FLAIR sequences

International Nuclear Information System (INIS)

Wiesmann, M.; Mayer, T.E.; Brueckmann, H.; Medele, R.

1999-01-01

Purpose: To evaluate MR imaging at 1.5 Tesla in patients suffering from acute subarachnoid hemorrhage (SAH) using proton-density weighted (PDW) fast spin echo (FSE) and fluid attenuated inversion recovery (FLAIR) sequences. Methods: 19 patients suffering from acute SAH as diagnosed by CT were studied 6 h to 3 days after hemorrhage. 10 patients without SAH were studied as a control group. The presence of subarachnoid blood as well as possible artifacts was recorded. Results: In all 19 patients subarachnoid hemorrhage was detected on both FLAIR and PDW images (100%). On the FLAIR images, the cerebral ventricles were partially obscured by flow artifacts in 7 of 19 patients, the basal cisterns in 6 of 19 patients. In 4 of these 13 regions blood was diagnosed on both PDW and CT images, while in the other 9 regions both PDW and CT were unremarkable. Conclusion: The sensitivity of MRI at 1.5 Tesla in the diagnosis of subarachnoid hemorrhage is comparable to CT. The combination of FLAIR and PDW FSE sequences helps to avoid false-positive results caused by flow artifacts. (orig.) [de

Contrast-enhanced FLAIR in the early diagnosis of infectious meningitis

International Nuclear Information System (INIS)

Splendiani, Alesssandra; Puglielli, Edoardo; Amicis, Rosanna De; Masciocchi, Carlo; Gallucci, Massimo; Necozione, Stefano

2005-01-01

We investigated the accuracy of MRI in the early diagnosis of infectious meningitis with emphasis on the value of gadolinium-enhanced fluid-attenuated inversion recovery (FLAIR) sequence. Twenty-seven patients with clinical suspicion of infectious meningitis were included. MRI was performed within 3 h of clinical evaluation. For all patients, T1-weighted spin-echo, dual-echo T2-weighted fast-spin-echo and FLAIR sequences were performed, followed by gadolinium-enhanced T1-weighted spin-echo and FLAIR sequences. Final diagnosis was based on the clinical findings and the analysis of cerebrospinal fluid, obtained by lumbar puncture after the MRI. Infectious meningitis was confirmed in 12 patients. In all of these patients of the plain studies, FLAIR was positive in only four patients. MRI gadolinium-enhanced FLAIR showed abnormal meningeal enhancement in all 12 patients, while gadolinium-enhanced T1-weighted spin-echo was positive only in six cases. There were no false-positive or false-negative results. It is concluded that MRI could have an important role in the early screening for infectious meningitis, provided a gadolinium-enhanced FLAIR sequence is used. (orig.)

Contrast-enhanced FLAIR in the early diagnosis of infectious meningitis

Energy Technology Data Exchange (ETDEWEB)

Splendiani, Alesssandra; Puglielli, Edoardo; Amicis, Rosanna De; Masciocchi, Carlo; Gallucci, Massimo [University of L' Aquila, Department of Radiology, L' Aquila (Italy); Necozione, Stefano [University of L' Aquila, Department of Statistic, L' Aquila (Italy)

2005-08-01

We investigated the accuracy of MRI in the early diagnosis of infectious meningitis with emphasis on the value of gadolinium-enhanced fluid-attenuated inversion recovery (FLAIR) sequence. Twenty-seven patients with clinical suspicion of infectious meningitis were included. MRI was performed within 3 h of clinical evaluation. For all patients, T1-weighted spin-echo, dual-echo T2-weighted fast-spin-echo and FLAIR sequences were performed, followed by gadolinium-enhanced T1-weighted spin-echo and FLAIR sequences. Final diagnosis was based on the clinical findings and the analysis of cerebrospinal fluid, obtained by lumbar puncture after the MRI. Infectious meningitis was confirmed in 12 patients. In all of these patients of the plain studies, FLAIR was positive in only four patients. MRI gadolinium-enhanced FLAIR showed abnormal meningeal enhancement in all 12 patients, while gadolinium-enhanced T1-weighted spin-echo was positive only in six cases. There were no false-positive or false-negative results. It is concluded that MRI could have an important role in the early screening for infectious meningitis, provided a gadolinium-enhanced FLAIR sequence is used. (orig.)

mTOR Inhibition Attenuates Dextran Sulfate Sodium-Induced Colitis by Suppressing T Cell Proliferation and Balancing TH1/TH17/Treg Profile.

Directory of Open Access Journals (Sweden)

Shurong Hu

Full Text Available It has been established that mammalian target of Rapamycin (mTOR inhibitors have anti-inflammatory effects in models of experimental colitis. However, the underlying mechanism is largely unknown. In this research, we investigate the anti-inflammatory effects of AZD8055, a potent mTOR inhibitor, on T cell response in dextran sulfate sodium (DSS-induced colitis in mice, a commonly used animal model of inflammatory bowel diseases (IBD. Severity of colitis is evaluated by changing of body weight, bloody stool, fecal consistency, histology evaluation and cytokine expression. We find that AZD8055 treatment attenuates DSS-induced body weight loss, colon length shortening and pathological damage of the colon. And AZD8055 treatment decreases colonic expression of genes encoding the pro-inflammatory cytokines interferon-γ, interleukin (IL-17A, IL-1β,IL-6 and tumor necrosis factor(TNF-a and increases colonic expression of anti-inflammatory cytokines IL-10. We show that AZD8055 treatment decreases the percentages of CD4+ T cells and CD8+ T cells in spleen, lymph nodes and peripheral blood of mice. We also find that AZD8055 treatment significantly reduces the number of T helper 1(TH1 cells and TH17 cells and increases regulatory T (Treg cells in the lamina propria and mesenteric lymph nodes. Furthermore, we demonstrates that AZD8055 suppresses the proliferation of CD4+ and CD8+ T cells and the differentiation of TH1/TH17 cells and expands Treg cells in vitro. The results suggest that, in experimental colitis, AZD8055 exerts anti-inflammatory effect by regulating T helper cell polarization and proliferation.

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

Science.gov (United States)

Siewert, C; Hosten, N; Felix, R

1994-07-01

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

Fat suppression at three-dimensional T1-weighted MR imaging of the hands: Dixon method versus CHESS technique.

Science.gov (United States)

Kirchgesner, T; Perlepe, V; Michoux, N; Larbi, A; Vande Berg, B

2018-01-01

To compare the effectiveness of fat suppression and the image quality of the Dixon method with those of the chemical shift-selective (CHESS) technique in hands of normal subjects at non-enhanced three-dimensional (3D) T1-weighted MR imaging. Both hands of 14 healthy volunteers were imaged with 3D fast spoiled gradient echo (FSPGR) T1-weighted Dixon, 3D FSPGR T1-weighted CHESS and 3D T1-weighted fast spin echo (FSE) CHESS sequences in a 1.5T MR scanner. Three radiologists scored the effectiveness of fat suppression in bone marrow (EFS BM ) and soft tissues (EFS ST ) in 20 joints per subject. One radiologist measured the signal-to-noise ratio (SNR) in 10 bones per subject. Statistical analysis used two-way ANOVA with random effects (PCHESS sequence and the 3D FSE T1-weighted CHESS sequence (PCHESS sequence (PCHESS sequence in the axial plane (P=0.0028). Mean SNR was statistically significantly higher for 3D FSPGR T1-weighted Dixon sequence than for 3D FSPGR T1-weighted CHESS and 3D FSE T1-weighted CHESS sequences (PCHESS technique at 3D T1-weighted MR imaging of the hands. Copyright © 2017 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

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.

Incidental pineal cysts in children who undergo 3-T MRI

International Nuclear Information System (INIS)

Whitehead, Matthew T.; Oh, Christopher C.; Choudhri, Asim F.

2013-01-01

Pineal cysts, both simple and complex, are commonly encountered in children. More cysts are being detected with MR technology; however, nearly all pineal cysts are benign and require no follow-up. To discover the prevalence of pineal cysts in children at our institution who have undergone high-resolution 3-T MRI. We retrospectively reviewed 100 consecutive 3-T brain MRIs in children ages 1 month to 17 years (mean 6.8 ± 5.1 years). We evaluated 3-D volumetric T1-W imaging, axial T2-W imaging, axial T2-W FLAIR (fluid attenuated inversion recovery) and coronal STIR (short tau inversion recovery) sequences. Pineal parenchymal and cyst volumes were measured in three planes. Cysts were analyzed for the presence and degree of complexity. Pineal cysts were present in 57% of children, with a mean maximum linear dimension of 4.2 mm (range 1.5-16 mm). Of these cysts, 24.6% showed thin septations or fluid levels reflecting complexity. None of the cysts demonstrated complete T2/FLAIR signal suppression. No cyst wall thickening or nodularity was present. There was no significant difference between the ages of children with and without cysts. Cysts were more commonly encountered in girls than boys (67% vs. 52%; P = 0.043). There was a slight trend toward increasing pineal gland volume with age. Pineal cysts are often present in children and can be incidentally detected by 3-T MRI. Characteristic-appearing pineal cysts in children are benign, incidental findings, for which follow-up is not required if there are no referable symptoms or excessive size. (orig.)

Comparison of 3- and 20-Gradient Direction Diffusion-Weighted Imaging in a Clinical Subacute Cohort of Patients with Transient Ischemic Attack

DEFF Research Database (Denmark)

Havsteen, Inger; Ovesen, Christian; Willer, Lasse

2017-01-01

Objective: Diffusion tensor imaging may aid brain ischemia assessment but is more time consuming than conventional diffusion-weighted imaging (DWI). We compared 3-gradient direction DWI (3DWI) and 20-gradient direction DWI (20DWI) standard vendor protocols in a hospital-based prospective cohort...... of patients with transient ischemic attack (TIA) for lesion detection, lesion brightness, predictability of persisting infarction, and final infarct size. Methods: We performed 3T-magnetic resonance imaging including diffusion and T2-fluid attenuated inversion recovery (FLAIR) within 72 h and 8 weeks after...... uniquely 20DWI positive. 3DWI was visually brightest for 34 lesions. 12 lesions were brightest on 20DWI. The median 3DWI lesion area was larger for lesions equally bright, or brightest on 20DWI [median (IQR) 39 (18-95) versus 18 (10-34) mm2, P = 0.007]. 3DWI showed highest measured relative lesion signal...

Randomized Double-Blind Placebo-Controlled Trial of Bevacizumab Therapy for Radiation Necrosis of the Central Nervous System

International Nuclear Information System (INIS)

Levin, Victor A.; Bidaut, Luc; Hou, Ping; Kumar, Ashok J.; Wefel, Jeffrey S.; Bekele, B. Nebiyou; Prabhu, Sujit; Loghin, Monica; Gilbert, Mark R.; Jackson, Edward F.

2011-01-01

Purpose: To conduct a controlled trial of bevacizumab for the treatment of symptomatic radiation necrosis of the brain. Methods and Materials: A total of 14 patients were entered into a placebo-controlled randomized double-blind study of bevacizumab for the treatment of central nervous system radiation necrosis. All patients were required to have radiographic or biopsy proof of central nervous system radiation necrosis and progressive neurologic symptoms or signs. Eligible patients had undergone irradiation for head-and-neck carcinoma, meningioma, or low- to mid-grade glioma. Patients were randomized to receive intravenous saline or bevacizumab at 3-week intervals. The magnetic resonance imaging findings 3 weeks after the second treatment and clinical signs and symptoms defined the response or progression. Results: The volumes of necrosis estimated on T 2 -weighted fluid-attenuated inversion recovery and T 1 -weighted gadolinium-enhanced magnetic resonance imaging scans demonstrated that although no patient receiving placebo responded (0 of 7), all bevacizumab-treated patients did so (5 of 5 randomized and 7 of 7 crossover) with decreases in T 2 -weighted fluid-attenuated inversion recovery and T 1 -weighted gadolinium-enhanced volumes and a decrease in endothelial transfer constant. All bevacizumab-treated patients-and none of the placebo-treated patients-showed improvement in neurologic symptoms or signs. At a median of 10 months after the last dose of bevacizumab in patients receiving all four study doses, only 2 patients had experienced a recurrence of magnetic resonance imaging changes consistent with progressive radiation necrosis; one patient received a single additional dose of bevacizumab and the other patient received two doses. Conclusion: The Class I evidence of bevacizumab efficacy from the present study in the treatment of central nervous system radiation necrosis justifies consideration of this treatment option for people with radiation necrosis

Using X-ray transmission/attenuation to quantify fluid absorption in cracked concrete

DEFF Research Database (Denmark)

Weiss, Jason; Geiker, Mette R.; Hansen, Kurt Kielsgaard

2015-01-01

Cracks can alter the rate of fluid transport in concrete. Unfortunately, however, quantitative information is lacking to provide definitive statements regarding the extent to which cracks reduce durability or long-term performance. This paper describes a study that used X-ray transmission......-ray attenuation measurements were taken using a grid of points around the crack. By repeating this measurement and comparing the change in X-ray transmission/attenuation, the ingress of the fluid could be determined by locating the position of the moisture front. An approach is presented to determine the geometry...

Improved differentiation between MS and vascular brain lesions using FLAIR* at 7 Tesla

Energy Technology Data Exchange (ETDEWEB)

Kilsdonk, Iris D.; Wattjes, Mike P.; Lopez-Soriano, Alexandra; Jong, Marcus C. de; Graaf, Wolter L. de; Conijn, Mandy M.A.; Barkhof, Frederik [VU University Medical Center, Department of Radiology, De Boelelaan 1118, HZ, Amsterdam (Netherlands); Kuijer, Joost P.A. [VU University Medical Center, Department of Physics and Medical Technology, Amsterdam (Netherlands); Polman, Chris H. [VU University Medical Center, Department of Neurology, Amsterdam (Netherlands); Luijten, Peter R. [University Medical Center, Department of Radiology, Utrecht (Netherlands); Geurts, Jeroen J.G. [VU University, Department of Anatomy and Neurosciences, Amsterdam (Netherlands); Geerlings, Mirjam I. [University Medical Center, Julius Center for Health Sciences and Primary Care, Utrecht (Netherlands)

2014-04-15

To investigate whether a new magnetic resonance image (MRI) technique called T2*-weighted fluid attenuation inversion recovery (FLAIR*) can differentiate between multiple sclerosis (MS) and vascular brain lesions, at 7 Tesla (T). We examined 16 MS patients and 16 age-matched patients with (risk factors for) vascular disease. 3D-FLAIR and T2*-weighted images were combined into FLAIR* images. Lesion type and intensity, perivascular orientation and presence of a hypointense rim were analysed. In total, 433 cerebral lesions were detected in MS patients versus 86 lesions in vascular patients. Lesions in MS patients were significantly more often orientated in a perivascular manner: 74 % vs. 47 % (P < 0.001). Ten MS lesions (2.3 %) were surrounded by a hypointense rim on FLAIR*, and 24 MS lesions (5.5 %) were hypointense on T2*. No lesions in vascular patients showed any rim or hypointensity. Specificity of differentiating MS from vascular lesions on 7-T FLAIR* increased when the presence of a central vessel was taken into account (from 63 % to 88 %), most obviously for deep white matter lesions (from 69 % to 94 %). High sensitivity remained (81 %). 7-T FLAIR* improves differentiation between MS and vascular lesions based on lesion location, perivascular orientation and presence of hypointense (rims around) lesions. circle A new MRI technique T2*-weighted fluid attenuation inversion recovery (FLAIR*) was investigated. circle FLAIR* at 7-T MRI combines FLAIR and T2* images into a single image. circle FLAIR* at 7 T does not require enhancement with contrast agents. (orig.)

Novel diffusion-weighted magnetic resonance imaging findings in leptomeningeal carcinomatosis: a case report

Energy Technology Data Exchange (ETDEWEB)

Hu, Y.F.; Chang, F.C.; Hu, H.H.; Hsu, L.C. [Taipei Veterans General Hospital, Taiwan (China). Depts. of Internal Medicine and Radiology, and Neurological Inst.

2006-12-15

This report presents a rare case of leptomeningeal carcinomatosis initially presenting with mental impairment and rapidly progressing to coma without any history of malignancy. In addition to highlighting the diagnostic difficulties, the linear high signal intensity along the cortex on the diffusion-weighted imaging (DWI) sequence of magnetic resonance (MR) imaging was identified accidentally. High signal change in the corresponding areas was also noted on unenhanced fluid-attenuated inversion recovery (FLAIR) MR imaging, which may be a novel method of diagnosing leptomeningeal carcinomatosis, which should be studied further.

Cognitive Function and 3-Tesla Magnetic Resonance Imaging Tractography of White Matter Hyperintensities in Elderly Persons

OpenAIRE

Reginold, William; Luedke, Angela C.; Tam, Angela; Itorralba, Justine; Fernandez-Ruiz, Juan; Reginold, Jennifer; Islam, Omar; Garcia, Angeles

2015-01-01

Background/Aims: This study used 3-Tesla magnetic resonance imaging (MRI) tractography to determine if there was an association between tracts crossing white matter hyperintensities (WMH) and cognitive function in elderly persons. Methods: Brain T2-weighted fluid-attenuated inversion recovery (FLAIR) and diffusion tensor MRI scans were acquired in participants above the age of 60 years. Twenty-six persons had WMH identified on T2 FLAIR scans. They completed a battery of neuropsychological tes...

Attenuation tomography in the western central Andes: A detailed insight into the structure of a magmatic arc

Science.gov (United States)

Haberland, Christian; Rietbrock, Andreas

2001-06-01

High-quality data from 1498 local earthquakes recorded by the PISCO '94 (Proyecto de Investigatión Sismológica de la Cordillera Occidental, 1994) and ANCORP '96 (Andean Continental Research Project, 1996) temporary seismological networks allowed the detailed determination of the three-dimensional (3-D) attenuation structure (Qp-1) beneath the recent magmatic arc in the western central Andes (20° to 24°S). Assuming a frequency-independent Qp-1 in a frequency band between 1 and 30 Hz, whole path attenuation (t*) was estimated from the amplitude spectra of the P waves using spectral ratios and a spectral inversion technique. The damped least squares inversion (tomography) of the data reveals a complex attenuation structure. Crust and mantle of the forearc and subducting slab are generally characterized by low attenuation (Qp > 1000). Crust and mantle beneath the magmatic arc show elevated attenuation. The strongest anomaly of extremely low Qp is found in the crust between 22° and 23°S beneath the recent volcanic arc (Qp < 100). N-S variations can be observed: The western flank of the crustal attenuation anomaly follows the curved course of the volcanic front. North of 21°S the attenuation is less developed. In the northern part of the study area the low-Qp zone penetrates in the forearc mantle down to the subducting slab. In the south a deeper zone of high attenuation is resolved between 23° and 24°S directly above the subducting slab. Low Qp in the mantle correlates with earthquake clusters. The strong crustal attenuation is confined to the distribution of young ignimbrites and silicic volcanism and is interpreted as a thermally weakened zone with partial melts. The attenuation pattern in the upper mantle might reflect the variable extent of the asthenosphere and maps variations of subduction-related hydration processes in the mantle wedge from slab-derived fluids.

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.

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

International Nuclear Information System (INIS)

Seitz, J.; Held, P.; Strotzer, M.; Voelk, M.; Nitz, W.R.; Dorenbeck, U.; Feuerbach, S.; Stamato, S.

2002-01-01

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

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

International Nuclear Information System (INIS)

Ganzetti, Marco; Mantini, Dante; Wenderoth, Nicole

2015-01-01

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.)

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.)

Detailed T1-Weighted Profiles from the Human Cortex Measured in Vivo at 3 Tesla MRI.

Science.gov (United States)

Ferguson, Bart; Petridou, Natalia; Fracasso, Alessio; van den Heuvel, Martijn P; Brouwer, Rachel M; Hulshoff Pol, Hilleke E; Kahn, René S; Mandl, René C W

2018-04-01

Studies into cortical thickness in psychiatric diseases based on T1-weighted MRI frequently report on aberrations in the cerebral cortex. Due to limitations in image resolution for studies conducted at conventional MRI field strengths (e.g. 3 Tesla (T)) this information cannot be used to establish which of the cortical layers may be implicated. Here we propose a new analysis method that computes one high-resolution average cortical profile per brain region extracting myeloarchitectural information from T1-weighted MRI scans that are routinely acquired at a conventional field strength. To assess this new method, we acquired standard T1-weighted scans at 3 T and compared them with state-of-the-art ultra-high resolution T1-weighted scans optimised for intracortical myelin contrast acquired at 7 T. Average cortical profiles were computed for seven different brain regions. Besides a qualitative comparison between the 3 T scans, 7 T scans, and results from literature, we tested if the results from dynamic time warping-based clustering are similar for the cortical profiles computed from 7 T and 3 T data. In addition, we quantitatively compared cortical profiles computed for V1, V2 and V7 for both 7 T and 3 T data using a priori information on their relative myelin concentration. Although qualitative comparisons show that at an individual level average profiles computed for 7 T have more pronounced features than 3 T profiles the results from the quantitative analyses suggest that average cortical profiles computed from T1-weighted scans acquired at 3 T indeed contain myeloarchitectural information similar to profiles computed from the scans acquired at 7 T. The proposed method therefore provides a step forward to study cortical myeloarchitecture in vivo at conventional magnetic field strength both in health and disease.

Myocardial T1 mapping at 3.0 tesla using an inversion recovery spoiled gradient echo readout and bloch equation simulation with slice profile correction (BLESSPC) T1 estimation algorithm.

Science.gov (United States)

Shao, Jiaxin; Rapacchi, Stanislas; Nguyen, Kim-Lien; Hu, Peng

2016-02-01

To develop an accurate and precise myocardial T1 mapping technique using an inversion recovery spoiled gradient echo readout at 3.0 Tesla (T). The modified Look-Locker inversion-recovery (MOLLI) sequence was modified to use fast low angle shot (FLASH) readout, incorporating a BLESSPC (Bloch Equation Simulation with Slice Profile Correction) T1 estimation algorithm, for accurate myocardial T1 mapping. The FLASH-MOLLI with BLESSPC fitting was compared with different approaches and sequences with regards to T1 estimation accuracy, precision and image artifact based on simulation, phantom studies, and in vivo studies of 10 healthy volunteers and three patients at 3.0 Tesla. The FLASH-MOLLI with BLESSPC fitting yields accurate T1 estimation (average error = -5.4 ± 15.1 ms, percentage error = -0.5% ± 1.2%) for T1 from 236-1852 ms and heart rate from 40-100 bpm in phantom studies. The FLASH-MOLLI sequence prevented off-resonance artifacts in all 10 healthy volunteers at 3.0T. In vivo, there was no significant difference between FLASH-MOLLI-derived myocardial T1 values and "ShMOLLI+IE" derived values (1458.9 ± 20.9 ms versus 1464.1 ± 6.8 ms, P = 0.50); However, the average precision by FLASH-MOLLI was significantly better than that generated by "ShMOLLI+IE" (1.84 ± 0.36% variance versus 3.57 ± 0.94%, P < 0.001). The FLASH-MOLLI with BLESSPC fitting yields accurate and precise T1 estimation, and eliminates banding artifacts associated with bSSFP at 3.0T. © 2015 Wiley Periodicals, Inc.

Bilateral hyperintense basal ganglia on T1-weighted image

International Nuclear Information System (INIS)

Baik, Seung Kug; Ahn, Woo Hyun; Choi, Han Yong; Kim, Bong Gi

1994-01-01

Bilateral high signal intensity in basal ganglia on T1-weighted images is unusual, the purpose of this study is to describe the pattern of high signal intensity and underlying disease. During the last three years, 8 patients showed bilateral high signal intensity in basal ganglia on T1-weighted image, as compared with cerebral white matter. Authors analyzed the images and underlying causes retrospectively. Of 8 patients, 5 were male and 3 were female. The age ranged from 15 days to 79 years. All patient were examined by a 0.5T superconductive MRI. Images were obtained by spin echo multislice technique. Underlying causes were 4 cases of hepatopathy, 2 cases of calcium metabolism disorder, and one case each of neurofibromatosis and hypoxic brain injury. These process were bilateral in all cases and usually symmetric. In all cases the hyperintense areas were generally homogenous without mass effect or edema, although somewhat nodular appearance was seen in neurofibromatosis. Lesions were located in the globus pallidus and internal capsule in hepatopathy and neurofibromatosis, head of the caudate nucleus in disorder of calcum metabolism, and the globus pallidus in hypoxic brain injury. Although this study is limited by its patient population, bilateral hyperintense basal ganglia is associated with various disease entities. On analysis of hyperintense basal ganglia lesion, the knowledge of clinical information improved diagnostic accuracy

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

International Nuclear Information System (INIS)

Mahon, R; Weiss, E; Karki, K; Hugo, G; Ford, J

2016-01-01

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

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

Chemical shift-selective snapshot FLASH MR imaging in combination with inversion-recovery T1 contrast at different field strengths

International Nuclear Information System (INIS)

Matthaei, D.; Haase, A.; Henrich, D.; Duhmke, E.

1991-01-01

With fast MR imaging, chemical shift contract becomes available to the clinician in seconds. The purpose of this paper is to evaluate the combination of chemical shift selective (CHESS) MR imaging using the snapshot FLASH MR method with the inversion-recovery technique and to obtain information concerning the signal-to-noise and chemical shift with the presaturation method at different field strengths. Investigations with volunteers and experimental animals were done at 2 and 3 T (whole body) and in a 4.7-T animal image. For the inversion-recovery experiments, saturation was done before every snapshot FLASH image. With increasing field strength due to signal-to-noise and chemical shift advantages, the method performs better. Increasing T1 values are also important at high field strengths. The combined technique is useful only for T1 water images with fat saturation. It also allows fast quantification of T1 in water-containing organs and pathologic processes. At high field strengths, fast CHESS and T1 imaging promise fast quantitative information. This is a possible argument for clinical high-field-strength MR imagining along with MR spectroscopy

Dynamic contrast-enhanced quantitative perfusion measurement of the brain using T-1-weighted MRI at 3T

DEFF Research Database (Denmark)

Larsson, H.B.W.; Hansen, A.E.; Berg, H.K.

2008-01-01

Purpose: To develop a method for the measurement of brain perfusion based on dynamic contrast-enhanced T-1-weighted MR imaging. Materials and Methods: Dynamic imaging of the first pass of a bolus of a paramagnetic contrast agent was performed using a 3T whole-body magnet and a T-1-weighted fast...... field echo sequence. The input function was obtained from the internal carotid artery. An initial T-1 measurement was performed in order to convert the MR signal to concentration of the contrast agent. Pixelwise and region of interest (ROI)based calculation of cerebral perfusion (CBF) was performed...... inside the infarct core was, 9 mL/100g/min in one of the stroke patients. The other stroke patient had postischemic hyperperfusion and CBF was 140 mL/100g/min. Conclusion: Absolute values of brain perfusion can be obtained using dynamic contrast-enhanced MRI. These values correspond,to expected values...

In vivo (1)H magnetic resonance spectroscopy of amniotic fluid and fetal lung at 1.5 T: technical challenges.

Science.gov (United States)

Kim, Dong-Hyun; Vahidi, Kiarash; Caughey, Aaron B; Coakley, Fergus V; Vigneron, Daniel B; Kurhanewicz, John; Mow, Ben; Joe, Bonnie N

2008-10-01

To identify the major technical challenges associated with in utero single-voxel proton spectroscopy of amniotic fluid and fetal lung and to evaluate the feasibility of performing in utero fetal spectroscopy for fetal lung maturity testing. Fetal magnetic resonance (MR) spectroscopy of amniotic fluid and fetal lung were performed at 1.5 T in 8 near-term pregnant women. Presence/absence of lactate and choline peaks was tabulated. Ex vivo spectra were obtained from amniotic fluid samples to investigate and refine sequence parameters. Spectroscopy failed in 3 of 8 cases due to maternal discomfort (n = 1) or fetal gastroschisis (n = 2). Both fetal motion and low signal-to-noise ratio were limiting factors for the remaining 5 clinical in vivo studies at 1.5 T. Ex vivo and in vivo studies suggested feasibility for detecting lactate from amniotic fluid within a reasonable clinical scan time (4-5 minutes). Lactate was detected in 3 of 5 patients. Choline detection was limited and was detected in 1 patient. Minor motion effects can be overcome but continuous fetal motion is problematic. Lactate detection seems clinically feasible, but choline detection requires additional technical development and, potentially, further imaging at a higher field strength because of the low signal-to-noise ratio at 1.5 T. (c) 2008 Wiley-Liss, Inc.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Physical Properties of Low-Molecular Weight Polydimethylsiloxane Fluids

Energy Technology Data Exchange (ETDEWEB)

Roberts, Christine Cardinal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Graham, Alan [Univ. of Colorado, Denver, CO (United States); Nemer, Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Phinney, Leslie M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Garcia, Robert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stirrup, Emily Kate [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-02-01

Physical property measurements including viscosity, density, thermal conductivity, and heat capacity of low-molecular weight polydimethylsiloxane (PDMS) fluids were measured over a wide temperature range (-50°C to 150°C when possible). Properties of blends of 1 cSt and 20 cSt PDMS fluids were also investigated. Uncertainties in the measurements are cited. These measurements will provide greater fidelity predictions of environmental sensing device behavior in hot and cold environments.

The interplay of T1- and T2-relaxation on T1-weighted MRI of hMSCs induced by Gd-DOTA-peptides.

Science.gov (United States)

Cao, Limin; Li, Binbin; Yi, Peiwei; Zhang, Hailu; Dai, Jianwu; Tan, Bo; Deng, Zongwu

2014-04-01

Three Gd-DOTA-peptide complexes with different peptide sequence are synthesized and used as T1 contrast agent to label human mesenchymal stem cells (hMSCs) for magnetic resonance imaging study. The peptides include a universal cell penetrating peptide TAT, a linear MSC-specific peptide EM7, and a cyclic MSC-specific peptide CC9. A significant difference in labeling efficacy is observed between the Gd-DOTA-peptides as well as a control Dotarem. All Gd-DOTA-peptides as well as Dotarem induce significant increase in T1 relaxation rate which is in favor of T1-weighted MR imaging. Gd-DOTA-CC9 yields the maximum labeling efficacy but poor T1 contrast enhancement. Gd-DOTA-EM7 yields the minimum labeling efficacy but better T1 contrast enhancement. Gd-DOTA-TAT yields a similar labeling efficacy as Gd-DOTA-CC9 and similar T1 contrast enhancement as Gd-DOTA-EM7. The underlying mechanism that governs T1 contrast enhancement effect is discussed. Our results suggest that T1 contrast enhancement induced by Gd-DOTA-peptides depends not only on the introduced cellular Gd content, but more importantly on the effect that Gd-DOTA-peptides exert on the T1-relaxation and T2-relaxation processes/rates. Both T1 and particularly T2 relaxation rate have to be taken into account to interpret T1 contrast enhancement. In addition, the interpretation has to be based on cellular instead of aqueous longitudinal and transverse relaxivities of Gd-DOTA-peptides. Copyright © 2014 Elsevier Ltd. All rights reserved.

T1ρ-weighted Dynamic Glucose-enhanced MR Imaging in the Human Brain.

Science.gov (United States)

Paech, Daniel; Schuenke, Patrick; Koehler, Christina; Windschuh, Johannes; Mundiyanapurath, Sibu; Bickelhaupt, Sebastian; Bonekamp, David; Bäumer, Philipp; Bachert, Peter; Ladd, Mark E; Bendszus, Martin; Wick, Wolfgang; Unterberg, Andreas; Schlemmer, Heinz-Peter; Zaiss, Moritz; Radbruch, Alexander

2017-12-01

Purpose To evaluate the ability to detect intracerebral regions of increased glucose concentration at T1ρ-weighted dynamic glucose-enhanced (DGE) magnetic resonance (MR) imaging at 7.0 T. Materials and Methods This prospective study was approved by the institutional review board. Nine patients with newly diagnosed glioblastoma and four healthy volunteers were included in this study from October 2015 to July 2016. Adiabatically prepared chemical exchange-sensitive spin-lock imaging was performed with a 7.0-T whole-body unit with a temporal resolution of approximately 7 seconds, yielding the time-resolved DGE contrast. T1ρ-weighted DGE MR imaging was performed with injection of 100 mL of 20% d-glucose via the cubital vein. Glucose enhancement, given by the relative signal intensity change at T1ρ-weighted MR imaging (DGEρ), was quantitatively investigated in brain gray matter versus white matter of healthy volunteers and in tumor tissue versus normal-appearing white matter of patients with glioblastoma. The median signal intensities of the assessed brain regions were compared by using the Wilcoxon rank-sum test. Results In healthy volunteers, the median signal intensity in basal ganglia gray matter (DGEρ = 4.59%) was significantly increased compared with that in white matter tissue (DGEρ = 0.65%) (P = .028). In patients, the median signal intensity in the glucose-enhanced tumor region as displayed on T1ρ-weighted DGE images (DGEρ = 2.02%) was significantly higher than that in contralateral normal-appearing white matter (DGEρ = 0.08%) (P brain glucose physiology and pathophysiologically increased glucose uptake and may have the potential to provide information about glucose metabolism in tumor tissue. © RSNA, 2017 Online supplemental material is available for this article.

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

International Nuclear Information System (INIS)

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

1993-01-01

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

Clinical Study White Matter Atrophy in Patients with Mesial Temporal Lobe Epilepsy: Voxel-Based Morphometry Analysis of T1- and T2-Weighted MR Images

International Nuclear Information System (INIS)

Braga, B.; Yasuda, C.L.; Cendes, F.

2012-01-01

Introduction. Mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis is highly refractory to clinical treatment. MRI voxel-based morphometry (VBM) of T1-weighted images has revealed a widespread pattern of gray matter (GM) and white matter (WM) atrophy in MTLE. Few studies have investigated the role of T2-weighted images in revealing WM atrophy using VBM. Objectives. To compare the results of WM atrophy between T1- and T2-weighted images through VBM. Methods. We selected 28 patients with left and 27 with right MTLE and 60 normal controls. We analyzed T1- and T2- weighted images with SPM8, using VBM/DARTEL algorithm to extract maps of GM and WM. The second level of SPM was used to investigate areas of WM atrophy among groups. Results. Both acquisitions showed bilateral widespread WM atrophy. T1-weighted images showed higher sensibility to detect areas of WM atrophy in both groups of MTLE. T2-weighted images also showed areas of WM atrophy in a more restricted pattern, but still bilateral and with a large area of superposition with T1-weighted images. Conclusions. In MTLE, T1-weighted images are more sensitive to detect subtle WM abnormalities using VBM, compared to T2 images, although both present a good superposition of statistical maps. 1. Introduction The mesial temporal lobe epilepsy (MTLE) is highly refractory to pharmacological treatment [1], and it is the main group of epilepsy referred to the tertiary care hospitals for surgical treatment [2]. MTLE shows a good surgical prognosis, with satisfactory seizures control in 60-80% of the patients [3]. In approximately 65%

Contrast-enhanced Magnetic Resonance Imaging of Pelvic Bone Metastases at 3.0 T: Comparison Between 3-dimensional T1-weighted CAIPIRINHA-VIBE Sequence and 2-dimensional T1-weighted Turbo Spin-Echo Sequence.

Science.gov (United States)

Yoon, Min A; Hong, Suk-Joo; Lee, Kyu-Chong; Lee, Chang Hee

2018-06-12

This study aimed to compare 3-dimensional T1-weighted gradient-echo sequence (CAIPIRINHA-volumetric interpolated breath-hold examination [VIBE]) with 2-dimensional T1-weighted turbo spin-echo sequence for contrast-enhanced magnetic resonance imaging (MRI) of pelvic bone metastases at 3.0 T. Thirty-one contrast-enhanced MRIs of pelvic bone metastases were included. Two contrast-enhanced sequences were evaluated for the following parameters: overall image quality, sharpness of pelvic bone, iliac vessel clarity, artifact severity, and conspicuity and edge sharpness of the smallest metastases. Quantitative analysis was performed by calculating signal-to-noise ratio and contrast-to-noise ratio of the smallest metastases. Significant differences between the 2 sequences were assessed. CAIPIRINHA-VIBE had higher scores for overall image quality, pelvic bone sharpness, iliac vessel clarity, and edge sharpness of the metastatic lesions, and had less artifacts (all P 0.05). Our results suggest that CAIPIRINHA-VIBE may be superior to turbo spin-echo for contrast-enhanced MRI of pelvic bone metastases at 3.0 T.

Comparison of diffusion-weighted images using short inversion time inversion recovery or chemical shift selective pulse as fat suppression in patients with breast cancer

International Nuclear Information System (INIS)

Kazama, Toshiki; Nasu, Katsuhiro; Kuroki, Yoshifumi; Nawano, Shigeru; Ito, Hisao

2009-01-01

Fat suppression is essential for diffusion-weighted imaging (DWI) in the body. However, the chemical shift selective (CHESS) pulse often fails to suppress fat signals in the breast. The purpose of this study was to compare DWI using CHESS and DWI using short inversion time inversion recovery (STIR) in terms of fat suppression and the apparent diffusion coefficient (ADC) value. DWI using STIR, DWI using CHESS, and contrast-enhanced T1-weighted images were obtained in 32 patients with breast carcinoma. Uniformity of fat suppression, ADC, signal intensity, and visualization of the breast tumors were evaluated. In 44% (14/32) of patients there was insufficient fat suppression in the breasts on DWI using CHESS, whereas 0% was observed on DWI using STIR (P<0.0001). The ADCs obtained for DWI using STIR were 4.3% lower than those obtained for DWI using CHESS (P<0.02); there was a strong correlation of the ADC measurement (r=0.93, P<0.001). DWI using STIR may be excellent for fat suppression; and the ADC obtained in this sequence was well correlated with that obtained with DWI using CHESS. DWI using STIR may be useful when the fat suppression technique in DWI using CHESS does not work well. (author)

Preemptive hemodynamic intervention restricting the administration of fluids attenuates lung edema progression in oleic acid-induced lung injury.

Science.gov (United States)

Gil Cano, A; Gracia Romero, M; Monge García, M I; Guijo González, P; Ruiz Campos, J

2017-04-01

A study is made of the influence of preemptive hemodynamic intervention restricting fluid administration upon the development of oleic acid-induced lung injury. A randomized in vivo study in rabbits was carried out. University research laboratory. Sixteen anesthetized, mechanically ventilated rabbits. Hemodynamic measurements obtained by transesophageal Doppler signal. Respiratory mechanics computed by a least square fitting method. Lung edema assessed by the ratio of wet weight to dry weight of the right lung. Histological examination of the left lung. Animals were randomly assigned to either the early protective lung strategy (EPLS) (n=8) or the early protective hemodynamic strategy (EPHS) (n=8). In both groups, lung injury was induced by the intravenous infusion of oleic acid (OA) (0.133mlkg -1 h -1 for 2h). At the same time, the EPLS group received 15mlkg -1 h -1 of Ringer lactate solution, while the EPHS group received 30mlkg -1 h -1 . Measurements were obtained at baseline and 1 and 2h after starting OA infusion. After 2h, the cardiac index decreased in the EPLS group (p<0.05), whereas in the EPHS group it remained unchanged. Lung compliance decreased significantly only in the EPHS group (p<0.05). Lung edema was greater in the EPHS group (p<0.05). Histological damage proved similar in both groups (p=0.4). In this experimental model of early lung injury, lung edema progression was attenuated by preemptively restricting the administration of fluids. Copyright © 2016 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Application of weighted early-arrival waveform inversion to shallow land data

KAUST Repository

Yu, Han; Zhang, Dongliang; Wang, Xin

2014-01-01

predictions and shows that the effects of noise and unpredicted amplitude variations in the inversion are reduced using this weighted early arrival waveform inversion (WEWI). We also apply this method to a 2D land data set for estimating the near

Inverse associations between obesity indicators and thymic T-cell production levels in aging atomic-bomb survivors.

Directory of Open Access Journals (Sweden)

Kengo Yoshida

Full Text Available Reduction of the naive T-cell population represents a deteriorating state in the immune system that occurs with advancing age. In animal model studies, obesity compromises the T-cell immune system as a result of enhanced adipogenesis in primary lymphoid organs and systemic inflammation. In this study, to test the hypothesis that obesity may contribute to the aging of human T-cell immunity, a thousand atomic-bomb survivors were examined for obesity status and ability to produce naive T cells, i.e., T-cell receptor excision circle (TREC numbers in CD4 and CD8 T cells. The number of TRECs showed a strong positive correlation with naive T cell numbers, and lower TREC numbers were associated with higher age. We found that the TREC number was inversely associated with levels of obesity indicators (BMI, hemoglobin A1c and serum CRP levels. Development of type-2 diabetes and fatty liver was also associated with lower TREC numbers. This population study suggests that obesity with enhanced inflammation is involved in aging of the human T-cell immune system. Given the fact that obesity increases the risk of numerous age-related diseases, attenuated immune competence is a possible mechanistic link between obesity and disease development among the elderly.

Inverse associations between obesity indicators and thymic T-cell production levels in aging atomic-bomb survivors.

Science.gov (United States)

Yoshida, Kengo; Nakashima, Eiji; Kubo, Yoshiko; Yamaoka, Mika; Kajimura, Junko; Kyoizumi, Seishi; Hayashi, Tomonori; Ohishi, Waka; Kusunoki, Yoichiro

2014-01-01

Reduction of the naive T-cell population represents a deteriorating state in the immune system that occurs with advancing age. In animal model studies, obesity compromises the T-cell immune system as a result of enhanced adipogenesis in primary lymphoid organs and systemic inflammation. In this study, to test the hypothesis that obesity may contribute to the aging of human T-cell immunity, a thousand atomic-bomb survivors were examined for obesity status and ability to produce naive T cells, i.e., T-cell receptor excision circle (TREC) numbers in CD4 and CD8 T cells. The number of TRECs showed a strong positive correlation with naive T cell numbers, and lower TREC numbers were associated with higher age. We found that the TREC number was inversely associated with levels of obesity indicators (BMI, hemoglobin A1c) and serum CRP levels. Development of type-2 diabetes and fatty liver was also associated with lower TREC numbers. This population study suggests that obesity with enhanced inflammation is involved in aging of the human T-cell immune system. Given the fact that obesity increases the risk of numerous age-related diseases, attenuated immune competence is a possible mechanistic link between obesity and disease development among the elderly.

Off-shell T-matrices from inverse scattering

International Nuclear Information System (INIS)

Von Geramb, H.V.; Amos, K.A.

1989-01-01

Inverse scattering theory is used to determine local, energy independent, coordinate space nucleon-nucleon potentials. Inversions are made of phase shifts obtained by analyzes of data and from meson exchange theory, in particular the Paris and the Bonn parametrizations. Half off-shell T-matrices are generated to compare the exact meson theoretical results with those of inversion and it is found that phase equivalent interactions have essentially the same off-shell behaviour for any physically significant range of momenta. 8 refs., 8 figs

Are T2-weighted images necessary in renal mass characterization?

International Nuclear Information System (INIS)

Dann, Phoebe; Thakur, Ravi; Chin, Deanne; Krinsky, Glenn; Israel, Gary M.

2006-01-01

Objective: To determine what role T2-weighted images play in characterizing renal masses. Methods: Forty-four pathologically proven renal masses (34 renal cell carcinomas, 8 oncocytomas, 1 metanephric adenoma, 1 angiomyolipoma without macroscopic fat) and 38 simple renal cysts were evaluated with T1- and T2-weighted images at 1.5 T. Two independent and blinded readers initially characterized all masses using only the T1-weighed images (in- and opposed-phase chemical shift, unenhanced frequency-selective fat-suppressed, gadolinium-enhanced frequency-selective fat-suppressed and subtraction images) and placed each mass into one of three categories: nonsurgical, in need of follow-up, or surgical. The masses were then re-evaluated with the addition of the T2-weighted images. It was determined if the T2-weighted images changed the initial classification. Results: Forty-three of the 44 (98%) pathologically proven renal masses were characterized as a surgical mass using only the T1-weighted images. The remaining renal mass (a renal cell carcinoma) was characterized as a mass in which follow-up exams would be suggested. Thirty-eight of 38 (100%) simple renal cysts were correctly characterized using only the T1-weighted images. The T2-weighted images did not change the initial interpretation of the T1-weighted images in any of the cases. Conclusion: The results of this study suggest that T2-weighted images are not necessary in the evaluation of all renal masses and are specifically not necessary in the differentiation of solid and cystic renal neoplasms from simple renal cysts

3T MR Spin Echo T1 Weighted Image at Optimization of Flip Angle

International Nuclear Information System (INIS)

Lim, Chung Hwang; Bae, Sung Jin

2009-01-01

This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). T1-weighted images of the cerebrum of brain were obtained from 50 degrees to 130 degrees FA with 10 interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp (-TR/T1) and Ernst angle cos = exp ((-TR/T1). The SNR of WM at 130 degrees FA is approximately 1.6 times higher than the SNR of WM at 50 degrees. The SNR of GM at 130 degrees FA is approximately 1.9 times higher than the SNR of GM at 50 degrees. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120 degrees FA, the SNR of GM started decreasing at less than 110 degrees. The highest SNRs of WM and GM were obtained at 130 degrees FA. The highest CNRs, however, were obtained at 80 degrees FA. Although SNR increased with the change of FA values from 50 degrees to 130 degrees at 3T SE T1WI, CNR was higher at 80 degrees FA than at the usually used 90 degrees FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.

Computer-assisted analysis of peripheral zone prostate lesions using T2-weighted and dynamic contrast enhanced T1-weighted MRI

Energy Technology Data Exchange (ETDEWEB)

Vos, Pieter C; Hambrock, Thomas; Barenstz, Jelle O; Huisman, Henkjan J [Department of Radiology, Radboud University Medical Centre, Nijmegen, 6525GA (Netherlands)], E-mail: p.vos@rad.umcn.nl

2010-03-21

In this study, computer-assisted analysis of prostate lesions was researched by combining information from two different magnetic resonance (MR) modalities: T2-weighted (T2-w) and dynamic contrast-enhanced (DCE) T1-w images. Two issues arise when incorporating T2-w images in a computer-aided diagnosis (CADx) system: T2-w values are position as well as sequence dependent and images can be misaligned due to patient movement during the acquisition. A method was developed that computes T2 estimates from a T2-w and proton density value and a known sequence model. A mutual information registration strategy was implemented to correct for patient movement. Global motion is modelled by an affine transformation, while local motion is described by a volume preserving non-rigid deformation based on B-splines. The additional value to the discriminating performance of a DCE T1-w-based CADx system was evaluated using bootstrapped ROC analysis. T2 estimates were successfully computed in 29 patients. T2 values were extracted and added to the CADx system from 39 malignant, 19 benign and 29 normal annotated regions. T2 values alone achieved a diagnostic accuracy of 0.85 (0.77-0.92) and showed a significantly improved discriminating performance of 0.89 (0.81-0.95), when combined with DCE T1-w features. In conclusion, the study demonstrated a simple T2 estimation method that has a diagnostic performance such that it complements a DCE T1-w-based CADx system in discriminating malignant lesions from normal and benign regions. Additionally, the T2 estimate is beneficial to visual inspection due to the removed coil profile and fixed window and level settings.

Musculoskeletal MRI at 3.0 T and 7.0 T: a comparison of relaxation times and image contrast.

Science.gov (United States)

Jordan, Caroline D; Saranathan, Manojkumar; Bangerter, Neal K; Hargreaves, Brian A; Gold, Garry E

2013-05-01

The purpose of this study was to measure and compare the relaxation times of musculoskeletal tissues at 3.0 T and 7.0 T, and to use these measurements to select appropriate parameters for musculoskeletal protocols at 7.0 T. We measured the T₁ and T₂ relaxation times of cartilage, muscle, synovial fluid, bone marrow and subcutaneous fat at both 3.0 T and 7.0 T in the knees of five healthy volunteers. The T₁ relaxation times were measured using a spin-echo inversion recovery sequence with six inversion times. The T₂ relaxation times were measured using a spin-echo sequence with seven echo times. The accuracy of both the T₁ and T₂ measurement techniques was verified in phantoms at both magnetic field strengths. We used the measured relaxation times to help design 7.0 T musculoskeletal protocols that preserve the favorable contrast characteristics of our 3.0 T protocols, while achieving significantly higher resolution at higher SNR efficiency. The T₁ relaxation times in all tissues at 7.0 T were consistently higher than those measured at 3.0 T, while the T₂ relaxation times at 7.0 T were consistently lower than those measured at 3.0 T. The measured relaxation times were used to help develop high resolution 7.0 T protocols that had similar fluid-to-cartilage contrast to that of the standard clinical 3.0 T protocols for the following sequences: proton-density-weighted fast spin-echo (FSE), T₂-weighted FSE, and 3D-FSE-Cube. The T₁ and T₂ changes were within the expected ranges. Parameters for musculoskeletal protocols at 7.0 T can be optimized based on these values, yielding improved resolution in musculoskeletal imaging with similar contrast to that of standard 3.0 T clinical protocols. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Cerebral toxoplasmosis: case review and description of a new imaging sign

International Nuclear Information System (INIS)

Masamed, R.; Meleis, A.; Lee, E.W.; Hathout, G.M.

2009-01-01

Toxoplasmosis can have catastrophic consequences in immunocompromised patients if left untreated. Accurate diagnosis is difficult, as there is substantial overlap between the imaging findings and presenting clinical syndromes of cerebral toxoplasmosis and primary central nervous system lymphoma. This paper reviews the previously described and fairly well-known post-contrast computed tomography (CT) and T1-weighted (W) magnetic resonance imaging (MRI) target signs seen in toxoplasmosis. In addition, it offers a new imaging sign, the T2W/FLAIR (fluid attenuated inversion recovery) target sign, which is often seen in clinical practice but not well-published, as an aid to the diagnosis of cerebral toxoplasmosis.

Cerebral toxoplasmosis: case review and description of a new imaging sign

Energy Technology Data Exchange (ETDEWEB)

Masamed, R. [Department of Radiological Sciences, UCLA Medical Center, Los Angeles, CA (United States)], E-mail: rmasamed@mednet.ucla.edu; Meleis, A. [Princeton University, New Jersey, CA (United States); Lee, E.W. [Department of Radiological Sciences, UCLA Medical Center, Los Angeles, CA (United States); Hathout, G.M. [Department of Radiological Sciences, UCLA Medical Center, Los Angeles, CA (United States); Department of Neuroradiology, Olive View UCLA Medical Center, Los Angeles, CA (United States); Department of Neuroradiology, West L.A. VA Medical Center, Los Angeles, CA (United States)

2009-05-15

Toxoplasmosis can have catastrophic consequences in immunocompromised patients if left untreated. Accurate diagnosis is difficult, as there is substantial overlap between the imaging findings and presenting clinical syndromes of cerebral toxoplasmosis and primary central nervous system lymphoma. This paper reviews the previously described and fairly well-known post-contrast computed tomography (CT) and T1-weighted (W) magnetic resonance imaging (MRI) target signs seen in toxoplasmosis. In addition, it offers a new imaging sign, the T2W/FLAIR (fluid attenuated inversion recovery) target sign, which is often seen in clinical practice but not well-published, as an aid to the diagnosis of cerebral toxoplasmosis.

Serial MR observation of cortical laminar necrosis caused by brain infarction

Energy Technology Data Exchange (ETDEWEB)

Komiyama, M.; Nakajima, H.; Nishikawa, M.; Yasui, T. [Department of Neurosurgery, Osaka City General Hospital (Japan)

1998-12-01

To examine the chronological changes characteristic of cortical laminar necrosis caused by brain infarction, 16 patients were repeatedly examined using T1-, T2-weighted spin-echo, T2{sup *}-weighted gradient echo, fluid attenuated inversion recovery (FLAIR) images, and contrast enhanced T1-weighted images at 1.0 or 1.5 T. High intensity cortical lesions were visible on the T1-weighted images from 2 weeks after ictus and became prominent at 1 to 3 months, then became less apparent, but occasionally remained at high intensity for 2 years. High intensity cortical lesions on FLAIR images became prominent from 1 month, and then became less prominent from 1 year, but occasionally remained at high intensity for 2 years. Subcortical lesions did not display high intensity on T1-weighted images at any stage. On FLAIR images, subcortical lesions initially showed slightly high intensity and then low intensity from 6 months due to encephalomalacia. Cortical lesions showed prominent contrast enhancement from 2 weeks to 3 months, but subcortical lesions were prominent from 2 weeks only up to 1 month. T2*-weighted images disclosed haemosiderin in 3 of 7 patients, but there was no correlation with cortical short T1 lesions. Cortical laminar necrosis showed characteristic chronological signal changes on T1-weighted images and FLAIR images. Cortical short T1 lesions were found not to be caused by haemorrhagic infarction. (orig.) With 5 figs., 1 tab., 9 refs.

In vivo determination of T1 and T2 in the brain of patients with severe but stable multiple sclerosis

DEFF Research Database (Denmark)

Larsson, H B; Frederiksen, J; Kjaer, L

1988-01-01

investigated, using a whole-body superconductive MR scanner, operating at 1.5 T. By employing 12-point (or 6-point) partial saturation inversion recovery (PSIR) and 32-echo multiple spin-echo sequences we measured T1 and T2 in MS plaques, white matter, and cortical gray matter. We also focused on the issue......, whether T1 and T2 relaxation processes in fact were monoexponential. T1 and T2 in plaques were found to cover a wide range, which could be explained only by inherent biophysical dissimilarity of the plaques, possibly due to differences in disease activity, edema and gliosis. T1 appeared monoexponential...... in all the plaques, but in seven cases T2 showed biexponential behavior. This was found to be most pronounced near the cerebrospinal fluid of the ventricles, probably caused by partial volume effects or increased free water content. The T2 of apparently normal white matter was significantly longer in MS...

Automatic, accurate, and reproducible segmentation of the brain and cerebro-spinal fluid in T1-weighted volume MRI scans and its application to serial cerebral and intracranial volumetry

Science.gov (United States)

Lemieux, Louis

2001-07-01

A new fully automatic algorithm for the segmentation of the brain and cerebro-spinal fluid (CSF) from T1-weighted volume MRI scans of the head was specifically developed in the context of serial intra-cranial volumetry. The method is an extension of a previously published brain extraction algorithm. The brain mask is used as a basis for CSF segmentation based on morphological operations, automatic histogram analysis and thresholding. Brain segmentation is then obtained by iterative tracking of the brain-CSF interface. Grey matter (GM), white matter (WM) and CSF volumes are calculated based on a model of intensity probability distribution that includes partial volume effects. Accuracy was assessed using a digital phantom scan. Reproducibility was assessed by segmenting pairs of scans from 20 normal subjects scanned 8 months apart and 11 patients with epilepsy scanned 3.5 years apart. Segmentation accuracy as measured by overlap was 98% for the brain and 96% for the intra-cranial tissues. The volume errors were: total brain (TBV): -1.0%, intra-cranial (ICV):0.1%, CSF: +4.8%. For repeated scans, matching resulted in improved reproducibility. In the controls, the coefficient of reliability (CR) was 1.5% for the TVB and 1.0% for the ICV. In the patients, the Cr for the ICV was 1.2%.

Marchiafava-Bignami disease with hyperintensity on late diffusion-weighted imaging

International Nuclear Information System (INIS)

Iwai, Takayasu; Matsuo, Koushun; Morii-Kitani, Fukiko; Azuma, Fumiko; Matsuo, Hisayasu; Takada, Masahiko; Nakagawa, Masanori; Mizuno, Toshiki; Yamada, Kei

2014-01-01

A 69-year-old man with a decades-long history of chronic alcohol consumption was admitted with gait disturbance (short steps and spasticity), deterioration of activity, and stuporous consciousness. Head magnetic resonance imaging (MRI) revealed hyperintensity on fluid-attenuated inversion recovery imaging in the corpus callosum and frontal white matter. The lesion later became more apparent on diffusion-weighted imaging. The clinical diagnosis was Marchiafava-Bignami disease (MBD). As temporary treatment, refraining from alcohol consumption and administration of vitamins were prescribed. The condition of the patient gradually improved. The purposes of this study were to demonstrate the clinical and radiological variety of MBD and to identify practical methods of treatment of this pathology

MRI of sporadic Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Kong, A.; Vliet, A. Van der.

2008-01-01

Full text: The key MRI findings in five cases of sporadic Creutzfeldt-Jakob disease (CJD) are illustrated with four 'definite' and one 'probable' according to World Health Organization criteria. Close attention to fluid-attenuation inversion recovery and diffusion-weighted imaging sequences are important for diagnosis, noting especially restricted diffusion in cortical and deep grey matter. Our study and those of others show predominant cortical, caudate and thalamic involvement. This pattern is highly sensitive and specific for the diagnosis. Fluid-attenuation inversion recovery and diffusion-weighted imaging signal abnormality becomes progressively more extensive and bilateral as disease progresses, but may become less pronounced in end-stage disease because of atrophy.

T 2 mapping of cerebrospinal fluid

DEFF Research Database (Denmark)

Spijkerman, Jolanda M; Petersen, Esben T; Hendrikse, Jeroen

2018-01-01

the performance of this method at 7 T and evaluated the influence of partial volume and B 1 and B 0 inhomogeneity. MATERIALS AND METHODS: T 2-preparation-based CSF T 2-mapping was performed in seven healthy volunteers at 7 and 3 T, and was compared with a single echo spin-echo sequence with various echo times......OBJECT: Cerebrospinal fluid (CSF) T 2 mapping can potentially be used to investigate CSF composition. A previously proposed CSF T 2-mapping method reported a T 2 difference between peripheral and ventricular CSF, and suggested that this reflected different CSF compositions. We studied....... The influence of partial volume was assessed by our analyzing the longest echo times only. B 1 and B 0 maps were acquired. B 1 and B 0 dependency of the sequences was tested with a phantom. RESULTS: T 2,CSF was shorter at 7 T compared with 3 T. At 3 T, but not at 7 T, peripheral T 2,CSF was significantly...

Repeated intravenous administration of gadobutrol does not lead to increased signal intensity on unenhanced T1-weighted images - a voxel-based whole brain analysis

Energy Technology Data Exchange (ETDEWEB)

Langner, Soenke; Kromrey, Marie-Luise [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Kuehn, Jens-Peter [University Medicine Greifswald, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany); University Hospital, Carl Gustav Carus University Dresden, Institute for Radiology, Dresden (Germany); Grothe, Matthias [University Medicine Greifswald, Department of Neurology, Greifswald (Germany); Domin, Martin [University Medicine Greifswald, Functional Imaging Unit, Institute of Diagnostic Radiology and Neuroradiology, Greifswald (Germany)

2017-09-15

To identify a possible association between repeated intravenous administration of gadobutrol and increased signal intensity in the grey and white matter using voxel-based whole-brain analysis. In this retrospective single-centre study, 217 patients with a clinically isolated syndrome underwent baseline brain magnetic resonance imaging and at least one annual follow-up examination with intravenous administration of 0.1 mmol/kg body weight of gadobutrol. Using the ''Diffeomorphic Anatomical Registration using Exponentiated Lie algebra'' (DARTEL) normalisation process, tissue templates for grey matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were calculated, as were GM-CSF and WM-CSF ratios. Voxel-based whole-brain analysis was used to calculate the signal intensity for each voxel in each data set. Paired t-test was applied to test differences to baseline MRI for significance. Voxel-based whole-brain analysis demonstrated no significant changes in signal intensity of grey and white matter after up to five gadobutrol administrations. There was no significant change in GM-CSF and grey WM-CSF ratios. Voxel-based whole-brain analysis did not demonstrate increased signal intensity of GM and WM on unenhanced T1-weighted images after repeated gadobutrol administration. The molecular structure of gadolinium-based contrast agent preparations may be an essential factor causing SI increase on unenhanced T1-weighted images. (orig.)

An age estimation method using brain local features for T1-weighted images.

Science.gov (United States)

Kondo, Chihiro; Ito, Koichi; Kai Wu; Sato, Kazunori; Taki, Yasuyuki; Fukuda, Hiroshi; Aoki, Takafumi

2015-08-01

Previous statistical analysis studies using large-scale brain magnetic resonance (MR) image databases have examined that brain tissues have age-related morphological changes. This fact indicates that one can estimate the age of a subject from his/her brain MR image by evaluating morphological changes with healthy aging. This paper proposes an age estimation method using local features extracted from T1-weighted MR images. The brain local features are defined by volumes of brain tissues parcellated into local regions defined by the automated anatomical labeling atlas. The proposed method selects optimal local regions to improve the performance of age estimation. We evaluate performance of the proposed method using 1,146 T1-weighted images from a Japanese MR image database. We also discuss the medical implication of selected optimal local regions.

Spot Sign in Acute Intracerebral Hemorrhage in Dynamic T1-Weighted Magnetic Resonance Imaging.

Science.gov (United States)

Schindlbeck, Katharina A; Santaella, Anna; Galinovic, Ivana; Krause, Thomas; Rocco, Andrea; Nolte, Christian H; Villringer, Kersten; Fiebach, Jochen B

2016-02-01

In computed tomographic imaging of acute intracerebral hemorrhage spot sign on computed tomographic angiography has been established as a marker for hematoma expansion and poor clinical outcome. Although, magnetic resonance imaging (MRI) can accurately visualize acute intracerebral hemorrhage, a corresponding MRI marker is lacking to date. We prospectively examined 50 consecutive patients with acute intracerebral hemorrhage within 24 hours of symptom onset. The MRI protocol consisted of a standard stroke protocol and dynamic contrast-enhanced T1-weighted imaging with a time resolution of 7.07 s/batch. Stroke scores were assessed at admission and at time of discharge. Volume measurements of hematoma size and spot sign were performed with MRIcron. Contrast extravasation within sites of the hemorrhage (MRI spot sign) was seen in 46% of the patients. Patients with an MRI spot sign had a significantly shorter time to imaging than those without (Pspot sign compared with those without (P≤0.001). Hematoma expansion was observed in the spot sign group compared with the nonspot sign group, although the differences were not significant. Spot sign can be detected using MRI on postcontrast T1-weighted and dynamic T1-weighted images. It is associated with worse clinical outcome. The time course of contrast extravasation in dynamic T1 images indicates that these spots represent ongoing bleeding. © 2015 American Heart Association, Inc.

Neuro-Behcet: about a clinical case

International Nuclear Information System (INIS)

Gonzalez, G.; Perez, R.; Satriano, R.; Rotondo, M.

2007-01-01

The case of a 7-year-old Uruguayan boy with recurrent episodes of fever, oral aphthas lesions and meningoencephalitis with elevated protein levels and lymphocytic pleocytosis is presented. Other diagnoses were excluded. MRI showed in acute stages CNS involvement in iso- or hipointense in T1- weighted images and hyperintense in T2-weighted or fluid- attenuated inversion recovery (FLAIR) images in mesodiencephalic junction, cerebellar peduncles, pons, corpus callosum, basal ganglia and internal capsule, and cerebral hemispheres. In the evolution skin lesions appeared, fulfilling the International Study Group Criteria for the Diagnosis of Behcet' Disease. Corticosteroids and immunosuppressant treatment was done.The main difficulty in children is having all the criteria for diagnosis; especially when recurrent genital ulceration and eye lesion rarely appear at this age. (author) [es

Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

International Nuclear Information System (INIS)

Kúdelčík, Jozef; Bury, Peter; Kopčanský, Peter; Timko, Milan

2015-01-01

The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined

Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

Energy Technology Data Exchange (ETDEWEB)

Kúdelčík, Jozef, E-mail: kudelcik@fyzika.uniza.sk [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Bury, Peter [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Kopčanský, Peter; Timko, Milan [Department of Magnetism, IEP SAS, Watsonova 47, 040 01 Košice (Slovakia)

2015-08-15

The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined.

Robust T1-weighted structural brain imaging and morphometry at 7T using MP2RAGE.

Directory of Open Access Journals (Sweden)

Kieran R O'Brien

Full Text Available PURPOSE: To suppress the noise, by sacrificing some of the signal homogeneity for numerical stability, in uniform T1 weighted (T1w images obtained with the magnetization prepared 2 rapid gradient echoes sequence (MP2RAGE and to compare the clinical utility of these robust T1w images against the uniform T1w images. MATERIALS AND METHODS: 8 healthy subjects (29.0 ± 4.1 years; 6 Male, who provided written consent, underwent two scan sessions within a 24 hour period on a 7T head-only scanner. The uniform and robust T1w image volumes were calculated inline on the scanner. Two experienced radiologists qualitatively rated the images for: general image quality; 7T specific artefacts; and, local structure definition. Voxel-based and volume-based morphometry packages were used to compare the segmentation quality between the uniform and robust images. Statistical differences were evaluated by using a positive sided Wilcoxon rank test. RESULTS: The robust image suppresses background noise inside and outside the skull. The inhomogeneity introduced was ranked as mild. The robust image was significantly ranked higher than the uniform image for both observers (observer 1/2, p-value = 0.0006/0.0004. In particular, an improved delineation of the pituitary gland, cerebellar lobes was observed in the robust versus uniform T1w image. The reproducibility of the segmentation results between repeat scans improved (p-value = 0.0004 from an average volumetric difference across structures of ≈ 6.6% to ≈ 2.4% for the uniform image and robust T1w image respectively. CONCLUSIONS: The robust T1w image enables MP2RAGE to produce, clinically familiar T1w images, in addition to T1 maps, which can be readily used in uniform morphometry packages.

Conspicuity of diffuse axonal injury lesions on diffusion-weighted MR imaging

International Nuclear Information System (INIS)

Kinoshita, Toshibumi; Moritani, Toshio; Hiwatashi, Akio; Wang, Henry Z.; Shrier, David A.; Numaguchi, Yuji; Westesson, Per-Lennart A.

2005-01-01

Objective: (1) To detect diffuse axonal injury (DAI) lesions by diffusion-weighted imaging (DWI), as compared with fluid-attenuated inversion recovery (FLAIR) imaging and (2) to evaluate hemorrhagic DAI lesions by b 0 images obtained from DWI, as compared with gradient-echo (GRE) imaging. Methods: We reviewed MR images of 36 patients with a diagnosis of DAI. MR imaging was performed 20 h to 14 days (mean, 3.7 days) after traumatic brain injury. We evaluated: (1) conspicuity of lesions on DWI and FLAIR and (2) conspicuity of hemorrhage in DAI lesions on b 0 images and GRE imaging. Results: DWI clearly depicted high-signal DAI lesions. The sensitivity of DWI to lesional conspicuity in DAI lesions was almost equal to that of FLAIR. The sensitivity of b 0 images to identification of hemorrhagic DAI lesions was inferior to that of GRE. Conclusion: DWI is as useful as FLAIR in detecting DAI lesions. GRE imaging is still the superior tool for the evaluation of hemorrhagic DAI

Adaptive forward-inverse modeling of reservoir fluids away from wellbores; TOPICAL

International Nuclear Information System (INIS)

Ziagos, J P; Gelinas, R J; Doss, S K; Nelson, R G

1999-01-01

This Final Report contains the deliverables of the DeepLook Phase I project entitled, ''Adaptive Forward-Inverse Modeling of Reservoir Fluids Away from Wellbores''. The deliverables are: (i) a description of 2-D test problem results, analyses, and technical descriptions of the techniques used, (ii) a listing of program setup commands that construct and execute the codes for selected test problems (these commands are in mathematical terminology, which reinforces technical descriptions in the text), and (iii) an evaluation and recommendation regarding continuance of this project, including considerations of possible extensions to 3-D codes, additional technical scope, and budget for the out-years. The far-market objective in this project is to develop advanced technologies that can help locate and enhance the recovery of oil from heterogeneous rock formations. The specific technical objective in Phase I was to develop proof-of-concept of new forward and inverse (F-I) modeling techniques[Gelinas et al, 1998] that seek to enhance estimates (images) of formation permeability distributions and fluid motion away from wellbore volumes. This goes to the heart of improving industry's ability to jointly image reservoir permeability and flow predictions of trapped and recovered oil versus time. The estimation of formation permeability away from borehole measurements is an ''inverse'' problem. It is an inseparable part of modeling fluid flows throughout the reservoir in efforts to increase the efficiency of oil recovery at minimum cost. Classic issues of non-uniqueness, mathematical instability, noise effects, and inadequate numerical solution techniques have historically impeded progress in reservoir parameter estimations. Because information pertaining to fluid and rock properties is always sampled sparsely by wellbore measurements, a successful method for interpolating permeability and fluid data between the measurements must be: (i) physics-based, (ii) conditioned by signal

Low-Molecular-Weight Iron Chelates May Be an Alternative to Gadolinium-based Contrast Agents for T1-weighted Contrast-enhanced MR Imaging.

Science.gov (United States)

Boehm-Sturm, Philipp; Haeckel, Akvile; Hauptmann, Ralf; Mueller, Susanne; Kuhl, Christiane K; Schellenberger, Eyk A

2018-02-01

Purpose To synthesize two low-molecular-weight iron chelates and compare their T1 contrast effects with those of a commercial gadolinium-based contrast agent for their applicability in dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging. Materials and Methods The animal experiments were approved by the local ethics committee. Two previously described iron (Fe) chelates of pentetic acid (Fe-DTPA) and of trans-cyclohexane diamine tetraacetic acid (Fe-tCDTA) were synthesized with stability constants several orders of magnitude higher than those of gadolinium-based contrast agents. The T1 contrast effects of the two chelates were compared with those of gadopentetate dimeglumine in blood serum phantoms at 1.5 T, 3 T, and 7 T. For in vivo studies, a human breast cancer cell line (MDA-231) was implanted in five mice per group. The dynamic contrast effects of the chelates were compared by performing DCE MR imaging with intravenous application of Fe-DTPA or Fe-tCDTA on day 1 and DCE MR imaging in the same tumors with gadopentetate dimeglumine on day 2. Quantitative DCE maps were generated with software and were compared by means of a one-tailed Pearson correlation test. Results Relaxivities in serum (0.94 T at room temperature) of Fe-tCDTA (r1 = 2.2 mmol -1 · sec -1 , r2 = 2.5 mmol -1 · sec -1 ) and Fe-DTPA (r1 = 0.9 mmol -1 · sec -1 , r2 = 0.9 mmol -1 · sec -1 ) were approximately twofold and fivefold lower, respectively, compared with those of gadopentetate dimeglumine (r1 = 4.1 mmol -1 · sec -1 , r2 = 4.8 mmol -1 · sec -1 ). Used at moderately higher concentrations, however, iron chelates generated similar contrast effects at T1-weighted MR imaging in vitro in serum, in vivo in blood, and for DCE MR imaging of breast cancer xenografts. The volume transfer constant values for Fe-DTPA and Fe-tCDTA in the same tumors correlated well with those observed for gadopentetate dimeglumine (Fe-tCDTA Pearson R, 0.99; P = .0003; Fe-DTPA Pearson R, 0.97; P

T1-weighted vs. short-TE-long-TR images. Usefulness for knee MR examinations of ligament and meniscal lesions

International Nuclear Information System (INIS)

Endo, Hideho; Wada, Mitsuyoshi; Shiotani, Seiji; Niitsu, Mamoru; Itai, Yuji

2000-01-01

The purpose of this study was to compare short-TE-long-TR images with T1-weighed images in knee MR examinations. Sagittal MR images of the knee were obtained in 31 patients with knee pain. T1-weighted images were obtained by the spin-echo technique (TR/TE =350/15), and short-TE-long-TR images by fast spin-echo (TR/TE =1300/15) with an echo-train length of 5. Contrast-to-noise-ratios (CNRs) of the anterior cruciate ligament and synovial space, meniscus and articular cartilage, and meniscal lesion and normal meniscus were compared between short-TE-long-TR images and T1-weighted images. On each of the three examinations, short-TE-long-TR images provided significantly higher CNRs than T1-weighted images. It was concluded that short-TE-long-TR images can be a useful alternative to T1-weighted images in evaluating the anterior cruciate ligament and meniscal lesions. (author)

T1-weighted vs. short-TE-long-TR images. Usefulness for knee MR examinations of ligament and meniscal lesions

Energy Technology Data Exchange (ETDEWEB)

Endo, Hideho; Wada, Mitsuyoshi; Shiotani, Seiji [Tsukuba Medical Center Hospital, Ibaraki (Japan); Niitsu, Mamoru; Itai, Yuji

2000-11-01

The purpose of this study was to compare short-TE-long-TR images with T1-weighed images in knee MR examinations. Sagittal MR images of the knee were obtained in 31 patients with knee pain. T1-weighted images were obtained by the spin-echo technique (TR/TE =350/15), and short-TE-long-TR images by fast spin-echo (TR/TE =1300/15) with an echo-train length of 5. Contrast-to-noise-ratios (CNRs) of the anterior cruciate ligament and synovial space, meniscus and articular cartilage, and meniscal lesion and normal meniscus were compared between short-TE-long-TR images and T1-weighted images. On each of the three examinations, short-TE-long-TR images provided significantly higher CNRs than T1-weighted images. It was concluded that short-TE-long-TR images can be a useful alternative to T1-weighted images in evaluating the anterior cruciate ligament and meniscal lesions. (author)

Intraindividual comparison of myocardial delayed enhancement MR imaging using gadobenate dimeglumine at 1.5 T and 3 T

Energy Technology Data Exchange (ETDEWEB)

Klumpp, Bernhard D.; Seeger, Achim; Fenchel, Michael; Kramer, Ulrich; Claussen, Claus D.; Miller, Stephan [Eberhard Karls University Tuebingen, Department for Diagnostic Radiology, Tuebingen (Germany); Sandstede, Joern [Roentgenzentrum, Hamburg (Germany); Lodemann, Klaus P. [Bracco Altana Pharma, Konstanz (Germany); Hoevelborn, Tobias [Eberhard Karls University Tuebingen, Department for Cardiology, Tuebingen (Germany)

2009-05-15

For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at 1.5 T and 3 T. Fifteen minutes after injection of contrast agent (0.1 mmol gadobenate dimeglumine per kg body weight), inversion recovery gradient recalled echo (IR-GRE) sequences were acquired (1.5 T/3 T: TR 11.0/9.9 ms, TE 4.4/4.9 ms, flip 30 /30 , slice thickness 6/6 mm) to assess myocardial viability. Two observers rated image quality (Wilcoxon signed rank test). Quantification of hyperenhanced myocardium and standardized SNR/CNR measurements were performed (Student's t test). There was no significant difference with respect to image quality (1.5 T/3 T: 3.5/3.3, p = 0.34, reader 1; 2.4/2.7, p = 0.12, reader 2) and infarction size (760 {+-} 566/828 {+-} 677 mm{sup 2} at 1.5 T, 808 {+-} 639/826 {+-} 726 mm{sup 2} at 3 T, reader 1/reader 2, p > 0.05). Mean SNR in hyperenhanced/normal myocardium was 19.2/6.2 at 1.5 T and 29.5/8.8 at 3 T (p < 0.05). Mean CNR was 14.3 at 1.5 T and 26.0 at 3 T (p < 0.05). Delayed enhancement MR imaging at 3 T is a robust procedure yielding superior tissue contrast at 3 T compared with 1.5 T which is, however, not reflected by increased image quality. (orig.)

Inverse relationship between changes of maximal aerobic capacity and changes in walking economy after weight loss.

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Borges, Juliano H; Carter, Stephen J; Singh, Harshvardhan; Hunter, Gary R

2018-05-16

The aims of this study were to: (1) determine the relationships between maximum oxygen uptake ([Formula: see text]O 2max ) and walking economy during non-graded and graded walking among overweight women and (2) examine potential differences in [Formula: see text]O 2max and walking economy before and after weight loss. One-hundred and twenty-four premenopausal women with a body mass index (BMI) between 27 and 30 kg/m 2 were randomly assigned to one of three groups: (a) diet only; (b) diet and aerobic exercise training; and (c) diet and resistance exercise training. All were furnished with standard, very-low calorie diet to reduce BMI to < 25 kg/m 2 . [Formula: see text]O 2max was measured using a modified-Bruce protocol while walking economy (1-net [Formula: see text]O 2 ) was obtained during fixed-speed (4.8 k·h -1 ), steady-state treadmill walking at 0% grade and 2.5% grade. Assessments were conducted before and after achieving target BMI. Prior to weight loss, [Formula: see text]O 2max was inversely related (P < 0.05) with non-graded and graded walking economy (r = - 0.28 to - 0.35). Similar results were also observed following weight loss (r = - 0.22 to - 0.28). Additionally, we also detected a significant inverse relationship (P < 0.05) between the changes (∆, after weight loss) in ∆[Formula: see text]O 2max , adjusted for fat-free mass, with non-graded and graded ∆walking economy (r = - 0.37 to - 0.41). Our results demonstrate [Formula: see text]O 2max and walking economy are inversely related (cross-sectional) before and after weight loss. Importantly though, ∆[Formula: see text]O 2max and ∆walking economy were also found to be inversely related, suggesting a strong synchrony between maximal aerobic capacity and metabolic cost of exercise.

[The Role of Imaging in Central Nervous System Infections].

Science.gov (United States)

Yokota, Hajime; Tazoe, Jun; Yamada, Kei

2015-07-01

Many infections invade the central nervous system. Magnetic resonance imaging (MRI) is the main tool that is used to evaluate infectious lesions of the central nervous system. The useful sequences on MRI are dependent on the locations, such as intra-axial, extra-axial, and spinal cord. For intra-axial lesions, besides the fundamental sequences, including T1-weighted images, T2-weighted images, and fluid-attenuated inversion recovery (FLAIR) images, advanced sequences, such as diffusion-weighted imaging, diffusion tensor imaging, susceptibility-weighted imaging, and MR spectroscopy, can be applied. They are occasionally used as determinants for quick and correct diagnosis. For extra-axial lesions, understanding the differences among 2D-conventional T1-weighted images, 2D-fat-saturated T1-weighted images, 3D-Spin echo sequences, and 3D-Gradient echo sequence after the administration of gadolinium is required to avoid wrong interpretations. FLAIR plus gadolinium is a useful tool for revealing abnormal enhancement on the brain surface. For the spinal cord, the sequences are limited. Evaluating the distribution and time course of the spinal cord are essential for correct diagnoses. We summarize the role of imaging in central nervous system infections and show the pitfalls, key points, and latest information in them on clinical practices.

Method and software to solution of inverse and inverse design fluid flow and heat transfer problems is compatible with CFD-software

Energy Technology Data Exchange (ETDEWEB)

Krukovsky, P G [Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kiev (Ukraine)

1998-12-31

The description of method and software FRIEND which provide a possibility of solution of inverse and inverse design problems on the basis of existing (base) CFD-software for solution of direct problems (in particular, heat-transfer and fluid-flow problems using software PHOENICS) are presented. FRIEND is an independent additional module that widens the operational capacities of the base software unified with this module. This unifying does not require any change or addition to the base software. Interfacing of FRIEND and the base software takes place through input and output files of the base software. A brief description of the computational technique applied for the inverse problem solution, same detailed information on the interfacing of FRIEND and CFD-software and solution results for testing inverse and inverse design problems, obtained using the tandem CFD-software PHOENICS and FRIEND, are presented. (author) 9 refs.

Method and software to solution of inverse and inverse design fluid flow and heat transfer problems is compatible with CFD-software

Energy Technology Data Exchange (ETDEWEB)

Krukovsky, P.G. [Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kiev (Ukraine)

1997-12-31

The description of method and software FRIEND which provide a possibility of solution of inverse and inverse design problems on the basis of existing (base) CFD-software for solution of direct problems (in particular, heat-transfer and fluid-flow problems using software PHOENICS) are presented. FRIEND is an independent additional module that widens the operational capacities of the base software unified with this module. This unifying does not require any change or addition to the base software. Interfacing of FRIEND and the base software takes place through input and output files of the base software. A brief description of the computational technique applied for the inverse problem solution, same detailed information on the interfacing of FRIEND and CFD-software and solution results for testing inverse and inverse design problems, obtained using the tandem CFD-software PHOENICS and FRIEND, are presented. (author) 9 refs.

The frequency of CD127low expressing CD4+CD25high T regulatory cells is inversely correlated with human T lymphotrophic virus type-1 (HTLV-1 proviral load in HTLV-1-infection and HTLV-1-associated myelopathy/tropical spastic paraparesis

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Chieia Marco

2008-07-01

Full Text Available Abstract Background CD4+CD25high regulatory T (TReg cells modulate antigen-specific T cell responses, and can suppress anti-viral immunity. In HTLV-1 infection, a selective decrease in the function of TReg cell mediated HTLV-1-tax inhibition of FOXP3 expression has been described. The purpose of this study was to assess the frequency and phenotype of TReg cells in HTLV-1 asymptomatic carriers and in HTLV-1-associated neurological disease (HAM/TSP patients, and to correlate with measures of T cell activation. Results We were able to confirm that HTLV-I drives activation, spontaneous IFNγ production, and proliferation of CD4+ T cells. We also observed a significantly lower proportion of CTLA-4+ TReg cells (CD4+CD25high T cells in subjects with HAM/TSP patients compared to healthy controls. Ki-67 expression was negatively correlated to the frequency of CTLA-4+ TReg cells in HAM/TSP only, although Ki-67 expression was inversely correlated with the percentage of CD127low TReg cells in healthy control subjects. Finally, the proportion of CD127low TReg cells correlated inversely with HTLV-1 proviral load. Conclusion Taken together, the results suggest that TReg cells may be subverted in HAM/TSP patients, which could explain the marked cellular activation, spontaneous cytokine production, and proliferation of CD4+ T cells, in particular those expressing the CD25highCD127low phenotype. TReg cells represent a potential target for therapeutic intervention for patients with HTLV-1-related neurological diseases.

Reduction of CSF flow artifact in fast fluid attenuated inversion recovery MR imaging. Study of excitation width in 180deg inversion pulse

International Nuclear Information System (INIS)

Tsuchihashi, Toshio; Yoshizawa, Satoshi; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Ken; Fujita, Isao

1998-01-01

A technique that increases slice thickness so that it becomes wider than the excitation width of the 180deg inversion pulse and in which TR is partitioned twice has been investigated with regard to fast FLAIR. This is a technique that reduces the flow artifact of CSF. It is thought that, with this technique, the flow artifact is reduced because the CSF that flows onto the slice reaches the null point. The cross talk effect of the 180deg inversion pulse appears as a high CSF signal. As a result, the number of slices needs to be partitioned two or three times before imaging. Thus the imaging time is doubled or tripled. Considering the cross talk effect of the 180deg inversion pulse and the imaging time needed for this technique, the optimal imaging technique would be one that uses an inversion pulse that is four times slice thickness plus slice space and for which the number of slices is partitioned twice. Furthermore, the null point of CSF was dependent on dividing TR in half. (author)

MALT1 Controls Attenuated Rabies Virus by Inducing Early Inflammation and T Cell Activation in the Brain.

Science.gov (United States)

Kip, E; Staal, J; Verstrepen, L; Tima, H G; Terryn, S; Romano, M; Lemeire, K; Suin, V; Hamouda, A; Kalai, M; Beyaert, R; Van Gucht, S

2018-04-15

MALT1 is involved in the activation of immune responses, as well as in the proliferation and survival of certain cancer cells. MALT1 acts as a scaffold protein for NF-κB signaling and a cysteine protease that cleaves substrates, further promoting the expression of immunoregulatory genes. Deregulated MALT1 activity has been associated with autoimmunity and cancer, implicating MALT1 as a new therapeutic target. Although MALT1 deficiency has been shown to protect against experimental autoimmune encephalomyelitis, nothing is known about the impact of MALT1 on virus infection in the central nervous system. Here, we studied infection with an attenuated rabies virus, Evelyn-Rotnycki-Abelseth (ERA) virus, and observed increased susceptibility with ERA virus in MALT1 -/- mice. Indeed, after intranasal infection with ERA virus, wild-type mice developed mild transient clinical signs with recovery at 35 days postinoculation (dpi). Interestingly, MALT1 -/- mice developed severe disease requiring euthanasia at around 17 dpi. A decreased induction of inflammatory gene expression and cell infiltration and activation was observed in MALT1 -/- mice at 10 dpi compared to MALT1 +/+ infected mice. At 17 dpi, however, the level of inflammatory cell activation was comparable to that observed in MALT1 +/+ mice. Moreover, MALT1 -/- mice failed to produce virus-neutralizing antibodies. Similar results were obtained with specific inactivation of MALT1 in T cells. Finally, treatment of wild-type mice with mepazine, a MALT1 protease inhibitor, also led to mortality upon ERA virus infection. These data emphasize the importance of early inflammation and activation of T cells through MALT1 for controlling the virulence of an attenuated rabies virus in the brain. IMPORTANCE Rabies virus is a neurotropic virus which can infect any mammal. Annually, 59,000 people die from rabies. Effective therapy is lacking and hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular

Characteristic signal changes in the pontine base on T2- and multishot diffusion-weighted images in spinocerebellar ataxia type 1

International Nuclear Information System (INIS)

Adachi, M.; Kawanami, T.; Ohshima, H.; Hosoya, T.

2006-01-01

The aim of the present study was to demonstrate characteristic signal changes of the pontine base on T2-weighted images of patients with SCA 1, and to elucidate the relationship between abnormal high-intensities of the pontine base on T2-weighted images and the findings on multishot diffusion-weighted images. We assessed abnormal signals of the pontine base on T2-weighted images from 50 controls and six patients with SCA 1 diagnosed by genetic analysis. At the same time, we evaluated the degeneration of the transverse pontine fibers in the pontine base by multishot diffusion-weighted imaging. A midline high-intensity was seen in the pontine base on T2-weighted images in two of the 50 controls and five of the six patients with SCA 1. The midline high-intensity had a sensitivity of 83.3% for patients and a specificity of 96.0% for controls. Multishot diffusion-weighted imaging demonstrated the degeneration - the amorphous-pattern signal - of the transverse pontine fibers in four (66.7%) of the six patients. In the other two patients, the zebra-pattern signal was seen in the pontine base. The midline high-intensity on T2-weighted images appears to be one of characteristic MRI findings of SCA 1. Multishot diffusion-weighted imaging suggested that the midline high-intensity should reflect the degeneration of the transverse pontine fibers. (orig.)

Myometrial invasion in endometrial cancer: diagnostic performance of diffusion-weighted MR imaging at 1.5-T

International Nuclear Information System (INIS)

Rechichi, Gilda; Sironi, Sandro; Galimberti, Stefania; Valsecchi, Maria Grazia; Signorelli, Mauro; Perego, Patrizia

2010-01-01

To determine the diagnostic accuracy of diffusion-weighted (DW) magnetic resonance (MR) imaging in the preoperative assessment of myometrial invasion by endometrial cancer. In this prospective study, 47 patients with histologically confirmed endometrial cancer underwent preoperative MR imaging and total hysterectomy. The MR protocol included spin-echo multishot T2-weighted, dynamic T1-weighted and DW images acquired with b-values of 0 and 500 s/mm 2 . Myometrial tumour spread was classified as superficial (<50%) or deep (≥50% myometrial thickness). Postoperative histopathological findings served as a reference standard. Indices of diagnostic performance were assessed for each sequence. At histopathological examination, superficial myometrial invasion was found in 34 patients and deep myometrial invasion in 13. In the assessment of tumour invasion, sensitivity, specificity, positive and negative predictive values of T2-weighted images were 92.3%, 76.5%, 60.0% and 96.3%, respectively. The corresponding values for dynamic images were 69.2%, 61.8%, 40.9% and 84.0%, and for DW images 84.6%, 70.6%, 52.4% and 92.3%. T2-weighted and DW imaging proved to be the most accurate techniques for tumour spread determination. DW imaging proved to be accurate in assessing myometrial invasion, and it could replace dynamic imaging as an adjunct to routine T2-weighted imaging for preoperative evaluation of endometrial cancer. (orig.)

Serum levels of brain-derived neurotrophicfactor correlate with the number of T2 MRI lesions in multiple sclerosis

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E.R. Comini-Frota

2012-01-01

Full Text Available The objective of the present study was to determine if there is a relationship between serum levels of brain-derived neurotrophic factor (BDNF and the number of T2/fluid-attenuated inversion recovery (T2/FLAIR lesions in multiple sclerosis (MS. The use of magnetic resonance imaging (MRI has revolutionized the study of MS. However, MRI has limitations and the use of other biomarkers such as BDNF may be useful for the clinical assessment and the study of the disease. Serum was obtained from 28 MS patients, 18-50 years old (median 38, 21 women, 0.5-10 years (median 5 of disease duration, EDSS 1-4 (median 1.5 and 28 healthy controls, 19-49 years old (median 33, 19 women. BDNF levels were measured by ELISA. T1, T2/FLAIR and gadolinium-enhanced lesions were measured by a trained radiologist. BDNF was reduced in MS patients (median [range] pg/mL; 1160 [352.6-2640] compared to healthy controls (1640 [632.4-4268]; P = 0.03, Mann-Whitney test and was negatively correlated (Spearman correlation test, r = -0.41; P = 0.02 with T2/FLAIR (11-81 lesions, median 42. We found that serum BDNF levels were inversely correlated with the number of T2/FLAIR lesions in patients with MS. BDNF may be a promising biomarker of MS.

Seismic attenuation in fractured porous media: insights from a hybrid numerical and analytical model

International Nuclear Information System (INIS)

Ekanem, A M; Li, X Y; Chapman, M; Main, I G

2015-01-01

Seismic attenuation in fluid-saturated porous rocks can occur by geometric spreading, wave scattering or the internal dissipation of energy, most likely due to the squirt-flow mechanism. In principle, the pattern of seismic attenuation recorded on an array of sensors contains information about the medium, in terms of material heterogeneity and anisotropy, as well as material properties such as porosity, crack density, and pore-fluid composition and mobility. In practice, this inverse problem is challenging. Here we provide some insights into the effects of internal dissipation by analysing synthetic data produced by a hybrid numerical and analytical model for seismic wave propagation in a fractured medium embedded within a layered geological structure. The model is made up of one anisotropic and three isotropic horizontal layers. The anisotropic layer consists of a porous, fluid-saturated material containing vertically aligned inclusions representing a set of fractures. This combination allows squirt-flow to occur between the pores in the matrix and the model fractures. Our results show that the fluid mobility and the associated relaxation time of the fluid-pressure gradient control the frequency range over which attenuation occurs. This induced attenuation increases with incidence angle and azimuth away from the fracture strike-direction. Azimuthal variations in the induced attenuation are elliptical allowing the fracture orientations to be obtained from the axes of the ellipse. These observations hold out the potential of using seismic attenuation as an additional diagnostic in the characterisation of rock formations for a variety of applications including hydrocarbon exploration and production, subsurface storage of CO 2 , and geothermal energy extraction. (paper)

Apical hypertrophy associated with rapid T wave inversion on the electrocardiogram.

Science.gov (United States)

Yamanari, H; Saito, D; Mikio, K; Nakamura, K; Nanba, T; Morita, H; Mizuo, K; Sato, T; Ohe, T

1995-01-01

A 53-year-old man who had no chest pain and no family history of heart disease demonstrated a rapid T wave change on an electrocardiogram, from a positive T wave to a giant negative T wave, within 1 year. Echocardiography showed no left ventricular hypertrophy before or after the T wave change. Cine-magnetic resonance imaging revealed focal apical hypertrophy after the appearance of the giant negative T wave. Although T wave inversions sometimes develop within a short period in patients with hypertrophic cardiomyopathy, they are rare in a patient without hypertension or chest pain.

Fully automatic detection of deep white matter T1 hypointense lesions in multiple sclerosis

Science.gov (United States)

Spies, Lothar; Tewes, Anja; Suppa, Per; Opfer, Roland; Buchert, Ralph; Winkler, Gerhard; Raji, Alaleh

2013-12-01

A novel method is presented for fully automatic detection of candidate white matter (WM) T1 hypointense lesions in three-dimensional high-resolution T1-weighted magnetic resonance (MR) images. By definition, T1 hypointense lesions have similar intensity as gray matter (GM) and thus appear darker than surrounding normal WM in T1-weighted images. The novel method uses a standard classification algorithm to partition T1-weighted images into GM, WM and cerebrospinal fluid (CSF). As a consequence, T1 hypointense lesions are assigned an increased GM probability by the standard classification algorithm. The GM component image of a patient is then tested voxel-by-voxel against GM component images of a normative database of healthy individuals. Clusters (≥0.1 ml) of significantly increased GM density within a predefined mask of deep WM are defined as lesions. The performance of the algorithm was assessed on voxel level by a simulation study. A maximum dice similarity coefficient of 60% was found for a typical T1 lesion pattern with contrasts ranging from WM to cortical GM, indicating substantial agreement between ground truth and automatic detection. Retrospective application to 10 patients with multiple sclerosis demonstrated that 93 out of 96 T1 hypointense lesions were detected. On average 3.6 false positive T1 hypointense lesions per patient were found. The novel method is promising to support the detection of hypointense lesions in T1-weighted images which warrants further evaluation in larger patient samples.

Developmental patterns of fetal fat and corresponding signal on T1-weighted magnetic resonance imaging

International Nuclear Information System (INIS)

Blondiaux, Eleonore; Chougar, Lydia; Ducou le Pointe, Hubert; Garel, Catherine; Gelot, Antoinette; Valence, Stephanie; Audureau, Etienne; Jouannic, Jean-Marie; Dhombres, Ferdinand

2018-01-01

Evaluation of subcutaneous fetal fat layer thickness on T1-weighted sequences can be used to predict birth weight. Little is known about normal MR signal patterns of subcutaneous tissue throughout pregnancy. To establish developmental patterns of subcutaneous fetal fat signal on T1-weighted sequences during the 2nd and 3rd trimesters. We retrospectively examined T1-weighted images of 110 fetal MRI scans. We measured signal intensity of subcutaneous fat on thighs, buttocks, trunk, nuchal region, chin and scalp. We then calculated the ratios of the obtained values with fetal muscle, amnios and maternal fat signal, and compared the results with those of immunohistochemical examination of adipose tissue extracted from the abdominal wall of fetuses as part of standard autopsy protocol. We included 60 MRI scans in fetuses without intra-uterine growth restriction or macrosomia of non-diabetic mothers (range 23-37 weeks of gestation). Fat T1 intensity of all anatomical regions was low in all fetuses before 26 weeks of gestation. It became more hyperintense with increasing gestational age, in the following order: chin and nuchal region, then buttocks, thighs and trunk, and eventually the scalp at 33 weeks of gestation. After 33 weeks of gestation, all fetal subcutaneous tissues demonstrated overall hyperintense signal. This progression followed the conversion at immunohistochemistry of fetal adipose tissue composition from predominant brown to white adipose cells in 19 fetuses (19-41 weeks of gestation). Between 26 weeks and 33 weeks of gestation, subcutaneous fetal fat signal changed in an orderly pattern from chin to buttocks and scalp. This may reflect the conversion from predominant brown to white adipose tissues in subcutaneous fetal fat. (orig.)

Spectrum of findings on magnetic resonance imaging of the brain in patients with neurological manifestations of dengue fever

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Tejeshwar Singh Jugpal

Full Text Available Abstract Objective: To describe the spectrum of magnetic resonance imaging (MRI findings in patients with neurological manifestations of dengue. Materials and Methods: We included nine patients with dengue fever (three females and six males; age range, 9–30 years, all of whom presented with neurological manifestations. The MRI examinations, performed in 1.5 T or 3 T scanners, included T1-weighted, T2-weighted, and fluid-attenuated inversion recovery (FLAIR sequences. Diffusion-weighted imaging with apparent diffusion coefficient mapping was also employed. Fast low-angle shot and susceptibility-weighted gradient-recalled echo sequences, as well as contrast-enhanced T1-weighted scans, were also obtained in order to assess parenchymal enhancement. MRI scans were analyzed for lesion distribution and imaging features. Results: All patients showed areas of altered signal intensity that appeared as hyperintensity on T2-weighted and FLAIR sequences. The most commonly affected site was the basal ganglia-thalamus complex. Other affected sites were the cerebellum, cerebral cortex, white matter, and brainstem. In all cases, we observed patchy areas of restricted diffusion and focal areas of hemorrhage. Conclusion: Dengue encephalitis commonly affects the basal ganglia, thalamus, cerebellum, cerebral cortex, and white matter. Therefore, MRI should be an indispensable part of the evaluation of patients with neurological complications of dengue fever.

Classification of hematopoietic regions in out-of-phase T1-weighted images. A quantitative comparison study with T1-weighted and STIR images

International Nuclear Information System (INIS)

Amano, Yasuo; Amano, Maki; Kijima, Tetsuji; Kumazaki, Tatsuo

1995-01-01

The hematopoietic regions were classified into two groups on the basis of out-of-phase T 1 -weighted images (op-TlWI): regions with lower intensity than that of muscle (LH) and regions with intensity equal to or higher than that of muscle (HH). We quantitatively evaluated the differences in signal intensity between LH and HH in order to examine this classification. Forty-two hematopoietic areas in aplastic anemia were classified into two groups of 23 LH and 19 HH. The signal ratios of hematopoietic areas to muscle on TlWI and STIR were calculated, and the differences between LH and HH were statistically evaluated. The signal ratios of LH were significantly higher on TlWI and lower on STIR than those of HH (unpaired t-test, p<0.05). This result indicated that LH consisted of more hypocellular marrow than HH. Op-TlWI were useful in differentiating between LH and HH and defining the degree of hematopoiesis in aplastic anemia. (author)

Radiation polymerization of acrylamide with super-high molecular weight in inverse emulsion

International Nuclear Information System (INIS)

Ye Qiang; Ge Xuewu; Xu Xiangling; Zhang Zhicheng

1998-01-01

The inverse emulsion polymerization of acrylamide has been studied with γ-ray initiation. Polyacrylamide with super high molecular weight over ten million (11 x 10 6 ), which is very important in application as flocculant, is obtained. In this work, some methods are taken to enhance the molecular weight as follows: (1) In order to prepare soluble polyacrylamide with super high molecular weight, the better conditions are: the emulsifier content is about 2% and the monomer concentration is about 20%∼24% in the composition of monomer emulsion, and the absorbed dose is about 500∼600 Gy. (2) Initiating with high dose rate and polymerizing with low dose rate can not only enhance the molecular weight of product, but also curtail the polymerizing time. (3) Stopping radiation when the conversion gets to about 10% and post-polymerizing outside the radiation source until the conversion gets to 82% can obtain polyacrylamide with super high molecular weight, and shorten the irradiation time as well

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.