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1.
目的:研究扩散张量成像(DTI)在急性颈髓损伤(CSCI)的成像特点,评估其临床应用价值。方法本组8例 CSCI 患者(发病72 h 内)均采用3.0T 磁共振仪进行快速颈髓 DTI 扫描,并在工作站进行扩散张量纤维束成像(DTT)。同时,在工作站分别测量并计算颈髓病变区及上下相对正常区的各向异性(FA)值和表观扩散系数(ADC)值,之后进行统计学组间配对 t 检验分析(SPSS 13.0)。结果急性 CSCI 以 C5~C6节段(占4/8)和 C4~C5节段(占3/8)多见,且快速 DTI 均获得了较好的图像质量。急性 CSCI 时病变区 FA 值和 ADC 值均明显低于相对正常区域数值(P <0.01),相应在 FA 图和 ADC 图均表现为低信号,而上下相对正常区 FA 值和 ADC 值间无明显区别;同时,DTT 有利于显示刀刺伤导致的颈髓纤维束断裂,颈髓闭合伤则主要表现为脊髓纤维束紊乱等。结论3.0T 快速 DTI 序列可以在2 min 扫描时间内获得临床较为满意的诊断图像,并通过 FA 值和 ADC 值更敏感地反映急性 CSCI 后髓鞘损伤导致的 FA 改变及细胞毒性水肿和血管源性水肿导致的水分子扩散的变化。 相似文献
2.
Ellingson BM Kurpad SN Li SJ Schmit BD 《Journal of magnetic resonance imaging : JMRI》2008,27(3):634-642
PURPOSE: To determine differences in diffusion measurements in white matter (WM) and gray matter (GM) regions of the rat cervical, thoracic, and cauda equina spinal cord using in vivo diffusion tensor imaging (DTI) with a 9.4T MR scanner. MATERIALS AND METHODS: DTI was performed on seven rats in three slices at the cervical, thoracic, and cauda equina regions of the spinal cord using a 9.4T magnet. Axial diffusion weighted images (DWIs) were collected at a b-value of 1000 seconds/mm(2) in six directions. Regions of interest were identified via T2-weighted images for the lateral, dorsal, and ventral funiculi, along with GM regions. RESULTS: Analysis of variance (ANOVA) results indicated significant differences between every WM funiculus compared to GM for longitudinal apparent diffusion coefficient (lADC), transverse apparent diffusion coefficient (tADC), fractional anisotropy (FA), measured longitudinal anisotropy (MA1), and anisotropy index (AI). A significant difference in mean diffusivity (MD) between regions of the spinal cord was not found. Diffusion measurements were significantly different at each spinal level. In general, GM regions were significantly different than WM regions; however, there were few significant differences between individual WM regions. CONCLUSION: In vivo DTI of the rat spinal cord at 9.4T appears sensitive to the architecture of neural structures in the rat spinal cord and may be a useful tool in studying trauma and pathologies in the spinal cord. 相似文献
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4.
Gray and white matter delineation in the human spinal cord using diffusion tensor imaging and fuzzy logic 总被引:1,自引:0,他引:1
RATIONALE AND OBJECTIVES: Diffusion tensor imaging (DTI) has been used extensively in determining morphology and connectivity of the brain; however, similar analysis in the spinal cord has proven difficult. The objective of this study was to improve the delineation of gray and white matter in the spinal cord by applying signal processing techniques to the eigenvalues of the diffusion tensor. Our approach involved creating anisotropy indices based on the difference between eigenvalues and mean diffusivity then using a fuzzy inference system (FIS) to delineate between gray and white matter in the human cervical spinal cord. MATERIALS AND METHODS: DTI was performed on the cervical spinal cord in five neurologically intact subjects. Distributions were extracted for regions of gray and white matter through the use of a digitized histologic template. Fuzzy membership functions were created based on these distributions. Detectability index and receiver operating characteristic (ROC) analysis was performed on traditional DTI indices and FIS classified regions. RESULTS: A significantly higher contrast between gray and white matter was observed using fuzzy classification compared with traditionally used DTI indices based on the detectability index (P < .001) and trends in the ROC analysis. Reconstructed images from the FIS qualitatively showed a better anatomical representation of the spinal cord compared with traditionally used DTI indices. CONCLUSIONS: Diffusion tensor imaging using an FIS for tissue classification provides high contrast between spinal gray and white matter compared with traditional DTI indices and may provide a noninvasive technique to quantify the integrity and morphology of the human spinal cord following injury. 相似文献
5.
John F. Griffin IV DVM DACVR Noah D. Cohen VMD MPH PhD DACVIM Benjamin D. Young MS DVM DACVR Bunita M. Eichelberger MS DVM DACVR Abraham Padua Jr BS David Purdy PhD Jonathan M. Levine DVM DACVIM‐Neurology 《Journal of magnetic resonance imaging : JMRI》2013,37(3):632-641
Purpose:
To analyze four clinically applicable diffusion tensor imaging (DTI) protocols (two each in the transverse and sagittal planes) in the normal dog.Materials and Methods:
Seven healthy Dachshund dogs were scanned with four DTI protocols. Within each plane, identical spatial resolution was used while the number of diffusion‐encoding directions and averages varied. Agreement of measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) was analyzed with Bland–Altman methods, subjective image quality within each plane was compared, and FA and ADC were explored as a function of anatomic location.Results:
There was good agreement in FA and ADC values within each plane. FA had the smallest bias and most precision. No difference was detected in subjective image quality within each plane. FA and ADC were slightly higher cranial to the lumbar intumescence compared to within it.Conclusion:
DTI is a promising tool in the assessment of spinal cord injury (SCI) in the study of dogs with intervertebral disk herniation as a preclinical model of human SCI. J. Magn. Reson. Imaging 2013;37:632–641. © 2013 Wiley Periodicals, Inc. 相似文献6.
Van Hecke W Leemans A Sijbers J Vandervliet E Van Goethem J Parizel PM 《Journal of magnetic resonance imaging : JMRI》2008,27(5):978-991
PURPOSE: To compare region of interest (ROI)-based and diffusion tensor tractography (DTT)-based methods for evaluating diffusion properties of the spinal cord as a function of age. MATERIALS AND METHODS: Commonly, an ROI segmentation is used to delineate the spinal cord. In this work, new segmentation methods are developed based on DTT. In a first, DTT-based, segmentation approach, the diffusion properties are calculated on the tracts. In a second method, the diffusion properties are analyzed in the spinal cord voxels that contain a certain number of tracts. We studied the changes in diffusion properties of the human spinal cord in subjects of different ages. Diffusion tensor imaging (DTI) measurements of the cervical spinal cord were acquired on 42 healthy volunteers (age range = 19-87 years). The fractional anisotropy (FA), the mean diffusivity (MD), and eigenvalues (lambda(1), lambda(2), and lambda(3)) were compared for the ROI- and DTT-based segmentation methods. RESULTS: Our automatic techniques are shown to be highly reproducible and sensitive for detecting DTI changes. FA decreased (r = -0.38; P < 0.05), whereas MD and eigenvalues increased (r = +/- 0.45; P < 0.05) with age. These trends were not statistically significant for the ROI-based segmentation (P > 0.05). CONCLUSION: DTT is a robust and reproducible technique to segment the voxels of interest in the spinal cord. 相似文献
7.
Hardave S Kharbanda David C Alsop Adam W Anderson Giovanni Filardo David B Hackney 《Magnetic resonance in medicine》2006,56(2):334-339
Measurement of diffusion and its dependence on direction has become an important tool for clinical and research studies of the brain. Diffusion imaging of the spinal cord may likewise prove useful as an indicator of tissue damage and axonal integrity; however, it is more challenging to perform diffusion imaging in the cord than in the brain. Here we report a study of the effects of motion on single-shot fast spin echo (FSE) diffusion tensor imaging (DTI) of the spinal cord. Diffusion imaging was performed at four different times in the cardiac cycle both without and with velocity compensation of the diffusion gradients. Uncompensated diffusion images demonstrated substantial signal loss artifacts in the cord that were strongly dependent on the delay after the pulse-oximeter trigger. Quantitative diffusion analysis was also strongly affected by this motion artifact. The use of flow-compensated gradients helped to restore normal signal in the cord, especially at particular trigger delays. Theoretical arguments suggest that improved spatial resolution may help eliminate this signal loss. Even with higher spatial resolution, motion-related signal attenuation may still occur in diffusion imaging of pathologies that alter the motion of the cord. However, this same cord motion may contain diagnostically valuable information when probed using appropriate diffusion imaging approaches. 相似文献
8.
Rossi C Boss A Steidle G Martirosian P Klose U Capuani S Maraviglia B Claussen CD Schick F 《Journal of magnetic resonance imaging : JMRI》2008,27(3):476-482
PURPOSE: To develop a reliable technique for diffusion imaging of the human spinal cord at 1.5 Tesla and to assess potential differences in diffusion anisotropy in cross-sectional images. MATERIALS AND METHODS: A single-shot echo-planar imaging sequence with double spin-echo diffusion preparation was optimized regarding cerebrospinal fluid artifacts, effective resolution, and contrast-to-noise ratios. Eleven healthy volunteers participated in the study for quantitative characterization of diffusion anisotropy in white matter (WM) and gray matter (GM) by means of two diffusion encoding schemes: octahedral-six-directions for fractional anisotropy (FA) evaluation and orthogonal-three-directions for anisotropy index (AI) calculation. RESULTS: Pulse-trigger gated sequences with optimal matrix size (read x phase = 64 x 32) and b-value (700 s/mm(2)) allowed the acquisition of high-resolved images (voxel size = 0.9 x 0.9 x 5.0 mm(3)). The GM butterfly shape was recognizable in both AI and FA maps. Both encoding schemes yielded high diffusion anisotropy in dorsal WM (FA = 0.79 +/- 0.07; AI = 0.39 +/- 0.04). Lateral WM showed slightly lower anisotropy (FA = 0.69 +/- 0.08; AI = 0.35 +/- 0.03) than dorsal WM. Clearly smaller anisotropy was found in regions containing GM (FA = 0.45 +/- 0.06; AI = 0.21 +/- 0.05). CONCLUSION: Diffusion anisotropy data of the spinal cord can be obtained in a clinical setting. Its application seems promising for the assessment of neurological disorders. 相似文献
9.
Wim Van Hecke PhD Guy Nagels MD PhD Griet Emonds MSc Alexander Leemans PhD Jan Sijbers PhD Johan Van Goethem MD PhD Paul M. Parizel MD PhD 《Journal of magnetic resonance imaging : JMRI》2009,30(1):25-34
Purpose
To examine the T2‐normal appearing spinal cord of patients with multiple sclerosis (MS) using diffusion tensor imaging.Materials and Methods
Diffusion tensor images of the spinal cord were acquired from 21 healthy subjects, 11 MS patients with spinal cord lesions, and 10 MS patients without spinal cord lesions on the T2‐weighted MR images. Different diffusion measures were evaluated using both a region of interest (ROI) ‐based and a diffusion tensor tractography‐based segmentation approach.Results
It was observed that the FA, the transverse diffusivity λ?, and the ratio of the longitudinal and transverse diffusivities (λ∥/λ ?) were significantly lower in the spinal cord of MS patients with spinal cord lesions compared with the control subjects using both the ROI method (P = 0.014, P = 0.028, and P = 0.039, respectively) and the tractography‐based approach (P = 0.006, P = 0.037, and P = 0.012, respectively). For both image analysis methods, the FA and the λ ∥/λ ? values were significantly different between the control group and the MS patient group without T2 spinal cord lesions (P = 0.013).Conclusion
Our results suggest that the spinal cord may still be affected by MS, even when lesions are not detected on a conventional MR scan. In addition, we demonstrated that diffusion tensor tractography is a robust tool to analyze the spinal cord of MS patients. J. Magn. Reson. Imaging 2009;30:25–34. © 2009 Wiley‐Liss, Inc.10.
PURPOSE: To determine whether differences in specific spinal cord white matter (WM) tracts can be detected with in vivo DTI. MATERIALS AND METHODS: In vivo DTI was performed on six rats at the lower thoracic region using a 4.7T magnet. Axial diffusion images were obtained with diffusion gradients applied in six independent directions, with low and high b-values equal to 0 and 692 seconds/mm(2), respectively. Regions of interest (ROIs) were selected corresponding to the major spinal cord tracts, including the dorsal cortical spinal tract (dCST), fasciculus gracilis (FG), rubrospinal tract (RST), vestibulospinal tract (VST), and reticulospinal tract (ReST). RESULTS: ANOVA demonstrated overall differences between tracts for all of the DTI parameters, including fractional anisotropy (FA), trace diffusion (Tr), longitudinal diffusivity (EL = lambda(1)), and transverse diffusivity (ET = (lambda(2) + lambda(3))/2). Similarly to previous ex vivo analyses, the spinal cord tract with the largest and most widely spaced axons (VST) had the largest EL and ET. CONCLUSION: The principal diffusivities appear to reflect axon morphologic differences between the WM tracts that are not as well appreciated with FA and Tr. 相似文献
11.
Quantifying the impact of underlying measurement error on cervical spinal cord diffusion tensor imaging at 3T
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Samantha By MS Alex K. Smith MS Lindsey M. Dethrage MS Bailey D. Lyttle BS Bennett A. Landman PhD Jeffrey L. Creasy MD Siddharama Pawate MD Seth A. Smith PhD 《Journal of magnetic resonance imaging : JMRI》2016,44(6):1608-1618
12.
目的:探讨磁共振扩散张量成像(DTI)在评估脊髓肿瘤患者神经功能方面的应用价值。方法对22例脊髓肿瘤患者和22例健康志愿者进行脊髓常规磁共振成像(MRI)和 DTI 扫描,分析各向异性分数(FA 值)、表观扩散系数(ADC)值和纤维束比值(FTR)的组间差异,及其与 McCormik 评分的相关性。结果2组病灶层的 FA 值(t =-5.587,P =0.000)、ADC 值(t =7.232, P =0.000)有显著差异;病灶上层的 FA 值(t=-0.438,P =0.666)、ADC 值(t =0.303,P =0.765)无显著差异;病灶下层的 FA 值(t=-1.777,P =0.090)无显著差异,ADC 值(t=2.113,P =0.047)有显著差异;2组的 FTR 值(t =-7.902,P =0.000)有显著差异。髓外肿瘤与髓内肿瘤的 FA 值、ADC 值和 FTR 值均有显著差异(P <0.05)。脊髓肿瘤组病灶层 FA 值、ADC 值、FTR 值与McCormik 分级均存在直线相关关系。结论DTI 能够直观地反映脊髓肿瘤患者的脊髓神经功能和损伤情况。 相似文献
13.
Purpose
To characterize DTI metric changes throughout the length of the entire spinal cord from the acute through chronic stages of spinal cord injury (SCI).Materials and Methods
Ex vivo DTI was performed at 9.4 Tesla to examine changes in water diffusion throughout the entire spinal cord (7‐cm) up to 25 weeks after injury in a rat model of contusive SCI. Animals were grouped according to recovery times after injury (2, 5, 15, 20, or 25 weeks), and various DTI metrics were evaluated including transverse and longitudinal apparent diffusion coefficient (tADC and lADC), mean diffusivity (MD), and fractional anisotropy (FA).Results
An overall decrease in lADC throughout the cord and decreases in MD remote from the lesion site were observed, along with an increase in tADC within fiber tracts throughout the recovery period. These trends were statistically significant at P < 0.05 and were found in both white and gray matter regions. tADC and lADC distributions in fiber bundles extracted using DTI tractography were well fit by an exponential model (R = 0.998) with time constants of 4.6 and 3.3 days, respectively.Conclusion
Results from the current study support the hypothesis that the spinal cord undergoes continual changes during recovery from SCI. J. Magn. Reson. Imaging 2008;28:1068–1079. © 2008 Wiley‐Liss, Inc. 相似文献14.
B J Wilm J Svensson A Henning K P Pruessmann P Boesiger S S Kollias 《Magnetic resonance in medicine》2007,57(3):625-630
A spin-echo single-shot echo-planar imaging (SS-EPI) technique with a reduced field of view (FOV) in the phase-encoding direction is presented that simultaneously reduces susceptibility effects and motion artifacts in diffusion-weighted (DW) imaging (DWI) of the spinal cord at a high field strength (3T). To minimize aliasing, an outer volume suppression (OVS) sequence was implemented. Effective fat suppression was achieved with the use of a slice-selection gradient-reversal technique. The OVS was optimized by numerical simulations with respect to T(1) relaxation times and B(1) variations. The optimized sequence was evaluated in vitro and in vivo. In simulations the optimized OVS showed suppression to <0.25% and approximately 3% in an optimal and worst-case scenario, respectively. In vitro measurements showed a mean residual signal of <0.95% +/- 0.42 for all suppressed areas. In vivo acquisition with 0.9 x 1.05 mm(2) in-plane resolution resulted in artifact-free images. The short imaging time of this technique makes it promising for clinical studies. 相似文献
15.
Qian W Chan Q Mak H Zhang Z Anthony MP Yau KK Khong PL Chan KH Kim M 《Journal of magnetic resonance imaging : JMRI》2011,33(6):1312-1320
Purpose:
To investigate whether quantitative MRI measures of cervical spinal cord white matter (WM) using diffusion tensor imaging (DTI) in neuromyelitis optica (NMO) differed from controls and correlated with clinical disability.Materials and Methods:
Ten referred patients and 12 healthy volunteers were imaged on a 3 Tesla scanner and patients were clinically assessed on the Expanded Disability Status Scale (EDSS). Two raters quantified DTI‐derived indices from all participants, including fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (lambda[parallel]) and perpendicular diffusivity (lambda[perpendicular]) at C1–C6 for lateral and dorsal columns. After the inter‐rater reliability test, univariate correlations between DTI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analysis was performed to investigate which DTI measures independently correlated with the clinical score.Results:
Statistical test results indicated high reliability of all DTI measurements between two raters. NMO patients showed reduced FA, increased MD and lambda[perpendicular] compared with controls while lambda[parallel] did not show any significant difference. The former three DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO (EDSS ≤ 3)Conclusion:
FA is a potentially useful quantitative biomarker of otherwise normal appearing WM damage in NMO. Such damage is associated with clinical disability. J. Magn. Reson. Imaging 2011;33:1312–1320. © 2011 Wiley‐Liss, Inc. 相似文献16.
Magnetic resonance imaging of mouse spinal cord. 总被引:2,自引:0,他引:2
Mehmet Bilgen Baraa Al-Hafez Nancy E J Berman Barry W Festoff 《Magnetic resonance in medicine》2005,54(5):1226-1231
The feasibility of performing high-resolution in vivo MRI on mouse spinal cord (SC) at 9.4 T magnetic field strength is demonstrated. The MR properties of the cord tissue were measured and the characteristics of water diffusion in the SC were quantified. The data indicate that the differences in the proton density (PD) and transverse relaxation time between gray matter (GM) and white matter (WM) dominate the contrast seen on the mouse SC images at 9.4 T. However, on heavily T(2)-weighted images these differences result in a reversal of contrast. The diffusion of water in the cord is anisotropic, but the WM exhibits greater anisotropy and principal diffusivity than the GM. The quantitative data presented here should establish a standard for comparing similar measurements obtained from the SCs of genetically engineered mouse or mouse models of SC injury (SCI). 相似文献
17.
Apparent diffusion coefficient and fractional anisotropy in spinal cord: age and cervical spondylosis-related changes 总被引:3,自引:0,他引:3
PURPOSE: To present the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) change with age in the normal spinal cord and in cervical spondylosis. MATERIALS AND METHODS: A total of 11 normal volunteers and 79 cervical spondylosis patients entered this study. Line scan diffusion tensor images were obtained in a 1.5-Tesla whole-body scanner using a phased-array spine coil. The ADC and FA values were measured on a sagittal section. Spearman correlation of ADC/FA vs. age for normal spinal cord was calculated. RESULTS: The mean ADC of the normal spinal cord was 0.81 +/- 0.03 microm(2)/msec at the relatively wide C2-C3 level and 0.75 +/- 0.06 microm(2)/msec at the more narrow C4-C7 level. The FA at the corresponding level was 0.70 +/- 0.05 and 0.66 +/- 0.03, respectively. With age, ADC showed positive correlation (Spearman, r = 0.242) and FA exhibited negative correlation (Spearman, r = -0.244). A total of 54% of all spondylosis cases showed elevated ADC (P < 0.001) and decreased FA (P < 0.001) at the stenotic spinal canal level compared with the normal spinal cord. The average ADC and FA of high-signal lesions on T2-weighted images (seven patients) were 1.28 +/- 0.33 microm(2)/msec and 0.46 +/- 0.12, respectively. CONCLUSION: ADC increases and FA decreases with age in the normal spinal cord. Elevated ADC and reduced FA were measured in the spinal cord of spondylosis cases with clinical symptoms of myelopathy. 相似文献
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19.
Henrik Lundell Dorothy Barthelemy Fin Biering‐Sørensen Julien Cohen‐Adad Jens Bo Nielsen Tim B. Dyrby 《Magnetic resonance in medicine》2013,69(1):144-149
Diffusion tensor imaging has been used in a number of spinal cord studies, but severe distortions caused by susceptibility induced field inhomogeneities limit its applicability to investigate small volumes within acceptable acquisition times. A way to evaluate image distortions is to map the point spread function of the voxel intensity in a reference scan. In this study, the point spread function was mapped for an echo‐planar imaging sequence in the human cervical spinal cord with isotropic resolution and large field of view. Correction with the point spread function map improved anatomical consistency, and full cervical tractography was thereby possible from a C1 seed region in healthy controls and one individual with spinal cord injury. It is suggested that point spread function mapping of the spinal cord can be used in combination with sequence‐based methods for reduction of susceptibility artifacts or in high‐field imaging settings where off‐resonance effects are pronounced. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
20.
John C. Ford David B. Hackney David C. Alsop Hernan Jara Peter M. Joseph Christopher M. Hand Perry Black 《Magnetic resonance in medicine》1994,31(5):488-494
Apparent diffusion coefficients (ADC) were measured in a rat spinal cord weight-drop injury model. After sacrifice, the spinal cords were fixed in situ and excised for MR imaging and ADC measurement. Diffusion is anisotropic in normal gray and white matter. There were significant decreases in ADCs measured along the longitudinal axis of the injured cord and increases in ADCs measured transverse to the cord. Injured segments demonstrated reductions in diffusion anisotropy in the white matter. Diffusion was completely isotropic at the epicenter of the weight-drop injury. Significant decreases in longitudinal ADC and increases in transverse ADC were observed in portions of the cord which appeared normal on conventional spin-echo and calculated T2 images. Thus ADC measurement may complement routine imaging for evaluation of spinal cord injury. 相似文献