多发性硬化及视神经脊髓炎患者颈髓的扩散张量成像定量研究

目的 运用3.0 T MR DTI技术探讨复发-缓解型多发性硬化(RRMS)患者及复发型视神经脊髓炎(RNMO)患者颈髓结构的改变,以及与临床评分的相关性.方法 应用3.0TMR对30例RRMS(MS组)、28例RNMO患者(NMO组)及20名健康志愿者(对照组)行颈髓DTI,分别测量C2 ～6颈髓中央灰质、右侧索、左侧索和后索等部位的平均扩散率(MD)和部分各向异性分数(FA),并对各测量值和扩展残疾状况量表(EDSS)评分进行相关性分析.统计学分析采用单因素方差分析及Spearman秩相关分析等.结果 (1)3组间MD值在C3水平后索和左侧索、C4水平中央灰质和后索、C5 ～6水平各部位差异具有统计学意义(F值为4.006 ～ 36.814,P值均＜0.05),3组间FA值在各层面差异均具有统计学意义(F值为5.561 ～98.128,P值均＜0.05).(2)MS组、NMO组和对照组两两比较:MS组、NMO组较对照组MD值升高,FA值降低,差异有统计学意义(t值为-0.320～3.138,P值均＜0.05);MS组和NMO组比较,MD值的差异无统计学意义(t值为-1.183 ～0.069,P值均＞0.05);NMO组在C4水平中央灰质、后索、右侧索、左侧索FA值分别为0.57±0.09、0.56±0.11、0.54±0.10、0.57±0.09,C5水平分别为0.55 ±0.11、0.52±0.13、0.55±0.11、0.54±0.13,C6水平分别为0.54±0.10、0.54 ±0.11、0.53 ±0.13、0.52 ±0.11;相对应MS组C4水平FA值为0.67 ±0.10、0.68±0.10、0.68 ±0.10、0.70±0.12,C5水平为0.68 ±0.11、0.69 ±0.10、0.68 ±0.11、0.69 ±0.12,C6水平为0.67±0.14、0.68 ±0.15、0.69±0.14、0.69±0.16,两组间C4 ～6水平FA值差异均有统计学意义(t值为-0.011 ～0.169,P值均＜0.05).(3)除C2及C4水平侧索外,其余各层面MD值同EDSS评分呈正相关(r值为0.324 ～0.541,P值均＜0.05),FA值同EDSS评分呈明显负相关(r值为-0.632 ～-0.294,p值均＜0.05).结论 DTI定量指标对颈髓的脱髓鞘病变敏感,在鉴别MS与NMO上具有潜在的应用价值;并可作为脱髓鞘病变临床监测的重要生物学指标.     

The cervical spinal cord in neuromyelitis optica patients: a comparative study with multiple sclerosis using diffusion tensor imaging

Introduction

This study aims to evaluate “in vivo” the integrity of the normal-appearing spinal cord in patients with neuromyelitis optica (NMO), using diffusion tensor MR imaging, comparing to controls and patients with multiple sclerosis (MS).

Materials and methods

We studied 8 patients with NMO and 17 without any neurologic disorder. Also, 32 MS patients were selected. Fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) were calculated within regions of interest at C2 and C7 levels in the four columns of the spinal cord.

Results

At C2, the FA value was decreased in NMO patients compared to MS and controls in the anterior column. Also in this column, RD value showed increase in NMO compared to MS and to controls. The FA value of the posterior column was decreased in NMO in comparison to controls. At C7, AD value was higher in NMO than in MS in the right column. At the same column, MD values were increased in NMO compared to MS and to controls.

Conclusions

There is extensive NASC damage in NMO patients, including peripheral areas of the cervical spinal cord, affecting the white matter, mainly caused by demyelination. This suggests a new spinal cord lesion pattern in NMO in comparison to MS.     

A diffusion tensor imaging group study of the spinal cord in multiple sclerosis patients with and without T2 spinal cord lesions

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.

     

Redefinition of multiple sclerosis plaque size using diffusion tensor MRI

OBJECTIVE: We used diffusion tensor MRI to redefine the size of multiple sclerosis (MS) plaques on fractional anisotropy (FA) maps. MATERIALS AND METHODS: Thirty-six white matter (WM) plaques were identified in 20 patients with MS. Plaque FA was measured by placing regions of interest (ROIs) on plaques on diffusion tensor images. We compared FA values in identical mirror-image ROIs placed on normal-appearing WM in the contralateral hemisphere. This comparison showed a mean decrease in FA of 41% in plaques, serving as the threshold for outlining abnormal regions in normal-appearing WM surrounding plaques. ROIs were placed around each plaque and FA values were compared with those in the mirror-image ROIs. Combined areas of perilesional normal-appearing WM with 40% or more FA reduction plus plaque were compared with the areas of abnormality on T2-weighted images using a paired Student's t test. A p value of 0.05 or less was considered significant. RESULTS: Mean plaque area was 60 mm(2) (range, 15-103 mm(2)), mean plaque FA was 0.251 (range, 0.133-0.436), and mean FA of contralateral normal-appearing WM was 0.429 (range, 0.204-0.712). Applying a threshold of 40% FA reduction, mean combined area of abnormal WM (including plaque seen on T2-weighted sequences) was 87 mm(2) (range, 30-251 mm(2)) or 145% of the mean plaque area that was seen on T2-weighted images (p < 0.001). CONCLUSION: Using an operator-defined threshold of abnormal FA values based on plaque anisotropy characteristics, we saw a statistically significant increase in plaque size.     

Postmortem MRI of the spinal cord in multiple sclerosis

Postmortem magnetic resonance imaging (MRI) of the spinal cord and the brainstem in a patient with multiple sclerosis are compared with the histopathological findings. Abnormal high signal intensity areas on T2-weighted images correspond precisely to demyelinated areas.     

脊髓多发性硬化的MRI诊断

目的：提高对脊我发性硬化ＭＲＩ特征的认识。材料与方法：地１４例脊髓多发性硬化患者进行颈部ＭＲＩ检查。对病变的长度，横断面上病变大小、位置及病变的强化进行评价结果：１４例患者共发现病变３１个。脊髓多发性硬化ＭＲＩ特征性表现为；大多数为矢状位长度小于２个椎体（８７．１％），病变长度大于宽度，病变局部脊髓政党或轻度肿胀。结论：ＭＲＩ不仅可以发现脊髓多发化病变，并且能显示其特征性表现，有助于与其他脊人病变     

Line scan diffusion tensor MRI of the cervical spinal cord in preterm infants

Line scan diffusion tensor magenetic resonance imaging (DT-MRI) of the cervical spinal cord was demonstrated in vivo for unsedated preterm (gestational age 24-30 weeks at birth), very low birthweight (birthweight 620-1300 g) infants at postmenstrual ages from 29-40 weeks. Scalar invariant measures of diffusion [apparent diffusion coefficient (ADC) and relative anisotropy (RA)] determined from a cervical cord region of interest in each case are reported, characterizing the maturational status of the normal third trimester and newborn spinal cord. Mean ADC of 11 infants was 1.2 +/- 0.1 microm(2)/msec and the mean RA was 24.3 +/- 4.9%. Normal infant cord neural fiber tract morphology was visualized using a mapping of the predominant diffusion tensor eigenvector. Potential clinical applications of line scan DT-MRI of the spinal cord of preterm and term newborns for assessment of spinal cord injury are discussed. J. Magn. Reson. Imaging 2001;13:949-953.     

肌萎缩侧索硬化症的颈髓MR扩散张量成像研究

目的 了解常规MR检查阴性的肌萎缩侧索硬化症(ALS)患者颈髓DTI的各项参数值的变化情况.方法 选取临床诊断为ALS患者(ALS组)16例及16名年龄、性别匹配的健康志愿者(正常组)行颈髓常规MRI及横断面DTI.DTI图像经工作站(AW4.2)后处理,获得ADC图、部分各向异性(FA)图和相对各向异性(RA)图.在C3椎体水平层面分别在颈髓前索区、后索区及双侧皮质脊髓侧束区4个区域内选取面积约5 mm ×5 mm的ROI,测定其ADC值、FA值和RA值.使用独立样本t检验对两组间各项参数值进行比较,使用Pearson相关分析分别对ALS患者异常参数值与ALS患者病程、Norris评分及功能质量相关评分(ALSFRS)进行相关性分析.结果 ALS组左、右侧皮质脊髓侧束的FA、RA值较正常组减低.其中ALs组左侧皮质脊髓侧束的FA、RA值为0.762±0.089、0.762±0.107,正常组为0.863±0.098、0.890±0.105;ALS组右侧皮质脊髓侧束的FA、RA值为0.751±0.065、0.772±0.082,正常组为0.843±0.118、0.863±0.134,差异均具有统计学意义(t值分别为2.575、4.195、2.246、2.218,P值均<0.05).ALS组左、右侧皮质脊髓侧束的ADC值分别为(0.744±0.162)、(0.767±0.141)×10~(-3)mm~2/s,正常组为(0.640±0.149)、(0.643±0.168)×10~(-3)mm~2/s,两组间差异无统计学意义(t值分别为-1.319、-1.087,P值均>0.05).ALS组前索FA、RA及ADC值分别为0.637±0.113、0.622±0.138、(0.950±0.354)× 10~(-3)mm~2/s,正常组分别为0.670±0.117、0.656±0.136、(0.865±0.238)×10~(-3)mm~2/s,两组间差异无统计学意义(t值分别为0.854、-0.704、-1.155,P值均>0.05).ALS组后索FA、RA及ADC值分别为0.886±0.073、0.920±0.100、(0.613±0.137)×10~(-3)mm~2/s,正常组分别为0.906±0.078、0.914±0.135、(0.636±0.224)×10~(-3)mm~2/s,两组间差异也无统计学意义(t值分别为1.655、-0.148,-1.360,P值均>0.05).ALS患者左、右侧皮质脊髓侧束FA、RA值与ALS病程、临床Norris评分及ALSFRS之间均无相关性(P值均>0.05).结论 SE-EPI序列DTI用于ALS患者颈髓的检测,其扫描方法简单且比较敏感,可以反映常规MRI上未能显示的病理学改变.     

肌萎缩侧索硬化症的颈髓MR扩散张量成像研究

Objective To determine whether normal-appearing cervical spinal cord in patients with amyotrophic lateral sclerosis (ALS) has abnormal changes based on the quantitative measurement in healthy volunteers. Methods Conventional MRI and axial DTI were obtained in 16 patients with ALS (ALS group) and 16 age-matched control subjects (normal group) . ADC, fractional anisotropy (FA) and relative anisotropy(RA)imagcs were obtained on workstation (AW4. 2). ROIs (5 mm × 5 mm) were placed in anterior funicalus, posterior funiculus, and bilateral lateral corticospinal tracts (LCTs), respectively, at the same slice (C3). Independent-sample t test was used for comparison of parameters between the two groups. Correlations between DTI parameters of ALS and ALS course, Norris score, and ALSFRS were carried out separately by Pearson correlation analysis. Results FA and RA values of bilateral LCTs were decreased significantly. FA/RA values of left LCT were 0.762±0.089 and 0.762±0.107 in ALS group, while they were 0.863±0.098 and 0.890±0.105 in control group, respectively. FA/RA values of right LCT were 0.751±0.065 and 0.772±0.082 in ALS group, and they were 0.843±0.118 and 0.863±0.134 in control group, respectively, they were decreased significantly (t = 2.575、4.195、2.246、2.218, P < 0.05). There were no significant differences (t = - 1.319, - 1.087, P > 0.05) between ADC values of left and right CSTs in ALS group [(0.744±0.162) × 10-3, (0.767±0.141) × 10-3 mm2/s] and control group [(0.640±0.149) ×10-3, (0.643±0.168) ×10-3 mm2/s)]. FA, RA and ADC values of ALS patients in anterior funiculus were 0.637±0.113, 0.622±0.138, (0.950±0.354)×10-3 mm2/s, in control group they were 0.670±0.117, 0.656±0.136, (0.865±0.238) × 10-3 mm2/s, there were no significant differences (t = 0.854, - 0.704, - 1.155,P > 0.05). FA, RA and ADC values of ALS patients in posterior funieulus were 0.886±0.073, 0.920±0.100, (0.613±0.137)×10-3 mm2/s, in control group they were 0.906±0.078, 0.914±0.135, (0.636±0.224) × 10-3 mm2/s, there were no significant differences (t = 1.655, - 0.148, - 1.360; P > 0.05). No significant correlation existed between FA and RA values and disease course, Norris and ALSFRS score (P > 0.05), in left and right LCTs. Conclusion DTI with SE-EPI technique is simple and sensitive to detect the pathological changes of the cervical spinal cord in ALS patients. DTI can reveal the abnormalities which are "normal appearing" on conventional T2WI.     

Medulla oblongata volume: a biomarker of spinal cord damage and disability in multiple sclerosis

BACKGROUND AND PURPOSE: While brain MR imaging is routinely performed, the MR imaging assessment of spinal cord pathology in multiple sclerosis (MS) is less frequent in clinical practice. The purpose of this study was to determine whether measurements of medulla oblongata volume (MOV) on routine brain MR imaging could serve as a biomarker of spinal cord damage and disability in MS.MATERIALS AND METHODS: We identified 45 patients with MS with both head and cervical spinal cord MR imaging and 29 age-matched and sex-matched healthy control subjects with head MR imaging. Disability was assessed by the expanded disability status scale (EDSS) and ambulation index (AI). MOV and upper cervical cord volume (UCCV) were manually segmented; semiautomated segmentation was used for brain parenchymal fraction (BPF). These measures were compared between groups, and linear regression models were built to predict disability.RESULTS: In the patients, MOV correlated significantly with UCCV (r = 0.67), BPF (r = 0.45), disease duration (r = −0.64), age (r = −0.47), EDSS score (r = −0.49) and AI (r = −0.52). Volume loss of the medulla oblongata was −0.008 cm³/year of age in patients with MS, but no significant linear relationship with age was found for healthy control subjects. The patients had a smaller MOV (mean ± SD, 1.02 ± 0.17 cm³) than healthy control subjects (1.15 ± 0.15 cm³), though BPF was unable to distinguish between these 2 groups. MOV was smaller in patients with progressive MS (secondary- progressive MS, 0.88 ± 0.19 cm³ and primary-progressive MS, 0.95 ± 0.30 cm³) than in patients with relapsing-remitting MS (1.08 ± 0.15 cm³). A model including both MOV and BPF better predicted AI than BPF alone (P = .04). Good reproducibility in MOV measurements was demonstrated for intrarater (intraclass correlation coefficient, 0.97), interrater (0.79), and scan rescan data (0.81).CONCLUSION: MOV is associated with disability in MS and can serve as a biomarker of spinal cord damage.

Multiple sclerosis (MS) is a multifactorial disease with a strong neurodegenerative component associated with progressive atrophy of the brain and spinal cord.¹ Previous studies have shown involvement of the spinal cord in more than 80% of the patients with clinically definite MS.^2–5 Atrophy of the spinal cord is thought to originate mainly from neurodegenerative changes, especially of the cervical segment,^4,6–10 which results in impairment of motor function.^11–16 In contrast, brain atrophy correlates well with neuropsychologic impairment.¹ The most severe and debilitating physical disability in MS seems to be of spinal origin. Therefore, it has been suggested that measurements of upper spinal cord volume provides information regarding disease progression that is complementary to the assessment of brain atrophy.Although head MR imaging is routinely performed in patients with MS, spinal cord MR imaging takes additional time and is therefore performed only on specific indications, both in the clinic and research.The medulla oblongata is the most caudal part of the brain stem and is continuous with the spinal cord. It contains nuclei that are important for autonomic control such as respiration, heart rate, blood pressure and reflexes, and white matter (WM) tracts that connect the rostral and caudal parts of the central nervous system (CNS). Ventral, dorsal, and lateral funiculi in the lower medulla oblongata are continuous with those of the spinal cord.The medulla oblongata is generally included in the field of view (FOV) of routine brain MR images of patients with MS. We set out to explore the feasibility and clinical relevance of volumetric measures of the lower medulla oblongata and hypothesized that these measures will reflect spinal cord atrophy. The relative ease to obtain such measurements from routinely performed clinical MR imaging examinations of the head makes this a potentially strong candidate for a biomarker of spinal cord damage and disability. In this work we present the results of a retrospective analysis of MR imaging-derived medulla oblongata volume (MOV) in MS to establish the relationship to spinal cord, its correlation with clinical disability and the reproducibility of this metric.     

多发性硬化患者脑灰质损害的MRI表现及扩散张量成像定量研究

目的 分析多发性硬化(MS)患者脑灰质病灶的MRI特征及表现正常的脑灰质(NAGM)是否存在隐匿性损伤.方法 对34例临床确诊的MS患者(MS组)和25名健康志愿者(对照组)行常规头颅MRI和扩散张量成像(DTI),观察MS的脑灰质病灶特征,测量深部灰质核团的平均扩散率(ADC)和各向异性分数(FA),采用非配对t检验比较两组间是否存在差异.结果 MR检查发现MS的脑灰质病灶共83个,占全部病灶(443个)的18.7%.分布以额叶最多,其次是颞叶与丘脑.大多数病灶呈圆形或类圆形,其中T2WI发现灰质病灶60个,液体衰减反转恢复(FLAIR)序列T2WI发现病灶78个,其中71个病灶呈高或稍高信号,3个病灶呈中心低、周围稍高的环形改变,4个呈低信号.扩散加权成像(DWI)发现高信号或低信号病灶36个,其中有9个小病灶在DWI呈明显高信号.其余病灶呈等信号而不能被发现.MS组尾状核头、壳核、丘脑的ADC值分别为(8.0±0.7)、(7.4 ±0.5)、(7.7±0.4)×10-4mm2/s,均高于对照组[分别为(7.4±0.6)、(7.0 ±0.5)、(7.2±0.7)×10-4mm2/s],差异具有统计学意义(t值分别为-3.079、-2.564、-2.722,P值均<0.05).结论 MS的脑灰质病灶在常规MRI和DWI上的表现有一定的特征,FLAIR联合DWI可提高病灶的检出,DTI可以反映出NAGM内的隐匿性损害.     

Diffusion tensor MR imaging of the cervical spinal cord in patients with multiple sclerosis

Our purpose was to evaluate the ability of diffusion tensor imaging (DTI) to characterize cervical spinal cord white matter (WM) in patients with multiple sclerosis (MS). DTI were obtained in 21 MS patients and 21 control subjects (CS). Regions of interest (ROIs) were placed at C2/3, C3/4, and C4/5 within the right, left, and dorsal (WM) to calculate fractional anisotropy (FA) and the apparent diffusion coefficient (ADC). Measurements in plaques and normal-appearing white matter (NAWM) of MS patients were compared with mean FA and ADC of WM in CS. FA was significantly lower in all regions in MS patients than in CS. ADC was significantly higher in all regions in MS patients than in CS except for in the dorsal WM at C2/3 and the bilateral WM at C4/5. The mean FA was 0.441 for plaques and 0.542 for NAWM, as compared with 0.739 in CS. The mean ADC was 0.810 × 10⁻³ mm²/s for plaques and 0.722 × 10⁻³ mm²/s for NAWM, as compared with 0.640 ×10⁻³ mm²/s for CS. FA and ADC showed significant differences between plaques, NAWM and control WM(P < 0.01).     

MR diffusion tensor imaging and fiber tracking in spinal cord arteriovenous malformations: a preliminary study

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) of the spinal cord in patients harboring spinal arteriovenous malformations (AVMs) was carried out to evaluate the feasibility of this new technique to determine the displacement of the spinal cord tracts and to correlate morphologic and functional DTI data (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) with the clinical symptoms. MATERIALS AND METHODS: Nine patients with spinal cord AVMs were investigated at 1.5T using a sagittal spin-echo single-shot echo-planar generalized autocalibrating partially parallel acquisition diffusion-weighted imaging sequence. ADC and FA maps were computed in different regions of interest (both above and below the nidus), and tractography was used to visualize the course of the tracts. The data were correlated with the clinical symptoms and compared with 12 healthy control subjects. RESULTS: At the level of the nidus, tracts were normal, shifted, separated, or interrupted but not intermingled with the nidus. Interruption of the tracts was coherent with the clinical symptoms. In patients with severe neurologic deficits, FA values caudal to the nidus showed a reduced anisotropy consistent with loss of white matter tracts. CONCLUSIONS: We demonstrate that AVMs may interrupt, displace, or separate the fiber tracts and that clinical symptoms may be reflected by the quantitative FA results and the morphologic loss of fibers distant to the lesion. DTI with fiber tracking offers a novel approach to image spinal cord AVMs and may open a window to understand the complex pathophysiology of these lesions.     

Diffusion tensor MRI of the spinal cord.

Apparent diffusion tensor (ADT) measurements on the spinal cord using a pulsed-field-gradient (PFG) multi-shot echo-planar imaging (EPI) sequence are presented. In a study of 10 healthy volunteers, the obtained rotationally invariant anisotropy information is compared to the results obtained by the rotationally dependent methods. The water diffusivity in the direction parallel to the fibers was found to be almost 2.5 times higher than the average diffusivity in directions perpendicular to the fibers and showed cylindrically symmetric anisotropy characteristics. The influence of partial volume effects and the point spread function on the measured results was evaluated, and it was the concluded that a resolution of 1 mm in the read and phase directions is required to obtain unbiased values. Possible clinical implications were demonstrated by investigating the diffusion characteristics of 10 patients suffering from narrowing of the cervical canal. The changes in the diffusion characteristics were found to be large enough to allow a robust detection of diffusion changes in the spine, even in cases in which conventional T(2) and T(1) weighted images were unable to detect any lesion.     

正常人颈髓扩散张量成像最佳参数研究

目的：比较不同 b 值、不同数量扩散梯度方向（NDGDs）3．0T 磁共振（MRI）扩散张量成像（DTI）对正常人颈髓成像的影响;探讨颈髓最佳 DTI 参数。方法：随机选取健康志愿者20例,进行颈髓矢状面 DTI 扫描,选用 b 值分别为0、200、400、600、800、1000 s/mm2,NDGDs 选择6、12、20。分别在不同 b 值、不同 NDGDs 条件下,分析图像质量以及颈髓各向异性（FA）值、表观扩散系数（ADC）值。结果：当 NDGDs 不变（20）,随 b 值增加图像信噪比及质量指数递减（F ＝28．694、30．272,P ＜0．05）,且不同 b 值条件下 FA、ADC 值无组间差异性（F ＝0．495、0．359,P ＞0．05）。当 b 值不变（600 s/mm2）,随 NDGDs 增加图像质量评分递增（F ＝11．927,P ＜0．05）,不同 NDGDs 条件下 FA、ADC 值无组间差异性（F ＝0．08、0．583,P ＞0．05）,但 NDGDs 为20与6、12分别两两比较,FA 值之间差异有统计学意义（P ＜0．05）。结论：使用西门子3．0T 磁共振 DTI 技术,选取 b 值为600 s/mm2,NDGDs 为20的条件下,得到最佳的颈髓 DTI 图像。     

颈髓白质纤维束磁共振扩散张量成像的初步研究

目的:利用磁共振弥散张量成像(DTI)研究正常成人颈髓的各向异性程度,探讨颈髓白质纤维束成像的可能性和应用价值。方法:使用单次激发自旋回波平面回波(SE-EPI)序列对14例MR检查正常的健康志愿者行颈髓弥散张量成像检查。重建FA图,在颈髓各节段分别测量FA值。利用日本东京大学Masutani开发的DTVⅡ和VolumeOne纤维束示踪成像软件进行白质纤维束成像。结果:颈髓平均FA值0.6583±0.0737,所有FA图上颈髓显示清晰,没有明显图像失真。白质纤维束成像三维显示颈髓大部分主要的纤维束。结论:DTI有效地显示颈髓白质纤维的各向异性特征及白质纤维束的分布和走向,对颈髓疾病的研究提供了新的方法。     

正常人颈髓MR扩散张量成像的初步研究

目的探讨颈髓扩散张量成像(DTI)的方法,获取正常人颈髓DTI的参数值,为颈髓病变的DTI研究提供依据。方法使用单次激发自旋回波平面回波(SE-EPI)序列对36例健康志愿者行颈髓扩散张量成像检查。在颈髓各节段分别测量其表观扩散系数(ADC)值、各向异性分数(FA)值、第1本征值(λ1)、第2本征值(λ2)以及第3本征值(λ3)。结果所有志愿者均完成该项检查,后处理图像上颈髓显示清晰,没有明显图像失真。颈髓ADC值为(914.44±82.61)×10-6mm2/s,FA值为(593.84±52.22)×10-3,λ1、λ2、λ3分别为(1585.10±130.07)×10-6mm2/s、(559.84±66.49)×10-6mm2/s、(613.28±128.71)×10-6mm2/s。λ1与λ2、λ3值比较,λ1值明显大于λ2及λ3,差异有统计学意义(P<0.05),λ2与λ3之间差异无统计学意义(P>0.05)。2λ1/(λ2+λ3)的比值为2.74±0.32。结论使用SE-EPI序列行颈髓DTI的检查能够获得比较满意的图像,测得的各项张量参数值稳定。平行于脊髓长轴方向的水分子扩散活动明显强于垂直于脊髓长轴方向的扩散,从而提示脊髓具有圆柱状的扩散特点。