Serial diffusion tensor imaging to characterize radiation-induced changes in normal-appearing white matter following radiotherapy in patients with adult low-grade gliomas

Purpose The aim of this study was to ascertain whether diffusion tensor imaging (DTI) metrics—fractional anisotropy (FA), mean diffusivity (MD), linear case (CL), planar case (CP), spherical case (CS)—can characterize a threshold dose and temporal evolution of changes in normal-appearing white matter (NAWM) of adults with low-grade gliomas (LGGs) treated with radiation therapy (RT). Methods and materials Conventional and DTI imaging were performed before RT in 5 patients and subsequently, on average, at 3 months (n = 5), 8 months (n = 3), and 14 months (n = 5) following RT for a total of 18 examinations. Isodose distribution at 5-Gy intervals were visualized in all the slices of fluid attenuated inversion recovery (FLAIR) and the corresponding DTI images without diffusion sensitization (b0DTI). The latter were exported for relative quantitative analysis. Results Compared to pre-RT values, FA and CL decreased, whereas CS increased at 3 and 8 months and recovered partially at 14 months for the dose bins > 55 Gy and 50–55 Gy. For the 45–50 Gy bin, the FA and CL decreased with an increase in CS at 3 months; no further change was seen at 8 or 14 months. For the >55 Gy and 50–55 Gy bins, CP decreased and MD increased at 3 months and returned to baseline at 8 months following RT. Conclusion Radiation-induced changes in NAWM can be detected at 3 months after RT, with changes in FA, CL, and CS (but not CP or MD) values seen at a thresh-old dose of 45–50 Gy. A partial recovery was evident by 14 months to regions that received doses of 50–55 Gy and >55 Gy, thus providing an objective measure of radiation effect on NAWM.     

Increased anisotropy in neonatal meningitis: an indicator of meningeal inflammation

Introduction Increased anisotropy in brain abscesses has been shown to be due to adhesion of inflammatory cells and is suggestive of an active inflammatory process. The objective of this study was to determine if similar changes occur in the pia-arachnoid on the surface of the cerebral cortex in patients with pyogenic meningitis, and if these changes regress following antibiotic therapy. Methods Diffusion tensor imaging (DTI) was performed on 14 term neonates (mean age 13 days) with bacterial meningitis and 10 healthy age- and sex-matched controls. Regions of interest (ROIs) were placed on areas including the leptomeninges, the cerebral cortex and adjoining subcortical white matter for quantitation of mean fractional anisotropy (FA) and diffusivity (MD) values. Follow-up MRI was performed in five of the neonates in the patient group after 2 weeks of antibiotic treatment. FA and MD values were compared in patients before and after antibiotic treatment as well as with those in the healthy controls. Results Significantly higher FA values but no difference in MD values were observed in the patient group as compared to the healthy controls at both time points (before and after antibiotic treatment). Significantly decreased FA values in the frontal, occipital and temporal cortical regions were observed in patients following antibiotic treatment. Conclusion DTI-derived FA may be of value in the noninvasive assessment of meningeal inflammatory activity and treatment response in neonates.     

Diffusion tensor imaging of the auditory pathway in sensorineural hearing loss: changes in radial diffusivity and diffusion anisotropy

PURPOSE: To prospectively compare diffusion tensor imaging (DTI) measures of axial diffusivity (lambda parallel), radial diffusivity (lambda perpendicular), mean diffusivity (MD), and fractional anisotropy (FA) along the auditory pathway of patients with sensorineural hearing loss (SNHL) and normal controls. MATERIALS AND METHODS: In 37 individuals with SNHL and 10 healthy controls, two regions of interest (ROIs) positioned along the auditory pathway-the lateral lemniscus (LL) and the inferior colliculus (IC)-were investigated bilaterally using diffusion tensor imaging at 3 T. SNHL patients were divided into three groups: patients with bilateral hearing loss, patients with unilateral hearing loss, and patients with partial hearing loss. DTI measures (lambda parallel, lambda perpendicular, MD, FA) of both ROIs were determined in all subjects. RESULTS: The FA value was reduced and the lambda perpendicular was increased both at the lateral lemniscus and the inferior colliculus of patients with SNHL compared with controls. Similar changes were seen between the ipsilateral and contralateral LL and IC for patients of unilateral profound hearing loss. No changes were observed in any other parameters. CONCLUSION: In SNHL patients DTI showed a high radial diffusivity that consequently led to a decreased fractional anisotropy in the LL and the IC.     

Diffusion tensor and tensor metrics imaging in intracranial epidermoid cysts

Purpose

To explore the utility of diffusion tensor imaging (DTI) and diffusion tensor metrics (DTM) in characterizing the structural pathology of epidermoid cysts. DTI gives information about the tissue structure; a high fractional anisotropy (FA) indicates a highly structured orientation of the tissue, fibers, or white matter tracts. Based on the tensor rank, a set of three metrics has been described that can be used to measure the directional dependence of diffusion: linear anisotropy (CL), planar anisotropy (CP), and spherical anisotropy (CS). DTM takes into account the shape of diffusion anisotropy and hence may provide better insight into the orientation of structures than FA.

Materials and Methods

DTI was performed in three patients with epidermoid cysts. FA, directionally‐averaged mean diffusivity (Dav), exponential apparent diffusion coefficient (eADC), and DTM, such as CL, CP, and CS, were measured from the tumor core as well as from the normal‐appearing white matter. Histopathological correlation was obtained.

Results

Epidermoid cysts showed high FA with Dav values similar to that of normal white matter. eADC maps did not show any restriction of diffusion. FA values were high, but not as high as that for the white matter. CP values were higher and CL values were lower than those obtained for the white matter in various regions.

Conclusion

High CP values suggest preferential diffusion of water molecules along a two‐dimensional geometry, which could be attributed to the well‐structured orientation of keratin filaments and flakes within the tumor as demonstrated by histopathology. Advanced imaging modalities like DTI with DTM can provide information regarding the microstructural anatomy of the epidermoid cysts. J. Magn. Reson. Imaging 2009;29:967–970. © 2009 Wiley‐Liss, Inc.     

Peritumoral diffusion tensor imaging of high-grade gliomas and metastatic brain tumors

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) is an advanced MR technique that describes the movement of water molecules by using two metrics, mean diffusivity (MD), and fractional anisotropy (FA), which represent the magnitude and directionality of water diffusion, respectively. We hypothesize that alterations in these values within the tissue surrounding brain tumors reflect combinations of increased water content and tumor infiltration and that these changes can be used to differentiate high-grade gliomas from metastatic lesions. METHODS: DTI was performed in 12 patients with high-grade gliomas and in 12 with metastatic lesions. DTI measurements were obtained from regions of interest (ROIs) placed on normal-appearing white matter and on the vasogenic edema, the T2 signal intensity abnormality surrounding each tumor. RESULTS: The peritumoral region of both gliomas and metastatic tumors displayed significant increases in MD (P <.005) and significant decreases in FA (P <.005) when compared with those of normal-appearing white matter. Furthermore, the peritumoral MD of metastatic lesions measured significantly greater than that of gliomas (P <.005). Peritumoral FA measurements, on the other hand, showed no such discrepancy. CONCLUSION: When compared with an internal control, diffusion metrics are clearly altered within the vasogenic edema surrounding both high-grade gliomas and metastatic tumors, reflecting increased extracellular water. Although peritumoral MD can be used to distinguish high-grade gliomas from metastatic tumors, peritumoral FA demonstrated no statistically significant difference. The FA changes surrounding gliomas, therefore, can be attributed not only to increased water content, but also to tumor infiltration.     

Voxel-based diffusion tensor magnetic resonance imaging evaluation of low-grade hepatic encephalopathy

PURPOSE: To quantify the changes in brain water diffusivity in hepatic encephalopathy (HE) associated with cirrhosis using diffusion tensor imaging (DTI) and to correlate with neuropsychological (NP) scores. MATERIALS AND METHODS: DTI was performed in 14 patients with low-grade HE and age/gender-comparable 16 healthy controls. Whole brain mean diffusivity (MD) and fractional anisotropy (FA) maps were calculated, normalized to common space, smoothed, and compared voxel-by-voxel between groups using analysis of covariance with age included as a covariate. The average MD and FA values were also calculated from individual subjects for selected brain regions and correlated with the neuropsychological scores. RESULTS: Patients with HE showed increased MD in the cortical gray and white matter and the internal capsule. Less extensive brain regions with decreased FA were observed in the bilateral frontal and occipital white matter. MD values from the corpus callosum correlated inversely with several NP scores among HE patients and controls. Positive correlations were observed with FA values and cognitive scores. CONCLUSION: Voxel-based DTI analysis showed widespread brain regions with increased MD values, indicating enhanced water content and decreased FA in cirrhotic patients with HE. The MD and FA values from selected regions correlated with the NP scores.     

Diffusion tensor imaging in multiple sclerosis: assessment of regional differences in the axial plane within normal-appearing cervical spinal cord

BACKGROUND AND PURPOSE: Evaluation of the spinal cord is important in the diagnosis and follow-up of patients with multiple sclerosis. Our purpose was to investigate diffusion tensor imaging (DTI) changes in different regions of normal-appearing spinal cord (NASC) in relapsing-remitting multiple sclerosis (RRMS). METHODS: Axial DTI of the cervical spinal cord was performed in 24 patients with RRMS and 24 age- and sex-matched control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated in separate regions of interest (ROIs) in the anterior, lateral, and posterior spinal cord, bilaterally, and the central spinal cord, at the C2-C3 level. Patients and control subjects were compared with respect to FA and MD with the use of an exact Mann-Whitney test. Logistic regression and receiver operating characteristic (ROC) curve analysis assessed the utility of each measure for the diagnosis of RRMS. RESULTS: DTI metrics in areas of NASC in MS were significantly different in patients compared with control subjects; FA was lower in the lateral (mean +/- SD of 0.56 +/- 0.10 versus 0.69 +/- 0.09 in control subjects, P < .0001), posterior (0.52 +/- 0.11 versus 0.63 +/- 0.10, P < .0001), and central (0.53 +/- 0.10 versus 0.58 +/- 0.10, P = .049) NASC ROIs. Assessing DTI metrics in the diagnosis of MS, a sensitivity of 87.0% (95% confidence interval [CI], 66.4 to 97.1) and a specificity of 91.7% (95% CI, 73.0 to 98.7) were demonstrated. CONCLUSION: The NASC in RRMS demonstrates DTI changes. This may prove useful in detecting occult spinal cord pathology, predicting clinical course, and monitoring disease progression and therapeutic effect in MS.     

轻微型肝性脑病的~1H-MRS和磁共振弥散张量成像研究

目的 探讨氢质子波谱(~1H-MRS)及弥散张量成像(DTI)在预测轻微型肝性脑病(MHE)中的价值.方法 29例肝硬化患者及14例年龄相匹配的健康对照者分别进行头部MRS与DTI扫描,其中15例患有MHE(经数字连接试验及数字符号试验测试).采用单体素激励回波采集序列(STEAM)行左侧基底节区MRS扫描,分别计算N-乙酰天门冬氨酸(NAA),肌酸(Cr),胆碱(Cho),肌醇(mIns),谷氨酰胺复合物(Glx)的峰下面积.并计算各自与Cr比值:NAA/Cr、Cho/Cr、mIns/Cr、Glx/Cr.DTI选用平均弥散率(MD)及各向异性分数(FA)作为参数,选取主要的白质及深部灰质共7个部位为感兴趣区,计算各部位MD及FA值.结果 MRS检查结果显示各组间NAA/Cr与Glx/Cr无显著性差异(P＞0.05),MHE组mIns/Cr与Cho/Cr降低,与无MHE组及对照组间有显著性差异(P＜0.05).而无MHE组与正常对照组间mIns/Cr与Cho/Cr无显著性差异(P＞0.05).DTI检查结果发现有与无MHE的肝硬化患者及对照组不同部位MD值间差异有统计学意义(P＜0.05);FA值无显著性差异(P＞0.05).与对照组比较,MHE组脑内5个部位的MD值显著性增加(P＜0.05);无MHE的肝硬化组仅在尾状核部MD值显著增加(P＜0.05).结论 MHE病人基底节区显示的代谢物改变以及脑内MD值增高不伴FA值的异常改变,提示MHE病人存在轻度细胞外间隙脑水肿,MRS及DTI在预测MHE中有一定价值.     

Diffusion tensor mode in imaging of intracranial epidermoid cysts: one step ahead of fractional anisotropy

INTRODUCTION: The signal characteristics of an epidermoid on T2-weighted imaging have been attributed to the presence of increased water content within the tumor. In this study, we explore the utility of diffusion tensor imaging (DTI) and diffusion tensor metrics (DTM) in knowing the microstructural anatomy of epidermoid cysts. MATERIALS AND METHODS: DTI was performed in ten patients with epidermoid cysts. Directionally averaged mean diffusivity (D (av)), exponential diffusion, and DTM-like fractional anisotropy (FA), diffusion tensor mode (mode), linear (CL), planar (CP), and spherical (CS) anisotropy were measured from the tumor as well as from the normal-looking white matter. RESULTS: Epidermoid cysts showed high FA. However, D (av) and exponential diffusion values did not show any restriction of diffusion. Diffusion tensor mode values were near -1, and CP values were high within the tumor. This suggested preferential diffusion of water molecules along a two-dimensional geometry (plane) in epidermoid cysts, which could be attributed to the parallel-layered arrangement of keratin filaments and flakes within these tumors. CONCLUSION: Thus, advanced imaging modalities like DTI with DTM can provide information regarding the microstructural anatomy of the epidermoid cysts.     

Measurement of DTI metrics in hemorrhagic brain lesions: possible implication in MRI interpretation

PURPOSE: To understand the biological basis of possible mechanisms responsible for increased fractional anisotropy (FA) in different stages of hemorrhage and hemorrhagic brain lesions. MATERIALS AND METHODS: A total of 19 patients with cerebral hemorrhage (CH), five patients with hemorrhagic infarct (HI), and nine patients with hemorrhagic brain tumor (HBT) were prospectively evaluated with diffusion tensor imaging (DTI) and the FA and mean diffusivity (MD) was quantified. Ex vivo DTI of blood clot and histology of the blood clot and HBT were performed to interpret the temporal changes in the DTI metrics. RESULTS: High FA (>0.20) with low MD in the acute and early subacute stage and low FA (<0.20) with increased MD in the late subacute and chronic stage of CH and HI were observed. HBT showed high FA with low MD at all stages. In CH and HI, a significant reduction in FA (P < 0.001) with increased MD (P < 0.001) was seen in the late subacute and chronic stages compared to the acute and early subacute stages, normal white matter (NWM), and HBT. In HBT, there was no significant statistical difference in the FA values between different stages. Histology of HBT and ex vivo blood clot showed structural organization of intact red blood cells (RBCs) with fibrin mesh where the FA values were high compared to normal tissue region that is devoid of blood. CONCLUSION: Intact RBCs entangled within fibrin mesh appear to be responsible for high FA in hemorrhagic brain lesions.     

Diffusion tensor imaging in polymicrogyria: a report of three cases

Introduction Polymicrogyria (PMG), a neuronal migration disorder, commonly manifests as a seizure disorder. The aim of this study was to look for the abnormalities in the underlying white matter using diffusion tensor imaging (DTI) that appeared normal on conventional magnetic resonance imaging (MRI) in patients with PMG.Methods DTI was performed in three patients with PMG and eight age- and sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for the cortex and adjoining subcortical white matter in both controls and patients.Results We observed a significantly decreased mean FA value with no significant change in the MD value in subcortical white matter underlying polymicrogyric cortex (FA=0.23±0.04, MD=1.0±0.05×10⁻³ mm²/s) as compared to both contralateral (FA=0.32±0.04, MD=1.0±0.05×10⁻³ mm²/s) and normal control (FA=0.32±0.04, MD=1.0±0.06×10⁻³ mm²/s) white matter. Significantly increased MD and decreased FA values were also observed in the polymicrogyric cortex (FA=0.08±0.01, MD=1.2±0.10×10⁻³ mm²/s) as compared to normal contralateral (FA=0.12±0.04, MD=1.1±0.09×10⁻³ mm²/s) and normal control (FA=0.12±0.01, MD=1.1±0.09×10⁻³ mm²/s) cortex.Conclusion Significantly decreased FA values with no change in MD values in the subcortical white matter subjacent to polymicrogyric cortex reflect microstructural changes in the white matter probably due to the presence of ectopic neurons.     

顺行性或逆行性改变:肌萎缩性侧索硬化的磁共振研究

目的 结合磁共振波谱成像(MRSI)、扩散张量成像技术(DTI)及MRI对肌萎缩性侧索硬化(ALS)进行对照研究,观察ALS皮质脊髓束(CST)走行区的代谢以及水分子运动的变化规律,探讨CST是否有顺、逆行性变化.资料与方法 采用MRI、MRSI及DTI技术对12例ALS患者和12名正常志愿者进行扫描,观察测量中央前回皮层下白质(SWM)、半卵圆中心(CS)、内囊后肢(PIC)、侧脑室体旁白质(PV)和大脑脚(CP)等5个CST不同解剖平面的氮-乙酰天门冬氨酸(NAA)与肌酸(Cr)比值,各向异性比(FA值)以及平均扩散率(MD值),分析比较ALS 患者和正常对照组以及不同侧别FA值、MD值以及NAA/Cr值的变化.结果 ALS的FA值较正常对照组明显降低(P＜0.001),在CST走行区的SWM、CS、PV 和 PIC平面,ALS组的FA值较正常组明显降低(P＜0.05或P＜0.01), MD值在ALS组有升高的趋势,但无统计学意义.在SWM和PV平面,ALS的NAA/Cr值较正常组降低明显(P＜0.05).FA值和MD值分别在PV和CP有左高右低的变化(P＜0.05).结论 MRSI与DTI相结合能够早期定量探测ALS患者CST的改变,左侧SWM可能为最先发生改变的区域,CST的改变可能为顺行性改变,在不同的平面改变不对称.     

Assessment of white matter damage in subacute sclerosing panencephalitis using quantitative diffusion tensor MR imaging

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE), a rare progressive degenerative disease, is caused by persistent infection with a defective measles virus. The correlation between the clinical staging and MR imaging is usually poor. The aim of the study was to investigate the role of diffusion tensor imaging (DTI) in the early detection of white matter damage in SSPE in the presence of normal findings on conventional imaging. METHODS: DTI was performed in 21 patients in stage II SSPE and 10 age/sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated in the periventricular white matter, corpus callosum, and posterior limb of the internal capsule in patients with normal and abnormal findings on conventional imaging as well as healthy controls. RESULTS: The patients were grouped into those with normal (n = 11) and abnormal (n = 10) findings on conventional imaging for the purpose of quantitative DTI analysis. Abnormal- and normal-appearing white matter on T2-weighted images showed significantly decreased FA values in all the regions compared with those in healthy controls. MD values were significantly increased in the periventricular white matter region of the frontal and parietooccipital lobe in patients with normal as well as abnormal findings on conventional imaging compared with those in healthy controls. CONCLUSION: DTI detects early white matter abnormalities that may have significant therapeutic implication, even in the presence of normal findings on conventional imaging, in patients with SSPE.     

Fractional anisotropy and mean diffusivity measurements on normal human brain: comparison between low- and high-resolution diffusion tensor imaging sequences

Non-invasive in vivo visualization of white matter fiber tracts is currently feasible by means of diffusion tensor imaging (DTI) techniques. DTI-derived metrics, like fractional anisotropy (FA) and mean diffusivity (MD), have the potential to improve tissue characterization. Technical optimization of diffusion tensor sequences, including signal-to-noise ratio and spatial resolution, was performed for 20 normal subjects. High- and low-resolution DTI sequences were applied on all subjects and FA, MD parametric maps were reconstructed for both protocols. Voxel-based statistical analysis revealed regions with significantly different FA and MD values between the two sequences, while the same type of analysis was performed to illustrate regions with significantly different signal-to-noise ratio. In conclusion, optimized DTI sequences may be applied routinely in clinical practice with a standard MR scanner, while accurate quantification of FA and MD may improve lesion characterization.     

新生儿和婴幼儿脑髓鞘发育的DTI

目的：探讨平均扩散率（MD）和部分各向异性（FA）在新生儿和婴幼儿脑髓鞘发育过程中的变化规律。方法：将97例围产史正常、无器质性神经系统疾病的足月新生儿和婴幼儿按年龄段分为7组,行颅脑扩散张量成像（DTI）扫描,测量主要白质结构的MD值和FA值,分析其在不同脑区的差异及随年龄变化的规律。结果：脑各部位的MD值随着年龄的增长而减低（P〈0.01）,FA值随年龄的增长而增高（P〈0.01）。脑同一部位的MD值和FA值在不同年龄段的变化速率有所不同,同一年龄段脑不同部位MD值和FA值的变化幅度不尽相同,不同部位的MD值和FA值也存在差异。结论：MD值和FA值相结合,能定量的分析髓鞘化进程,评估脑白质发育情况。     

阿尔茨海默病患者联络纤维的DTI诊断价值

目的采用磁共振扩散张量成像(diffusion tensor imaging,DTI)观察阿尔茨海默病(Alzheimer’s disease,AD)患者联络纤维的改变情况。资料与方法对10例轻中度AD患者和18名健康老年人(对照组)行常规MRI[(T1WI、T2WI、T2液体衰减反转恢复序列(FLAIR)]及DTI检查,DTI测量双侧扣带束、上纵束Ⅱ、钩束及额枕下束8个感兴趣区(ROI)的部分各向异性分数(FA)值。采用简易精神状态量表(MMSE)和蒙特利尔认知评估量表(MoCA)对AD患者的认知功能进行测定。结果与对照组相比,AD组MMSE评分和MoCA评分较对照组明显下降(P<0.05),AD组常规MRI上ROI白质信号无明显变化,ROI部位的FA值均显著下降(P<0.05),且上纵束Ⅱ的FA值与MMSE(右侧r=0.672,P=0.033,左侧r=0.919,P<0.01)和MoCA(右侧r=0,747,P=0.013;左侧r=0.679,P=0.031)评分呈正相关。结论轻中度AD患者存在联络纤维损害且上纵束Ⅱ的损害程度与认知功能密切相关。     

创伤性脑白质损伤的扩散张量成像研究

目的:评价扩散张量成像(DTI)在创伤性脑白质损伤(WMI)中的应用价值。方法:16例创伤性脑外伤后经临床诊断有WMI的患者通过Philips 1.5TIntera Achieva MR扫描仪行常规MRI和DTI。后处理获得部分各向异性指数(FA)、表观弥散系数(ADC)和纤维示踪成像三维图。根据T2WI及T2快速场回波图像,分别于WMI区域、同侧同名或对侧同名纤维束正常区域取感兴趣区,测量FA值和ADC值并进行比较。结果:脑外伤患者损伤脑白质中挫伤和出血、仅挫伤和仅出血区域三者之间的FA值(F=0.68,P>0.05)和ADC值(F=0.53,P>0.05)均未见明显不同。除仅出血区域的ADC值与对照区域相比差异无统计学意义(t=1.36,P>0.05),挫伤和出血(t=9.72,P<0.05)、仅挫伤(t=8.28,P<0.05)和仅出血(t=5.44,P<0.05)区域的FA值较正常对照区域明显降低,挫伤和出血(t=4.71,P<0.05)、仅挫伤(t=4.81,P<0.05)的ADC值较正常对照明显增高,纤维示踪成像显示损伤区域脑白质较正常区域稀疏、分离、缺失。结论:DTI技术能够显示患者WMI区域的异常改变,但ADC值对出血的判断有局限性。     

Quantitative assessment of the cervical spinal cord damage in neuromyelitis optica using diffusion tensor imaging at 3 Tesla

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.     

复发好转型多发性硬化表现正常脑白质DTI研究

目的:利用扩散张量成像(DTI)直方图分析,明确复发好转型多发性硬化(RRMS)患者表现正常脑白质(NAWM)的异常改变及DTI直方图指标与扩展残疾状态(EDSS)评分的相关性。方法:对29例RRMS患者和35例健康志愿者行常规MRI和DTI检查,分割提取NAWM后,绘制出NAWM的平均扩散率(MD)和部分各向异性(FA)直方图,并对其进行分析。结果:与健康志愿者比较,RRMS患者NAWM平均MD直方图右移、峰高降低;平均FA直方图左移、峰高增高。RRMS患者NAWM的平均MD、MD直方图峰位置和FA直方图峰高明显高于健康志愿者(P<0.001),而MD直方图峰高和平均FA明显低于健康志愿者(P<0.001)。在RRMS患者,所有NAWM的MD和FA直方图指标与EDSS评分均无相关性。结论:RRMS患者NAWM内存在明显扩散异常。     

Late structural alterations of cerebral white matter in long-term survivors of childhood leukemia

PURPOSE: To look for the presence and age-dependence of late structural alterations of otherwise normal-appearing cerebral gray and white matter after radiation and chemotherapy in adult survivors of acute lymphoblastic leukemia (ALL) during childhood. MATERIALS AND METHODS: In a group of 13 adult survivors 17-37 years old, who had been treated by total brain radiation (18-24 Gy) and chemotherapy 16-28 years ago, prospective MR examinations including diffusion tensor imaging (DTI) were performed. Evaluation included volumetry, calculation of mean diffusivity (MD) and fractional anisotropy (FA), and comparison of results to an age-matched control group. RESULTS: DTI showed significantly reduced FA values in the temporal lobes (difference of 0.069 units, P < 0.001), hippocampi (difference of 0.033 units, P < 0.001), and thalami (difference of 0.046 units, P = 0.001), which were accompanied by significant white matter volume loss (difference of 92 cm(3), P < 0.001). Significant elevations of MD were limited to the temporal white matter (difference of 42 x 10(-6) mm(2)/s, P = 0.005). Global and frontal white matter MD correlated negatively to increasing age of the survivors (P < 0.01). CONCLUSION: With regard to structural white matter alterations, adult long-term survivors of childhood ALL, who had received total brain radiation and chemotherapy, apparently show the same overall age dependence as controls. Follow-up studies are needed for confirmation.