White matter abnormalities in obsessive-compulsive disorder: a diffusion tensor imaging study

CONTEXT: Several neurobiological models of obsessive-compulsive disorder (OCD) posit a primary role for dysfunction of the anterior cingulate gyrus. Both functional and structural neuroimaging studies have implicated anterior cingulate gray matter abnormalities in the pathophysiology of OCD, but there has been little investigation of the anterior cingulate white matter in this disorder. OBJECTIVE: To test the hypothesis that patients with OCD have abnormal white matter microstructure in the anterior cingulate gyrus compared with healthy volunteers as inferred from diffusion tensor imaging. Additional analyses examined group differences in white matter integrity across the entire brain. DESIGN, SETTING, AND PARTICIPANTS: Fifteen patients with a DSM-IV diagnosis of OCD and 15 healthy volunteers matched for age, sex, and handedness underwent diffusion tensor imaging and structural magnetic resonance imaging examinations. Fractional anisotropy (FA), a robust intravoxel measure of water self-diffusion, was compared between groups on a voxel-by-voxel basis in the anterior cingulate white matter after standardization in Talairach space. MAIN OUTCOME MEASURES: Clinical ratings of symptom severity (ie, Yale-Brown Obsessive-Compulsive Scale) and FA. RESULTS: Compared with healthy volunteers, patients demonstrated significantly lower FA bilaterally in 3 areas of the anterior cingulate gyrus white matter. Additional analyses conducted across the rest of the brain white matter revealed lower FA bilaterally in the parietal region (supramarginal gyri), right posterior cingulate gyrus, and left occipital lobe (lingual gyrus). No areas of significantly higher FA were observed in patients compared with healthy volunteers. Lower FA in the parietal region correlated significantly with higher Yale-Brown Obsessive-Compulsive Scale scores. CONCLUSIONS: These preliminary findings provide evidence of an abnormality that involves the anterior cingulate white matter in the pathogenesis of OCD and are consistent with neurobiological models that posit a defect in connectivity in the anterior cingulate basal ganglia-thalamocortical circuit. White matter abnormalities in other brain regions may also be implicated in the neurobiology of OCD.     

轻微型肝性脑病磁共振扩散加权成像和扩散张量成像的定量研究

目的通过磁共振扩散加权成像(DWI)和扩散张量成像(DTI)定量分析轻微型肝性脑病(MHE)患者脑功能的异常改变,探讨DWI和DTI在MHE中的应用价值。方法30例肝硬化患者经神经心理测试评分量表测试后,分为MHE组16例和无MHE单纯肝硬化组14例,同时选取15例健康志愿者为正常对照组。所有受试者均行DWI与DTI扫描,选取脑内8个部位为感兴趣区,计算各部位的表观扩散系数(ADC)值和各向异性分数(FA)值。结果18例肝硬化患者于T1WI图像上可见到双侧内囊、苍白球对称性高信号。额叶、枕叶白质、胼胝体膝部、胼胝体压部、内囊前肢、内囊后肢、尾状核头部由正常组、单纯肝硬化组至MHE组ADC值逐渐增加,且MHE组的ADC值较肝硬化组和正常组增加,差异有统计学意义(P<0.05);胼胝体膝部和压部的FA值由正常组、单纯肝硬化组至MHE组逐渐降低,差异有统计学意义(P<0.05)。结论DWI与DTI联合应用能够预测肝硬化患者MHE的进展程度,具有潜在的临床价值。     

Involvement of motor pathways in corticobasal syndrome detected by diffusion tensor tractography

Corticobasal syndrome (CBS) is a progressive parkinsonian disease characterized by cortical and subcortical neuronal loss. Although motor disabilities are a core feature of CBS, the involvement of motor pathways in this condition has not been completely clarified. We used magnetic resonance diffusion tensor imaging (DTI) to study corticospinal and transcallosal motor projections in CBS, and applied fiber tractography to analyze the axonal integrity of white matter projections. Ten patients with CBS were compared with 10 age‐matched healthy controls. Fiber tracts were computed using a Monte‐Carlo simulation approach. Tract‐specific mean values of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were determined. CBS patients showed a reduction of corticospinal tract (CST) fibers on the first affected side with significantly increased ADC and reduced FA values. In the corpus callosum (CC), particularly in the posterior trunk, patients also had significantly reduced fiber projections, with a higher ADC and lower FA than controls. This pattern indicates changes of the white matter integrity in both CST and CC. Thus, magnetic resonance DTI can be used to assess motor pathway involvement in CBS patients. © 2008 Movement Disorder Society     

Diffusion tensor imaging and tract-based spatial statistics in obsessive-compulsive disorder

There is increasing evidence of white matter abnormalities in patients with obsessive-compulsive disorder (OCD). The results of previous diffusion tensor imaging (DTI) studies, however, are inconsistent. Reasons for this inconsistency may include methodological issues such as misregistration, the differences in smoothing voxel-based morphometry style analysis or both. To date there are no DTI studies with tract-based spatial statistics (TBSS) which overcome these issues. In addition, previous studies had few drug-free patients, thus potentially reducing their power and obscuring their findings. Therefore, the aim of present study was to investigate white matter abnormalities using DTI and TBSS analysis in a large sample of drug-free patients with OCD. Thirty drug-free patients with OCD and 30 healthy controls underwent DTI. Fourteen of 30 patients were drug naïve. Voxel-wise group comparison of white matter fractional anisotropy (FA) was performed using TBSS. Compared to healthy volunteers, OCD patients had statistically less FA in the anterior body of corpus callosum (CC) (p < .05, corrected). They also had a trend for a lower FA in the large portion of CC, the right cingulum, and the left anterior limb of internal capsule (ALIC). There were no areas of the brain with significantly higher FA. This is the first study that has investigated white matter abnormalities in non-medicated patients with OCD using DTI and TBSS analyses. Microstructural white matter abnormalities in the CC, the cingulum, and the ALIC might be involved in the pathophysiology of OCD.     

A voxel-based diffusion tensor imaging study of temporal white matter in patients with schizophrenia

Diffusion tensor imaging (DTI) is a relatively new technique used to detect changes in the anisotropic diffusion of white matter. The study of the disruption of brain connectivity may increase our understanding of cognitive deficits associated with schizophrenia. Here we analysed DTI data in 25 patients with DSM-IV schizophrenia and 24 healthy controls. Two complementary measures, fractional anisotropy (FA) and the apparent diffusion coefficient (ADC), were considered and analysed using voxel-based morphometry. Declarative memory functions were also investigated and their associations with DTI data were analysed. FA was significantly reduced, and the ADC increased in the left sub-gyral white matter of the temporal lobe, which involves the posterior part of the fornix. In the schizophrenic group, females had lower FA than males in the genu of the corpus callosum. Memory functions correlate with FA values. These data provide further evidence for the disruption of white matter connectivity in the left medial temporal lobe, and for its contribution to the declarative memory deficit in schizophrenia.     

精神分裂症首次发病患者的磁共振弥散张量显像研究

目的探讨从未用过药的精神分裂症首次发病(以下简称首发)患者的重要白质及部分灰质区的磁共振弥散张量显像(DTI)的特点。方法选取9例首发精神分裂症患者(患者组)及9名年龄、性别、受教育程度与患者组相配对的健康者,应用DTI成像技术检测脑额颞交界处、内囊等白质区和颞中回灰质、中央前回、中央后回等灰质区的各向异性(FA)、表观扩散系数(ADC)及双侧海马体积。结果患者组及对照组组内左右两侧兴趣区FA值及ADC值的差异无统计学意义(P>0.05);患者组与对照组各感兴趣区FA值差异无统计学意义(P>0.05),但患者组颞中回灰质(8.655×10-9)、中央前回(7.816×10-9)、中央后回(7.855×10-9)ADC值高于对照组(分别为7.428×10-9,6.921×10-9,7.013×10-9;P=0.049,0.009,0.005);两组内及组间双侧海马体积比较,差异均无统计学意义(P>0.05)。结论首发精神分裂症患者与健康者DTI参数之间没有明显区别。     

不接受/禁忌思维亚型强迫障碍患者的脑白质磁共振弥散张量成像研究

目的:运用磁共振扩散张量成像技术探讨未经治疗的不接受/禁忌思维亚型强迫障碍(OCD)患者脑白质的变化及与临床症状之间的相关性。方法:对26例不接受/禁忌思维亚型OCD患者和28名性别、年龄、受教育程度相匹配的健康对照者进行弥散张量成像(DTI)扫描,采用耶鲁-布朗强迫量表(Y-BOCS)、17项汉密尔顿抑郁量表(HAMD-17)、汉密尔顿焦虑量表(HAMA)等评估临床症状,采用基于纤维束空间统计分析(TBSS)等方法比较两组全脑DTI的各向异性分数(FA),得出有差异脑区,并分析患者组脑白质改变与临床症状严重程度之间的关系。结果:和正常对照组相比,患者组的大脑胼胝体、右侧上纵束、右侧下额-枕束、右侧丘脑后辐射(视辐射部)等部位的FA值显著降低;未发现任何脑区的FA值与临床行为学量表之间的相关性。结论:多个脑白质区的结构异常可能构成不接受/禁忌思维亚型OCD患者的病理生理基础,这些脑白质区的变化可能是此亚型OCD的特征标志。     

Corticospinal tract degeneration and possible pathogenesis in ALS evaluated by MR diffusion tensor imaging.

BACKGROUND: MR diffusion tensor imaging (DTI) appears to be a powerful method to investigate the neuronal and axonal fibre distribution in the human brain. Changes in diffusion characteristics of water molecules in the white matter can be estimated as the apparent diffusion coefficient (ADC) and the fractional anisotropy index (FA). OBJECTIVES: To characterize DTI changes at three different levels in the corticospinal tract (CST) (corona radiata, internal capsule and pons) in order to elucidate if pathogenesis of ALS is due to an anterograde or retrograde axonal degeneration. METHODS: We studied eight ALS patients with clinical signs of upper motor neuron involvement. The patients were compared with 11 healthy age-matched controls. RESULTS: ADC was significantly increased in the CST in ALS patients at the level of the internal capsule and also increased in the pons, but without statistical significance. ADC was unchanged at the level of the corona radiata. FA was significantly reduced at the lowest level (pons), only tended to be reduced in the internal capsule, but was also unchanged in the corona radiata. CONCLUSIONS: Segmentation of the CST into three regions supports the hypothesis of a 'dying back' mechanism in ALS and suggests that ADC is a more sensitive measure than FA to detect pathological changes in ALS.     

Abnormal frontal white matter tracts in bipolar disorder: a diffusion tensor imaging study

OBJECTIVES: Prefrontal white matter has been hypothesized to be integral to the pathophysiology of bipolar disorder. Recent morphometric studies however, have not observed changes in white matter in bipolar patients. We hypothesized that changes in prefrontal function in bipolar disorder, widely reported in the literature, may be related to a loss of white matter tract integrity with a resultant dysconnectivity syndrome. In this study we utilized diffusion tensor imaging (DTI) to examine prefrontal white matter in patients with bipolar disorder. METHODS: Nine patients with bipolar disorder and nine healthy controls were recruited. DTI and localizing anatomic data were acquired, and regions of interest (ROIs) identified in the prefrontal white matter at 15, 20, 25, and 30 mm superior to the anterior commissure (AC). Fractional anisotropy (FA) and trace apparent diffusion coefficient (TADC) were compared by ROI between study groups. RESULTS: The FA of ROIs 25 and 30 mm above the AC was significantly reduced in patients with bipolar disorder; FA of all ROIs showed high-medium to large effect sizes. No significant group differences were identified in TADC. CONCLUSIONS: Our findings suggest that a loss of bundle coherence is present in prefrontal white matter. This loss of coherence may contribute to prefrontal cortical pathology in patients with bipolar disorder.     

健康者三叉神经磁共振扩散张量成像研究

目的 测量三叉神经桥池段的表观扩散系数(ADC)值和部分各向异性分数(FA)值,了解三叉神经桥池段各参数的特点。 方法 选择50例健康志愿者三叉神经桥池段距离脑干发出点0mm、3mm、6mm、9mm共四处,利用DTI图像与B-TFE或THRIVE图像融合成像,提高三叉神经桥池段显示的空间分辨率,并利用该图像测量并分别记录ADC值与FA值,对所有受检者行三叉神经桥池段追踪成像。 结果 受检者左侧与右侧三叉神经桥池段的ADC值和FA值差异均无统计学意义(P＞0.05)。越靠近脑干发出点,左右两侧三叉神经桥池段的各导出量越呈现左右不对称的趋势。双侧三叉神经桥池段距脑干不同距离各位置的DTI导出量分析发现：相邻两距离间ADC值差异均有统计学意义(P＜0.05),出脑干后随距离增加ADC值逐渐升高,但行至6～9 mm间突然回转下降;FA值在0～6 mm间随距离增加而逐渐降低,且相邻两距离间差异均有统计学意义(P＜0.05),但行至6～9 mm间FA值不再有明显变化。 结论 DTI图像能够清晰分辨双侧三叉神经桥池段,可实现DTI各项导出量的测量。随着距脑干发出点距离的不同,各导出量发生有规律的变化,预示着DTI在明确区分三叉神经的中枢神经系统段、过渡段和周围神经系统段以及检出颅神经血管压迫方面的应用前景。     

White matter abnormalities observed in bipolar disorder: a diffusion tensor imaging study

OBJECTIVES: An increased incidence in white matter abnormalities is among the most frequently reported brain change in patients with bipolar disorder. The objective of the present study was to examine white matter tract integrity, using diffusion tensor imaging (DTI), in bipolar patients and healthy comparison subjects. METHODS: Eleven DSM-IV bipolar I patients and 10 healthy age- and sex-matched controls were studied. DTI data were acquired on a 1.5 Tesla scanner. Fractional anisotropy (FA) and diffusivity (trace) were determined from axial images using region of interest (ROI) analyses. The ROIs were manually placed in the midline and forward projecting arms of the genu (anterior) and the midline of the splenium (posterior) of the corpus callosum. RESULTS: Bipolar patients had significantly higher FA in the midline of the genu compared with healthy controls. Regional white matter differences were also observed, with significantly lower FA in the genu than forward projecting regions in both groups and lower FA in the genu than the splenium in controls. CONCLUSIONS: Diffusion tensor imaging revealed significant microstructural differences in the genu, as measured by elevated FA in bipolar patients compared with healthy controls. These preliminary findings further support the hypothesis that anomalous frontal brain mechanisms may be associated with bipolar disorder.     

MR spectroscopy and diffusion tensor imaging of the brain in congenital muscular dystrophy with merosin deficiency: metabolite level decreases, fractional anisotropy decreases, and apparent diffusion coefficient increases in the white matter

Brain magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in one patient with merosin-deficient congenital muscular dystrophy (MDCMD) revealed significant metabolite (choline, creatine, N-acetyl aspartate) level reductions, fractional anisotropy (FA) reduction and increased apparent diffusion coefficient (ADC) in the white matter (p<0.01, all). In the gray matter, the MRS properties did not differ significantly from those in controls. The ADC and FA, however, differed significantly as in the white matter, although the differences were less pronounced. This is the first quantitative MR study of the brain in a patient with MDCMD, which revealed that the concentrations of all MRS measured metabolites were decreased only in the white matter. This observation, combined with the DTI observed ADC increases and FA decrease, indicated a presence of vasogenic edema in the white matter.     

三叉神经痛的磁共振扩散张量成像研究

目的 研究血管压迫三叉神经桥池段的扩散张量成像(DTI)表现及临床应用价值.方法 对60例经手术证实的因责任血管压迫引起三叉神经痛(TN)患者(TN组)和50例健康志愿者(对照组)行常规MRI和横轴面DTI成像,测量其表观扩散系数(ADC)值、部分各向异性分数(FA)值. 结果 对照组的三叉神经的ADC值为(1.76±0.98)×10-3 mm2/s,FA值为0.40±0.18,左侧与右侧三叉神经桥池段的ADC值和FA值差异均无统计学意义(P>0.05);对照组与TN组中B组(轻度压迫组)、C(重度压迫组)、D组(受压变形并萎缩)3组比较,ADC、FA值差异均存在统计学意义(P均<0.05);压迫部位ADC值增高28例,不变4例,平均ADC值明显高于对照组(P<0.05);压迫部位FA值下降15例.不变11例,增高5例,平均FA值明显低于对照组(P<0.05). 结论 DTI对判断血管压迫三叉神经有一定价值,三叉神经压迫程度越大,ADC值越高,FA值越低.     

Diffusion tensor imaging patterns differ in bulbar and limb onset amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is characterized by pronounced clinical heterogeneity in terms of onset and disease progression. Widespread changes in white matter fibres could be observed by diffusion tensor imaging (DTI), which detects alterations in the degree (diffusivity, ADC) and directedness (fractional anisotropy, FA) of proton movement. The aim of the current study was to determine whether different ALS onset types were reflected in different DTI brain patterns.

Methods

Seventeen patients with a diagnosis of ALS (6 bulbar, 11 limb onset) and seventeen age-matched controls received 1.5T DTI, where FA and ADC were analyzed using statistical parametric mapping.

Results

In ALS patients, an increased diffusivity in the white matter was found below the precentral gyrus and along the corticospinal tract (CST) right into the internal capsule. The FA was decreased in the posterior limb of internal capsule and in the subcortical white matter in the precentral gyrus. In bulbar onset increased diffusivity was found in the CST, whilst in limb onset, frontal subcortical areas displayed an increased diffusivity.

Conclusion

DTI changes can be regarded as prominent features in ALS. Herein we were able to demonstrate discriminating brain DTI patterns due to bulbar or limb onset.     

Lower Orbital Frontal White Matter Integrity in Adolescents With Bipolar I Disorder

ObjectiveTo examine white matter microstructure, as assessed via diffusion tensor imaging (DTI), in adolescents with bipolar I disorder compared with control volunteers.MethodTwenty-six (12 male and 14 female subjects) adolescents (mean age, 16.0 years) with bipolar I disorder and 26 (14 male and 12 female subjects) control volunteers (mean age, 15.3 years) completed structural and DTI examinations. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were compared between groups in the brain white matter using a voxelwise analysis after intersubject registration to Talairach space. Exploratory analyses were performed to assess structure-function correlations in a subgroup of 11 patients with available neuropsychological measures.ResultsCompared with the control volunteers, the patients demonstrated abnormalities in white matter regions predicted to differ a priori between groups, including lower FA in the right orbital frontal lobe and higher ADC in the right and left subgenual region (p < .005, uncorrected; cluster size ≥ 100). There were no areas of higher FA or lower ADC in patients compared with control volunteers. Lower FA across regions that differed significantly between groups correlated significantly with slower visuomotor speed among patients with bipolar disorder.ConclusionsAbnormalities involving the orbital frontal and subgenual white matter in adolescents with bipolar disorder are consistent with neurobiological models that implicate dysregulation of affective systems and impulsivity in the pathophysiology of the disorder. Preliminary findings suggest that white matter abnormalities in pediatric bipolar disorder have functional correlates and may be useful in constructing neurobiological models of the disorder.     

Increased water self-diffusion in chronic plaques and in apparently normal white matter in patients with multiple sclerosis

A new method for measurement of water self-diffusion compensating for zeroth and first order movements was used to study the apparent diffusion coefficient (ADC) in 15 patients with chronic multiple sclerosis (MS) and in two patients with acute MS. Ten healthy volunteers served as controls. A significantly higher ADC was found within chronic plaques compared to the apparently normal white matter of the chronic patients. The ADC was higher in the acute plaques compared to the chronic plaques. The ADC in apparently normal white matter of the chronic patients were significantly higher than in white matter of healthy volunteers. We hypothesize that an increase of the ADC in plaques may be related to an increase in the extracellular space due to oedema and demyelination. The increased ADC in apparently normal white matter suggests that there may be a change in the composition of the white matter of chronic MS patients, perhaps related to oedema and expanded extracellular space.     

Multivariate pattern analysis of DTI reveals differential white matter in individuals with obsessive‐compulsive disorder

Diffusion tensor imaging (DTI) studies have revealed group differences in white matter between patients with obsessive‐compulsive disorder (OCD) and healthy controls. However, the results of these studies were based on average differences between the two groups, and therefore had limited clinical applicability. The objective of this study was to investigate whether fractional anisotropy (FA) of white matter can be used to discriminate between patients with OCD and healthy controls at the level of the individual. DTI data were acquired from 28 OCD patients and 28 demographically matched healthy controls, scanned using a 3T MRI system. Differences in FA values of white matter between OCD and healthy controls were examined using a multivariate pattern classification technique known as support vector machine (SVM). SVM applied to FA images correctly identified OCD patients with a sensitivity of 86% and a specificity of 82% resulting in a statistically significant accuracy of 84% (P ≤ 0.001). This discrimination was based on a distributed network including bilateral prefrontal and temporal regions, inferior fronto‐occipital fasciculus, superior fronto‐parietal fasciculus, splenium of corpus callosum and left middle cingulum bundle. The present study demonstrates subtle and spatially distributed white matter abnormalities in individuals with OCD, and provides preliminary support for the suggestion that that these could be used to aid the identification of individuals with OCD in clinical practice. Hum Brain Mapp 35:2643–2651, 2014. © 2013 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. .     

弥散张量成像在脑深部肿瘤术前评估中的应用

目的 探讨弥散张量成像(DTI)在脑深部肿瘤术前评估和手术设计中的作用.方法 回顾性分析20例脑深部肿瘤病人的临床资料,利用各向异性分数(FA)图和纤维示踪图(DTT),观察白质纤维束结构、走行及其与肿瘤的毗邻关系,测量病侧白质纤维束及其对应健侧白质纤维束的FA值、弥散系数(ADC)值.结果 白质纤维束单纯推移5例,单纯破坏7例,推移并破坏8例.单纯破坏、推移并破坏者.其病侧与健侧FA值、ADC值比较均有显著差异(P <0.05);而单纯推移者,其病侧与健侧队值、ADC值比较无显著差异(P >0.05).肿瘤全切除15例,次全切除3例,部分切除2例.12例随访6个月-2年,平均1年.正常工作、学习8例,生活自理但未参加工作3例,死亡1例.结论 DTI有助于准确判断肿瘤与周围白质纤维束的毗邻关系,对脑深部肿瘤术前评估和手术设计有重要指导意义.     

White matter abnormalities in drug-naïve patients with obsessive-compulsive disorder: a diffusion tensor study before and after citalopram treatment

Objective: The aim was to investigate the white matter abnormalities of drug‐naïve patients with obsessive–compulsive disorder (OCD) using diffusion tensor‐imaging and the white matter changes in the patients after pharmacotherapy. Method: Thirteen drug‐naïve OCD patients and 13 age‐ and sex‐matched healthy comparison subjects were examined using diffusion tensor‐imaging and structural magnetic resonance imaging. Measurements were made in OCD patients before and after 12 weeks of citalopram treatment. Results: Compared with controls, the drug‐naïve OCD patients showed significant increases in fractional anisotropy (FA) in the corpus callosum, the internal capsule and white matter in the area superolateral to the right caudate. The increases in FA were mostly no longer observed in patients after 12 weeks of treatment compared with controls. Conclusion: Our findings suggest that white matter alterations are associated with the pathophysiology of OCD, and the abnormalities may be partly reversible with pharmacotherapy.     

皮质下缺血性血管性痴呆患者脑白质损害的磁共振弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)观察皮质下缺血性血管性痴呆(SIVD)患者脑白质损害程度,探讨DTI对SIVD白质损害的评估及与阿尔茨海默病(AD)鉴别诊断价值。方法:研究对象分为3组,分别是健康老年人(NC)、皮质下缺血性血管性痴呆(SIVD)患者、AD患者,每组各20例。行常规MR I和DTI扫描后,测定相同感兴趣区(RO I)的各向异性分数(FA)值和表观扩散系数(ADC)值进行比较。结果:SIVD组下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位FA值下降,ADC值升高,与NC、AD组比较差异有统计学意义(P<0.05)。与NC组比较,AD组前额叶、颞叶、海马、下额枕束、胼胝体膝部和扣带束等部位FA值降低,颞叶、海马等部位ADC值升高,两组差异具有显著性(P<0.05);结论:DTI可以用来评估痴呆患者白质损害的程度,SIVD患者以下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位受累为主,可作为与AD鉴别的客观指标。