Tract-based Spatial Statistics Method Research Articles

White matter biomarker for predicting de novo Parkinson's disease using tract-based spatial statistics: a machine learning-based model.

Parkinson's disease (PD) is an irreversible, chronic degenerative disease of the central nervous system, potentially associated with cerebral white matter (WM) lesions. Investigating the microstructural alterations within the WM in the early stages of PD can help to identify the disease early and enable intervention to reduce the associated serious threats to health. This study selected 227 cases from the Parkinson's Progression Markers Initiative (PPMI) database, including 152 de novo PD patients and 75 normal controls (NC). Whole-brain voxel analysis of the WM was performed using the tract-based spatial statistics (TBSS) method. The WM regions with statistically significant differences (P<0.05) between the PD and NC groups were identified and used as masks. The mask was applied to each case's fractional anisotropy (FA) image to extract voxel values as feature vectors. Geometric dimensionality reduction was then applied to eliminate redundant values in the feature vectors. Subsequently, the cases were randomly divided into a training group (158 cases, including 103 PD patients and 55 NC) and a test group (69 cases, including 49 PD patients and 20 NC). The least absolute shrinkage and selection operator (LASSO) regression algorithm was employed to extract the minimal set of relevant features, then the random forest (RF) algorithm was utilized for classification using 5-fold cross validation. The resulting model was further integrated with clinical factors to create a comprehensive prediction model. In comparison to the NC group, the FA values in PD patients exhibited a statistically significant decrease (P<0.05), indicating the presence of widespread WM lesions across multiple brain regions. Moreover, the PD prediction model, constructed based on these WM lesion regions, yielded prediction accuracy (ACC) and area under the receiver operating characteristic (ROC) curve (AUC) values of 0.778 and 0.865 in the validation set, and 0.783 and 0.831 in the test set, respectively. Furthermore, the performance of the integrated model showed some improvement, with ACC and AUC values in the test set reaching 0.804 and 0.844, respectively. The quantitative calculation of WM lesion area on FA images using the TBSS method can serve as a neuroimaging biomarker for diagnosing and predicting early PD at the individual level. When integrated with clinical variables, the predictive performance improves.

Diffusion kurtosis imaging of brain white matter alteration in patients with coronary artery disease based on the TBSS method.

The aim of our study was to examine the alterations in microstructure in patients with coronary artery disease (CAD) and cognitive impairment (CI) using diffusion kurtosis imaging (DKI). Additionally, we aimed to investigate the potential correlation between DKI parameters and cognitive function. A total of 28 CAD patients and 30 healthy controls (HC) were prospectively enrolled in our study. All participants underwent routine and diffusion sequences of head imaging. DKE software was utilized to generate various diffusion kurtosis imaging parameters (DKI), including kurtosis fractional anisotropy (KFA), mean kurtosis (MK), axial kurtosis (AK), radial kurtosis (RK), fractional anisotropy (FA), and mean diffusivity (MD). Nonparametric tests were conducted using tract-based spatial statistics (TBSS) to compare the parameter values between the two groups. The parameter values of the significantly different fiber tracts were extracted and correlated with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores. Compared to the HC group, patients with coronary artery disease exhibited significant reductions in FA values in the bilateral Superior corona radiata, bilateral Anterior corona radiata, bilateral Posterior corona radiata, corpus callosum, left Posterior thalamic radiation, right Posterior limb of internal capsule, Anterior limb of internal capsule, and Cerebral peduncle, as well as in the left Superior longitudinal fasciculus. Additionally, KFA values decreased in the bilateral Anterior corona radiata, bilateral Anterior limb of internal capsule, and Genu of the corpus callosum. The MK values decreased in the right Posterior corona radiata, Retrolenticular part of the internal capsule, Posterior thalamic radiation (including optic radiation), Superior longitudinal fasciculus, and left Posterior thalamic radiation (including optic radiation). Moreover, the RK values decreased in the bilateral Retrolenticular part of the internal capsule, right Posterior thalamic radiation (including optic radiation), and Superior longitudinal fasciculus, as well as in the left Superior longitudinal fasciculus and Posterior thalamic radiation (including optic radiation) (p < 0.01, TFCE corrected), while no significant differences were observed in other parameter values (p > 0.01, TFCE corrected). The FA values of the right posterior limb of the internal capsule (r = 0.610, p = 0.001) and the right cerebral peduncle (r = 0.622, p < 0.001) were positively correlated with MMSE scores. Additionally, a significant correlation between kurtosis and diffusion coefficient parameters (FA and KFA) was observed. CAD patients showed radial shrinkage and complexity of brain white matter microstructure. Whole-brain white matter analysis based on TBSS DKI can objectively reflect the characteristics of white matter damage in CAD patients, providing a basis for the auxiliary diagnosis of CAD with CI.

Microstructural white matter abnormalities in overactive bladder syndrome evaluation with diffusion kurtosis imaging tract-based spatial statistics analysis.

This prospective study aimed to explore the microstructural alterations of the white matter in overactive bladder syndrome (OAB) using the Tract-based Spatial Statistics (TBSS) method of diffusion kurtosis imaging (DKI). A total of 30 patients were enrolled and compared with 30 controls. White matter (WM) status was assessed using tract-based spatial statistics for DKI. The differences in DKI-derived parameters, including kurtosis fractional anisotropy (KFA), fractional anisotropy (FA), mean kurtosis (MK), mean diffusivity (MD), radial kurtosis (RK), axial kurtosis (AK), axial diffusivity (AD), and radial diffusivity (RD), were compared between the two groups using the TBSS method. The correlation between the altered DKI-derived parameters and the (OABSS) scores was analyzed. A receiver operating characteristic curve (ROC) was used to evaluate the diagnostic performance of different white matter parameters. As a result, compared with the HC group, the KFA, and FA values decreased significantly in the OAB group. Compared with the HC group, the MK and MD values increased significantly in the OAB group. The KFA values of the genu of corpus callosum (GCC) were significantly correlated with the OABSS scores (r = -0.509; p = 0.004). The FA values of anterior corona radiata (ACR) were significantly correlated with OABSS scores (r = -0.447; p = 0.013). The area under the ROC curve (AUC) for the genu of corpus callosum KFA values was higher than FA for the diagnosis of OAB patients. DKI is a promising approach to the investigation of the pathophysiology of OAB and a potential biomarker for clinical diagnosis of OAB.

Diffusion tensor imaging in photosensitive and nonphotosensitive juvenile myoclonic epilepsy

Introduction/backgroundJuvenile myoclonic epilepsy (JME) syndrome is known to cause alterations in brain structure and white matter integrity. The study aimed to determine structural white matter changes in patients with JME and to reveal the differences between the photosensitive (PS) and nonphotosensitive (NPS) subgroups by diffusion tensor imaging (DTI) using the tract-based spatial statistics (TBSS) method. MethodsThis study included data from 16 PS, 15 NPS patients with JME, and 41 healthy participants. The mean fractional anisotropy (FA) values of these groups were calculated, and comparisons were made via the TBSS method over FA values in the whole-brain and 81 regions of interest (ROI) obtained from the John Hopkins University White Matter Atlas. ResultsIn the whole-brain TBSS analysis, no significant differences in FA values were observed in pairwise comparisons of JME patient group and subgroups with healthy controls (HCs) and in comparison between JME subgroups. In ROI-based TBSS analysis, an increase in FA values of right anterior corona radiata and left corticospinal pathways was found in JME patient group compared with HC group. When comparing JME-PS patients with HCs, an FA increase was observed in the bilateral anterior corona radiata region, whereas when comparing JME-NPS patients with HCs, an FA increase was observed in bilateral corticospinal pathway. Moreover, in subgroup comparison, an increase in FA values was noted in corpus callosum genu region in JME-PS compared with JME-NPS. ConclusionsOur results support the disruption in thalamofrontal white matter integrity in JME, and subgroups and highlight the importance of using different analysis methods to show the underlying microstructural changes.

Brain White Matter Structural Alteration in Hemifacial Spasm: A Diffusion Tensor Imaging Study

To analyze the changes in the white matter structure of the whole brain in hemifacial spasm (HFS) patients by using the tract-based spatial statistics (TBSS) method. 29 HFS patients without anxiety and depression and 29 healthy controls with matching age, sex, and education were selected. All subjects received a 3.0T magnetic resonance (MR) brain diffusion tensor imaging scan. Tract-based spatial statistics method was used to analyze the changes in white matter structure in the whole brain and obtained the cerebral white matter fibrous areas exhibiting significant intergroup differences. The fractional anisotropy (FA), mean diffusivity, axial diffusivity, and radial diffusivity of these areas were abstracted. Analyzed the correlation between these diffusion metrics and clinical variables (disease duration, spasm severity). Compared with the healthy controls group, the HFS group exhibited significantly lower FA in the forceps minor, bilateral anterior thalamic radiation, and right superior longitudinal fasciculus ( P <0.05, threshold-free cluster enhancement corrected). Cohen grading scale of HFS patients was negatively correlated with FA of forceps minor. Based on TBSS analysis, the injury of white matter fiber tracts in HFS patients was found, including forceps minor, bilateral anterior thalamic radiation, and right superior longitudinal fasciculus. The changes of FA values in forceps minor were negatively correlated with the Cohen grading scale, suggesting that the alteration of white matter fiber in the genu-of-corpus-callosum-cortex circuit plays an important role in the neuro-pathological mechanism of HFS. Combined with previous research, it is also necessary to further explore the change of the superior longitudinal fasciculus in the future.

Per1 gene polymorphisms influence the relationship between brain white matter microstructure and depression risk.

Circadian rhythm was involved in the pathogenesis of depression. The detection of circadian genes and white matter (WM) integrity achieved increasing focus for early prediction and diagnosis of major depressive disorder (MDD). This study aimed to explore the effects of PER1 gene polymorphisms (rs7221412), one of the key circadian genes, on the association between depressive level and WM microstructural integrity. Diffusion tensor imaging scanning and depression assessment (Beck Depression Inventory, BDI) were performed in 77 healthy college students. Participants also underwent PER1 polymorphism detection and were divided into the AG group and AA group. The effects of PER1 genotypes on the association between the WM characteristics and BDI were analyzed using tract-based spatial statistics method. Compared with homozygous form of PER1 gene (AA), more individuals with risk allele G of PER1 gene (AG) were in depression state with BDI cutoff of 14 (χ2 = 7.37, uncorrected p = 0.007). At the level of brain imaging, the WM integrity in corpus callosum, internal capsule, corona radiata and fornix was poorer in AG group compared with AA group. Furthermore, significant interaction effects of genotype × BDI on WM characteristics were observed in several emotion-related WM tracts. To be specific, the significant relationships between BDI and WM characteristics in corpus callosum, internal capsule, corona radiata, fornix, external capsule and sagittal stratum were only found in AG group, but not in AA group. Our findings suggested that the PER1 genotypes and emotion-related WM microstructure may provide more effective measures of depression risk at an early phase.

A study on longitudinal changes in white matter microstructure of parents who have lost their only child based on diffusion tensor imaging and its relationship with symptoms of posttraumatic stress disorder

Objective: To investigate the longitudinal changes of white matter microstructural based on diffusion tensor imaging in parents who lost their only child without psychiatric disorders and its relationship with symptoms of posttraumatic stress disorder (PTSD). Methods: Parents who had who lost their only child and without psychiatric disorders in Jiangsu Province, from September 2016 to March 2017, were retrospectively collected (TENP group, 32). MRI scans were performed at baseline and at the end of 5-year follow-up, and the Clinician Administered PTSD Scales (CAPS) were used for assessing the severity of symptoms. Additionally, sex, age and education level matched healthy subjects were recruited as healthy controls (control group, 27) and underwent MRI scanning using the same protocol. The differences of fractional anisotropy (FA) values between TENP group and control group at baseline were analyzed by using Tract-based spatial statistics method, and the brain areas of lateral differences were used as the regions of interest for longitudinal follow-up analysis of TENP group. Partial correlation analysis was used to evaluate the relationship between FA values changes in longitudinal differences in brain regions and CAPS scores. Results: Compared with the control group, FA values of the right cingulate gyrus, Uncinate fasciculus, superior longitudinal fasciculus, corticospinal tract, Inferior fronto-occipital fasciculus, Inferior longitudinal fasciculus and forceps major in TENP group were decreased at baseline ((0.613±0.032) vs (0.631±0.034), (0.539±0.048) vs (0.563±0.045), (0.534±0.033) vs (0.558±0.039), (0.560±0.038) vs (0.580±0.030), (0.519±0.023) vs(0.549±0.024), (0.489±0.038) vs (0.518±0.027), (0.499±0.027) vs (0.533±0.032); all P<0.05). From baseline to follow-up, scores of trauma reexperience symptoms and avoidance/numbness symptoms were decreased ((5.2±2.8) vs (8.1±4.9), (4.0±3.2) vs (6.6±5.4); all P<0.05); FA values of the right corticospinal tract, Inferior fronto-occipital fasciculus, Inferior longitudinal fasciculus and forceps major were decreased ((0.523±0.049) vs (0.537±0.049), (0.568±0.052) vs (0.590±0.050), (0.540±0.063) vs (0.559±0.059), (0.520±0.059) vs (0.547±0.059); all P<0.05); The decrease of FA values of the right Inferior fronto-occipital fasciculus and right Inferior longitudinal fasciculus was negatively correlated with the decrease of avoidance/numbness symptoms scores (r=-0.458, -0.374, respectively, all P<0.05). Conclusions: The trauma of parents who lost their only child can result in impaired microstructural integrity of white matter. As the post-traumatic time goes by, parents who have lost their only child do not develop to PTSD and other psychiatric disorders, and the clinical symptoms are alleviated, the damage of the white matter microstructure continued to progress.

Diffusion kurtosis imaging and comparison of microstructural change between older adults with Alzheimer's disease and major depressive disorder

<h3>Introduction</h3> Alzheimer's disease and major depression in older adults share common clinical presentations of cognitive dysfunction. Diffusion kurtosis imaging (DKI), an extension of diffusion tensor imaging, had shown a potential to detect better microstructural changes than conventional imaging. The authors hypothesized that DKI technique can differentiate the microstructural abnormalities in these two diseases. The aim of the current study was to compare microstructural changes among older treatment naïve participants with Alzheimer's disease (AD), major depressive disorder (MDD), and healthy controls using diffusion kurtosis imaging whole-brain analysis with tract-based spatial statistics (TBSS). <h3>Methods</h3> Participants aged 60 years or older were recruited from Psychiatric and Geriatrics Clinics at Siriraj Hospital in Bangkok, Thailand. Forty-seven participants were included in this pilot study (16 AD, 11 MDD, and 20 healthy age-matched controls; mean age 70.5 years). All participants underwent an MRI study including institutional dementia protocol and DKI sequence. Post-processing analysis of images was obtained using FMRIB Software Library and Diffusion Kurtosis Estimator software with TBSS method focusing on Fractional Anisotropy (FA) parameter. <h3>Results</h3> Participants with AD showed significantly smaller values of FA in subcortical white matter of the bilateral frontal lobe, the genu, the body, and the splenium of the corpus callosum, the inferior longitudinal fasciculus, the superior longitudinal fasciculus, the pons, and the cerebellar peduncle compared to controls. There were no significant differences in FA parameters between participants with MDD and controls. This study detected a smaller in FA values in the subcortical white matter of the bilateral frontal regions in participants with MDD compared to AD. <h3>Conclusions</h3> Diffusion kurtosis imaging is a promising approach to differentiate MDD from AD participants by detection of reduction in FA values especially at subcortical areas of bilateral frontal regions. Further analysis with other diffusional parameters and a larger group of participants will expand the knowledge about pathophysiology related to microstructural changes among the elderly with AD and MDD. <h3>This research was funded by</h3> Faculty of Medicine Siriraj Hospital, Mahidol University.

Reduced Inter-Voxel White Matter Integrity in Subjective Cognitive Decline: Diffusion Tensor Imaging With Tract-Based Spatial Statistics Analysis.

Subjective cognitive decline (SCD), a self-reported worsening in cognition concurrent with normal performance on standardized neuropsychological tests, has gained much attention due to its high risks in the development of mild cognitive impairments or Alzheimer’s disease. The existing cross-sectional diffusion tensor imaging (DTI) studies in SCD have shown extremely controversial findings. Furthermore, all of these studies investigated diffusion properties within the voxel, such as fractional anisotropy, mean diffusivity, or axial diffusivity (DA). However, it remains unclear whether individuals with SCD demonstrate alterations of diffusion profile between voxels and their neighbors, as indexed by local diffusion homogeneity (LDH). We selected 30 healthy controls (HCs) and 23 SCD subjects to acquire their whole-brain DTI. Diffusion images were compared using the tract-based spatial statistics method. Diffusion indices with significant between-group tract clusters were extracted from each individual for further region-of-interest (ROI)-based comparisons. Our results showed that subjects with SCD demonstrated reduced LDH in the left superior frontal gyrus (SFG) and DA in the right anterior cingulate cortex compared with the HC group. In contrast, the SCD group showed higher LDH values in the left lingual gyrus (LG) compared with the HC group. Notably, LDH in the left SFG was significantly and negatively correlated with LDH in the left LG. In conclusion, white matter (WM) integrity in the left SFG, right ACC, and left LG is altered in SCD, suggesting that individuals with SCD exhibit detectable changes in WM tracts before they demonstrate objective cognitive deficits.

White Matter Hyperintensities after Five-Year Follow-Up and a Cross-Sectional FA Decrease in Bipolar I and Major Depressive Patients

Introduction: An increase in brain white matter hyperintensities (WMHs) and a decrease in white matter fractional anisotrophy (FA) have been detected in bipolar I (BPI), II (BPII), and major depressive disorder (MDD) patients. Their relationship, and differences in diagnostic groups are obscure. Longitudinal studies are rare. Objective: After 5-year follow-up, we evaluated WMHs in BPI, BPII, and MDD patients as compared with controls, and studied the effects of clinical variables. We also explored the associations of clinical variables with cross-sectional whole brain FA. Methods: Eight BPI, 8 BPII, 6 MDD patients, and 19 controls participated in magnetic resonance imaging at baseline and follow-up. Diffusion weighted imaging was included at follow-up. WMHs were rated by the Coffey scale, and a tract-based spatial statistics method was used for diffusion data. The general linear model, ANOVA, Fisher’s exact, Wilcoxon sign, and Kruskal-Wallis tests were used for statistical analyses. Results: Periventricular WMHs were increased in BPI patients (p = 0.047) and associated with the duration of disorder and lifetime occurrence of substance use disorder (p = 0.018). FA decrease was found in the corpus callosum of BPI patients (p < 0.01). MDD patients showed FA decrease in the right cerebellar middle peduncle (RCMP) (p < 0.01). In BPI patients, the duration of disorder associated with FA increase in RCMP (p < 0.05). No FA decrease was detected in patients with WMHs as compared with those without. Conclusions: Preceding illness burden associated modestly with WMHs, and FA increase in RCMP in BPI patients. MDD patients had FA decrease in RCMP. No association with FA decrease and WMHs was found.

Microstructural white matter alterations in Alzheimer's disease and amnestic mild cognitive impairment and its diagnostic value based on diffusion kurtosis imaging: a tract-based spatial statistics study.

This prospective study aimed to explore the white matter microstructural alterations in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) using the Tract-based Spatial Statistics (TBSS) method of diffusion kurtosis imaging (DKI).Diffusion images were collected from 45AD patients, 42 aMCI patients, and 35 healthy controls (HC). The differences of DKI-derived parameters, including kurtosis fractional anisotropy (KFA), mean kurtosis (MK), fractional anisotropy (FA), and mean diffusivity (MD), were compared across the three groups using the TBSS method. Correlation between the altered DKI-derived parameters and the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores were analyzed. A receiver operating characteristic curve (ROC) was used to evaluate the diagnostic performance of different white matter parameters with the strongest correlations. As a result, compared with the HC group, KFA values decreased significantly in the aMCI group. Compared with both the HC and aMCI groups, the FA, KFA, and MK values decreased significantly and the MD value increased significantly in the AD group. FA, MD, KFA, and MK values of many white matter fiber tracts were significantly correlated with MMSE and MoCA scores. The area under the ROC curve (AUC) for the splenium of corpus callosum KFA values were highest for the diagnosis of aMCI and AD patients. In conclusion, the compactness and complexity of white matter microstructures were reduced in AD and aMCI patients. DKI can provide information about the severity of AD progression, and KFA might be more sensitive for the detection of white matter microstructural alterations.

Altered white matter integrity in patients with monocular blindness: A diffusion tensor imaging and tract-based spatial statistics study.

BackgroundVisual deprivation can lead to abnormal and plastic changes in the brain's visual system and other systems. Although the secondary changes of gray matter in patients have been well studied, the study of white matter is rare. In fact, subtle changes in white matter may be revealed by diffusion tensor imaging, and tract‐based spatial statistics can be used to analyze DTI image data.PurposeIn the present study, diffusion tensor imaging (DTI) and tract‐based spatial statistics (TBSS) were used to investigate abnormal structural changes in the white matter (WM) of patients with monocular blindness (MB).MethodsWe recruited 16 healthy controls (HC) (fourteen males and two females) and 16 patients (fifteen males and one female) with right‐eye blindness (without differences in left‐eye vision). All patients were of similar age. Data acquisition was performed using magnetic resonance imaging (MRI) and DTI. Voxel‐based whole brain comparisons of fractional anisotropy (FA) and radial diffusivity (RD) of WM fibers in patients and HC were performed using the TBSS method. The mean FA and RD values for altered brain regions in MB patients were analyzed via the receiver operating characteristic (ROC) curve. Correlation analysis was performed to investigate the relationships between the average FA (RD) value of the whole brain and anxiety score, depression score, and visual function questionnaire score in MB patients.ResultsIn MB patients, the mean FA of the whole brain was decreased versus HC. Moreover, the FA values of the corpus callosum, the corona radiata, the posterior thalamic radiation, and the right retrolenticular part of internal capsule were significantly decreased. In addition, the average RD value of the whole brain in MB patients was higher than that observed in HC. The mean FA and RD values of brain regions were analyzed using the ROC curve, and the results showed that the area under the ROC curve was more accurate. Furthermore, the average FA and RD values of the whole brain were significantly correlated with anxiety score, depression score, and visual function‐related quality of life score.ConclusionDTI and TBSS may be useful in examining abnormal spontaneous alterations in the WM of MB patients. The observed changes in FA and RD values may imply the larvaceous neurological mechanism involved in MB.

Evaluating the Changes of White Matter Microstructures in Tobacco Addicts Based on Diffusion Tensor Imaging

BackgroundThe tract-based spatial statistics (TBSS) method was used to investigate the changes of white matter microstructure in tobacco addicts, and to analyze its correlation with smoking index, smoking years, and daily smoking amount.Material/MethodsRoutine magnetic resonance imaging (excluding intracranial lesions) and diffusion tensor imaging (DTI) sequence scanning were performed in 156 nicotine addicts (nicotine dependence group) and 81 non-nicotine addicts (control group) recruited from the study group. TBSS method was used to preprocess DTI data, and age and education level were taken as covariables to statistically analyze relevant parameters between nicotine dependence group and control group, such as fractional anisotropy (FA) value and smoking index. Spearman correlation analysis was performed on smoking status and FA values in brain regions with significant differences between nicotine dependent group and control group, and the test level α was 0.05.ResultsCompared with control group, FA values of white matter in part of the posterior limb of the right inner capsule (r=−0.428, P=0.003), the right superior radiating crown (r=−0.136, P=0.004), the right posterior radiating crown (r=−0.229, P=0.003), the right superior longitudinal bundle (r=−0.474, P=0.002), the right inferior longitudinal bundle (r=−0.354, P=0.003) and the inferior frontal occipital bundle (r=−0.310, P=0.002) were decreased, which were negatively correlated with smoking index (P<0.05).ConclusionsNicotine can damage the microstructure of white matter in specific brain regions and damage neurons, with cumulative effects.

Abnormal brain white matter in patients with hemifacial spasm: a diffusion tensor imaging study.

Refractory hemifacial contraction and comorbid emotional disorders are major annoyance suffered by patients with hemifacial spasm (HFS). It is currently unknown how whiter matter (WM) abnormalities in the brain contribute to HFS. To investigate WM alterations in HFS, 26 patients and 29 matched healthy controls were ultimately recruited in this experiment. The whole brain diffusion tensor imaging (DTI) was acquired at 3.0 Tesla scanner. Tract-based spatial statistics (TBSS) analysis was applied to investigate the differences of DTI metrics (fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) axial diffusivity (AD)) between HFS patients and controls throughout brain WM. The relationship between the severity of facial spasm and affective disturbance in HFS patients, and WM abnormalities was examined using spearman correlation analyses. TBSS method showed structural alterations in the genu and body of corpus callosum; bilateral inferior longitudinal fasciculus (ILF) and inferior frontal-occipital fasciculus (IFOF); left superior longitudinal fasciculus, anterior, posterior, and superior portion of corona radiata; left posterior limb of the internal capsule; and left posterior thalamic radiation in HFS patients compared with healthy subjects. In addition, the overlapped region of decreased FA together with increased RD and MD was merely localized in the right ILF and IFOF in the HFS group, and abnormality of RD value in this region was positively correlated with the patients' spasm score. The present study indicate extensive disruptions of WM integrity, especially the RD changes in right ILF and IFOF, which may provide alternative imaging clues for evaluating the characteristics of HFS.

Disrupted structural brain connectome underlying the cognitive deficits in remitted late-onset depression.

Cognitive deficit is a key feature of late-onset depression (LOD) and remains after clinical recovery. LOD has been associated with widespread neurobiological difficulties, including atrophy in gray and white matter (WM) tissue in areas distributed throughout the brain. However, little is known about the topological pattern changes of WM structural networks in LOD in the remitted state and its relationship to cognitive deficits. We acquired diffusion tensor images in 37 remitted LOD (rLOD) patients and 30 healthy controls. The tract-based spatial statistics method was employed to investigate WM tract integrity in rLOD. Graph-theory based network models were further used to characterize the topological organization of WM structural networks between the two groups. Compared with controls, rLOD patients showed decreased fractional anisotropy values in the left posterior cingulate bundle, right inferior fronto-occipital fasciculus and superior longitudinal fasciculus. Moreover, rLOD patients showed abnormal small-world architecture (i.e., increased path length and decreased network efficiency) in the WM structural networks. rLOD patients also showed reduced nodal efficiencies predominantly in the frontal-striatal-occipital and posterior default-mode regions. Importantly, these structural connectomic changes significantly correlated with cognitive deficits in the rLOD patients. Finally, rLOD networks showed more vulnerable to targeted attacks compared with healthy controls. These findings provide structural evidence to support the concept of rLOD that the core aspects of the pathophysiology of this disease are associated with disruptive alterations in the coordination of large-scale brain networks and advance our understanding of the neurobiological mechanism underlying cognitive deficits in the rLOD patients.

Reduced axial diffusivity and increased mode and T2 signals in cerebral white matter of chronic obstructive pulmonary disease using tract-based spatial statistics.

Chronic obstructive pulmonary disease (COPD) is considered to be a multi-systemic disease involving pathological changes in the brain. This study investigated how diffusion tensor imaging (DTI) parameters in patients with non-hypoxemic COPD differ from those in controls. Moreover, we tried to examine whether the mode of anisotropy (MO) reflects early changes in white matter (WM) integrity in COPD. DT images were obtained from 13 male COPD patients and 13 age- and sex-matched healthy controls. Raw DT images were processed using an automated tract-based spatial statistics (TBSS) pipeline. DTI scalars of fractional anisotropy (FA); axial, radial, and mean diffusivities (AD, RD, and MD, respectively); MO; and raw T2 signal (S0) were statistically compared between COPD patients and controls. TBSS methods were used for analysis. In patients with COPD, decreased AD was observed in the temporal stem (TS), corticospinal tract (CST), thalamus, subiculum, crus cerebri, and midbrain. Increased MO values were found in the corpus callosum, CST, internal capsule, cerebellar peduncle (CP), and medial lemniscus (ML). Additionally, increased S0 was found in the TS, CP, pons, and cerebellar tonsil (threshold-free cluster enhancement to a family-wise error rate of p < 0.05). The results revealed decreased AD and increased MO scalars in COPD patients compared with the controls, although there were no differences in FA, RD, and MD scalars. Decreased AD and increased MO scalars may reflect early changes in WM integrity in COPD patients.

Analysis of alterations in white matter integrity of adult patients with comitant exotropia.

ObjectiveThis study was performed to investigate structural abnormalities of the white matter in patients with comitant exotropia using the tract-based spatial statistics (TBSS) method.MethodsDiffusion tensor imaging data from magnetic resonance images of the brain were collected from 20 patients with comitant exotropia and 20 age- and sex-matched healthy controls. The FMRIB Software Library was used to compute the diffusion measures, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). These measures were obtained using voxel-wise statistics with threshold-free cluster enhancement.ResultsThe FA values in the right inferior fronto-occipital fasciculus (IFO) and right inferior longitudinal fasciculus were significantly higher and the RD values in the bilateral IFO, forceps minor, left anterior corona radiata, and left anterior thalamic radiation were significantly lower in the comitant exotropia group than in the healthy controls. No significant differences in the MD or AD values were found between the two groups.ConclusionsAlterations in FA and RD values may indicate the underlying neuropathologic mechanism of comitant exotropia. The TBSS method can be a useful tool to investigate neuronal tract participation in patients with this disease.

Gestational Age at Birth and Brain White Matter Development in Term-Born Infants and Children.

Studies on infants and children born preterm have shown that adequate gestational length is critical for brain white matter development. Less is known regarding how variations in gestational age at birth in term infants and children affect white matter development, which was evaluated in this study. Using DTI tract-based spatial statistics methods, we evaluated white matter microstructures in 2 groups of term-born (≥37 weeks of gestation) healthy subjects: 2-week-old infants (n = 44) and 8-year-old children (n = 63). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated by voxelwise and ROI methods and were correlated with gestational age at birth, with potential confounding factors such as postnatal age and sex controlled. Fractional anisotropy values, which are markers for white matter microstructural integrity, positively correlated (P < .05, corrected) with gestational age at birth in most major white matter tracts/regions for the term infants. Mean diffusivity values, which are measures of water diffusivities in the brain, and axial and radial diffusivity values, which are markers for axonal growth and myelination, respectively, negatively correlated (P < .05, corrected) with gestational age at birth in all major white matter tracts/regions excluding the body and splenium of the corpus callosum for the term infants. No significant correlations with gestational age were observed for any tracts/regions for the term-born 8-year-old children. Our results indicate that longer gestation during the normal term period is associated with significantly greater infant white matter development (as reflected by higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity values); however, similar associations were not observable in later childhood.

Reduced fractional anisotropy in patients with major depressive disorder and associations with vascular stiffness.

Previous studies revealed several alterations of the cerebral white matter in patients with major depressive disorder. However, it is unknown if these alterations are associated with vascular changes in the brain and other body parts. We compared diffusion tensor imaging derived fractional anisotropy in a well characterized sample of middle-aged patients with major depressive disorder (n = 290) and never-depressed controls (n = 346) by the method of tract-based spatial statistics. Subsequently, the potential role of pulse wave velocity as a mediator of depression- and age-related changes in extracted estimates of fractional anisotropy were analyzed.The results of the tract-based analysis revealed significantly reduced fractional anisotropy in the left posterior thalamic radiation associated with depression. Analyses of extracted data indicated additional reductions of fractional anisotropy bilaterally in the posterior thalamic radiation and in the left sagittal stratum. The analyses of indirect effects did not show any significant mediation of depression-related effects on fractional anisotropy via pulse wave velocity. However, age-related effects on fractional anisotropy were partially mediated by pulse wave velocity.In conclusion, major depressive disorder is associated with detrimental effects on cerebral white matter microstructure properties which are independent of vascular changes, as measured by pulse wave velocity. However, a portion of age-related detrimental effects on white matter is explained by vascular changes. Longitudinal studies are required for investigating changes in white matter and vascular parameters over time and their association with incident depression.

Beyond the Arcuate Fasciculus: Damage to Ventral and Dorsal Language Pathways in Aphasia.

Previous regional-based diffusion tensor imaging (DTI) studies focused on impairment of the arcuate fasciculus in aphasia; little is known about the extent to which aphasia severity is affected by damage to both ventral and dorsal language white matter (WM) pathways. To understand whether disconnection of these pathways contributes to clinical symptoms, we assessed the relationship between the alterations of WM integrity and clinical characteristics in acute aphasia after stroke. Eighteen patients with acute aphasia and age-, gender-, and education-matched healthy controls underwent language assessment and DTI scanning. The whole brain unbiased tract-based spatial statistics method was employed to quantitate WM integrity (fractional anisotropy) for both groups. Linear correlation analyses were performed to evaluate the relationship between WM integrity and clinical features. The aphasic patients showed decreased WM integrity in the left inferior fronto-occipital fasciculus/inferior longitudinal fasciculus (IFOF/ILF) and the left uncinate fasciculus, which represents components of ventral language pathway, and the left superior longitudinal fasciculus (SLF), which relates to dorsal language pathway. In addition, WM integrity of the left IFOF and SLF showed a positive correlation with aphasia quotient, performance quotient, and cortical quotient, respectively. These findings suggested that impaired WM integrity in both language pathways not only contributed to language performance, but also to general cognitive status. We suggest that aphasia involves a breakdown of multiple connections of dorsal and ventral streams that directly contributes to language deficits. Damage to these dual-streams may serve as a neuromarker for aphasias after stroke.