Correlation between degree of white matter hyperintensities and global gray matter volume decline rate

Introduction  

Whether the degree of white matter hyperintensities (WMHs) shows a significant correlation with the rate of global gray matter volume decline over a period following initial baseline measurement remains unclear. The purpose of the present study was to reveal the relationship between the degree of WMHs at baseline and the rate of global gray matter volume decline by applying a longitudinal design.     

Impact of white matter hyperintensities on surrounding white matter tracts

Purpose

It is unclear how white matter hyperintensities disrupt surrounding white matter tracts. The aim of this tractography study was to determine the spatial relationship between diffusion characteristics along white matter tracts and the distance from white matter hyperintensities.

Methods

Diffusion tensor 3-T MRI scans were acquired in 29 participants with white matter hyperintensities. In each subject, tractography by the fiber assignment by continuous tracking method was used to segment corticospinal tracts. Mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy were measured along corticospinal tracts in relation to white matter hyperintensities. Diffusion characteristics along tracts were correlated with distance from white matter hyperintensities and were also compared between tracts traversing and not traversing white matter hyperintensities.

Results

In tracts not traversing through white matter hyperintensities, increasing distance from white matter hyperintensities was associated with decreased mean diffusivity (p?=?0.002) and increased fractional anisotropy (p?=?0.006). In tracts traversing white matter hyperintensities, compared to tracts not traversing white matter hyperintensites, the mean diffusivity was higher at 6–8 voxels, axial diffusivity higher at 4–8 voxels, and radial diffusivity higher at 7 voxels away from white matter hyperintensities (all p?<?0.006).

Conclusion

White matter hyperintensities are associated with two patterns of altered diffusion characteristics in the surrounding white matter tract network. Diffusion characteristics along white matter tracts improve further away from white matter hyperintensities suggestive of a local penumbra pattern. Also, altered diffusion extends further along tracts traversing white matter hyperintensities suggestive of a Wallerian-type degenerative pattern.

     

Quantitative analysis of [18F]FDDNP PET using subcortical white matter as reference region

Purpose  

Subcortical white matter is known to be relatively unaffected by amyloid deposition in Alzheimer’s disease (AD). We investigated the use of subcortical white matter as a reference region to quantify [¹⁸F]FDDNP binding in the human brain.     

Magnetic resonance imaging and diffusion-weighted imaging of normal-appearing white matter in children and young adults with tuberous sclerosis complex

Introduction  

Patients with tuberous sclerosis complex (TSC) frequently present with neurocognitive deficits which may be related to impaired white matter maturation. The purposes of our study were (a) to evaluate the white matter maturation in children and young adults with TSC by comparing the apparent diffusion coefficient (ADC) values of normal-appearing white matter (NAWM) with age-matched healthy controls and (b) to determine the association of NAWM-ADC values with the severity of neurological symptoms in TSC patients.     

The prognostic value of multivoxel magnetic resonance spectroscopy determined metabolite levels in white and grey matter brain tissue for adverse outcome in term newborns following perinatal asphyxia

Objective  

Magnetic resonance spectroscopy can identify brain metabolic changes in perinatal asphyxia by providing ratios of metabolites, such as choline (Cho), creatine (Cr), N-acetyl aspartate (NAA) and lactate (Lact) [Cho/Cr, Lact/NAA, etc.]. The purpose of this study was to quantify the separate white and grey matter metabolites in a slab cranial to the ventricles and relate these to the outcome.     

Punctate white matter lesions in infants: new insights using susceptibility-weighted imaging

Introduction  

Punctate white matter lesions (PWML) are recognized with magnetic resonance imaging (MRI) as hypersignal on T1-weighted imaging and hyposignal on T2-weighted imaging. Our aim was to assess how often a hemorrhagic component was present in PWML using susceptibility-weighted imaging (SWI).     

Disrupted white matter structure underlies cognitive deficit in hypertensive patients

Objectives

Hypertension is considered a risk factor of cognitive impairments and could result in white matter changes. Current studies on hypertension-related white matter (WM) changes focus only on regional changes, and the information about global changes in WM structure network is limited.

Methods

We assessed the cognitive function in 39 hypertensive patients and 37 healthy controls with a battery of neuropsychological tests. The WM structural networks were constructed by utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. The direct and indirect correlations among cognitive impairments, brain WM network disruptions and hypertension were analyzed with structural equation modelling (SEM).

Results

Hypertensive patients showed deficits in executive function, memory and attention compared with controls. An aberrant connectivity of WM networks was found in the hypertensive patients (P _Eglob?=?0.005, P _Lp?=?0.005), especially in the frontal and parietal regions. Importantly, SEM analysis showed that the decline of executive function resulted from aberrant WM networks in hypertensive patients (p?=?0.3788, CFI?=?0.99).

Conclusions

These results suggest that the cognitive decline in hypertensive patients was due to frontal and parietal WM disconnections. Our findings highlight the importance of brain protection in hypertension patients.

Key points

? Hypertension has a negative effect on the performance of the cognitive domains ? Reduced efficiencies of white matter networks were shown in hypertension ? Disrupted white matter networks are responsible for poor cognitive function in hypertension

     

New multispectral MRI data fusion technique for white matter lesion segmentation: method and comparison with thresholding in FLAIR images

Objective  

Brain tissue segmentation by conventional threshold-based techniques may have limited accuracy and repeatability in older subjects. We present a new multispectral magnetic resonance (MR) image analysis approach for segmenting normal and abnormal brain tissue, including white matter lesions (WMLs).     

Whole-brain voxel-based morphometry of white matter in mild cognitive impairment

Purpose

The purpose of this study was to analyze whole-brain white matter changes in mild cognitive impairment (MCI).

Materials and methods

We studied 14 patients with MCI and 14 age- and sex-matched healthy control subjects using voxel-based morphometry (VBM) on T1-weighted 3D datasets. The data were collected on a 3T MR system and analyzed by SPM2 to generate white matter volume maps.

Results

Voxel-based morphometry revealed diffusively reduced white matter in MCI prominently including the bilateral temporal gyrus, the right anterior cingulate, the bilateral superior and medial frontal gyrus and right parietal angular gyrus. White matter reduction was more prominent in anterior regions than that in posterior regions.

Conclusion

Whole-brain white matter reduction in MCI patients detected with VBM has special distribution which is in line with the white matter pathology of MCI.     

MR spectroscopy of cerebral white matter in type 2 diabetes; no association with clinical variables and cognitive performance

Introduction  

Type 2 diabetes (DM2) is associated with cognitive decline, but the pathogenesis of this important complication remains unclear. We investigated whether abnormalities in neuronal metabolism or membrane integrity in normal appearing cerebral white matter are associated with cognitive impairment in patients with DM2.     

Evaluation of deep gray matter volume,cortical thickness and white matter integrity in patients with typical absence epilepsy: a study using voxelwise-based techniques

Introduction

The objective of this study was to evaluate the cortical thickness and the volume of deep gray matter structures, measured from 3D T1-weighted gradient echo imaging, and white matter integrity, by diffusion tensor imaging (DTI) in patients with typical absence epilepsy (AE).

Methods

Patients (n = 19) with typical childhood AE and juvenile AE, currently taking antiepileptic medication, were compared with control subjects (n = 19), matched for gender and age. 3D T1 magnetization-prepared rapid gradient echo-weighted imaging and DTI along 30 noncolinear directions were performed using a 1.5-T MR scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of deep gray matter structures. For tract-based spatial statistics analysis of DTI, a white matter skeleton was created, along with a permutation-based inference with 5000 permutations. A threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The mean, radial, and axial diffusivities were also projected onto the mean FA skeleton.

Results

Patients with AE presented decreased FA and increased mean diffusivity and radial diffusivity values in the genu and the body of the corpus callosum and right anterior corona radiata, as well as decreased axial diffusivity in the left posterior thalamic radiation, inferior cerebellar peduncle, right cerebral peduncle, and right corticospinal tract. However, there were no significant differences in cortical thickness or deep gray matter structure volumes between patients with AE and controls.

Conclusion

Abnormalities found in white matter integrity may help to better understand the pathophysiology of AE and optimize diagnosis and treatment strategies.

     

Presence of a central vein within white matter lesions on susceptibility weighted imaging: a specific finding for multiple sclerosis?

Introduction  

Susceptibility weighted imaging depicts the perivenous extent of multiple sclerosis white matter lesions (MS-WML) in vivo by directly visualizing their centrally running vein. The aim of this study was to investigate the specificity of this finding for MS.     

Is sequential cranial ultrasound reliable for detection of white matter injury in very preterm infants?

Introduction  

Cranial ultrasound (cUS) may not be reliable for detection of diffuse white matter (WM) injury. Our aim was to assess in very preterm infants the reliability of a classification system for WM injury on sequential cUS throughout the neonatal period, using magnetic resonance imaging (MRI) as reference standard.     

Functional connectivity and microstructural white matter changes in phenocopy frontotemporal dementia

Objectives

Phenocopy frontotemporal dementia (phFTD) is a rare and poorly understood clinical syndrome. PhFTD shows core behavioural variant FTD (bvFTD) symptoms without associated cognitive deficits and brain abnormalities on conventional MRI and without progression. In contrast to phFTD, functional connectivity and white matter (WM) microstructural abnormalities have been observed in bvFTD. We hypothesise that phFTD belongs to the same disease spectrum as bvFTD and investigated whether functional connectivity and microstructural WM changes similar to bvFTD are present in phFTD.

Methods

Seven phFTD patients without progression or alternative psychiatric diagnosis, 12 bvFTD patients and 17 controls underwent resting state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI). Default mode network (DMN) connectivity and WM measures were compared between groups.

Results

PhFTD showed subtly increased DMN connectivity and subtle microstructural changes in frontal WM tracts. BvFTD showed abnormalities in similar regions as phFTD, but had lower increased DMN connectivity and more extensive microstructural WM changes.

Conclusions

Our findings can be interpreted as neuropathological changes in phFTD and are in support of the hypothesis that phFTD and bvFTD may belong to the same disease spectrum. Advanced MRI techniques, objectively identifying brain abnormalities, would therefore be potentially suited to improve the diagnosis of phFTD.

Key points

? PhFTD shows brain abnormalities that are similar to bvFTD. ? PhFTD shows increased functional connectivity in the parietal default mode network. ? PhFTD shows microstructural white matter abnormalities in the frontal lobe. ? We hypothesise phFTD and bvFTD may belong to the same disease spectrum.

     

Diffuse vascular injury: convergent-type hemorrhage in the supratentorial white matter on susceptibility-weighted image in cases of severe traumatic brain damage

Introduction  

Susceptibility-weighted image (SWI) is one of the most sensitive methods for detect microbleeding and useful for evaluation of traumatic brain damage. The purpose of this study is to delineate the characteristics and importance of supratentorial deep white matter hemorrhages detected by SWI in cases of traumatic brain damage.     

Assessment of damage to cerebral white matter fiber in the subacute phase after carbon monoxide poisoning using fractional anisotropy in diffusion tensor imaging

Introduction  

Chronic neuropsychiatric symptoms after carbon monoxide (CO) poisoning are caused by demyelination of cerebral white matter fibers. We examined whether diffusion tensor imaging can sensitively represent damage to fibers of the centrum semiovale in the subacute phase after CO intoxication.     

Age-related white matter changes in high b-value q-space diffusion-weighted imaging

Introduction

To assess and compare age-related diffusion changes in the white matter in different cerebral lobes, as quantified by diffusion-weighted imaging (DWI) and high b-value q-space imaging (QSI).

Methods

Seventy-three cases without neurological symptoms or imaging abnormalities were grouped by age as young (<30 years, n?=?20), middle-aged (30–49 years, n?=?19), old (50–69 years, n?=?18), and very old (>70 years, n?=?16) and imaged by a 1.5-T MR scanner for DWI and QSI. Apparent diffusion coefficient (ADC) and mean displacement (MDP) values were calculated in the white matter of frontal, parietal, and temporal lobes and compared using Dunnett’s test, with the young group as a control.

Results

MDP values in frontal and parietal lobes were significantly higher in old and very old age groups than in the young, while those in the temporal lobes were significantly higher only in the very old group. ADC values were significantly higher in all three lobes in the very old group.

Conclusion

QSI is more sensitive than DWI to age-related myelin loss in white matter.     

White matter hyperintensities and changes in white matter integrity in patients with Alzheimer’s disease

Introduction  

White matter hyperintensities (WMHs) are a risk factor for Alzheimer’s disease (AD). This study investigated the relationship between WMHs and white matter changes in AD using diffusion tensor imaging (DTI) and the sensitivity of each DTI index in distinguishing AD with WMHs.     

Whole brain white matter changes revealed by multiple diffusion metrics in multiple sclerosis: a TBSS study

Objective

To investigate whole brain white matter changes in multiple sclerosis (MS) by multiple diffusion indices, we examined patients with diffusion tensor imaging and utilized tract-based spatial statistics (TBSS) method to analyze the data.

Methods

Forty-one relapsing-remitting multiple sclerosis (RRMS) patients and 41 age- and gender-matched normal controls were included in this study. Diffusion weighted images were acquired by employing a single-shot echo planar imaging sequence on a 1.5 T MR scanner. Voxel-wise analyses of multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were performed with TBSS.

Results

The MS patients had significantly decreased FA (9.11%), increased MD (8.26%), AD (3.48%) and RD (13.17%) in their white matter skeletons compared with the controls. Through TBSS analyses, we found abnormal diffusion changes in widespread white matter regions in MS patients. Specifically, decreased FA, increased MD and increased RD were involved in whole-brain white matter, while several regions exhibited increased AD. Furthermore, white matter regions with significant correlations between the diffusion metrics and the clinical variables (the EDSS scores, disease durations and white matter lesion loads) in MS patients were identified.

Conclusion

Widespread white matter abnormalities were observed in MS patients revealed by multiple diffusion metrics. The diffusion changes and correlations with clinical variables were mainly attributed to increased RD, implying the predominant role of RD in reflecting the subtle pathological changes in MS.     

In vivo evaluation of white matter pathology in patients of progressive supranuclear palsy using TBSS

Introduction

The purpose of this research is to study white matter (WM) changes in patients of progressive supranuclear palsy (PSP) using automated analysis of diffusion tensor imaging (DTI) indices.

Methods

This was a prospective study comprising of 24 patients of PSP and 26 matched healthy controls. Fractional anisotropy, mean diffusivity (MD), axial diffusivity, and radial diffusivity (RD) changes were studied in the WM of the PSP patients using an automated analysis technique, tract-based spatial statistics (TBSS). Two subtypes of PSP, i.e., classic Richardson’s syndrome (PSP-RS) and parkinsonian type (PSP-P), were also compared among themselves to identify relative severity of WM changes as well as identify spatial distribution of the differences. Clinicoradiological correlation was done to determine the strength of correlation between WM abnormalities identified using TBSS and clinical scores.

Results

There were areas of significant abnormality seen in the frontoparietal cerebral WM, thalamus, midbrain tectum, superior cerebellar peduncle, and cerebellar WM. The abnormalities were more spatially widespread on MD and RD maps. Compared to PSP-P, the patients of PSP-RS had more spatial abnormalities localized to the frontal WM. There was no correlation between the observed WM changes and clinical rating scales.

Conclusions

The TBSS analysis showed widespread WM abnormalities in PSP patients including areas which have been shown to be involved in previous pathological studies. PSP-RS showed more severe white matter abnormality compared to the PSP-P subtype.