Analysis of Age-Related White Matter Microstructures Based on Diffusion Tensor Imaging.
Ontology highlight
ABSTRACT:
SUBMITTER: Ouyang Y
PROVIDER: S-EPMC8273390 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Diffusion tensor imaging (DTI) has been used extensively to investigate white matter (WM) microstructural changes during healthy adult aging. However, WM fibers are known to shrink throughout the lifespan, leading to larger interstitial spaces with age. This could allow more extracellular free water molecules to bias DTI metrics, which are relied upon to provide WM microstructural information. Using a cohort of 212 participants, we demonstrate that WM microstructural changes in aging are potentially less pronounced than previously reported once the free water compartment is eliminated. After free water elimination, DTI parameters show age-related differences that match histological evidence of myelin degradation and debris accumulation. The fraction of free water is further shown to associate better with age than any of the conventional DTI parameters. Our findings suggest that DTI analyses involving free water are likely to yield novel insight into retrospective re-analysis of data and to answer new questions in ongoing DTI studies of brain aging.
| S-EPMC6179151 | biostudies-literature
Project description:Microstructural changes of White Matter (WM) associated with aging have been widely described through Diffusion Tensor Imaging (DTI) parameters. In parallel, White Matter Hyperintensities (WMH) as observed on a T2-weighted MRI are extremely common in older individuals. However, few studies have investigated both phenomena conjointly. The present study investigates aging effects on DTI parameters in absence and in presence of WMH. Diffusion maps were constructed based on 21 directions DTI scans of young adults (n = 19, mean age = 33 SD = 7.4) and two age-matched groups of older adults, one presenting low-level-WMH (n = 20, mean age = 78, SD = 3.2) and one presenting high-level-WMH (n = 20, mean age = 79, SD = 5.4). Older subjects with low-level-WMH presented modifications of DTI parameters in comparison to younger subjects, fitting with the DTI pattern classically described in aging, i.e., Fractional Anisotropy (FA) decrease/Radial Diffusivity (RD) increase. Furthermore, older subjects with high-level-WMH showed higher DTI modifications in Normal Appearing White Matter (NAWM) in comparison to those with low-level-WMH. Finally, in older subjects with high-level-WMH, FA, and RD values of NAWM were associated with to WMH burden. Therefore, our findings suggest that DTI modifications and the presence of WMH would be two inter-dependent processes but occurring within different temporal windows. DTI changes would reflect the early phase of white matter changes and WMH would appear as a consequence of those changes.
| S-EPMC4718031 | biostudies-literature
Project description:Well-established literature indicates that older adults have poorer cerebral white matter integrity, as measured through diffusion tensor imaging (DTI). Age differences in DTI have been observed widely across white matter, although some tracts appear more sensitive to the effects of aging than others. Factors like APOE ε4 status and sex may contribute to individual differences in white matter integrity that also selectively impact certain tracts, and could influence DTI changes in aging. The present study explored the degree to which age, APOE ε4, and sex exerted global vs. tract specific effects on DTI metrics in cognitively healthy late middle-aged to older adults. Data from 49 older adults (ages 54-92) at two time-points separated by approximately 2.7 years were collected. DTI metrics, including fractional anisotropy (FA) and mean diffusivity (MD), were extracted from nine white matter tracts and global white matter. Results showed that across timepoints, FA and MD increased globally, with no tract-specific changes observed. Baseline age had a global influence on both measures, with increasing age associated with lower FA and higher MD. After controlling for global white matter FA, age additionally predicted FA for the genu, callosum body, inferior fronto-occipital fasciculus (IFOF), and both anterior and posterior cingulum. Females exhibited lower global FA on average compared to males. In contrast, MD was selectively elevated in the anterior cingulum and superior longitudinal fasciculus (SLF), for females compared to males. APOE ε4 status was not predictive of either measure. In summary, these results indicate that age and sex are associated with both global and tract-specific alterations to DTI metrics among a healthy older adult cohort. Older women have poorer white matter integrity compared to older men, perhaps related to menopause-induced metabolic changes. While age-related alterations to white matter integrity are global, there is substantial variation in the degree to which tracts are impacted, possibly as a consequence of tract anatomical variability. The present study highlights the importance of accounting for global sources of variation in DTI metrics when attempting to investigate individual differences (due to age, sex, or other factors) in specific white matter tracts.
| S-EPMC8006297 | biostudies-literature
Project description:This study set out to determine whether there is white matter involvement in essential tremor (ET), the most common movement disorder. We collected diffusion MRI and analysed differences in fractional anisotropy (FA) and mean diffusivity (MD) between ET patients and control subjects as markers of white matter integrity. We used both classical ROI-based statistics and whole-brain analysis techniques, including voxel-wise analysis with SPM5 and tract-based spatial statistics (TBSS). Using region of interest (ROI) analysis, we found increased MD bilaterally in the inferior cerebellar peduncles (ICP) and reduced FA in the right-sided ICP of ET patients. Whole-brain analyses with TBSS detected increased MD distributed in both motor and nonmotor white matter fibers of ET patients predominantly in the left parietal white matter, while there were no significant FA differences in these areas between ET patients and controls. Voxel-wise analysis with SPM detected significant increase of MD congruent with the highest probability of difference as detected by TBSS. VBM analysis of T1 images did not detect significant differences in either gray or white matter density between our study groups. In summary, we found evidence for changes in white matter MRI properties in ET. The circumscript pathology of the ICP corroborates the pathogenetic concept of the cerebellum and its projections as key structures for tremor generation in ET. Moreover, increased diffusivity in white matter structures of both hemispheres suggests widespread alterations of fiber integrity in motor and nonmotor networks in ET patients. The underlying cause of the DTI changes observed remains to be elucidated.
| S-EPMC6870356 | biostudies-literature
Project description:BackgroundThe results of recent diffusion tensor imaging (DTI) studies on amyotrophic lateral sclerosis (ALS) are inconclusive and controversial. We performed a voxel-based meta-analysis to identify a statistical consensus among published DTI studies of altered white matter (WM) microarchitecture in ALS.MethodsA systematic search was conducted for relevant studies that used voxel-wise analyses of WM microarchitecture in patients with ALS. Anisotropic effect size-signed differential mapping (AES-SDM) was applied to analyze fractional anisotropy (FA) differences between ALS patients and healthy controls. Meta-regression analysis was used to explore the effects of clinical characteristics on WM integrity in patients with ALS.ResultsA total of 14 studies with 16 datasets that included 396 patients and 360 healthy controls were identified. The pooled meta-analysis revealed that patients with ALS exhibited significant FA reductions in two clusters relative to healthy controls. The largest cluster exhibited a peak coordinate in the left corona radiata, extending to the body and splenium of the corpus callosum, left superior longitudinal fasciculus, posterior limb of the internal capsule, right corona radiata, and bilateral cingulate gyrus. The other cluster exhibited decreased FA in the right corticospinal tract that extended to the right cerebral peduncle. The Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) score was positively correlated with the FA reduction in the left corona radiata. Mean age and illness duration were not linearly correlated with the FA reductions.ConclusionsThis study provides a thorough profile of WM microarchitecture alterations in patients with ALS and further evidence that the neuronal degeneration is not limited to the corticospinal tract but also includes extra-motor areas, which supports the view that ALS is a multisystem degenerative disorder that involves the white matter.
| S-EPMC6051469 | biostudies-literature
Project description:Background and purposeCurrent approaches to diffusion tensor imaging (DTI) analysis do not permit identification of individual-level changes in DTI indices. We investigated the ability of wild bootstrapping analysis to detect subject-specific changes in brain white matter (WM) before and after sports-related concussion.Materials and methodsA prospective cohort study was performed in nine high school athletes engaged in hockey or football and six controls. Subjects underwent DTI pre- and postseason within a 3-month interval. One athlete was diagnosed with concussion (scanned within 72 h), and eight suffered between 26 and 399 subconcussive head blows. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in each WM voxel. Bootstrap samples were generated, and a permuted t test was used to compare voxel-wise FA/MD changes in each subject pre- vs. postseason.ResultsThe percentage of WM voxels with significant (p<.05) pre-post FA changes was highest for the concussion subject (3.2%), intermediary for those with subconcussive head blows (mean 1.05%±.15%) and lowest for controls (mean 0.28%±.01%). Similarly, the percentage of WM voxels with significant MD changes was highest for the concussion subject (3.44%), intermediary for those with subconcussive head blows (mean 1.48%±.17%) and lowest for controls (mean 0.48%±.05%). Significantly changed FA and MD voxels colocalized in the concussion subject to the right corona radiata and right inferior longitudinal fasciculus.ConclusionsWild bootstrap analysis detected significantly changed WM in a single concussed athlete. Athletes with multiple subconcussive head blows had significant changes in a percentage of their WM that was over three times higher than controls. Efforts to understand the significance of these WM changes and their relationship to head impact forces appear warranted.
| S-EPMC3254806 | biostudies-literature
Project description:OBJECTIVES:Idiopathic-generalized epilepsy (IGE) is currently considered to be a genetic disease without structural alterations on conventional MRI. However, voxel-based morphometry has shown abnormalities in IGE. Another method to analyze the microstructure of the brain is diffusion-tensor imaging (DTI). We sought to clarify which structural alterations are present in IGE and the most frequent subsyndrome juvenile myoclonic epilepsy (JME). EXPERIMENTAL DESIGN:We studied 25 patients (13 IGE and 12 JME) and 44 healthy controls with DTI. Fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivity (AD/RD) were calculated and group differences were analyzed using tract-based spatial statistics (TBSS). Additionally we performed a target-based classification of TBSS results based on the Freesurfer cortical regions. PRINCIPLE OBSERVATIONS: TBSS showed widespread FA reductions as well as MD and RD increases in patients compared to controls. Affected areas were corpus callosum, corticospinal tract, superior and inferior longitudinal fasciculus and supplementary motor regions. No significant differences were found between JME and IGE subgroups. The target-based classification confirmed a particular involvement of the superior frontal gyrus (mesiofrontal area) in IGE/ME. CONCLUSIONS:IGE and JME patients showed clear microstructural alterations in several large white matter tracts. Similar findings have been reported in rodent models of IGE. Previous, region-of-interest-based DTI studies may have under-estimated the spatial extent of structural loss associated with generalized epilepsy. The comparison of clinically defined JME and IGE groups revealed no significant DTI differences in our cohort.
| S-EPMC6869818 | biostudies-literature
Project description:Alcoholism-related deficits in cognition and emotion point toward frontal and limbic dysfunction, particularly in the right hemisphere. Prefrontal and anterior cingulate cortices are involved in cognitive and emotional functions and play critical roles in the oversight of the limbic reward system. In the present study, we examined the integrity of white matter tracts that are critical to frontal and limbic connectivity.Diffusion tensor magnetic resonance imaging (DT-MRI) was used to assess functional anisotropy (FA), a measure of white matter integrity, in 15 abstinent long-term chronic alcoholic and 15 demographically equivalent control men. Voxel-based and region-based analyses of group FA differences were applied to these scans.Alcoholic subjects had diminished frontal lobe FA in the right superior longitudinal fascicles II and III, orbitofrontal cortex white matter, and cingulum bundle, but not in corresponding left hemisphere regions. These right frontal and cingulum white matter regional FA measures provided 97% correct group discrimination. Working Memory scores positively correlated with superior longitudinal fascicle III FA measures in control subjects only.The findings demonstrate white matter microstructure deficits in abstinent alcoholic men in several right hemisphere tracts connecting prefrontal and limbic systems. These white matter deficits may contribute to underlying dysfunction in memory, emotion, and reward response in alcoholism.
| S-EPMC4105344 | biostudies-literature
Project description:Multiple functional methods including functional magnetic resonance imaging, transcranial magnetic stimulation, and positron emission tomography have shown cortical reorganization in response to blindness. We investigated microanatomical correlates of this reorganization using diffusion tensor imaging and diffusion tensor tractography (DTT). Five early blind (EB) were compared with 7 normally sighted (NS) persons. DTT showed marked geniculocalcarine tract differences between EB and NS participants. All EB participants showed evidence of atrophy of the geniculocortical tracts. Connections between visual cortex and the orbital frontal and temporal cortices were relatively preserved in the EB group. Importantly, no additional tracts were found in any EB participant. Significant alterations of average diffusivity and relative anisotropy were found in the white matter (WM) of the occipital lobe in the EB group. These observations suggest that blindness leads to a reorganization of cerebral WM and plausibly support the hypothesis that visual cortex functionality in blindness is primarily mediated by corticocortical as opposed to thalamocortical connections.
| S-EPMC3789517 | biostudies-literature
Project description:Tuberculous meningitis (TBM) and cryptococcal meningitis (CM) are two of the most common types of chronic meningitis. This study aimed to assess whether chronic neuro-psychological sequelae are associated with micro-structure white matter (WM) damage in HIV-negative chronic meningitis. Nineteen HIV-negative TBM patients, 13 HIV-negative CM patients, and 32 sex- and age-matched healthy volunteers were evaluated and compared. The clinical relevance of WM integrity was studied using voxel-based diffusion tensor imaging (DTI) magnetic resonance imaging. All of the participants underwent complete medical and neurologic examinations, and neuro-psychological testing. Differences in DTI indices correlated with the presence of neuro-psychological rating scores and cerebrospinal fluid (CSF) analysis during the initial hospitalization. Patients with CM had more severe cognitive deficits than healthy subjects, especially in TBM. There were changes in WM integrity in several limbic regions, including the para-hippocampal gyrus and cingulate gyrus, and in the WM close to the globus pallidus. A decline in WM integrity close to the globus pallidus and anterior cingulate gyrus was associated with worse CSF analysis profiles. Poorer DTI parameters directly correlated with worse cognitive performance on follow-up. These correlations suggest that WM alterations may be involved in the psychopathology and pathophysiology of co-morbidities. Abnormalities in the limbic system and globus pallidus, with their close relationship to the CSF space, may be specific biomarkers for disease evaluation.
| S-EPMC4043527 | biostudies-literature