Characterizing dementia with Lewy bodies by means of diffusion tensor imaging

Abstract

Objective: To investigate patterns of in vivo white matter tract change using diffusion tensor imaging (DTI), we conducted a cross-sectional study of dementia with Lewy bodies (DLB) in comparison with Alzheimer disease (AD) and normal aging. Methods:The study included 106 subjects (35 with DLB, 36 with AD, and 35 elderly controls) who underwent clinical and neuropsychological assessment and diffusion tensor MRI. We used tract-based spatial statistics to investigate patterns of reduced fractional anisotropy (FA) and increased mean diffusivity (MD) across the entire white matter tract skeleton and also investigated correlations with clinical features. Results:Areas of reduced FA in subjects with DLB vs controls were found primarily in parietooccipital white matter tracts; in AD, the changes were much more diffuse. DLB was also associated with reduced FA in the pons and left thalamus, in comparison with AD. The pattern of MD increase was diffuse in AD and DLB. We found an association between DTI parameters and impaired episodic memory, letter fluency, and severity of motor parkinsonism in DLB. Conclusions:Despite a similar level of dementia severity, patterns of DTI changes in AD and DLB differed significantly. The selective involvement of the visual association areas and subcortical structures and the significant clinical correlations highlight the potential importance of white matter tract change in the pathogenesis of DLB. DTI may be a useful technique to investigate early and possible preclinical changes in DLB and warrants further investigation. Neurology Dementia with Lewy bodies (DLB) is a common form of neurodegenerative dementia in older people, second to Alzheimer disease (AD). The separation between AD and DLB clinically remains a challenge. We therefore need to establish in vivo biomarkers that can distinguish the differing pathologies and their contribution to the clinical features of the conditions. Diffusion tensor imaging (DTI) utilizes the anisotropic nature of diffusion in neuronal white matter tracts.1 With neuronal degeneration, the mean diffusivity (MD) increases with the loss of structural barriers that normally restrict diffusion, and diffusion becomes less directionally oriented, which is associated with a reduction in fractional anisotropy (FA). 2Previous studies investigating the DTI changes in DLB have used conventional region of interest (ROI) or voxel-based morphometry (VBM) methods.3-8 Some studies found widespread FA changes in comparison with healthy controls, 3,7 whereas others have found very little

Tissue microstructural changes in dementia with Lewy bodies revealed by quantitative MRI

“…It shares common clinical and neuropsychological features with other subtypes of dementia such as AD and Parkinson's disease dementia (PDD), but has a distinctive pattern of pathological changes [2,3]. In comparison to AD, DLB has been shown to have less severe atrophy than AD, but with a more diffuse and less focal pattern [4,5], with relatively preserved medial temporal lobes [2,[6][7][8].…”

“…In comparison to AD, DLB has been shown to have less severe atrophy than AD, but with a more diffuse and less focal pattern [4,5], with relatively preserved medial temporal lobes [2,[6][7][8]. One of the most notable characteristics of DLB is visuo-spatial deficit, and imaging studies using mostly PET/SPECT in DLB have highlighted the involvement of occipital [9][10][11], temporoparietal [1,3,12] and subcortical areas [13][14][15]. These characteristics of functional rather than structural changes make conventional volumetric MR technique insufficient to fully describe DLB.…”

Classifying Alzheimer's disease, Lewy body dementia, and normal controls using 3D texture analysis in magnetic resonance images

“…WML segmentation is unsatisfactory developed and very often demanding manual outlining is required as well as a FLAIR MR image, where WML is hyper intense, while WM segmentation is readily available from many well known and freely downloadable software packages needing only a 3DT1 MR image which is a common part of a clinical MR protocol. In addition recent focus on diffusion tensor imaging (DTI) in vascular disease [167], amnestic mild cognitive impairment (aMCI) [168], and dementia [169,170,68] strengthens the view that age-related changes in WM plays an important role in the development of dementia. DTI is never the less not suffi-ciently available and at the same time costly making other approaches for WM analysis, like ours, a valuable addition.…”

“…Another MR imaging approach showing promising results concerning analysis of white matter integrity is diffusion tensor MRI (DT-MRI) [68]. DT-MRI is an MRI method which is sensitive to the diffusion, or Brownian motion, of water molecules.…”

Dementia with Lewy Bodies

“…Diffusion tensor imaging has also demonstrated decreased fractional anisotropy (FA) in the precuneus versus both normal controls and AD patients. [49][50][51] Fluorodeoxyglucose positron emission tomography (FDG-PET) demonstrates decreased occipital glucose metabolism, which is helpful in distinguishing among other neurodegenerative diseases, with one study showing 71% decrease in occipital metabolism without much asymmetry. 52 Other studies found temporo-parieto-occipital cortical hypometabolism as well as hypometabolism within the basal ganglia and pulvinar of the thalami.…”