MRI Markers for Mild Cognitive Impairment: Comparisons between White Matter Integrity and Gray Matter Volume Measurements

Abstract

The aim of the study was to evaluate the value of assessing white matter integrity using diffusion tensor imaging (DTI) for classification of mild cognitive impairment (MCI) and prediction of cognitive impairments in comparison to brain atrophy measurements using structural MRI. Fifty-one patients with MCI and 66 cognitive normal controls (CN) underwent DTI and T1-weighted structural MRI. DTI measures included fractional anisotropy (FA) and radial diffusivity (DR) from 20 predetermined regions-of-interest (ROIs) in the commissural, limbic and association tracts, which are thought to be involved in Alzheimer's disease; measures of regional gray matter (GM) volume included 21 ROIs in medial temporal lobe, parietal cortex, and subcortical regions. Significant group differences between MCI and CN were detected by each MRI modality: In particular, reduced FA was found in splenium, left isthmus cingulum and fornix; increased DR was found in splenium, left isthmus cingulum and bilateral uncinate fasciculi; reduced GM volume was found in bilateral hippocampi, left entorhinal cortex, right amygdala and bilateral thalamus; and thinner cortex was found in the left entorhinal cortex. Group classifications based on FA or DR was significant and better than classifications based on GM volume. Using either DR or FA together with GM volume improved classification accuracy. Furthermore, all three measures, FA, DR and GM volume were similarly accurate in predicting cognitive performance in MCI patients. Taken together, the results imply that DTI measures are as accurate as measures of GM volume in detecting brain alterations that are associated with cognitive impairment. Furthermore, a combination of DTI and structural MRI measurements improves classification accuracy.

Mediterranean diet and preserved brain structural connectivity in older subjects

“…Still, our results may provide a few clues to start deciphering these pathways. First, the strong relation of the MeDi with WM microstructure in extensive areas (with no specific involvement of tracts generally altered in AD, e.g., the cingulum and fornix) along with the absence of meaningful association with GM atrophy (specifically in AD regions, e.g., the hippocampus) suggests that mechanisms are not primarily related to AD neurodegeneration [35][36][37][38][39][40]. It remains possible that our study was underpowered to detect associations with volumes; however, we were able to detect the effect of age, suggesting sufficient power in this sample to capture wellestablished risk factors for brain atrophy.…”

Effects of low-level sarin and cyclosarin exposure on white matter integrity in Gulf War Veterans

“…Yamasue et al (2007) also reported significant correlations between somatic complaints in sarin attack victims and reduced FA in the temporal stem bilaterally (peak MNI coordinates: 34, 0, −15; −38, 2, −16), which corresponded to the bilateral uncinate fasciculus in the DTI atlas, and left subinsula (peak MNI coordinates: −28, −6, 8), which corresponded to the left external capsule in the DTI atlas. For each participant, we extracted the mean FA, axial and radial diffusivity value from each tract using a previously described method (Zhang et al, 2013). To protect against type I error, we reduced the number of measurements by averaging the DTI values from the left and right sagittal straitum and uncinate fasciculus to create one temporal stem ROI.…”

White matter hyperintensities, cognitive impairment and dementia: an update

“…[19][20][21][22][23] Furthermore, evidence is accumulating that novel imaging techniques, such as diffusion tensor imaging (DTI), can detect subtle impairments in white matter tract integrity before they can be seen on conventional MRI, suggesting that WMHs represent only the extreme end of a continuous spectrum of white matter injury. 24,25 MRI also enables the measurement of progression of WMHs over time. [26][27][28] As regards the underlying pathology, there is little doubt that the majority of these lesions are ischaemic in origin.…”