title: 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.
authors.affiliation: Center for Imaging of Neurodegenerative Diseases, San Francisco VA Medical Center, San Francisco, California, United States of America. Yu.Zhang@ucsf.edu
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Norbert
authors.initials: N
authors.lastname: Schuff
authors.forename: Monica
authors.initials: M
authors.lastname: Camacho
authors.forename: Linda L
authors.initials: LL
authors.lastname: Chao
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Fletcher
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.forename: Susan C
authors.initials: SC
authors.lastname: Woolley
authors.forename: Catherine
authors.initials: C
authors.lastname: Madison
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Rosen
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Miller
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D015415:Biomarkers / Q000032:analysis; D001931:Brain Mapping; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D056324:Diffusion Tensor Imaging; D005260:Female; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000473:pathology* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D013702:Temporal Lobe / Q000473:pathology* / Q000503:physiopathology
chemical_list: D015415:Biomarkers