Regional pattern of increased water diffusivity in hippocampus and corpus callosum in mild cognitive impairment.
BACKGROUND
Corpus callosum atrophy possibly indicates neuronal degeneration in association cortex in Alzheimer's disease (AD). Water diffusivity allows detecting physiological changes that probably occur earlier than structural shrinkage in cerebral regions during the development of AD.


OBJECTIVE
To simultaneously investigate the focal volumetric and early structural changes with apparent diffusion coefficient (ADC) of corpus callosum in mild cognitive impairment (MCI), and to explore the regional pattern of ADC increase in hippocampus and corpus callosum.


METHODS
Thirteen subjects with MCI and 13 healthy age-matched control subjects were studied. With three-dimensional volumetric spoiled gradient recalled echo MRI images, we measured the volume of hippocampus and corpus callosum. Using MRI-guided diffusion-weighted imaging analysis, we calculated ADCs from hippocampus and corpus callosum. Within the receiver-operation curve (ROC) statistical framework, areas under ROC curves from hippocampal and callosal ADCs were compared in differentiating between MCI and controls.


RESULTS
After normalization to intracranial volume, hippocampal, not callosal, volume was significantly reduced in MCI. ADC values were increased in hippocampus and corpus callosum in MCI. The extent of ADC increase was similar between hippocampus and corpus callosum.


CONCLUSIONS
Alterations in water diffusivity may precede corpus callosum atrophy during the development of MCI. Diffusion changes might occur simultaneously in allocortex and neocortex in MCI.
Wang
Huali
H
Institute of Mental Health, Peking University, Beijing, P.R. China. hauli_wang@bjmu.edu.cn
Su
Min-Ying
MY
D000368:Aged; D001284:Atrophy; D001834:Body Water / Q000502:physiology*; D002540:Cerebral Cortex / Q000378:metabolism / Q000473:pathology; D003072:Cognition Disorders / Q000378:metabolism* / Q000473:pathology*; D003337:Corpus Callosum / Q000378:metabolism* / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D019579:Neocortex / Q000378:metabolism / Q000473:pathology