Cortical Damage in Alzheimer's Disease. Estimation in Medial and Lateral Aspects of the Cerebrum using an Improved Mapping Method based on Diffusion-Weighted Magnetic Resonance Imaging

Rationale and Objectives: A method of estimating and mapping the cortical damage resulting from neurodegenerative diseases based on diffusion-weighted imaging was recently proposed. We improved on this method to visualize the cortical damage in Alzheimer's disease (AD) in the lateral and medial aspects of the cerebral hemispheres and to provide anatomic references. Materials and Methods: Damage in the cerebral cortex was estimated based on diffusivity in the subcortical white matter according to a previously published method. A map of subcortical mean diffusivity (MD) was superimposed on the corresponding anatomic image so that the spatial extent of the abnormality could be anatomically localized. The right and left hemispheres were separated to evaluate the medial and lateral aspects of each hemisphere. This method was applied to 10 healthy subjects and 11 AD patients. MDs within 20 cortical regions were visually evaluated and statistically compared between AD and healthy subjects at a significance level of P < .01. Results: In addition to the involvement of the lateral aspects of the bilateral parietal and temporal lobes and clear sparing of the bilateral pericentral regions that were previously reported, significant MD elevation was observed in the medial aspects of the right frontal, bilateral parietal, and right temporal lobes. The extent of MD abnormalities was easily identified by the background anatomic image. Conclusions: Results suggested that AD damage in the lateral and medial cerebral cortex can be visualized with an anatomic reference using our method.