Double diffusion encoded MRI to identify Alzheimer’s disease pathology in postmortem brainstem by Diffusion Tensor Subspace Imaging (DiTSI)

Motivation: Diffusion MRI may provide clinically relevant markers of degenerative pathology in Alzheimer's disease if the specificity of the frameworks can be improved. Double diffusion encoding frameworks are promising for their improved selectivity. Goal(s): Optimization of methods and initial description of alterations in postmortem brainstem imaging with diffusion MRI including single diffusion frameworks of DTI and MAP-MRI as well as the DDE DiTSI framework. Approach: High-resolution, high-quality diffusion MRI scans over a comprehensive encoding range were used to map metric in healthy and AD pathologic brain stem tissue Results: Four anisotropy metrics across the three frameworks were different in contrast and alteration with pathology. Impact: If double diffusion encoding MRI can be optimized for the detection of specific pathology in Alzheimer's disease and other brain disorders, a new class of improved imaging markers may be possible.