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Principal Investigator  
Principal Investigator's Name: Ali Khan
Institution: The University of Western Ontario
Department: Medical Biophysics
Proposed Analysis: We are seeking to use the ADNI dataset to validate previously developed imaging methods within the hippocampus, as well as develop new markers of hippocampal integrity for Alzheimer’s disease (AD). Analysis 1: Using structural MRI we plan to evaluate the performance of a novel surface-based method (HippUnfold, https://doi.org/10.1101/2021.12.03.471134 ) to automatically segment the hippocampal subfields in the AD and control group. Firstly, this will allow us to assess and validate the utility of this method when there is structural degradation within the hippocampus. Secondly, we can compare this method to the ASHS method which is already provided with the ADNI dataset. If this method is able to perform well, we will then compare the volumes of the segmented subfields between the AD and control group, further comparing with the volumes provided by ASHS. Analysis 2: Using diffusion MRI, we plan to examine whether there are any differences in the primary direction of diffusion relative to canonical hippocampal axes (anterior-posterior, proximal-distal, and inner-outer) between the AD and control group. Hippocampal microstructure tends to be highly aligned along one of these axes (similar to the radial and tangential orientation of microstructure in the neocortex). Thus, any significant differences in the primary direction of diffusion relative to these axes may indicate the degradation of a particular microstructure with a stereotyped orientation along a particular axis. Analysis 3: Using diffusion MRI, we plan to apply a group of common microstructural models as well as develop a new set of microstructure models tailored to the hippocampus. A newly developed microstructure model may consider the stereotyped orientation of the hippocampal microstructure to develop priors which can be fitted to representations of multiple neurites (i.e. sticks in a diffusion model). We will examine which models may provide the best imaging markers to delineate the AD and control group.
Additional Investigators  
Investigator's Name: Bradley Karat
Proposed Analysis: Bradley Karat is the PhD student that will carry out this aforementioned analysis.