Quad-mesh based radial distance biomarkers for Alzheimer's disease

Detailed analysis of brain structures is essential in identifying anatomical biomarkers in Alzheimer's disease (AD). In this paper, we develop a new radial distance model to compare different hippocampal shapes and measure their atrophies over time. Using harmonic mappings, we project hippocampal surfaces onto cylinders to obtain evenly-spaced quadrilateral meshes. Surface radial distances estimated via the quad-meshes are invariant to global shifts in the surrounding tissues, leading to a powerful way to detect localized anatomical progressions. The novel quad-meshing method also provides an efficient means to align anatomical surfaces across subjects. Through regions of interest (ROI) analysis, we extract discriminative patches of radial distance and atrophy, and utilize them as anatomical features for patient classification. The effectiveness of the proposed surface modeling and feature extraction strategies in identifying shape biomarkers for AD/MCI is evaluated using the ADNI dataset.