Shape Analysis of Amygdala Atrophy Using SPHARM-OT

We propose SPHARM-OT, an enhanced spherical harmonic (SPHARM) surface modeling method using optimal transport (OT) for spherical parameterization. To demonstrate its effectiveness, we apply it to shape analysis of amygdala atrophy in Alzheimer's disease (AD). Of note, identifying morphological abnormalities of medial temporal structures such as hippocampus and amygdala is an important research topic for early diagnosis of AD. Our empirical study includes two steps: (1) the newly proposed SPHARM-OT method is used to model amygdala shapes of 101 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI); (2) using the random field theory to perform surface-based statistical analysis for detecting shape changes between cognitively normal (CN) and AD participants. We demonstrate that (1) the new SPHARM-OT method could effectively reduce surface mapping distortion and lead to a more accurate shape reconstruction result; and (2) significant shape changes between CN and AD participants are identified on certain amygdalar surface regions.