HippMetric: A skeletal-representation-based framework for cross-sectional and longitudinal hippocampal substructural morphometry

Na Gao; Chenfei Ye; Yanwu Yang; Anqi Li; Zhengbo He; Li Liang; Zhiyuan Liu; Xingyu Hao; Ting Ma; Tengfei Guo

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arXiv · 2512.19214

HippMetric: A skeletal-representation-based framework for cross-sectional and longitudinal hippocampal substructural morphometry

Na Gao·Chenfei Ye·Yanwu Yang·Anqi Li·Zhengbo He·Li Liang·Zhiyuan Liu·Xingyu Hao·Ting Ma·Tengfei Guo

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Abstract

Accurate characterization of hippocampal substructure is crucial for detecting subtle structural changes and identifying early neurodegenerative biomarkers. However, high inter-subject variability and complex folding pattern of human hippocampus hinder consistent cross-subject and longitudinal analysis. Most existing approaches rely on subject-specific modelling and lack a stable intrinsic coordinate system to accommodate anatomical variability, which limits their ability to establish reliable inter- and intra-individual correspondence. To address this, we propose HippMetric, a skeletal representation (s-rep)-based framework for hippocampal substructural morphometry and point-wise correspondence across individuals and scans. HippMetric builds on the Axis-Referenced Morphometric Model (ARMM) and employs a deformable skeletal coordinate system aligned with hippocampal anatomy and function, providing a biologically grounded reference for correspondence. Our framework comprises two core modules: a skeletal-based coordinate system that respects the hippocampus' conserved longitudinal lamellar architecture, in which functional units (lamellae) are stacked perpendicular to the long-axis, enabling anatomically consistent localization across subjects and time; and individualized s-reps generated through surface reconstruction, deformation, and geometrically constrained spoke refinement, enforcing boundary adherence, orthogonality and non-intersection to produce mathematically valid skeletal geometry. Extensive experiments on two international cohorts demonstrate that HippMetric achieves higher accuracy, reliability, and correspondence stability compared to existing shape models.

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BibTeX RIS

Na Gao, Chenfei Ye, Yanwu Yang, Anqi Li, Zhengbo He, Li Liang, Zhiyuan Liu, Xingyu Hao, Ting Ma, Tengfei Guo. 2025-12-22. HippMetric: A skeletal-representation-based framework for cross-sectional and longitudinal hippocampal substructural morphometry. https://arxiv.org/abs/2512.19214

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