Shape Quantification
Quantitative shape biomarkers for cortical morphology and brain disorders
Method
LGI: Cortical Shape-Adaptive Local Gyrification Index

The amount of cortical folding, or gyrification, is typically measured within local cortical regions covered by an equidistant geodesic or nearest neighborhood-ring kernel. Without careful design, such a kernel can easily cover multiple sulcal and gyral regions that may not be functionally related, resulting in blurring of local gyrification measurements. We propose a novel kernel shape for locally quantifying cortical gyrification within sulcal and gyral regions. We adapt wavefront propagation to generate a spatially varying kernel that encodes cortical folding patterns, including neighboring gyral crowns, sulcal fundi, and sulcal banks. To achieve this, we perform anisotropic wavefront propagation by solving a static Hamilton–Jacobi partial differential equation. The resulting kernel adaptively elongates along gyral crowns and sulcal fundi, while maintaining a uniform shape over flat regions such as sulcal banks.
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A Cortical Shape-Adaptive Approach to Local Gyrification Index
Ilwoo Lyu, Sun Hyung Kim, Jessica Girault, John Gilmore, Martin Styner
Medical Image Analysis, 48, 244–258, 2018
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Novel Local Shape-Adaptive Gyrification Index with Application to Brain Development
Ilwoo Lyu, Sun Hyung Kim, Jessica Bullins, John Gilmore, Martin Styner
Medical Image Computing and Computer Assisted Intervention (MICCAI) 2017, LNCS10433, 31–39, Quebec City, Canada, 2017
Applications
Brain Disorder / Disease / Developmental Studies

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Long-term effects of preterm birth on cortical folding trajectories in early childhood
Yong Hun Jang, Jongmin Kim, Bong Gun Lee, Jeong-Kyu Hoh, Gang Yi Lee, Hyun Ho Kim, Ilwoo Lyu, Hyun Ju Lee
Brain Communications, 8(3), fcag097, 2026
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Local Gyrification Index and Sulcal Depth as Imaging Markers of Cognitive Decline in Alzheimer's Disease
Yongsik Sim, Changmin Seo, Young-gun Lee, Byoung Seok Ye, Ilwoo Lyu, Beomseok Sohn
Frontiers in Aging Neuroscience, 17, 1635861, 2025
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Comprehensive Shape Analysis of the Cortex in Huntington's Disease
Zachary Stoebner, Kilian Hett, Ilwoo Lyu, Hans Johnson, Jane Paulsen, Jeffrey Long, Ipek Oguz
Human Brain Mapping, 44(4), 1417–1431, 2023
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Cortical Morphology in Autism: Findings from a Cortical Shape-Adaptive Approach to Local Gyrification Indexing
Alisa Zoltowski, Ilwoo Lyu, Michelle Failla, Lisa Mash, Kacie Dunham, Jacob Feldman, Tiffany Woynaroski, Mark Wallace, Laura Barquero, Tin Nguyen, Laurie Cutting, Hakmook Kang, Bennett Landman, Carissa Cascio
Cerebral Cortex, 31(11), 5188–5205, 2021