title: Surface-based vector analysis using heat equation interpolation: a new approach to quantify local hippocampal volume changes.
abstract: Analysis of surface-based displacement vectors using spherical harmonic description (SPHARM) localizes shape changes accurately. However, it does not allow differentiating volume variations from shifting and/or bending. We propose a new approach to quantify local volume changes by computing the surface-based Jacobian determinant. This measurement is computed on the displacement vector fields estimated by a heat equation interpolation on the displacement vectors produced by SPHARM. Data simulation showed that the surface-based Jacobian determinant enables accurate quantification of local volume changes without interference of shifting/bending. In patients with temporal lobe epilepsy and left hippocampal atrophy, SPHARM detected widespread inward deformation related to atrophy in the hippocampal head and body, and showed areas of mirrored inward/outward deformations mostly at the level of the hippocampal tail. In these areas, the surface-based Jacobian determinant showed atrophy. Our method facilitates the interpretation of SPHARM because it allows decomposing volume changes and shifting/bending. Furthermore, it provides a better delineation of the extent of hippocampal atrophy.
authors.affiliation: Department of Neurology and Brain Imaging Center, McGill University, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada.
authors.forename: Hosung
authors.initials: H
authors.lastname: Kim
authors.forename: Pierre
authors.initials: P
authors.lastname: Besson
authors.forename: Olivier
authors.initials: O
authors.lastname: Colliot
authors.forename: Andrea
authors.initials: A
authors.lastname: Bernasconi
authors.forename: Neda
authors.initials: N
authors.lastname: Bernasconi
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D004735:Energy Transfer; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis*; D006624:Hippocampus / Q000473:pathology*; D006358:Hot Temperature; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity