Docteur de l'université Automatic Segmentation and Shape Analysis ...

Chapter 4
Statistical shape model of Hippocampus
In nova fert animus mutatas dicere formas corpora
Ovid, Metamorphoses, 1.1.
The study of hippocampal shape using statistical shape model (SSM) models the
distribution of its shape among the population. It provides not only a characteri-
zation of the hippocampal shape variance, which is of interest in the investigations
into the morphological changes induced upon the hippocampus by neurodegener-
ative diseases, but also the prior information which can be used to direct the
automatic segmentation of hippocampus in medical images. SSMs are built from
corresponding shape surface representations, to model the variability in the dis-
tribution of each landmark. Manually locating the anatomical landmarks used in
earlier studies (e.g. gorilla skulls by O’Higgins and Dryden, 1993, midsagittal brain
MR scans of normal and schizophrenic subjects by Bookstein, 1996) becomes te-
dious and cumbersome when the shape analysis is carried out on large data set of
3D image volumes, with more densely populated landmarks on the surface of the
objects of interest. Automated methods have been developed to reduce spurious
correspondences and identify the corresponding landmarks.
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