Deformation analysis for shape based classification

P. Golland, W. E. L. Grimson, M. E. Shenton, R. Kikinis
Lecture Notes in Computer Science
Volume 2082, Pages 517-530
2001

Download full paper

Abstract

Statistical analysis of anatomical shape differences between two different populations can be reduced to a classification problem, i.e., learning a classifier function for assigning new examples to one of the two groups while making as few mistakes as possible. In this framework, feature vectors representing the shape of the organ are extracted from the input images and are passed to the learning algorithm. The resulting classifier then has to be interpreted in terms of shape differences between the two groups back in the image domain. We propose and demonstrate a general approach for such interpretation using deformations of outline meshes to represent shape differences. Given a classifier function in the feature space, we derive a deformation that corresponds to the differences between the two classes while ignoring shape variability within each class. The algorithm essentially estimates the gradient of the classification function with respect to node displacements in the outline mesh and constructs the deformation of the mesh that corresponds to moving along the gradient vector. The advantages of the presented algorithm include its generality (we derive it for a wide class of non-linear classifiers) as well as its flexibility in the choice of shape features used for classification. It provides a link from the classifier in the feature space back to the natural representation of the original shapes as surface meshes. We demonstrate the algorithm on artificial examples, as well as a real data set of the hippocampus-amygdala complex in schizophrenia patients and normal controls.

Reference

Golland P, Grimson WEL, Shenton ME, Kikinis R. Deformation analysis for shape based classification. In MF Insana, RM Leahy, eds., Lecture Notes in Computer Science, volume 2082. Springer-Verlag GmbH, 2001;517-530.

Grants

NSF IIS 9610249, NIH/NIMH 2K02 MH01110, NIH RO1 MH50747, NIH P01-CA67165, NIH R01 RR11747, NIH P41 RR13218, NSF ERC 9731748

Research area

shapeanalysis
© 2013 Psychiatry Neuroimaging Laboratory | Last updated 04.15.2013