Validation and Improved Registration of Bone Segmentation Using Contour Coherency

A method is presented to validate the segmentation of computed tomography (CT) image sequences, and im prove the accuracy and efficiency of the subsequent registration of the 3D surfaces that are reconstructed from the segmented slices. The method compares the shapes of contours extracted from neighborhoods of slices in CT stacks of tibias. The bone is first segmented by an automatic segmentation technique, and the bone contour for each slice is parameterized as a 1-D function of normalized arc length versus inscribed angle. These functions are represented as vectors within a K-dimensional space comprising the first K amplitude coefficients of their Fourier Descriptors. The similarity or coherency of neighboring contours is measured by comparing statistical properties of their vector representations within this space. Experimentation has demonstrated this technique to be very effective at automatically identifying low coherency segmentations, the removal of which significantly improved the accuracy and time efficiency of the registration of 3-D bone surface models