3D GEOMETRICAL FEATURES OF ANATOMIC STRUCTURES - THE EXAMPLE OF THE ULNA AND RADIUS BONES

This paper addresses two important issues of three-dimensional (3D) na tural shape analysis. The first concerns the segmentation of these sha pes into 3D primitives and the second deals with their geometric chara cterisation by means of intrinsic features. Restricting ourselves to 3 D objects formed from two-dimensional (2D) cross-sectional adjacent sl ices (i.e., long bones), we present a method of contextual classificat ion and results concerning the ulnar bone. With respect to the second issue, a curvature-torsion analysis of the medullar axis is introduced and the results are represented by means of torsion images. A first a pplication to ulnar structures is given. It is shown that radius bones have zero torsion and that their curvatures can be studied in 2D. A p reliminary statistical study of the 2D curvature of the radius is also presented.