Elastic registration of 3D cartilage surfaces from MR image data for detecting local changes in cartilage thickness

The objective of this work was to develop and validate a computational meth od for the registration (matching) of 3D cartilage plates from MR image dat a sets. The technique tracks local cartilage thickness changes over time. A 3D elastic registration technique was applied that identifies correspondin g points of the bone-cartilage interface in MR data sets of 3D-reconstructe d cartilage plates. In a first rigid preregistration step, the surfaces are aligned, using the principal axes decomposition to correct for different j oint positions and orientations in the MR scanner. In a second step, the su rfaces are deformed elastically, based on geometric surface features, until they are sufficiently similar to identify corresponding surface points. Th e method was validated against artificially corrupted cartilage surfaces an d MR data obtained from in vivo and in vitro compression experiments. The i n vivo reproducibility was tested on patellar data sets of volunteers, with repositioning of the joint in between replicate acquisitions. (C) 2000 Wil ey-Liss, Inc.