Measuring the thickness of articular cartilage from MR images.

We have developed an algorithm to estimate and display the spatial distribution of the thickness of articular cartilage in human knees. We used a simulation to derive the most appropriate formula for estimating thickness in digital images. The algorithm was tested by imaging a thickness phantom and comparing the results with the known dimensions of the phantom. The results demonstrated that the maximum error encountered in estimating thickness is one pixel while the average error is 0.4 pixels. We imaged a human knee on a cadaver in two separate sessions and used the two image sets to derive thickness maps of the patellar articular cartilage. The thickness maps generated independently from these image sets were very similar, indicating the reliability of the method in deriving accurate thickness estimates. J. Magn. Reson. Imaging 2001;13:120-126. Copyright 2001 Wiley-Liss, Inc.