TRABECULAR BONE DENSITOMETRY USING INTERACTIVE IMAGE-ANALYSIS

Interactive image analysis is a novel application of digital image processing to the densitometry of trabecular bone. Briefly, the exposed surfaces of bleached slices of bone are illuminated so that the trabecular tips are bright in relation to the interstices. The image is then captured by a TV camera and digitized with an interactive image analysis system. A grey scale is then chosen that differentiates the bone at the surface from the background. Finally, a computer program calculates the area fraction of bone within a user-specified box which, by Delesse's principle, is an estimate of the volume fraction of bone. The reproducibility of the technique (expressed as an average SD) is +/- 1.5 vol.% and has surface-discriminating capabilities comparable to the traditional point-counting method but is faster and more precise. Most importantly, the technique permits biomechanical testing of the sample after its density has been determined.