Cancellous bone structure: analysis of high-resolution CT images with the run-length method.

Quantitative computed tomography is extensively used to assess bone density; its potential to quantify bone structure, however, remains to be explored. In this work we present the modifications of the run-length method necessary to enable an analysis of the trabecular bone structure at the distal radius and the distal tibia. Furthermore, the close relationship between histomorphometric values and the run-length parameters is shown. The procedure may be regarded as a noninvasive, reproducible biopsy. For an adequate analysis, high resolution CT images are required. To obtain such images, we modified a special purpose CT system and achieved a high contrast resolution of 0.25 mm. The procedure was applied to groups of normal volunteers and osteoporotic patients, and the results are interpreted with the help of simple two- and three-dimensional models of the trabecular architecture.