Novel algorithm detecting trabecular termini in μCT and MRI images

In this paper, a novel algorithm detecting trabecular termini in three-dimensional images of trabecular bone is introduced. The algorithm is applied to the analysis of μCT and MRI images of distal radius trabecular bone samples. In μCT images, the volume of the trabecular termini constitutes at most 2.1% of the bone volume fraction BV/TV and is typically smaller than 1% of BV/TV. Isolated trabeculae are not observed in the interior of the trabecular bone samples. Trabecular bone structure assessed with μCT appears thus highly optimized. The volume and the number of the trabecular termini do not correlate with BV/TV. These quantities do not correlate also with apparent Young's modulus of the samples. In contrast in MRI images, segmented with the dual reference limit method, the volume of the trabecular termini and the volume of isolated parts constitute even up to 14% of the apparent bone volume fraction App.BV/TV. For MRI images, the volume of the trabecular termini increases significantly with decreasing App.BV/TV. The volume and the number of the trabecular termini, derived from MRI images do not correlate with Young's modulus. There is also no correlation between the number and the volume of the trabecular termini, estimated from MRI and μCT images. The volume of the trabecular termini is overestimated 15 times in MRI images. App.BV/TV correlates strongly with BV/TV. Young's modulus derived from MRI images correlates strongly with Young's modulus found for μCT data. It is shown that the diagnostic significance of latter result is highly limited.