Connectivity in human cancellous bone by three-dimensional magnetic resonance imaging.

Bone architecture affects strength and resistance to fracture. Trabecular connectivity is now recognized as an important measure of bone quality, and could be useful as an indicator of the osteoporotic condition, as well as a tool for measuring the effectiveness of therapies. We have applied three-dimensional magnetic resonance imaging microscopy to human cancellous bone biopsies, and report the results of connectivity measurements. Sample heterogeneity was examined on the basis of connectivity density for subvolumes. The choice of examination volume had a significant effect on connectivity density measurements, but sample volumes greater than 100 mm3 were found to give stable results. Connectivity density was strongly correlated with nodal density, and two-dimensional estimates of connectivity, but not bone volume fraction. Repeat measurement at constant resolution (69 x 138 x 109 microns, signal-to-noise ratio of about 35) showed reproducibility of about 5% for connectivity density. Our most recent results have significantly enhanced resolution (69 x 69 x 43 microns); bone fraction remained constant, but apparent connectivity density is greater.