Trabecular bone structure of the calcaneus: preliminary in vivo MR imaging assessment in men with osteoporosis.

Abstract

To use magnetic resonance (MR) imaging to evaluate potential differences in bone structure between men with and men without osteoporosis. Sagittal MR images of the calcaneus were obtained in 50 men (26 patients with osteoporosis and 24 age-matched healthy control subjects). Osteoporosis was defined as a low bone mineral density (at least 2.5 SDs below the normal value for young adults at either the lumbar spine or proximal femur) as measured with dual-energy x-ray absorptiometry. Seventeen patients had a history of osteoporotic fractures. For each participant, 10 consecutive sagittal three-dimensional gradient-echo MR sections were analyzed by using a rectangular region of interest. Twenty structural measurements were obtained from these images. Additionally, density measurements at the calcaneus were obtained in 46 participants. The significance of differences between the two groups was calculated by using the unpaired Student t test. The odds ratios for fracture per 1 SD decrease in the control group were calculated with logistic regression analysis. Adjustment for participant weight and height was performed if necessary. Thirteen of 20 structural parameters, especially connectivity parameters, showed significant differences between control subjects and patients (P <.05). Differences between the two groups were more significant (P <.001) for apparent bone marrow skeleton length, apparent node count, apparent node-to-node strut count, and apparent terminus-to-terminus strut count. Odds ratios for 11 of 13 structural parameters but not for calcaneus density were significant (P <.05). After adjustment for calcaneus density, these parameters were still significant predictors of osteoporotic fracture. Structural measurements derived from MR images of the calcaneus may be used in vivo to characterize trabecular bone architecture in men with osteoporosis.