High-resolution three-dimensional micro-computed tomography detects bone loss and changes in trabecular architecture early: comparison with DEXA and bone histomorphometry in a rat model of disuse osteoporosis.

RATIONALE AND
OBJECTIVES: The ability of three-dimensional micro-computed tomography (3D-microCT) to detect changes in a rat model of disuse osteoporosis was evaluated and compared with two reference techniques: dual x-ray absorptiometry (DEXA) for bone mass, and bone histomorphometry (BHM) for bone mass and trabecular micro-architecture.
METHODS: Forty-two rats were divided into controls or were hindlimb unloaded for 7, 13, and 23 days. DEXA bone mineral density measurements were performed on right tibiae. Then, after plastic embedding, bone volume (BV/TV) and trabecular (Tb)-derived parameters of trabecular bone architecture (Tb Th, thickness; Tb N, number) were measured with BHM. 3D-microCT measurements of BV/TV, Tb Th, and Tb N were carried out on left tibiae.
RESULTS: Unloaded rats lost bone in a time-dependent manner. DEXA and 3D-microCT detected bone loss earlier than BHM. The decreases in Tb Th and Tb N were observed at day 13 only with 3D-microCT (P < 0.05 and P < 0.01, respectively). All bone mass and architectural parameters measured with the three techniques correlated significantly (0.59, 0.89, P < 0.001), except Tb Th.
CONCLUSIONS: 3D-microCT is a valid technique for bone mass and micro-architecture measurements in this rat model of disuse osteoporosis.