To investigate trabecular bone structure of lumbar vertebrae using routine multislice computed tomography (MSCT) of the thorax and abdomen and to compare this with bone mineral density (BMD) in differentiating postmenopausal women with and without osteoporotic spine fractures.

We examined 102 postmenopausal women (average age 67.7 ± 8.2) with a routine abdominal or thoracoabdominal MSCT (abdominal: 43; thoracoabdominal: 59) using a standard protocol (parameters: collimation 16x0.75 mm, 200 mAs, 120 kVp) with a spatial resolution of approximately 450 x 450 µm². In addition images were reconstructed with a collimation of 1 mm and an increment of 0.8 mm. CT-derived structure measures based on standard histomorphometry of the first to third lumbar vertebra (L1-3) were calculated in the 1 mm sections using an oval region of interest (ROI) avoiding the cortical bone. In addition BMD of L1-3 was obtained with a recently introduced conversion factor from MSCT to quantitative CT (QCT). In sagittal reformations of the spine and lateral digital radiographs osteoporotic spine fractures were graded according to the spinal fracture index (SFI). Receiver operating characteristics (ROC) analyses were used to determine the diagnostic performance in differentiating patients with and without osteoporotic spine fractures.

Significant differences between the fracture group (27/102; mean age 71.5 ± 9.2) and the patients without osteoporotic spine fractures (75/102; mean age 65.6 ± 7.1) were obtained using structure analysis and spine BMD (p<0.05). Using ROC-analysis the highest AUC (area und the curve) value was found for BMD of the spine (AUC = 0.74). Lower AUC values were calculated for the best structure parameter, which was the apparent trabecular number (app. Tr.N) of the third lumbar vertebra (AUC = 0.68).

The diagnostic performance of structure measures analogous to standard histomorphometry determined in routine MS-CT scans to differentiate patients with and without osteoporotic fractures is limited and worse than that of BMD of the same vertebrae.