Assessment of vertebral bone mineral density using volumetric quantitativeCT

Purpose: The purpose of this work was to determine the precision and diagno stic efficacy of hone mineral density (BMD) measures based on volumetric qu antitative CT (QCT) of the spine. Method: Volumetric CT scans of L1 and L2 (GE-9800Q; 80 kVp, 140 mAs, 3 mm s lices) were acquired in a cohort of 62 osteoporotic women (mean age 70.4 ye ars, T-DXA hip or spine < -2.5), of whom 20 had vertebral fractures and 42 were nonfractured control subjects. An image analysis technique delineated trabecular, cortical, and integral regions in reference to a vertebra-fixed coordinate system. We computed precision Values and fracture control diffe rences for these new regions and for single-slice QCT and dual X-ray absorp tiometry (DXA) measures synthesized from the volumetric data. Results: Volumetric trabecular BMD showed higher precision (1.3%) than the synthesized single-slice measures (2.1-2.8%). Volumetric and single-slice t rabecular BMD showed equivalent decrements between fractured and nonfractur ed subjects (17-19%), with integral BMD showing smaller and less significan t differences (7-8%), Conclusion: Volumetric and single-slice QCT techniques are equivalent for v ertebral fracture risk estimation, but volumetric techniques should be supe rior for monitoring therapy efficacy.