Spinal bone mineral density measured with quantitative CT: effect of region of interest, vertebral level, and technique.

Abstract

This study documents the relationship between different vertebral bone compartments with quantitative computed tomography (CT). Four distinct patient groups were investigated: healthy pre- and early postmenopausal women as well as healthy and osteoporotic late postmenopausal women. Three different regions of interest (ROIs) were employed: the elliptical ROI located in the anterior trabecular portion of the vertebral body, the peeled ROI of irregular shape that circumscribes most of the trabecular bone, and the integral ROI including all bone except for the transverse processes. Both single- and dual-energy quantitative CT techniques were employed at T-12 through L-3. Correlation between measurements in the elliptical and peeled ROIs was high (r = .985). The authors concluded that either ROI is acceptable for clinical use. The decrements in bone mineral density (BMD) for the integral ROI were smaller than those for the elliptical ROI. Dual-energy measurements were consistently higher than single-energy measurements. BMD as a function of vertebral level decreased systematically from T-12 to L-3. However, the average density of T-12 through L-3 can be accurately predicted by the average density of L-1 and L-2 (r = .997). Precision did not deteriorate significantly when BMD was expressed as the average of L-1 and L-2 (1.5%) instead of T-12 through L-3 (1.4%). In this study the data suggest a modified quantitative CT protocol for clinical applications in which BMD of only L-1 and L-2 are measured at a fixed gantry tilt.

Changes in biochemical markers of bone metabolism and BMD during the first year after a hip fracture

“…The error in precision has been estimated at 2% for bone mineral density in the proximal femur, 4% and 5% in the distal femur and proximal tibia and 3% for muscle volume in the mid-femur. These estimates were made in our department with the same equipment (Neander et al 1997a), and are similar to those reported elsewhere (Steiger et al 1990, Karantanas et al 1991.…”

Biochemical bone markers and bone density in hip fracture patients: Weak correlation in 106 women

“…The precision error has earlier been estimated at 2% for bone mineral density in the middle femur, 4% and 5% of the distal femur and the proximal tibia, respectively, and 3% for muscle volume of the the middle femur in our department with the same equipment (Neander et al 1997). These values are similar to those that others have found (Steiger et al 1990, Karantanas et al 1991.…”

Degenerative changes at the lumbar spine—implications for bone mineral density measurement in elderly women

“…Moreover, standard spinal DXA scans are influenced by also by the posterior portions of the vertebrae and not directly visible. Spinal QCT are superior in detecting true bone loss (34) with comparative studies indicating a progressive bone loss in the anterior vertebral body portions rich in trabecular bone and not detected by DXA (35)(36)(37). Nevertheless, DXA is currently the mainstay in terms of clinical utility which warrants improved understanding on how to interpret the findings, particularly in the aged.…”