Comparison of Three Bone Densitometry Methods in Osteoporotic Women

Three techniques of bone mass measurement were evaluated in the diagnosis of postmenopausal osteoporosis; the overlap in the measurements and the capacity for discriminating was determined among 51 postmenopausal normal (mean age 66.6 ± 8.4 years) and 42 postmenopausal osteoporotic women (mean age 68.5 ± 7.5 years). All bone mass was evaluated by total body bone mineral content (BMC_TB), density (BMD_TB), ultrasound bone velocity (UBV) in proximal phalanxes 2–5 of the nondominant hand (UBV = mean value of all ultrasound measurements), and peripheral quantitative computed tomography of the nondominant forearm (pQCT). BMC_TB was found to be significantly better (P < 0.0001) for diagnosing postmenopausal osteoporosis than the other methods; both cortical and trabecular pQCT measurements were more discriminating than the corresponding UBV measurements (P < 0.001). T-score values in normals, subjects versus osteoporotic ones were BMC_TB−1.15 ± 0.79 versus −3.17 ± 0.74; BMD_TB−1.01 ± 0.97 versus −3.28 ± 0.81; UBV −1.51 ± 1.02 versus −2.34 ± 1.21; trabecular-pQCT −0.40 ± 0.72 versus −1.57 ± 0.37; cortical-pQCT −1.00 ± 0.87 versus −2.67 ± 0.53; and total-pQCT −0.65 ± 1.01 versus −2.34 ± 0.27, respectively. The overlap in values between the postmenopausal normal and postmenopausal osteoporotic groups was 50% with UBV, 6% with BMC_TB, 9% with BMD_TB, 25% with cortical pQCT, and 42% with trabecular pQCT. BMC_TB, BMD_TB, UBV, and pQCT correlated well with each other as measurements of bone mass, but BMC_TB was more discriminating than the other measurements in the diagnosis of osteoporosis. Received: 7 June 1995 / Accepted: 21 May 1997