Bone mineral density measurements using peripheral quantitative computed tomography (pQCT) – An evaluation of its clinical utility – *
Bone densitometry has bccome a major tool lor the risk assessment of osteoporosis. Peripheral quantitative computed tomography (pQCT) has the potential to measure true volumctric bone mineral density (BMD, g/cm3) separating cortical and trabecular BMD. The most widely used dual-energy X-ray absorptiometry (DXA) provides areal BMD (mg/cm2). The purpose of this study was to clarify the clinical usefulness of pQCT as a method for bone mineral measurement. The pQCT measurements were carried out at the ultradistal- and mid-radius and the tibia using a Densiscan-1000 (Scanco Medical AG). In both sexes, radial and tibial BMDs in the elderly group (aged more than 60 y.o., 17 men, and 26 women) were significantly lower than those in the young group (aged 20-44 y.o., 107 men and 78 women). The percent difference between the two groups was the greatest in trabecular BMD (D50). As to the sex-related difference, the mean values of radial and tibial BMD in men were significantly higher than in women in elderly groups. The radial BMDs measured by pQCT correlated significantly with BMDs in the lumbar spine, radius and femoral ncck measured by DXA (p <0.001). Lumbar BMD measured by DXA showed the highest correlation to rD50 measured by pQCT. Diagnostic ability of pQCT and DXA to detect osteoporosis was determined by comparing BMD measurements. Kappa statistics showed that in general the diagnostic agreement between these measurements was fair or moderate. The discriminative ability of these methods for vertebral fracture was assessed by receiver operating characteristic (ROC) analysis. The areas under the ROC curves were 0.68,0.71, 0.69 and 0.78 for D50, D100, P100 and L-BMD, respectively. These results indicate that BMD measurements made by pQCT can provide information regarding both trabecular and cortical BMD, and that this method has potential for the diagnosis and management of osteoporosis. (Accepted on April 8, 1999) Kawasaki Igakkaishi 25( 1): 25-33, 1999
