DIAGNOSTIC SENSITIVITY OF PERIPHERAL QUANTITATIVE COMPUTED-TOMOGRAPHYMEASUREMENTS AT ULTRADISTAL AND PROXIMAL RADIUS IN POSTMENOPAUSAL WOMEN

Peripheral quantitative computed tomography (pQCT) is a bone densitome try technique that is able to provide real volumetric bone density val ues not only of the total but also of trabecular and cortical bone sep arately. Normal reference curves were constructed with cross-sectional data obtained in 275 postmenopausal women (50-85 years), measured at 4% of the ulnar length (ultradistal region), and data for total, trabe cular, and cortical bone density were obtained. In these postmenopausa l subjects, continuously significant (p < 0.0001) age-dependent declin es in bone density of 1.14%, 1.1%, and 0.57% for total, trabecular, an d cortical bone, respectively, were observed while similar declines of 0.9%, 0.9%, and 0.4% per year since menopause, respectively, were fou nd. The estimated mechanical stability index also showed linear depend encies with decreases of 0.84%/year and 0.6%/year since menopause (p < 0.0001), A more proximal acquisition at 15% of the ulnar length, an a lmost pure cortical region, resulted in linear declines of 0.41%/year and 0.27%/year (p < 0.0001) for the cortical bone and the mechanical s tability index with significant changes of -0.27% and -0.23% per year, respectively, since menopause, Covariance analysis shelved similar ag e dependencies of the different bone indices obtained in both regions of interest except for the stability index. A significant size adaptat ion of the bone with ape was also observed, which was seen in the rela tionships of the trabecular and cortical bone areas to age and to bone density. Diagnostic sensitivity of all parameters for established ost eoporosis was assessed by receiver operating characteristic (ROC) curv es, comparing 99 patients with at least one fracture to the reference population. The area under these curves was highest in the ultradistal pure trabecular density of the radius (75%), followed by stability in dex (72%) and the area of cortical bone (65%) of the proximal site. No distinguishing power was seen for the cortical bone density values ob tained in either the ultradistal (51%) or proximal radius (52%). (C) 1 998 by Elsevier Science Inc. All rights reserved.