IMPROVED REPRODUCIBILITY OF BROAD-BAND ULTRASOUND ATTENUATION OF THE OS CALCIS BY USING A SPECIFIC REGION OF INTEREST

Quantitative ultrasound (QUS) bone measurement is a promising, relativ ely new technique for the diagnosis of osteoporosis, Contrary to the m ore established method of bone densitometry (measurement of bone miner al density, BMD, e.g., using dual X-ray absorptiometry, DEXA), QUS doe s not employ ionizing radiation, It has, however, been a problem to ac hieve sufficient reproducibility of the QUS measurements, The aim of t his study is to evaluate the possible advantages of measuring broadban d ultrasound attenuation (BUA) at a region of interest (ROI) instead o f at a fixed position, in terms of in vivo precision and correlation t o hip bone mineral density, BUA was measured in 27 premenopausal women , 28 postmenopausal women, and 22 men on the DTU-one. Using high resol ution images, a ROI is defined in the posterior part of the os calcis as an area with a local minimum of attenuation and a fixed position wi thin the os calcis is defined relative to the water bath, All BUA meas urements were performed twice. BMD at the hip was measured on the QDR- 2000. The mean BUA values were significantly different between pre and postmenopausal women, p = 0.0001 for both the ROI (BUA(ROI)) and the fixed position (BUA(FIX)). The ROI was found in all subjects and was r eadily reproducible, The precision at the ROI: 1.20 CV% (95% CI: 1.01- 1.29 CV%) was significantly better than at the fixed position: 3.87 CV % (95% CI: 3.23-4.48 CV%). BUA(ROI) (r = 0.64) correlated significantl y better than BUA(FIX) (r = 0.35) with HIP BMD. In conclusion, the use of an imaging technique enables BUA measurements to be performed at a ROI, The precision of BUA at the ROI is significantly better than at the fixed position, BUA measured at the ROI correlates better with HIP BMD than BUA measured at the fixed position. (C) 1997 by Elsevier Sci ence Inc. All rights reserved.