SHOULD BROAD-BAND ULTRASONIC-ATTENUATION BE NORMALIZED FOR THE WIDTH OF THE CALCANEUS

Broadband ultrasonic attenuation (BUA) is a measure of ultrasound tran smission through the calcaneus that is dependent on bone thickness as well as the density of scattering centres. This report examines whethe r the normalization of BUA (units dB MHz(-1)) for calcaneal width (nBU A: units dB MHz(-1)] mm(-1)) improves the discrimination of clinical s tudies. BUA and calcaneal width were measured in 200 women using a con tact ultrasound (CUBA-Research) system and nBUA evaluated by dividing BUA by bone width. 150 subjects were early post-menopausal and the rem aining 50 were osteoporotic women with confirmed vertebral crush fract ure. The ability of BUA and nBUA to differentiate between the two grou ps of subjects was compared using receiver operating characteristic (R OC) analysis, The areas (and standard errors) under the ROC curves wer e 0.878 (0.033) for BUA and 0.910 (0.028) for nBUA. The difference (ac id standard error) between the areas under the ROC curves was 0.033 (0 .026) and was not statistically significant.