Broadband ultrasound attenuation imaging: influence of location of region of measurement

Abstract.

The aim of the study was to investigate the effect of three different regions of interest (ROIs) varying in size and shape on broadband ultrasound attenuation (BUA) measurements of the calcaneus. Two hundred and sixty-five postmenopausal Caucasian women participated in this study. In 43 women osteoporotic fractures were documented on spinal radiographs. Bone mineral density (BMD) measurements of the lumbar spine and the femur were made using dual-energy X-ray absorptiometry. BUA measurements were obtained at a circular ROI automatically determined by the imaging system (ROI_c), at a manually traced irregular ROI encompassing the posterior part of the calcaneus (ROI_i), and at an anatomical square ROI located in the posterior part of the calcaneus (ROI_s). Reproducibility was better in ROI_c than in ROI_i and ROI_s. High correlations were found between BUA measurements with ROI_c and ROI_s (r=0.981, P<0.0001) as well as between those with ROI_c and ROI_i (r=0.965, P<0.0001). There were no significant differences between the correlations of BUA with axial BMD at ROI_c compared with ROI_i and ROI_s. No significant difference was found between the areas under the ROC curve at ROI_i, ROI_c, and ROI_s for women with fractures. The results show that superior reproducibility makes ROI_c the most appropriate region of BUA measurement in a comparison with ROI_i and ROI_s.