An evaluation of a new gel-coupled ultrasound device for the quantitative assessment of bone

Quantitative ultrasound (QUS) is now being accepted as a tool in the assess ment of bone status. Most QUS devices measure broadband ultrasound attenuat ion (BUA) and speed of sound (SOS). A newly introduced device, the Acoustic Osteo-Screener (AOS-100), measures both SOS and an attenuation related par ameter called the transmission index (TI) and provides a derived parameter called osteo sono-assessment index (OSI). The purpose of this study was to examine the reproducibility of this new device, compare the results with th e UBA575+ and evaluate the effect of using two platforms to compensate for different foot sizes on the measured values. 83 subjects aged 21-89 years, who gave informed consent, were recruited. Subjects were assigned to three different groups determined by age and health status. The short-term measur ement precision (expressed as root mean square coefficient of variation) of SOS (0.13-0.16%) and TI (1.18-1.96%) was similar to and better than that o btained for the UBA 575+. Significant negative correlations were found betw een the differences in SOS measured with the two platforms (adaptors to adj ust the position of the foot relative to the foot plate) and foot length (p <0.0001). This implies that small feet are more influenced by the differenc es of measured location. All QUS parameters measured with the small platfor m were found to be significantly smaller than those with the large platform (p<0.0001). The mean percentage differences were 0.6% in SOS, 2.8% in TI a nd 4.3% in OSI with the large foot platform giving larger value results. Pr oper use of the platforms resulted in more reproducible SOS and TI. This st udy demonstrated that the newly developed AOS-100 parameters TI and OSI wer e highly reproducible. This study also demonstrated that the use of an inap propriate platform can cause discrepancies in QUS readings and poor reprodu cibility.