In vivo performance evaluation of the Achilles Insight QUS device

Achilles plus (GE, Lunar) has been widely used worldwide for more than a decade, and for its precision, ability to predict fragility fractures and comparability to central DXA, it can be considered a reference standard among quantitative ultrasound devices. As a water-bath system, Achilles plus has obvious practical drawbacks. Achilles Insight is a new-generation device that gives ultrasound parameters in less than 1 min, providing real-time imaging of the os calcis. The aim of this study was to evaluate the in vivo performance of Achilles Insight in comparison to Achilles plus. The precision showed a coefficient of variation (CV) of 0.5 and 0.4%, 4.1 and 3.0%, 2.7 and 2.1%, respectively, for speed of sound (SOS), broadband ultrasound attenuation (BUA), and Stiffness obtained with Achilles plus and Achilles Insight. We also studied 117 postmenopausal women (mean age: 67.1+/-8.8 yr), 47 with and 70 without fragility fractures. Ultrasound parameters obtained by the two devices significantly (p<0.001) correlated and resulted in agreement according to the Bland and Altman method. Achilles plus and Achilles Insight showed similar values of areas under receiver operating characteristics (ROC) curves in discriminating patients with or without fractures (0.884, 0.82, and 0.879 for SOS, BUA, and Stiffness, respectively, with Achilles plus, and 0.882, 0.828, and 0.889, respectively, for Achilles Insight). In conclusion, the better precision of the Achilles Insight with respect to Achilles plus could be explained by the fact that the measurement with Achilles Insight needs less time and gives a consequent reduction in motion artifacts. The high correlation and the similar ability to identify postmenopausal women with vertebral fracture suggest the possibility of using the database of Achilles plus for Achilles Insight.