An evaluation of the reproducibility and responsiveness of four 'state-of-the-art' ultrasonic heel bone measurement systems using phantoms.

This paper evaluates four modern ultrasonic heel bone scanners: the Osteometer DTU-one, Hologic Sahara, CUBA Clinical and Lunar Achilles+. Six phantoms, ranging in porosity from 50% to 83%, were used to evaluate the range of values of broadband ultrasonic attenuation (BUA), speed of sound (SOS) and Stiffness/quantitative ultrasound index (where available) from each machine. Differences in inter-system variability between the lowest and highest porosity phantoms up to a factor of 3.8 were demonstrated. The reproducibility of each system was measured using a single phantom and gave values of 0.03-0.15% for SOS, 0.39-1.6% for BUA and 0.73-1.11% for Stiffness. This contrasted with values of range normalized standard deviation (CX) of 0.2-1.19% for SOS, 0.71-1.86% for BUA and 0.83-1.12% for Stiffness when the output range of the measurement is taken into account. Measures of all quantities differed between machines and care should be taken when expressing and comparing results from different systems.