On the ultrasonic attenuation and its frequency dependence in the os calcis assessed with a multielement receiver

Measurements of broadband ultrasound attenuation (BUA) on a single sample u sing different devices have previously shown significant variations. We hav e used a new 3 x 3 array transducer to allow the evaluation of three new ap proaches to the BUA algorithms and the extent to which the variations might be reduced. Ten human os calces were measured using the array. The attenua tion and its slope, the BUA, were calculated using three methods: 1, A phas e sensitive approach, summing the individual signals from the multielement array in the time domain (TD); 2, a phase insensitive approach, summing the signals in the frequency domain (FD); 3. averaging of the individually mea sured attenuation and BUA values (AV), The TD and AV approaches resulted in slightly larger values for both attenuation (approximate to 4%) and BUA (a pproximate to 7%) than with the FD method. The differences between the TD a nd FD method may be due to phase cancellation. However, the three sets of r esults were not significantly different (p < 0.05), which suggests that mea surements on commercial equipment using large receiver apertures are not st rongly affected by phase cancellation, averaging or scattering. Nevertheles s, it is not clear if the differences observed are of clinical relevance, w hich should be investigated in the future. Our study shows that the 3 appro aches are strongly related (r(2) > 0.94), suggesting that translation may b e possible between methods. (C) 1998 World Federation for Ultrasound in Med icine & Biology.