THE NONLINEAR RELATIONSHIP BETWEEN BUA AND POROSITY IN CANCELLOUS BONE

There is growing interest in assessing the clinical value of ultrasoun d in the prediction and management of osteoporosis. However, the mecha nism of ultrasound propagation in cancellous bone is not well understo od. The Blot theory is one approach to modelling the interaction of so und waves with cancellous structure, and porosity is one of its input parameters. In this paper we report the relationship between broadband ultrasonic attenuation (BUA) corrected for specimen thickness (nBUA) and porosity in a porous Perspex cancellous bone mimic, a stereolithog raphy cancellous bone mimic and in natural human and bovine tissue. nB UA and porosity have a non-linear parabolic relationship. The maximum nBUA value (nBUA(max)) occurs at approximately 30% porosity in the Per spex mimic, approximately 70% in the stereolithography mimic and appro ximately 75% in natural cancellous bone. We discuss the effect of stru cture on the form of the nBUA-porosity relationship.