In-vivo measurement of osteoporotic bone fragility with apparent velocity of ultrasound

Loss of mechanical strength due to bone conditions such as osteoporosis causes spontaneous fractures despite the absence of significant physical trauma. Well-established theory and in vitro experiment suggest the potential for ultrasound velocity to assess such deterioration of bone strength. Nevertheless, technical obstacles have precluded in vivo application until recently. A novel approach is described for achieving accuracy and reproducibility by overcoming difficulties with inhomogeneity, anisotropy, overlying soft tissue, and multipath propagation. Key elements of the design include anatomical-site selection, propagation-path determination, ultrasound generation and detection, digital signal processing, and apparent-velocity estimation.