Abstract
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.