Linear acoustics of trabecular bone

During the two recent decades, quantitative ultrasound (QUS) methods have been developed for in vivo diagnostics of trabecular bone. Mostly, trabecular bone QUS measurements are conducted in through-transmission and pulse-echo geometry. Since the first in vivo QUS measurements at the heel, the research efforts have also been focused on enabling QUS measurements at important fracture sites, such as proximal femur or lumbar vertebra. This chapter introduces the experimental QUS methods and reviews the recent developments in in vitro and in vivo measurement methods and results on linear acoustic properties of trabecular bone. Specifically, ultrasound parameters determined in through-transmission and pulse-echo measurements are introduced and their frequency dependency as well as feasibility for characterization of bone density, structure, composition and mechanical properties is reviewed. Finally, potential of QUS for clinical diagnostics of osteoporosis and prediction of bone fracture risk are discussed, with some suggestions