Bone quality beyond bone mineral density - new diagnostic perspectives by quantitative ultrasound

Osteoporosis is a skeletal disease that is only partially explained by variations in bone mineral density. Bone quality is determined by a variety of compositional and ultra-structural properties of the mineralized tissue matrix. In contrast to x-ray based methods, the interaction of acoustic waves with bone tissue generates information on the elastic and structural properties of this tissue. Quantitative ultrasound (QUS) is a first class alternative to ionizing x-ray based assessment of fracture risk. New methods measure at fragile anatomical regions, e. g. the distal radius and the proximal femur. Experimentally, ultrasound frequencies up to the GHz range allow an "elastic view" into the lamellar bone structure. The potential of high resolution microelastic images measured by scanning acoustic microscopy in combination with numerical sound propagation simulations for the optimization and validation of novel QUS methods will be discussed.