Our work involves developing quantitative methods in medical ultrasound. Within that effort are developments of experimental methods for estimating specific parameters (such as the acoustic backscatter coefficient (to quantify acoustic scattering on an absolute scale), effective scatterer size (to describe the tissue microstructure), and the nonlinear elastic modulus (to describe the tissue stiffness on an absolute scale)). Also within that effort are developments of test objects with known material properties (phantoms) that can be used to evaluate performance of these quantitative techniques, and performance descriptors that provide metrics to compare performance. The effort also involves integration of these methods into clinical imaging systems and tests in animal models, clinical trials in human subjects, and observer performance studies to test efficacy.