Support is requested for a Resource-Related Research Project in the category of Resource Technology Improvement under the auspices of the Biotechnology Resource Program (BRP) of the Division of Research Resources. Our objective is to advance the technology of quantitative ultrasonic imaging so that ultrasound can be used for the non-invasive identification of tissue pathologies. To provide the foundation for this goal we plan an interdisciplinary approach which combines basic studies in physics, engineering and medicine with the development of techniques for generating two-dimensional image of tissue properties. Specifically we intend 1) to build on our previous studies of the interaction of ultrasound and tissue by investigating the magnitude and character of anisotropy in tissue, 2) to systematize the representation of the ultrasonic field and to reduce the data needed to describe that field by determining the moments of the spatial distribution of energy over the receiver aperture, 3) to seek improvement in measurement capability of imaging systems via interactive, adaptive beamforming for both linear and variable-aperture transducer arrays, 4) to test the hypothesis that quantitative images on intrinsic tissue properties can be produced with reflected ultrasound, and 5) to construct a digital multiprocessor system to perform pulse-echo ultrasonic estimation of attenuation, phase velocity and backscatter in two-dimensions. To carry out these aims we will establish a processing environment with a computer interfaced to an ultrasonic tomographic scanner, an existing digital echocardiograph, and an array processor. This environment will be used for both simulations and experimenal studies of tissue models and tissue samples. The digital multiprocessor imaging system will be evaluated on in vitro specimens and through in vivo animal studies to be carried out under independent support from NHLBI to the Cardiovascular Division of the Department of Medicine.