The principal objectives of the proposed research are to determine the ultrasonic propagation properties in intact tissue and to correlate these parameters to those obtained with the ultrasonic computer-assisted tomographic technique. Specifically, ultrasonic properties of attenuation, velocity, and absorption will be compared to the tissue constituents water, total protein, collagen, and fat with the view of determining the influence of such constituents upon ultrasonic propagation properties. Four measurement techniques will be employed to determine the spatial distribution of ultrasonic attenuation, velocity, and absorption. They include a radiation force balance technique, the transient thermoelectric technique, the scanning laser acoustic microscope technique, and ultrasonic computer-assisted tomographic technique. Collaboration between the Ultrasonics Research Laboratory at Mayo Clinic and the Bioacoustics Research Laboratory at the University of Illinois will continue to 1) develop methods for calibrating basic measurements at both laboratories, 2) result in evaluation at both labs of human tissue taken from the same organ, and of calibration phantoms.