Angle Scan and Frequency-Swept Ultrasonic Scattering Characterization of Tissue

Ultrasonic wave interference has been applied to characterize tissue by measuring scattered wave intensity as a function of frequency and angle. The measurements were made using a computer-based system for collection, processing, and display of data. Model studies consisted of data collection from deterministic targets of regular arrays of nylon filaments and random targets made from small spherical particles of cross-linked dextran in suspension. Angle and frequency scans have been made on post mortem human liver specimens. The model studies demonstrate that regular scatterer spacing can be inferred from measured diffraction data by Fourier inversion, and that scattering differences can be observed from particles of different sizes. Scattering from liver indicates the importance of off-axis scattering which may be related to scatterer size.