- Reflections of 4 MHz ultrasound pulses from 60 sites on 15 human aorta specimens were analysed using the plane-wave Born approximation (PWBA) inverse scattering method. The recovered high-resolution acoustic impedance profile for each site was correlated with an analysis (by microscope) of sections taken from that site. The shape of the impedance profile was found to be sensitive to the pathology of the tissue at each site. The severity of the various conditions could be gauged from the recovered impedance profiles. Some of the insonifications were done on aorta specimens that were shielded from the ultrasound transducer by a human tissue specimen about 1.25 cm thick in order to study the effects of intervening tissue. We found that it was possible to compensate for the distortion due to the frequency dependent attenuation of the intervening tissue. We conclude that ultrasound imaging, with the reflections analysed by means of PWBA inverse scattering provides a promising non-invasive tissue characterization modality.