Acoustic remote palpation: initial in vivo results

An ultrasonic method for remote palpation of tissue is under investigation. In this method, a single ultrasonic transducer array is used to both apply localized radiation forces within tissue and to track the resulting displacements. The magnitude of the tissue displacement is inversely proportional to the local stiffness of the tissue. There are many possible clinical applications for this method, including detecting and characterizing soft tissue lesions, and detecting atherosclerosis. We have previously presented results from studies investigating the application of a single radiation force location in the presence and absence of a lesion in tissue-mimicking phantoms. In this paper, results are presented from in vivo experiments using a single pushing location, and phantom experiments in which multiple pushing locations are used to interrogate a two-dimensional field of view (FOV). Displacements on the order of 10 to 30 microns are observed in vivo after 10 milliseconds of force application, and the resulting displacement images exhibit structural information about the tissue. Remote palpation images generated using multiple pushing locations display local variations in tissue stiffness at high resolution. These results suggest considerable clinical potential for remote palpation imaging, and the potential for real-time implementation on commercial diagnostic scanners.