Intracorporeal imaging and differentiation of living tissue with an ultra-high-frequency ultrasound probe

Intraoperative diagnostic tissue differentiation is expected to be useful clinically. We have fabricated a 3-mm diameter rod-shaped ultrasound (US) probe mounted with a 120-MHz transducer whose lateral resolution is the same as the cellular size of 13 microm. The probe can image a microscopic structure (i.e., the cellular arrangement inside intracorporeal living tissue). We imaged normal kidney tissue of a living mouse and tumor tissue implanted in another mouse kidney. We anesthetized the mice, exteriorized the kidneys, and punctured the kidneys with the probe. Renal corpuscle-like structures were seen in the healthy kidney, but a wavy spindle-like structure was seen in the tumor. The similarity between the ultrasonic images and histological sections taken from the imaged organs demonstrates the possibility of real-time tissue differentiation by ultra-high-frequency US.