Histomorphologic features of ultrasonic renal injury.

Fifteen-second exposure of rabbit kidneys to 2 MHz focused ultrasound with approximately 900 w/sq cm acoustic power consistently produced localized parenchymal destruction. Evolution of the lesions was followed histologically over a one-year period. The lesions were sharply delineated from outlying renal tissue and had a concentric multizonal structure. Resorption of the damaged tissue with scarring was completed in 6 to 12 months following intermediate phases characterized by cellular infiltration. The lesions are compared to other models of renal injury, particularly with respect to cellular infiltration. A combination of mechanical, thermal, and ischemic factors seem to be responsible for development of ultrasonic lesions. The sharply circumscribed nature and ultimate complete scarring of the lesions suggest the feasibility of ultrasound in achieving selective complete destruction of renal parenchyma.