A feasibility study for the non-invasive treatment of superficial bladder tumours with focused ultrasound

Objective To determine whether high-intensity focused ultrasound can be used to ablate bladder wall tissue using a transabdominal approach in a large animal model, and whether it can be developed as a noninvasive treatment for superficial bladder tumours. Materials and methods The bladder wall of 25 large white pigs was treated with a 1.7 MHz extracorporeal focused-bowl ultrasonic transducer. Animals were killed either 2 h, 3 days or 4 weeks after treatment and the bladder wall examined macroscopically and histologically. Results Acute bladder wall damage was detected in 15 of 16 animals at 2 h and in all six animals examined after 3 days. Areas of healing were seen in 10 of 12 animals at 4 weeks. Histological analysis of the treated areas revealed that the urothelium was denuded within 2 h and was associated with an acute inflammatory response in the bladder wall. At 4 weeks, the urothelium had regenerated oner a maturing scar. Conclusions Focused ultrasound can be used successfully to destroy regions of the bladder wall in a large animal model in vivo.