Acoustic radiation force to reposition kidney stones in humans

This is a report of the first clinical study to reposition kidney stones with acoustic radiation force. Studies were conducted with the approval of the University of Washington IRB and a U.S. FDA Investigational Device Exemption. Of the 15 subjects, average age was 56 ± 11 years; average BMI was 29 ± 3; and stone size range was dust to 13 mm. Two patients reported skin discomfort and sensation at depth with a few pushes. Otherwise, there was no pain or adverse effects associated with the treatment. Stones were repositioned in 14 subjects. Stones were repositioned to a new location in all 6 post-lithotripsy patients, while 4 of the 6 passed over 30 stone fragments within a few days of treatment. De novo stones and stones as large as 8 mm were repositioned. In four of the 15 subjects, what was noted in clinical imaging as a single, potentially unpassable stone was shown to be several passable stones upon repositioning with ultrasound. Ultrasonic propulsion can safely and without pain reposition kidney stones in humans. [Work supported by NIH NIDDK grants DK043881and DK092197 and National Space Biomedical Research Institute through NASA NCC 9-58.]