Flexible ultrasound-based system for clinical trial of burst wave lithotripsy and pushing of kidney stones

Abstract

Fragmentation of kidney stones by burst-wave lithotripsy (BWL) has shown promising results in preclinical and clinical trials. Based on initial findings, the system was upgraded to enhance imaging, target stones at deeper depths, fragment small stones, and potentially conduct dusting of stones. A 64-element, single-crystal, phased-array imaging probe is coaxially aligned with the therapy probe for image guidance and therapy feedback. Imaging is controlled through a Verasonics Vantage research ultrasound engine capable of harmonic imaging to enhance stone resolution and contrast. These features improve targeting and endpoint detection, particularly for small stones and fragments. New therapy probes were added to effectively target stones with greater skin-to-stone distance, including a higher (800 kHz) frequency transducer to effectively break <4mm stones into sub-millimeter fragments to facilitate passage. The amplifier was upgraded to a custom class D/E design with increased power required by the therapy transducers and is capable of ultrasonic propulsion and real time monitoring of electrical power. This system will provide capabilities to treat a larger patient population as we begin trials breaking and expelling stones in the clinic setting. [Work supported by NIH-P01-DK043881.]