Connors BA et al, 2013: Comparison of Tissue Injury from Focused Ultrasonic Propulsion of Kidney Stones Versus Extracorporeal Shock Wave Lithotripsy
Connors BA, Evan AP, Blomgren PM, Hsi RS, Harper JD, Sorensen MD, Wang YN, Simon JC, Paun M, Starr F, Cunitz BW, Bailey MR, Lingeman JE
Department of Anatomy and Cell Biology, Indiana University School of Medicine,Indianapolis, Indiana
PURPOSE: Focused ultrasonic propulsion is a new non-invasive technique designed to move kidney stones and stone fragments out of the urinary collecting system. However, the extent of tissue injury associated with this technique is not known. As such, we quantitated the amount of tissue injury produced by focused ultrasonic propulsion under simulated clinical treatment conditions, and under conditions of higher power or continuous duty cycles, and compared those results to SWL injury.
MATERIALS AND METHODS: A human calcium oxalate monohydrate stone and/or nickel beads were implanted (with ureteroscopy) into 3 kidneys of live pigs (45-55 kg) and repositioned using focused ultrasonic propulsion. Additional pig kidneys were exposed to SWL level pulse intensities or continuous ultrasound exposure of 10 minutes duration (ultrasound probe either transcutaneous or on the kidney). These kidneys were compared to 6 kidneys treated with an unmodified Dornier HM3 Lithotripter (2400 shocks, 120 SWs/min and 24 kV). Histological analysis was performed to assess the volume of hemorrhagic tissue injury created by each technique (% functional renal volume, FRV).
RESULTS: SWL produced a lesion of 1.56#x00B1;0.45% FRV. Ultrasonic propulsion produced no detectable lesion with the simulated clinical treatment. A lesion of 0.46#x00B1;0.37% FRV or 1.15#x00B1;0.49% FRV could be produced if excessive treatment parameters were used while the ultrasound probe was placed on the kidney.
CONCLUSIONS: Focused ultrasonic propulsion produced no detectable morphological injury to the renal parenchyma when using clinical treatment parameters and produced injury comparable in size to SWL when using excessive treatment parameters.
J Urol. 2013 Aug 2. pii: S0022-5347(13)05053-2. doi: 10.1016/j.juro.2013.07.087. [Epub ahead of print]
PMID:23917165 [PubMed - as supplied by publisher]. FREE ARTICLE
The use of focused ultrasonic propulsion of stones/stone fragments residing in the kidney after SWL is a highly interesting treatment concept. By avoiding endoscopic intervention the complete stone removing procedure can remain non-invasive.
This animal experiment aimed at investigating the possible tissue damage caused by the ultrasonic treatment. No such damage was recorded with treatment parameters used clinically. This finding was contrasting to that recorded following SWL with the Dornier HM3 device.
Not even at over-treatment conditions were there any important morphological changes. It thus seems reassuring that focused ultrasound propulsion, that in the reported experiments was very successful, can be used without any obvious risk of kidney injury.