# Enhanced lithotripsy through coalescence and dispersion of cavitation bubbles

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $356,816

## Abstract

Abstract
 Extracorporeal shockwave lithotripsy (SWL) revolutionized the treatment of urinary stones when first introduced
three decades ago. Instead of open stone surgery, acoustic energy could be applied from outside the body to fragment
stones in situ. Although widely utilized for treatment of stones, SWL has not fully lived up to its potential. Incomplete
fragmentation of stones can result in significant pain (when fragments migrate down the ureter and obstruct urine
outflow) and a high rate of residual fragments that need subsequent additional therapy. SWL research has shown the
complex role of acoustic cavitation in the stone comminution process. While cavitation has been demonstrated to be an
essential component of the fragmentation process, the bubbles produced also interfere with subsequent shockwaves
reducing their effectiveness and sometimes causing tissue injury. SWL treatments at extremely low rates (i.e. <30
shocks/min) have been shown in the laboratory to be substantially more efficient and cause less tissue injury because
there is sufficient time for most of the cavitation bubbles to dissolve. However, ultra-low rates have not been adopted
clinically because of the impractically long procedure times that would be required. We have previously demonstrated
that unfocused low amplitude acoustic bursts can stimulate rapid coalescence and dispersion of cavitation bubbles
during SWL clearing the pathway for subsequent shockwaves within tens of milliseconds. By this method we can recover
the stone fragmentation efficiency and safety of very low shockwave rates at standard clinical rates. Initial studies
outlined in this proposal are designed to optimize the bubble coalescence and dispersion process for use with a standard
clinical electromagnetic shockwave lithotripsy system. The following studies will then demonstrate safety and improved
efficacy on a porcine model such that a pilot clinical trial could be initiated following this work.

## Key facts

- **NIH application ID:** 9924525
- **Project number:** 5R01DK091267-09
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Timothy L Hall
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $356,816
- **Award type:** 5
- **Project period:** 2011-09-15 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9924525

## Citation

> US National Institutes of Health, RePORTER application 9924525, Enhanced lithotripsy through coalescence and dispersion of cavitation bubbles (5R01DK091267-09). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9924525. Licensed CC0.

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