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Mike Bailey

Senior Principal Engineer

Associate Professor, Mechanical Engineering and Adjunct Assistant Professor, Urology

Email

bailey@apl.washington.edu

Phone

206-685-8618

Research Interests

Medical Ultrasound, Acoustic Cavitation

Biosketch

Dr. Bailey's current research focuses on the role of cavitation in lithotripsy (kidney stone treatment) and ultrasound surgery. He is the lead APL-UW researcher on two collaborative programs among the Laboratory, Indiana University, Moscow State University, and the California Institute of Technology to optimize acoustic waves to exploit bioeffects due to cavitation. Previously, he was one of the designers of a shock wave lithotripter developed at APL-UW to concentrate cavitation and damage on the kidney stone and not on the kidney tissue. Dr. Bailey joined APL-UW in 1996.

Education

B.S. Mechanical Engineering, Yale University, 1991

M.S. Mechanical Engineering, The University of Texas at Austin, 1994

Ph.D. Mechanical Engineering, The University of Texas at Austin, 1997

Videos

Ultrasonic tweezers: Technology to lift and steer solid objects in a living body

In a recent paper, a CIMU team describes successful experiments to manipulate a solid object within a living body with ultrasound beams transmitted through the skin.

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15 Jul 2020

A collaborative, international research teams developed and tuned an ultrasound transducer to create vortex shaped beams that can trap, grab, levitate, and move in three dimensions mm-scale objects. The team is working to apply this technology to their all-in-one kidney stone treatment system that, in clinical trials, uses ultrasound to non-invasively break, erode, and move stones and stone fragments out of the kidney so that they may pass naturally from the body.

Mechanical Tissue Ablation with Focused Ultrasound

An experimental noninvasive surgery method uses nonlinear ultrasound pulses to liquefy tissue at remote target sites within a small focal region without damaging intervening tissues. A multi-institution, international team led by CIMU researchers is applying the method to the focal treatment of prostate tumors.

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19 Mar 2020

Boiling histotripsy utilizes sequences of millisecond-duration HIFU pulses with high-amplitude shocks that form at the focus by nonlinear propagation effects. Due to strong attenuation of the ultrasound energy at the shocks, these nonlinear waves rapidly heat tissue and generate millimeter-sized boiling bubbles at the focus within each pulse. Then the further interaction of subsequent shocks with the vapor cavity causes tissue disintegration into subcellular debris through the acoustic atomization mechanism.

The method was proposed at APL-UW in collaboration with Moscow State University (Russia) and now is being evaluated for various clinical applications. It has particular promise because of its important clinical advantages: the treatment of tissue volumes can be accelerated while sparing adjacent structures and not injuring intervening tissues; it generates precisely controlled mechanical lesions with sharp margins; the method can be implemented in existing clinical systems; and it can be used with real-time ultrasound imaging for targeting, guidance, and evaluation of outcomes. In addition, compared to thermal ablation, BH may lead to faster resorption of the liquefied lesion contents.

Characterizing Medical Ultrasound Sources and Fields

For every medical ultrasound transducer it's important to characterize the field it creates, whether for safety of imaging or efficacy of therapy. CIMU researchers measure a 2D acoustic pressure distribution in the beam emanating from the source transducer and then reconstruct mathematically the exact field on the surface of the transducer and in the entire 3D space.

11 Sep 2017

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Publications

2000-present and while at APL-UW

First series using ultrasonic propulsion and burst wave lithotripsy to treat ureteral stones

Hall, M.K., and 22 others including J. Thiel, B. Dunmire, and M.R. Bailey, "First series using ultrasonic propulsion and burst wave lithotripsy to treat ureteral stones," J. Urol., 208, 1075-1082, doi:10.1097/JU.0000000000002864, 2022.

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1 Nov 2022

Purpose:
Our goal was to test transcutaneous focused ultrasound in the form of ultrasonic propulsion and burst wave lithotripsy to reposition ureteral stones and facilitate passage in awake subjects.

Materials and Methods:
Adult subjects with a diagnosed proximal or distal ureteral stone were prospectively recruited. Ultrasonic propulsion alone or with burst wave lithotripsy was administered by a handheld transducer to awake, unanesthetized subjects. Efficacy outcomes included stone motion, stone passage, and pain relief. Safety outcome was the reporting of associated anticipated or adverse events.

Results:
Twenty-nine subjects received either ultrasonic propulsion alone (n = 16) or with burst wave lithotripsy bursts (n = 13), and stone motion was observed in 19 (66%). The stone passed in 18 (86%) of the 21 distal ureteral stone cases with at least 2 weeks follow‐up in an average of 3.9±4.9 days post-procedure. Fragmentation was observed in 7 of the burst wave lithotripsy cases. All subjects tolerated the procedure with average pain scores (0-10) dropping from 2.1±2.3 to 1.6±2.0 (P = .03). Anticipated events were limited to hematuria on initial urination post-procedure and mild pain. In total, 7 subjects had associated discomfort with only 2.2% (18 of 820) propulsion bursts.

Conclusions:
This study supports the efficacy and safety of using ultrasonic propulsion and burst wave lithotripsy in awake subjects to reposition and break ureteral stones to relieve pain and facilitate passage.

Removal of small, asymptomatic kidney stones and incidence relapse

Sorensen, M.D., and 10 others including M.R. Bailey, "Removal of small, asymptomatic kidney stones and incidence relapse," N. Engl. J. Med., 387, 506-513, doi:10.1056/NEJMoa2204253, 2022.

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11 Aug 2022

The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery.

The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery.

Improving burst wave lithotripsy effectiveness for small stones and fragments by increasing frequency: Theoretical modeling and ex vivo study

Bailey, M.R., A.D. Maxwell, S. Cao, S. Ramesh, Z. Liu, J.C. Williams, J. Thiel, B. Dunmire, T. Colonius, E. Kuznetsova, W. Kreider, M.D. Sorensen, J.E. Lindeman, and O.A. Sapozhnikov, "Improving burst wave lithotripsy effectiveness for small stones and fragments by increasing frequency: Theoretical modeling and ex vivo study," J. Endourol., 36, doi:10.1089/end.2021.0714, 2022.

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5 Jul 2022

Introduction and Objective: In clinical trial NCT03873259, a 2.6-mm lower pole stone was treated transcutaneously and ex vivo with 390-kHz burst wave lithotripsy (BWL) for 40 minutes and failed to break. The stone was subsequently fragmented with 650-kHz BWL after a 4-minute exposure. This study investigated how to fragment small stones and why varying the BWL frequency may more effectively fragment stones to dust.

Methods: A linear elastic theoretical model was used to calculate the stress created inside stones from shock wave lithotripsy (SWL) and different BWL frequencies mimicking the stone's size, shape, lamellar structure, and composition. To test model predictions about the impact of BWL frequency, matched pairs of stones (1–5 mm) were treated at (1) 390 kHz, (2) 830 kHz, and (3) 390 kHz followed by 830 kHz. The mass of fragments > 1 and 2 mm was measured over 10 minutes of exposure.

Results: The linear elastic model predicts that the maximum principal stress inside a stone increases to more than 5.5 times the pressure applied by the ultrasound wave as frequency is increased, regardless of the composition tested. The threshold frequency for stress amplification is proportionate to the wave speed divided by the stone diameter. Thus, smaller stones may be likely to fragment at a higher frequency, but not at a lower frequency below a limit. Unlike with SWL, this amplification in BWL occurs consistently with spherical and irregularly shaped stones. In water tank experiments, stones smaller than the threshold size broke fastest at high frequency (p = 0.0003), whereas larger stones broke equally well to submillimeter dust at high, low, or mixed frequencies.

Conclusions: For small stones and fragments, increasing frequency of BWL may produce amplified stress in the stone causing the stone to break. Using the strategies outlined here, stones of all sizes may be turned to dust efficiently with BWL.

More Publications

In The News

NEJM Study Suggests If Having Kidney Stone Surgery, Treat All the Stones

Medical Research .com, Marie Benz

Mike Bailey is interviewed about the recently published paper, saying, "When getting stone surgery, treat all stones."

11 Aug 2022

Leaving small kidney stones behind causes problems later

UW Medicine Newsroom, Barbara Clements

When surgeons remove patients' kidney stones, they typically leave behind small stones that appear not to be causing problems.

A new randomized controlled study showed, however, that leaving these asymptomatic stones behind significantly increases the risk of a patient's relapse in the following five years.

11 Aug 2022

We’ve mastered acoustic levitation — and it is surprisingly useful

New Scientist, Michael Allen

Sonic tractor beams lift and manipulate objects with sound waves. They could be used to precisely deliver drugs inside our bodies or assemble delicate computer chips in mid air. Novel applications of this technology can be used from treating and moving kidney stones on Earth, minimizing the known risk of kidney stone development during space flights, and possibly guiding a pill-sized medical camera through a patient’s body.

15 Sep 2021

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Inventions

Method and System for MRI-based Targeting, Monitoring, and Quantification of Thermal and Mechanical Bioeffects in Tissue Induced by High Intensity Focused Ultrasound

Example embodiments of system and method for magnetic resonance imaging (MRI) techniques for planning, real-time monitoring, control, and post-treatment assessment of high intensity focused ultrasound (HIFU) mechanical fractionation of biological material are disclosed. An adapted form of HIFU, referred to as "boiling histotripsy" (BH), can be used to cause mechanical fractionation of biological material. In contrast to conventional HIFU, which cause pure thermal ablation, BH can generate therapeutic destruction of biological tissue with a degree of control and precision that allows the process to be accurately measured and monitored in real-time as well as the outcome of the treatment can be evaluated using a variety of MRI techniques. Real-time monitoring also allow for real-time control of BH.

Patent Number: 10,694,974

Vera Khokhlova, Wayne Kreider, Adam Maxwell, Yak-Nam Wang, Mike Bailey

Patent

30 Jun 2020

Broadly Focused Ultrasonic Propulsion Probes, Systems, and Methods

Disclosed herein are ultrasonic probes and systems incorporating the probes. The probes are configured to produce an ultrasonic therapy exposure that, when applied to a kidney stone, will exert an acoustic radiation force sufficient to produce ultrasonic propulsion. Unlike previous probes configured to produce ultrasonic propulsion, however, the disclosed probes are engineered to produce a relatively large (both wide and long) therapy region effective to produce ultrasonic propulsion. This large therapy region allows the probe to move a plurality of kidney stones (or fragments from lithotripsy) in parallel, thereby providing the user the ability to clear several stones from an area simultaneously. This "broadly focused" probe is, in certain embodiments, combined in a single handheld unit with a typical ultrasound imaging probe to produce real-time imaging. Methods of using the probes and systems to move kidney stones are also provided.

Patent Number: 10,667,831

Mike Bailey, Bryan Cunitz, Barbrina Dunmire, Adam Maxwell, Oren Levy

Patent

2 Jun 2020

Confinement or Movement of an Object Using Focused Ultrasound Waves to Generate an Ultrasound Intensity Well

Patent Number: 10,535,332

Adam Maxwell, Oleg Sapozhnikov, Wayne Kreider, Mike Bailey

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Patent

14 Jan 2020

A method includes transmitting a focused ultrasound wave into a medium to form (i) an ultrasound intensity well within the medium that exhibits a first range of acoustic pressure and (ii) a surrounding region of the medium that surrounds the ultrasound intensity well and exhibits a second range of acoustic pressure that exceeds the first range of acoustic pressure. The method further includes confining an object within the ultrasound intensity well. Additionally, an acoustic lens is configured to be acoustically coupled to an acoustic transducer. The acoustic lens has a varying longitudinal thickness that increases proportionally with respect to increasing azimuth angle of the acoustic lens. Another acoustic lens is configured to be acoustically coupled to an acoustic that increases proportionally with respect to increasing azimuth angle of the segment.

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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