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Barbrina Dunmire

Senior Engineer

Email

mrbean@apl.washington.edu

Phone

206-685-6953

Education

BS Aeronautics & Astronautics, University of Washington, 1989

MS Aeronautics & Astronautics, University of Washington, 1991

MS Bioengineering, University of Washington, 1998

Videos

SonoMotion: A Budding Start-up Company

A research team has developed new technologies to treat kidney stone disease with an ultrasound-based system. Embraced by clinicians, their advances are now being taken to the next step: transition the prototype to an approved device that will roll into hospitals and clinics around the world.

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11 Feb 2013

At the Center for Industrial and Medical Ultrasound a team of scientists, engineers, and students has developed an ultrasound-based system that may provide an office procedure to speed the natural passage of kidney stones. The system uses commercial ultrasound components to locate stones in kidneys. It creates clear pictures of them and then applies an acoustic radiative force, repositioning stones in the kidney so they are more likely to pass naturally.

As a research team, considerable technical advancements have been made and valuable feedback and cooperation has been garnered from the user community – the clinicians. The scientists, engineers, urologists, and commercialization experts are now collaborating to take the next steps.

SonoMotion has partnered with a hardware manufacturing company and licensed the ultrasonic propulsion of kidney stones technology with the University of Washington. The next big step will be to transition the prototype system into one that will pass the rigors of FDA review and be ready to roll into hospitals and clinics around the world.

Center for Industrial and Medical Ultrasound - CIMU

CIMU is a group of scientists, engineers, and technicians dedicated to research across the field of bio-medical ultrasonics with the goal of developing technologies that will be used in a clinic to treat patients.

1 Nov 2010

Publications

2000-present and while at APL-UW

Preclinical safety and effectiveness studies of ultrasonic propulsion of kidney stones

Harper, J.D., B. Dunmire, Y.-N. Wang, J.C. Simon, D. Liggitt, M. Paun, B.W. Cunitz, F. Starr, M.R. Bailey, K.L. Penniston, F.C. Lee, R.S. Hsi, and M.D. Sorensen, "Preclinical safety and effectiveness studies of ultrasonic propulsion of kidney stones," Urology, 84, 484-489, doi:10.1016/j.urology.2014.04.041, 2014.

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1 Aug 2014

Objective
To provide an update on a research device to ultrasonically reposition kidney stones transcutaneously. This article reports preclinical safety and effectiveness studies, survival data, modifications of the system, and testing in a stone-forming porcine model. These data formed the basis for regulatory approval to test the device in humans.

Materials and Methods
The ultrasound burst was shortened to 50 ms from previous investigations with 1-s bursts. Focused ultrasound was used to expel 2- to 5-mm calcium oxalate monohydrate stones placed ureteroscopically in 5 pigs. Additionally, de novo stones were imaged and repositioned in a stone-forming porcine model. Acute safety studies were performed targeting 2 kidneys (6 sites) and 3 pancreases (8 sites). Survival studies followed 10 animals for 1 week after simulated treatment. Serum and urine analyses were performed, and tissues were evaluated histologically.

Results
All ureteroscopically implanted stones (6/6) were repositioned out of the kidney in 14 ± 8 minutes with 13 ± 6 bursts. On average, 3 bursts moved a stone more than 4 mm and collectively accounted for the majority of relocation. Stones (3 mm) were detected and repositioned in the 200-kg stone-forming model. No injury was detected in the acute or survival studies.

Conclusion
Ultrasonic propulsion is safe and effective in the porcine model. Stones were expelled from the kidney. De novo stones formed in a large porcine model were repositioned. No adverse effects were identified with the acute studies directly targeting kidney or pancreatic tissue or during the survival studies indicating no evidence of delayed tissue injury.

Focused ultrasound to displace renal calculi: Threshold for tissue injury

Wang, Y.-N., J.C. Simon, B.W. Cunitz, F.L. Starr, M. Paun, D.H. Liggitt, A.P. Evan, J.A. McAteer, Z. Liu, B. Dunmire, and M.R. Bailey, "Focused ultrasound to displace renal calculi: Threshold for tissue injury," J. Therapeut. Ultrasound, 2, doi:10.1186/2050-5736-2-5, 2014.

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31 Mar 2014

The global prevalence and incidence of renal calculi is reported to be increasing. Of the patients that undergo surgical intervention, nearly half experience symptomatic complications associated with stone fragments that are not passed and require follow-up surgical intervention. In a clinical simulation using a clinical prototype, ultrasonic propulsion was proven effective at repositioning kidney stones in pigs. The use of ultrasound to reposition smaller stones or stone fragments to a location that facilitates spontaneous clearance could therefore improve stone-free rates. The goal of this study was to determine an injury threshold under which stones could be safely repositioned.

Kidneys of 28 domestic swine were treated with exposures that ranged in duty cycle from 0%–100% and spatial peak pulse average intensities up to 30 kW/cm2 for a total duration of 10 min. The kidneys were processed for morphological analysis and evaluated for injury by experts blinded to the exposure conditions.

At a duty cycle of 3.3%, a spatial peak intensity threshold of 16,620 W/cm2 was needed before a statistically significant portion of the samples showed injury. This is nearly seven times the 2,400-W/cm2 maximum output of the clinical prototype used to move the stones effectively in pigs.

The data obtained from this study show that exposure of kidneys to ultrasonic propulsion for displacing renal calculi is well below the threshold for tissue injury.

Content and face validation of a curriculum for ultrasonic propulsion of calculi in a human renal model

Hsi, R.S., B. Dunmire, B.W. Cunitz, X. He, M.D. Sorensen, J.D. Harper, M.R. Bailey, and T.S. Lendvay, "Content and face validation of a curriculum for ultrasonic propulsion of calculi in a human renal model," J. Endourol., 28, 459-463, doi:10.1089/end.2013.0589, 2014.

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20 Mar 2014

Purpose: Ultrasonic propulsion to reposition urinary tract calculi requires knowledge about ultrasound image capture, device manipulation, and interpretation. The purpose of this study was to validate a cognitive and technical skills curriculum to teach urologists ultrasonic propulsion to reposition kidney stones in tissue phantoms.

Materials and Methods: Ten board-certified urologists recruited from a single institution underwent a didactic session on renal ultrasound imaging. Subjects completed technical skills modules in tissue phantoms, including kidney imaging, pushing a stone through a translucent maze, and repositioning a lower pole calyceal stone. Objective cognitive and technical performance metrics were recorded. Subjects completed a questionnaire to ascertain face and content validity on a five-point Likert scale.

Results: Eight urologists (80%) had never attended a previous ultrasound course, and nine (90%) performed renal ultrasounds less frequently than every 6 months. Mean cognitive skills scores improved from 55% to 91% (p<0.0001) on pre- and post-didactic tests. In the kidney phantom, 10 subjects (100%) repositioned the lower pole calyceal stone to at least the lower pole infundibulum, while 9 (90%) successfully repositioned the stone to the renal pelvis. A mean±SD (15.7±13.3) pushes were required to complete the task over an average of 4.6±2.2 minutes. Urologists rated the curriculum's effectiveness and realism as a training tool at a mean score of 4.6/5.0 and 4.1/5.0, respectively.

Conclusions: The curriculum for ultrasonic propulsion is effective and useful for training urologists with limited ultrasound proficiency in stone repositioning technique. Further studies in animate and human models will be required to assess predictive validity.

More Publications

A reflectance model for non-contact mapping of venous oxygen saturation using a CCD camera

Li, J., B. Dunmire, K.W. Beach, and D.F. Leotta, "A reflectance model for non-contact mapping of venous oxygen saturation using a CCD camera," Opt. Commun., 308-78-84, doi:10.1016/j.optcom.2013.06.041, 2013.

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1 Nov 2013

A method of non-contact mapping of venous oxygen saturation (SvO2) is presented. A CCD camera is used to image skin tissue illuminated alternately by a red (660 nm) and an infrared (800 nm) LED light source. Low cuff pressures of 30–40 mmHg are applied to induce a venous blood volume change with negligible change in the arterial blood volume. A hybrid model combining the Beer–Lambert law and the light diffusion model is developed and used to convert the change in the light intensity to the change in skin tissue absorption coefficient. A simulation study incorporating the full light diffusion model is used to verify the hybrid model and to correct a calculation bias. SvO2 in the fingers, palm, and forearm for five volunteers are presented and compared with results in the published literature. Two-dimensional maps of venous oxygen saturation are given for the three anatomical regions.

An ultrasound system to identify and characterize kidney stones

Cunitz, B.W., B.L. Dunmire, M.D. Sorensen, R. Hsi, F. Lee, O.A. Sapozhnikov, J.D. Harper, and M. Bailey, "An ultrasound system to identify and characterize kidney stones," J. Acoust. Soc. Am., 134, 3976, doi:10.1121/1.4830485, 2013.

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1 Nov 2013

Ultrasound imaging has tissue and blood imaging modes. This report describes development of a kidney stone imaging mode. Two plane pulses generate a B-mode image. Overlaid in color are regions of high decorrelation between the pulses. Our previous data [UMB, 39, 1026-1038 (2013)] indicate the pulses excite bubbles on the stone surface, which causes the decorrelation. As such this mode automatically identifies stones in the image while scanning at a high frame rate. Further in a control box placed on the stone, highly focused beams are scanned across the stone and a harmonic B-mode image is produced to sharpen the lateral resolution. This mode is used to refine the size and shape of the stone. The first mode is used to aid visualization of stones. Our team is also using it to target and track stones that move with respiration during shock wave lithotripsy (SWL) and as an indicator of stone susceptibility to SWL since surface bubbles contribute to comminution. Improved stone sizing by the second mode aids treatment planning, and resolution of surface roughness is another indicator of stone fragility.

Holography and numerical projection methods for characterizing the three-dimensional acoustic fields of arrays in continuous-wave and transient regimes

Kreider, W., A.D. Maxwell, P.V. Yuldashev, B.W. Cunitz, B. Dunmire, O.A. Sapozhnikov, and V.A. Khokhlova, "Holography and numerical projection methods for characterizing the three-dimensional acoustic fields of arrays in continuous-wave and transient regimes," J. Acoust. Soc. Am., 134, 4153, doi:10.1121/1.4831222, 2013.

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1 Nov 2013

The use of projection methods is increasingly accepted as a standard way of characterizing the 3D fields generated by medical ultrasound sources. When combined with hydrophone measurements of pressure amplitude and phase over a surface transverse to the wave propagation, numerical projection can be used to reconstruct 3D fields that account for operational details and imperfections of the source. Here, we use holography measurements to characterize the fields generated by two array transducers with different geometries and modes of operation. First, a seven-element, high-power therapy transducer is characterized in the continuous-wave regime using holography measurements and nonlinear forward-projection calculations. Second, a C5-2 imaging probe (Philips Healthcare) with 128 elements is characterized in the transient regime using holography measurements and linear projection calculations. Results from the numerical projections for both sources are compared with independent hydrophone measurements of select waveforms, including shocked focal waveforms for the therapy transducer. Accurate 3D field representations have been confirmed, though a notable sensitivity to hydrophone calibrations is revealed. Uncertainties associated with this approach are discussed toward the development of holography measurements combined with numerical projections as a standard metrological tool.

Focused ultrasound to expel calculi from the kidney: Safety and efficacy of a clinical prototype device

Harper, J.D., M.D. Sorensen, B.W. Cunitz, Y.-N. Wang, J.C. Simon, F. Starr, M. Paun, B. Dunmire, H.D. Liggitt, A.P. Evan, J.A. McAteer, R.S. Hsi, and M.R. Bailey, "Focused ultrasound to expel calculi from the kidney: Safety and efficacy of a clinical prototype device," J. Urol., 190, 1090-1095, doi:10.1016/j.juro.2013.03.120, 2013.

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9 Apr 2013

Purpose
Focused ultrasound has the potential to expel small stones or residual stone fragments from the kidney, or move obstructing stones to a non-obstructing location. The purpose of this study was to evaluate the efficacy and safety of ultrasonic propulsion in a live porcine model.

Material and Methods
Calcium oxalate monohydrate kidney stones and laboratory model stones (2–8 mm) were ureteroscopically implanted within the renal pelvicalyceal system of 12 kidneys in eight domestic swine. Transcutaneous ultrasonic propulsion was performed using a Philips HDI C5-2 imaging transducer and Verasonics diagnostic ultrasound platform. Successful stone relocation was defined as stone movement from the calyx to the renal pelvis, ureteropelvic junction (UPJ) or proximal ureter. Efficacy and procedure time were determined. Three blinded experts evaluated for histologic injury to the kidney in control, sham, and treatment arms.

Results
All stones were observed to move during treatment, and 65% (17/26) were relocated successfully to the renal pelvis (3), UPJ (2), or ureter (12). Average successful procedure time was 14±8 min and required 23±16 ultrasound bursts of ~1 sec duration. There was no evidence of gross or histologic injury to the renal parenchyma in kidneys exposed to 20 bursts (1 sec duration, 33 sec intervals) at the same output (2400 W/cm2) used to push stones.

Conclusions
Non-invasive transcutaneous ultrasonic propulsion is a safe, effective, and time-efficient means to relocate calyceal stones to the renal pelvis, UPJ, or ureter. This technology holds promise as a useful adjunct to the surgical management of renal calculi.

Characterizing an Agar/Gelatin phantom for image guided dosing and feeback control of high-intensity focused ultrasound

Dunmire, B., J.C. Kucewicz, S.B. Mitchell, L.A. Crum, and K.M Sekins, "Characterizing an Agar/Gelatin phantom for image guided dosing and feeback control of high-intensity focused ultrasound," Ultrasound Med. Biol., 39, 300-311, 2013.

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1 Feb 2013

The temperature dependence of an agar/gelatin phantom was evaluated. The purpose was to predict the material property response to high-intensity focused ultrasound (HIFU) for developing ultrasound guided dosing and targeting feedback. Changes in attenuation, sound speed, shear modulus and thermal properties with temperature were examined from 20°C to 70°C for 3 weeks post-manufacture. The attenuation decreased with temperature by a power factor of 0.15. Thermal conductivity, diffusivity and specific heat all increased linearly with temperature for a total change of approximately 16%, 10% and 6%, respectively. Sound speed had a parabolic dependence on temperature similar to that of water. Initially, the shear modulus irreversibly declined with even a slight increase in temperature. Over time, the gel maintained its room temperature shear modulus with moderate heating. A stable phantom was achieved within 2 weeks post-manufacture that possessed quasi-reversible material properties up to nearly 55°C.

Autoregressive ultrasound imaging method to enhance kidney stone twinkling and suppress blood flow

Kucewicz, J.C., B.W. Cunitz, B. Dunmire, M.R. Bailey, and L.A. Crum, "Autoregressive ultrasound imaging method to enhance kidney stone twinkling and suppress blood flow," J. Acoust. Soc. Am., 129, 2376, doi:10.1121/1.3587699, 2011.

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1 Apr 2011

"Twinkling" is a widely reported ultrasound artifact whereby kidney stones and other similar calcified, strongly reflective objects appear as turbulent, flowing blood in color and power Doppler. The twinkling artifact has been shown to improve kidney stone detection over B-mode imaging alone, but its use has several limitations. Principally, twinkling can be confused with blood flow, potentially leading to an incorrect diagnosis. Here a new method is reported for explicitly suppressing the display of color from blood flow to enhance and/or isolate the twinkle signal. The method applies an autoregressive model to standard Doppler pulses in order to differentiate tissue, blood flow, and twinkling. The algorithm was implemented on a software-based, open architecture ultrasound system and tested by a sonographer on phantoms and on stones implanted in a live porcine kidney. Stones of 3-10 mm were detected reproducibly while suppressing blood flow in the image. In conclusion, a new algorithm designed to specifically detect stones has been tested and has potential clinical utility especially as efforts are made to reduce radiation exposure on diagnosis and monitoring.

Understanding changes in tissue phantom material properties with temperature

Dunmire, B.L., J.C. Kucewicz, S.B. Mitchell, L.A. Crum, and K.M. Sekins, "Understanding changes in tissue phantom material properties with temperature," J. Acoust. Soc. Am., 129, 2405, doi:10.1121/1.3587832, 2011.

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1 Apr 2011

Phantoms used for high intensity focused ultrasound (HIFU) applications require rigorous evaluation of material properties since, locally, the material experiences extreme changes in temperature and stresses with the HIFU treatment. Here we present the testing of an agar-gelatin phantom intended for both acoustic radiation force imaging (ARFI) and HIFU applications. The phantom shear modulus, speed of sound, attenuation, and thermal properties were all evaluated over the range of room temperature to 80C. With the exception of the thermal properties, all measurements were taken during both heating and cool down. Cavitation threshold and melting point were also tested. The change in material sound speed and thermal properties with temperature were quasireversible and similar to that of water. Material attenuation showed a slight decrease with temperature, but appeared to also be reversible. Shear modulus decreased significantly with temperature, going to near zero. The response was not reversible, returning to only approximately one-third of the starting value. These results demonstrate the complex material response that can occur with HIFU treatment. The results also raise the question of how well the test procedures, and thus results, properly reflect the true HIFU conditions.

Tissue pulsatility imaging of cerebral vasoreactivity during hyperventilation

Kucewicz, J.C., B. Dunmire, N.D. Giardino, D.F. Leotta, M. Paun, S.R. Dager, and K.W. Beach, "Tissue pulsatility imaging of cerebral vasoreactivity during hyperventilation," Ultrasound Med. Biol., 34, 1200-1208, doi:10.1016/j.ultrasmedbio.2008.01.001, 2008.

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1 Aug 2008

Tissue Pulsatility Imaging (TPI) is an ultrasonic technique that is being developed at the University of Washington to measure tissue displacement or strain due to blood flow over the cardiac and respiratory cycles. This technique is based in principle on plethysmography, an older non-ultrasound technology for measuring expansion of a whole limb or body part due to perfusion. TPI adapts tissue Doppler signal processing methods to measure the "plethysmographic" signal from hundreds or thousands of sample volumes in an ultrasound image plane. This paper presents a feasibility study to determine if TPI can be used to assess cerebral vasoreactivity. Ultrasound data were collected transcranially through the temporal acoustic window from four subjects before, during, and after voluntary hyperventilation. In each subject, decreases in tissue pulsatility during hyperventilation were observed that were statistically correlated with the subject's end-tidal CO2 measurements.

Functional tissue pulsatility imaging of the brain during visual stimulation

Kucewicz, J.C., B. Dunmire, D.F. Leotta, H. Panagiotides, M. Paun, and K.W. Beach, "Functional tissue pulsatility imaging of the brain during visual stimulation," Ultrasound Med. Biol., 33, 681-690, 2007.

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1 May 2007

Functional tissue pulsatility imaging is a new ultrasonic technique being developed to map brain function by measuring changes in tissue pulsatility as a result of changes in blood flow with neuronal activation. The technique is based in principle on plethysmography, an older, nonultrasound technology for measuring expansion of a whole limb or body part as a result of perfusion. Perfused tissue expands by a fraction of a percent early in each cardiac cycle when arterial inflow exceeds venous outflow, and it relaxes later in the cardiac cycle when venous drainage dominates. Tissue pulsatility imaging (TPI) uses tissue Doppler signal processing methods to measure this pulsatile "plethysmographic" signal from hundreds or thousands of sample volumes in an ultrasound image plane. A feasibility study was conducted to determine if TPI could be used to detect regional brain activation during a visual contrast-reversing checkerboard block paradigm study. During a study, ultrasound data were collected transcranially from the occipital lobe as a subject viewed alternating blocks of a reversing checkerboard (stimulus condition) and a static, gray screen (control condition). Multivariate analysis of variance was used to identify sample volumes with significantly different pulsatility waveforms during the control and stimulus blocks. In 7 of 14 studies, consistent regions of activation were detected from tissue around the major vessels perfusing the visual cortex.

In vivo ultrasonic measurement of tissue vibration at a stenosis: A case study

Plett, M.I., K.W. Beach, B. Dunmire, K.G. Brown, J.F. Primozich, and E. Strandness Jr., "In vivo ultrasonic measurement of tissue vibration at a stenosis: A case study," Ultrasound Med. Biol., 27, 1049-1058, 2001.

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1 Aug 2001

It is known that bruits often can be heard downstream from stenoses. They are thought to be produced by disturbed blood flow and vessel wall vibrations. Our understanding of bruits has been limited, though, to analysis of sounds heard at the level of the skin. For direct measurements from the stenosis site, we developed an ultrasonic pulse-echo multigate system using quadrature phase demodulation. The system simultaneously measures tissue displacements and blood velocities at multiple depths. This paper presents a case study of a severe stenosis in a human infrainguinal vein bypass graft. During systole, nearly sinusoidal vessel wall vibrations were detected. Solid tissue vibration amplitudes measured up to 2 microm, with temporal durations of 100 ms and frequencies of roughly 145 Hz and its harmonics. Cross-axial oscillations were also found in the lumen that correlate with the wall vibrations, suggesting coupling between wall vibration and blood velocity oscillation.

Inventions

Applications of Ultrasonic Propulsion

Record of Invention Number: 47073

Mike Bailey, Bryan Cunitz, Barbrina Dunmire

Disclosure

3 Oct 2014

Assortment of Push Profiles for Pushing a Variety of Kidney Stones

Record of Invention Number: 47072

Mike Bailey, Bryan Cunitz, Barbrina Dunmire, Oleg Sapozhnikov

Disclosure

3 Oct 2014

Single Element Broadly Focused Ultrasonic Propulsion Device

Record of Invention Number: 47074

Mike Bailey, Bryan Cunitz, Barbrina Dunmire

Disclosure

3 Oct 2014

More Inventions

Ultrasound to rotate an obstructing kidney stone

Record of Invention Number: 47066

Mike Bailey, Bryan Cunitz, Barbrina Dunmire

Disclosure

29 Sep 2014

Apparatus and Method for Disrupting Oil Pipeline Plugs

Record of Invention Number: 46417

Larry Crum, Barbrina Dunmire, Wayne Kreider, Tom Matula, Oleg Sapozhnikov

Disclosure

26 Feb 2013

Non-Contact Reflectance Imaging of Oxygen Saturation in Venous Blood

Record of Invention Number: 46171

Jun Li, Barbrina Dunmire, Dan Leotta

Disclosure

1 Aug 2012

An Ultrasound Phantom for Detecting and Repositioning Kidney Stones

Record of Invention Number: 45981

Mike Bailey, Bryan Cunitz, Barbrina Dunmire

Disclosure

1 Mar 2012

Computational Flow Modeling for Dialysis Access Surgical Planning

Record of Invention Number: 8701D

Barbrina Dunmire, Dan Leotta, Alberto Aliseda, James J. Riley, Kirk W. Beach, Edward Stutzman, R. Eugene Zierler

Disclosure

20 May 2010

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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