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Andrew Brayman

Principal Physicist





Research Interests

Acoustic Cavitation, Ultrasonic Drug Delivery, Microbubble Dynamics


Dr. Brayman's research interests include acoustic cavitation, ultrasonic delivery of non-viral gene vectors and drugs, acoustically-activated microbubble interactions with cells and tissues, non-thermal therapeutic application of ultrasound, and thermal ablation of tissues with high-frequency focused ultrasound.

Topics of his current research projects include:

- Image-guided HIFU for tumor ablation
- Dynamics of contrast agent microbubbles in intravascular environments
- Ultrasound- and microbubble-enhanced non-viral gene delivery for the treatment of hemophilia A and B
- The influence of microbubble shell loading on acoustically-induced bubble dynamics

Dr. Brayman joined APL-UW's Center for Industrial and Medical Ultrasound in 1999.


B.S. Biology, SUNY, Fredonia, 1976

M.S. Plant Physiology, SUNY, College of Environ. Sci. & Forestry/Syracuse University, 1980

Ph.D. Plant Physiology & Biophysics, SUNY, College of Environ. Sci. & Forestry/Syracuse University, 1985


Non-invasive Treatment of Abscesses with Ultrasound

Abscesses are walled-off collections of fluid and bacteria within the body. They are common complications of surgery, trauma, and systemic infections. Typical treatment is the surgical placement of a drainage catheter to drain the abscess fluid over several days. Dr. Keith Chan and researchers at APL-UW's Center for Industrial + Medical Ultrasound are exploring how to treat abscesses non-invasively, that is, from outside the body, with high-intensity focused ultrasound (HIFU). This experimental therapy could reduce pain, radiation exposure, antibiotic use, and costs for patients with abscesses. Therapeutic ultrasound could also treat abscesses too small or inaccessible for conventional drainage.

20 Jun 2016

Flow Cytometry Techniques Advance Microbubble Science

Researchers at the Center for Industrial and Medical Ultrasound (CIMU) are measuring the physical properties of ultrasound contrast agents — tiny gas bubbles several microns in diameter used to increase sonogram imaging efficiency in the body. When injected to the general circulation they can act as probes and beacons within the body, and can carry and deploy chemotherapeutic payloads.

CIMU researchers have developed a hybrid instrument that combines an off-the-shelf flow cytometer with an acoustic transducer. The cytometer's laser interrogation counts and measures the bubbles while the acoustic interrogation reveals the bubbles' viscosity and elasticity at megahertz frequencies.

5 Dec 2013


2000-present and while at APL-UW

Preliminary observations on the spatial correlation between short-burst microbubble oscillations and vascular bioeffects

Chen, H., A.A. Brayman, A.P. Evan, and T.J. Matula, "Preliminary observations on the spatial correlation between short-burst microbubble oscillations and vascular bioeffects," Ultrasound Med. Biol., 12, 2151-2162, doi:10.1016/j.ultrasmedbio.2012.08.014, 2012.

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1 Dec 2012

The objective of this preliminary study was to examine the spatial correlation between microbubble (MB)-induced vessel wall displacements and resultant microvascular bioeffects. MBs were injected into venules in ex vivo rat mesenteries and insonated by a single short ultrasound pulse with a center frequency of 1 MHz and peak negative pressures spanning the range of 1.5%u20135.6 MPa. MB and vessel dynamics were observed under ultra-high speed photomicrography. The tissue was examined by histology or transmission electron microscopy for vascular bioeffects. Image registration allowed for spatial correlation of MB-induced vessel wall motion to corresponding vascular bioeffects, if any. In cases in which damage was observed, the vessel wall had been pulled inward by more than 50% of the its initial radius. The observed damage was characterized by the separation of the endothelium from the vessel wall. Although the study is limited to a small number of observations, analytic statistical results suggest that vessel invagination comprises a principal mechanism for bioeffects in venules by microbubbles.

Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles

Chen, H., A.A. Brayman, and T.J. Matula, "Characteristic microvessel relaxation timescales associated with ultrasound-activated microbubbles," Appl. Phys. Lett., 101, 163704, doi:10.1063/1.4761937, 2012.

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15 Oct 2012

Ultrasound-activated microbubbles were used as actuators to deform microvessels for quantifying microvessel relaxation timescales at megahertz frequencies. Venules containing ultrasound contrast microbubbles were insonified by short 1 MHz ultrasound pulses. Vessel wall forced-deformations were on the same microsecond timescale as microbubble oscillations. The subsequent relaxation of the vessel was recorded by high-speed photomicrography. The tissue was modeled as a simple Voigt solid. Relaxation time constants were measured to be on the order of ~10 µs. The correlation coefficients between the model and 38 data sets were never lower than 0.85, suggesting this model is sufficient for modeling tissue relaxation at these frequencies. The results place a bound on potential numerical values for viscosity and elasticity of venules.

Acoustic and optical characterization of ultrasound contrast agents via flow cytometry

Perez, C., A. Brayman, J. Tu, J. Swalwell, H. Chen, and T. Matula, "Acoustic and optical characterization of ultrasound contrast agents via flow cytometry," J. Acoust. Soc. Am., 132, 1906, 2012.

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1 Sep 2012

Characterizing ultrasound contrast agents (UCAs) involve measuring the size and population distribution. However, these instruments do not allow for characterization of shell properties, which are important for (1) stability to administration and circulation throughout the vasculature; (2) UCA response to ultrasound; and (3) conjugating ligands for molecular imaging. Thus it is critical to understand the physical and rheological properties of shells. We previously developed a light scattering technique to characterize the shell properties of UCAs [Guan and Matula, JASA, vol. 116(5), 2004; Tu, et al., IEEE Trans. Ultrason., Ferroelec., and Freq. Control, vol. 58(5), 2011]. The most recent manifestation involves a flow cytometer modified with a custom square quartz flow cell in place of the standard nozzle and fluid jet. Acoustic coupling to the carrier sheath fluid and UCA samples occurred through a PZT bonded to one side of the flow cell. The PZT-driven UCA oscillations were processed and fitted to the Marmottant UCA model. Shell properties for UCAs (including Definity, Optison, SonoVue, and even homemade bubbles) were determined. The focus of this talk will be on pressure calibration and additional measurements of unpublished data from Optison and homemade bubbles.

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Systems, Devices, and Methods for Separating, Concentrating, and/or Differentiating Between Cells from a Cell Sample

Embodiments are generally related to differentiating and/or separating portions of a sample that are of interest from the remainder of the sample. Embodiments may be directed towards separating cells of interest from a cell sample. In some embodiments, acoustic impedances of the cells of interest may be modified. For example, the acoustic properties of the cells of interest may be modified by attaching bubbles to the cells of interest. The cell sample may then be subjected to an acoustic wave. The cells of interest may be differentiated and/or separated from the remainder of the sample based on relative displacements and/or volumetric changes experienced by the cells of interest in response thereto. The cells of interest may be separated using a standing wave and sorted into separate channels of a flow cell. Optionally, the cells may be interrogated by a light source and differentiated by signals generated in response thereto.

Patent Number: 9,645,080

Tom Matula, Andrew Brayman, Oleg Sapozhnikov, Brian MacConaghy, Jarred Swalwell, Camilo Perez


9 May 2017

Ultrasonic Persistence Imaging of Tissues in Which Acoustic Microbubble Destruction has Occurred

Record of Invention Number: 46066

Andrew Brayman


3 May 2012

Ultrasound Target Vessel Occlusion Using Microbubbles

Patent Number: US 7,591,996 B2

Joo Ha Hwang, Andrew Brayman

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22 Sep 2009

Selective occlusion of a blood vessel is achieved by selectively damaging endothelial cells at a target location in the blood vessel, resulting in the formation of a fibrin clot proximate to the damaged endothelial cells. Additional fibrinogen can then be introduced into the blood vessel if occlusion is not achieved, as the fibrinogen is converted to fibrin by enzymes released by the exposed thrombogenic tissue and activated platelets. Endothelial cells are selectively damaged using thermal effects induced by ultrasound, by mechanical effects induced by ultrasound, or by mechanical effects produced by a tool introduced into the blood vessel (such as catheter-based tool). A particularly preferred technique for selectively damaging endothelial cells involves introducing an ultrasound activatable agent into the blood vessel, and causing cavitation in that agent using pulses of high-intensity focused ultrasound having a duration insufficient to induce thermal damage in adjacent perivascular tissue.

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