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Matthew Bruce

Principal Scientist/Engineer

Email

mbruce@apl.washington.edu

Phone

206-685-2283

Education

B.S. Electrical and Computer Engineering, Michigan Technological University, 1991

M.S. Electrical and Computer Engineering, Virginia Polytechnic University, 1993

Ph.D. Bioengineering, University of Washington, 2004

Matthew Bruce's Website

http://staff.washington.edu/mbruce

Publications

2000-present and while at APL-UW

Ultrasound imaging of micro bubble activity during sonoporation pulse sequences

Keller, S., M. Bruce, and M.A. Averkiou, "Ultrasound imaging of micro bubble activity during sonoporation pulse sequences," Ultrasound Med. Biol., 45, 833-845, doi:10.1016/j.ultrasmedbio.2018.11.011, 2019.

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1 Mar 2019

Ultrasound-mediated drug delivery using the mechanical action of oscillating and/or collapsing microbubbles has been studied on many different experimental platforms, both in vitro and in vivo; however, the mechanisms remain to be elucidated. Many groups use sterile, enclosed chambers, such as Opticells and Clinicells, to optimize acoustic parameters in vitro needed for effective drug delivery in vivo, as well as for mechanistic investigation of sonoporation or the use of sound to permeate cell membranes. In these containers, cell monolayers are seeded on one side, and the remainder of the volume is filled with a solution containing microbubbles and a model drug. Ultrasound is then applied to study the effect of different parameters on model drug uptake in cell monolayers. Despite the simplicity of this system, the field has been unable to appropriately address what parameters and microbubble concentrations are most effective at enhancing drug uptake and minimizing cellular toxicity. In this work, a common in vitro sonoporation experimental setup was characterized through quantitative analysis of microbubble-dependent acoustic attenuation in combination with high-frame-rate and high-resolution imaging of bubble activity during sonoporation pulse sequences. The goal was to visualize the effect that ultrasound parameters have on microbubble activity. It was observed that under literature-derived sonoporation conditions (0.1–1 MPa, 20–1000 cycles and 10,000 to 10,000,000 microbubbles/mL), there is strong and non-linear acoustic attenuation, as well as bubble destruction, gas diffusion and bubble motion resulting in spatiotemporal pressure and concentration gradients. Ultimately, it was found that the acoustic conditions in common in vitro sonoporation setups are much more complex and confounding than often assumed.

Spontaneous nucleation of stable perfluorocarbon emulsions for ultrasound contrast agents

Li, D.S., S. Schneewind, M. Bruce, Z. Khaing, M. O'Donnell, and L. Pozzo, "Spontaneous nucleation of stable perfluorocarbon emulsions for ultrasound contrast agents," Nano Lett., 19, 173-181, doi:10.1021/acs.nanolett.8b03585, 2019.

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9 Jan 2019

Phase-change contrast agents are rapidly developing as an alternative to microbubbles for ultrasound imaging and therapy. These agents are synthesized and delivered as liquid droplets and vaporized locally to produce image contrast. They can be used like conventional microbubbles but with the added benefit of reduced size and improved stability. Droplet-based agents can be synthesized with diameters on the order of 100 nm, making them an ideal candidate for extravascular imaging or therapy. However, their synthesis requires low boiling point perfluorocarbons (PFCs) to achieve activation (i.e., vaporization) thresholds within FDA approved limits. Minimizing spontaneous vaporization while producing liquid droplets using conventional methods with low boiling point PFCs can be challenging. In this study, a new method to produce PFC nanodroplets using spontaneous nucleation is demonstrated using PFCs with boiling points ranging from –37 to 56°C. Sometimes referred to as the ouzo method, the process relies on saturating a cosolvent with the PFC before adding a poor solvent to reduce solvent quality, forcing droplets to spontaneously nucleate. This approach can produce droplets ranging from under 100 nm to over 1 μm in diameter. Ternary plots showing solvent and PFC concentrations leading to droplet nucleation are presented. Additionally, acoustic activation thresholds and size distributions with varying PFC and solvent conditions are measured and discussed. Finally, ultrasound contrast imaging is demonstrated using ouzo droplets in an animal model.

3D perfusion imaging using principal curvature detection rendering

Tremblay-Darveau, C., P.S. Sheeran, C.K. Vu, R. Williams, M. Bruce, and P.N. Burns, "3D perfusion imaging using principal curvature detection rendering," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 65, 2286-2295, doi:10.1109/TUFFC.2018.2854727, 2018.

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1 Dec 2018

Three-dimensional contrast-enhanced ultrasound (CEUS) imaging presents a clear advantage over its 2D counterpart in detecting and characterizing suspicious lesions as it properly surveys the inherent heterogeneity of tumours. However, 3D CEUS is also slow compared to 2D CEUS and tends to undersample the microbubble wash-in. This makes it difficult to resolve the feeding vessels, an important oncogenic marker, from the background perfusion cloud. Contrast-enhanced Doppler is helpful in isolating this conduit flow, but requires too many pulses in conventional line-by-line beamforming design. Recent breakthroughs in plane-wave imaging have greatly accelerated the volumetric imaging frame rate, but volumetric Doppler angiography still remains challenging when considering realtime limitations on the Doppler ensemble length. In this work, we demonstrate the feasibility of volumetric CEUS angiography subjected to real-time imaging constraints. Namely, we show how principal curvature detection can significantly improve 3D rendering of relatively noisy ultrasound angiograms without degrading the spatial resolution while subjected to a reasonable Doppler ensemble size. Singular Value Decomposition is also shown to be capable of identifying the quasi-stationary capillary perfusion.

More Publications

Inventions

Improved Detection of Kidney Stones with Ultrasound

Record of Invention Number: 47629

Matthew Bruce

Disclosure

19 Feb 2016

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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