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Dan Leotta

Senior Engineer

Email

dfleotta@apl.washington.edu

Phone

206-616-6787

Education

B.S. Bioengineering, Syracuse University, 1982

M.S. Electrical Engineering, Massachusetts Institute of Technology, 1985

Ph.D. Bioengineering, University of Washington, 1998

Publications

2000-present and while at APL-UW

Histotripsy treatment of abscesses

Matula, T.J., Y.-N. Wang, T. Khokhlova, D.F. Leotta, J. Kucewicz, A.A. Brayman, M. Bruce, A.D. Maxwell, B.E. MacConaghy, G. Thomas, K. Richmond, K. Chan, and W. Monsky, "Histotripsy treatment of abscesses," in Proc., IEEE International Ultrasonics Symposium, 7-11 September, Las Vegas, NV, doi:10.1109/IUS46767.2020.9251683 (IEEE, 2020).

More Info

7 Sep 2020

Abscesses are walled-off collections of infected fluids containing pus and bacteria. They are often treated with percutaneous drainage in which a drainage catheter may be sutured in place for up to several weeks. Complications such as clogged drains or secondary infections require rehospitalization and wound management. Bacteria are susceptible to mechanical damage, and thus we hypothesize that histotripsy may be a potential new paradigm for treating abscesses noninvasively, without the need for long term catheterization and antibiotics. We developed a porcine animal model that recapitulates some of the features of human abscesses (including size and loculations). Boiling and cavitation histotripsy treatments were applied to subcutaneous and intramuscular abscesses in this porcine model. Ultrasound imaging was used to evaluate abscess maturity, for treatment monitoring and assessment of post-treatment outcomes. Disinfection was quantified by counting bacteria colonies from samples aspirated before and after treatment. Histopathological evaluation of the abscesses was performed to identify changes resulting from histotripsy treatment and potential collateral damage. The results of this pilot study suggest focused ultrasound may lead to a technology for in situ treatment of acoustically accessible abscesses.

Ultrasound imaging of abscesses before and during histotripsy treatment

Bruce, M., D.F. Leotta, Y.-N. Wang, T. Khokhlova, J. Kucewicz, A.D. Maxwell, K. Chan, W. Monsky, and T.J. Matula, "Ultrasound imaging of abscesses before and during histotripsy treatment," in Proc., IEEE International Ultrasonics Symposium, 7-11 September, Las Vegas, NV, doi:10.1109/IUS46767.2020.9251386 (IEEE, 2020).

More Info

7 Sep 2020

Abscesses are walled-off collections of infected fluids most often treated with percutaneous drains placed under CT guidance. Complications such as clogged drains or secondary infections require rehospitalization and wound management. Histotripsy treatment has the potential to eliminate the need for long term catheterization and antibiotics. The progression of abscess development has yet to be fully described. The objective of this study was to use the latest advances in non-contrast ultrasound technologies to characterize abscess development in a porcine animal model. Intramuscular or subcutaneous injections of bacteria plus dextran particles as an irritant led to identifiable abscesses over a 2- to 3-week period. Ultrasound imaging was performed at least weekly, in some cases with a 3D tracking device that provided quantifiable size and shape measurements. Abscess progression was also measured with a plane-wave Doppler mode providing increased sensitivity to low-velocity flows, while abscess stiffness was quantified using shear wave elastography. Most of the mature abscesses were characterized by a rounded core of varying echogenicity surrounded by a hypoechoic capsule that was highly vascularized on Doppler imaging. A treatable abscess was defined by its hypervascular rim and avascular core. Stiffness varied within the abscess but generally decreased over time. Abscess echogenicity, shape, stiffness and vascularity potentially provide features to identify lesions suitable for treatment.

Analysis of factors influencing accuracy of volume flow measurement in dialysis access fistulas based on duplex ultrasound simulation

Ziegler, R.E., D.F. Leotta, K. Samson, A. Aliseda, M.D. Anderson, and F.H. Sheehan, "Analysis of factors influencing accuracy of volume flow measurement in dialysis access fistulas based on duplex ultrasound simulation," Vasc. Endovasc. Surg., 53, 529-535, doi:10.1177/1538574419858811, 2019.

More Info

1 Oct 2019

We developed a duplex ultrasound simulator and used it to assess accuracy of volume flow measurements in dialysis access fistula (DAF) models. The simulator consists of a mannequin, computer, and mock transducer. Each case is built from a patient's B-mode images that are used to create a 3-dimensional surface model of the DAF. Computational fluid dynamics is used to determine blood flow velocities based on model vessel geometry. The simulator displays real-time B-mode and color-flow images, and Doppler spectral waveforms are generated according to user-defined settings. Accuracy was assessed by scanning each case and measuring volume flow in the inflow artery and outflow vein for comparison with true volume flow values. Four examiners made 96 volume flow measurements on four DAF models. Measured volume flow deviated from the true value by 35 ± 36%. Mean absolute deviation from true volume flow was lower for arteries than veins (22 ± 19%, N = 48 vs. 58 ± 33%, N = 48, p < 0.0001). This finding is attributed to eccentricity of outflow veins which resulted in underestimating true cross-sectional area. Regression analysis indicated that error in measuring cross-sectional area was a predictor of error in volume flow measurement (β = 0.948, p < 0.001). Volume flow error was reduced from 35 ± 36% to 9 ± 8% (p < 0.000001) by calculating vessel area as an ellipse. Duplex volume flow measurements are based on a circular vessel shape. DAF inflow arteries are circular, but outflow veins can be elliptical. Simulation-based analysis showed that error in measuring volume flow is mainly due to assumption of a circular vessel.

More Publications

Inventions

Vascular Velocity Waveform Analysis from 2D Color Doppler Images

Record of Invention Number: 49097

Dan Leotta

Disclosure

26 Oct 2020

Device and Method to Break Urinary Stones in Pets

Record of Invention Number: 48640

Mike Bailey, Dan Leotta, Elizabeth Lynch, Brian MacConaghy, Adam Maxwell

Disclosure

28 May 2019

Easy 3D Ultrasound Imaging and Volume Quantification

Record of Invention Number: 48367

Mike Bailey, Bryan Cunitz, Dan Leotta

Disclosure

28 May 2019

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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