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Yak-Nam Wang

Senior Engineer






B.S. Biomedical Materials Science & Engineering, Queen Mary & Westfield College, University of London, UK, 1996

Ph.D. Biomedical Materials, Queen Mary & Westfield College, University of London, UK, 2000


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.

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


2000-present and while at APL-UW

Differentiation of burn wounds in an in vivo porcine model using terahertz spectroscopy

Osman, O.B., T.J. Tan, S. Henry, A. Warsen, N. Farr, A.M. McClintic, Y.-N. Wang, S. Arbabi, and M.H. Arbab, "Differentiation of burn wounds in an in vivo porcine model using terahertz spectroscopy," Biomed. Opt. Express, 11, 6528-6535, doi:10.1364/BOE.397792, 2020.

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1 Nov 2020

The accuracy of current burn triage techniques has remained between 50–70%. Accordingly, there is a significant clinical need for the quantitative and accurate assessment of partial-thickness burn injuries. Porcine skin represents the closest animal model to human skin, and is often used in surgical skin grafting procedures. In this study, we used a standardized in vivo porcine burn model to obtain terahertz (THz) point-spectroscopy measurements from burns with various severities. We then extracted two reflection hyperspectral parameters, namely spectral area under the curve between approximately 0.1 and 0.9 THz (–10 dB bandwidth in each spectrum), and spectral slope, to characterize each burn. Using a linear combination of these two parameters, we accurately classified deep partial- and superficial partial-thickness burns (p = 0.0159), compared to vimentin immunohistochemistry as the gold standard for burn depth determination.

Image-guided treatment of primary liver cancer in mice leads to vascular disruption and increased drug penetration

Keller, S.B., D. Suo, Y.-N. Wang, H. Kenerson, R.S. Young, and M.A. Averkiou, "Image-guided treatment of primary liver cancer in mice leads to vascular disruption and increased drug penetration," Front. Pharmacol., 11, doi:10.3389/fphar.2020.584344, 2020.

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30 Sep 2020

Despite advances in interventional procedures and chemotherapeutic drug development, hepatocellular carcinoma (HCC) is still the fourth leading cause of cancer-related deaths worldwide with a <30% 5-year survival rate. This poor prognosis can be attributed to the fact that HCC most commonly occurs in patients with pre-existing liver conditions, rendering many treatment options too aggressive. Patient survival rates could be improved by a more targeted approach. Ultrasound-induced cavitation can provide a means for overcoming traditional barriers defining drug uptake. The goal of this work was to evaluate preclinical efficacy of image-guided, cavitation-enabled drug delivery with a clinical ultrasound scanner. To this end, ultrasound conditions (unique from those used in imaging) were designed and implemented on a Philips EPIQ and S5-1 phased array probe to produced focused ultrasound for cavitation treatment. Sonovue microbubbles, which are clinically approved as an ultrasound contrast agent, were used for both imaging and cavitation treatment. A genetically engineered mouse model was bred and used as a physiologically relevant preclinical analog to human HCC. It was observed that image-guided and targeted microbubble cavitation resulted in selective disruption of the tumor blood flow and enhanced doxorubicin uptake and penetration. Histology results indicate that no gross morphological damage occurred as a result of this process. The combination of these effects may be exploited to treat HCC and other challenging malignancies and could be implemented with currently available ultrasound scanners and reagents.

Noninvasive acoustic manipulation of objects in a living body

Ghanem, M.A., A.D. Maxwell, Y.-N. Wang, B.W. Cunitz, V.A. Khokhlova, O.A. Sopozhnikov, and M.R. Bailey, "Noninvasive acoustic manipulation of objects in a living body," Proc. Nat. Acad. Sci. USA, 117, 16,848-16,855, doi:10.1073/pnas.2001779117, 2020.

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21 Jul 2020

In certain medical applications, transmitting an ultrasound beam through the skin to manipulate a solid object within the human body would be beneficial. Such applications include, for example, controlling an ingestible camera or expelling a kidney stone. In this paper, ultrasound beams of specific shapes were designed by numerical modeling and produced using a phased array. These beams were shown to levitate and electronically steer solid objects (3-mm-diameter glass spheres), along preprogrammed paths, in a water bath, and in the urinary bladders of live pigs. Deviation from the intended path was on average <10%. No injury was found on the bladder wall or intervening tissue.

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Histotripsy treatment of hematoma

A rapid, definitive intervention aiming at evacuation of the space-occupying hematoma would reduce pain, improve function, and avoid long term sequelae. Ultrasound is known to promote intravascular clot breakdown, as both a standalone procedure and used in conjunction with thrombolytic drugs and/or microbubbles. In-vitro and in-vivo studies have been conducted over the years, and acoustic cavitation is widely accepted as the dominant mechanism for mechanical disruption of the clot integrity and partial or complete recanalization of the vessel. Recently, a technique termed histotripsy that employs high-intensity focused ultrasound (HIFU) has been demonstrated to dissolve large in vitro and in vivo vascular clots without thrombolytic drugs within 1.5-5 minutes into debris 98% of which were smaller than 5 microns. However, this approach cannot be applied to the large extravascular hematomas due to their large volume (20-50 cc's) compared to intravascular clots, which necessitates much higher thrombolysis rates to complete the treatment within clinically relevant times (.about.15-20 minutes).

Patent Number: 10,702,719

Tatiana Khokhlova, Tom Matula, Wayne Monsky, Yak-Nam Wang


7 Jul 2020

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


30 Jun 2020

Audio Feedback for Improving the Accuracy of BWL Targeting

Record of Invention Number: 48254

Mike Bailey, Bryan Cunitz, Barbrina Dunmire, Christopher Hunter, Wayne Kreider, Adam Maxwell, Yak-Nam Wang


25 Jan 2018

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