APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

Yak-Nam Wang

Senior Engineer

Email

ynwang@apl.washington.edu

Phone

206-616-6673

Videos

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.

More Info

23 Mar 2017

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

Publications

2000-present and while at APL-UW

Histomorphological and biochemical properties of plantar soft tissue in diabetes

Wang, Y.-N., K. Lee, J.B. Shofer, and W.R. Ledoux, "Histomorphological and biochemical properties of plantar soft tissue in diabetes," The Foot, 33, doi:10.1016/j.foot.2017.06.001, 2017.

More Info

1 Dec 2017

Highlights

This paper presents the evaluation of the histomorphometric and biochemical changes that could occur in human plantar tissue with diabetes.

This is the first paper to evaluate the histomorphologic and biochemical properties separated by both disease status and foot location.

The main findings were differences in the elastin content and the septal wall thickness, with diabetes and location, which could translate to changes in the mechanical properties and subsequent sensitivities to ulcer formation.

Focused ultrasound for immuno-adjuvant treatment of pancreatic cancer: An emerging clinical paradigm in the era of personalized oncotherapy

Maloney, E., T. Khokhlova, V.G. Pillarisetty, G.R. Schade, E.A. Repasky, Y.-N. Wang, L. Giuliani, M. Primavera, and J.H. Hwang, "Focused ultrasound for immuno-adjuvant treatment of pancreatic cancer: An emerging clinical paradigm in the era of personalized oncotherapy," Int. Rev. Immunol., 36, 338-351, doi:10.1080/08830185.2017.1363199, 2017.

More Info

29 Sep 2017

Current clinical treatment regimens, including many emergent immune strategies (e.g., checkpoint inhibitors) have done little to affect the devastating course of pancreatic ductal adenocarcinoma (PDA). Clinical trials for PDA often employ multi-modal treatment, and have started to incorporate stromal-targeted therapies, which have shown promising results in early reports. Focused ultrasound (FUS) is one such therapy that is uniquely equipped to address local and systemic limitations of conventional cancer therapies as well as emergent immune therapies for PDA. FUS methods can non-invasively generate mechanical and/or thermal effects that capitalize on the unique oncogenomic/proteomic signature of a tumor. Potential benefits of FUS therapy for PDA include: (1) emulsification of targeted tumor into undenatured antigens in situ, increasing dendritic cell maturation, and increasing intra-tumoral CD8+/ T regulatory cell ratio and CD8+ T cell activity; (2) reduction in intra-tumoral hypoxic stress; (3) modulation of tumor cell membrane protein localization to enhance immunogenicity; (4) modulation of the local cytokine milieu toward a Th1-type inflammatory profile; (5) up-regulation of local chemoattractants; (6) remodeling the tumor stroma; (7) localized delivery of exogenously packaged immune-stimulating antigens, genes and therapeutic drugs. While not all of these results have been studied in experimental PDA models to date, the principles garnered from other solid tumor and disease models have direct relevance to the design of optimal FUS protocols for PDA. In this review, we address the pertinent limitations in current and emergent immune therapies that can be improved with FUS therapy for PDA.

Safety and effectiveness of a longer focal beam and burst duration in ultrasonic propulsion for repositioning urinary stones and fragments

Janssen, K.M., T.C. Brand, B.W. Cunitz, Y.-N. Wang, J.C. Simon, F. Starr, H.D. Liggitt, J. Thiel, M.D. Sorensen, J.D. Harper, M.R. Bailey, and B. Dunmire, "Safety and effectiveness of a longer focal beam and burst duration in ultrasonic propulsion for repositioning urinary stones and fragments," J. Endourol., 31, 793-799, doi:10.1089/end.2017.0167, 2017.

More Info

1 Aug 2017

Purpose: In the first-in-human trial of ultrasonic propulsion, subjects passed collections of residual stone fragments repositioned with a C5-2 probe. Here, effectiveness and safety in moving multiple fragments are compared between the C5-2 and a custom (SC-50) probe that produces a longer focal beam and burst duration.

Materials and Methods: Effectiveness was quantified by the number of stones expelled from a calyx phantom consisting of a 30-mm deep, water-filled well in a block of tissue mimicking material. Each probe was positioned below the phantom to move stones against gravity. Single propulsion bursts of 50 ms or 3 s duration were applied to three separate targets: 10 fragments of 2 different sizes (1–2 and 2–3 mm) and a single 4 x 7 mm human stone. Safety studies consisted of porcine kidneys exposed to an extreme dose of 10-minute burst duration, including a 7-day survival study and acute studies with surgically implanted stones.

Results: Although successful in the clinical trial, the shorter focal beam and maximum 50 ms burst duration of the C5-2 probe moved stones, but did not expel any stones from the phantom's 30-mm deep calyx. The results were similar with the SC-50 probe under the same 50 ms burst duration. Longer (3 s) bursts available with the SC-50 probe expelled all stones at both 4.5 and 9.5 cm "skin-to-stone" depths with lower probe heating compared to the C5-2. No abnormal behavior, urine chemistry, serum chemistry, or histological findings were observed within the kidney or surrounding tissues for the 10 min burst duration used in the animal studies.

Conclusions: A longer focal beam and burst duration improved expulsion of a stone and multiple stone fragments from a phantom over a broad range of clinically relevant penetration depths and did not cause kidney injury in animal studies.

More Publications

Inventions

MRI-Guided Lithotripsy of Urinary Tract Stones

Record of Invention Number: 47984

Mike Bailey, Wayne Kreider, Adam Maxwell, Yak-Nam Wang

Disclosure

23 Feb 2017

Methods of Soft Tissue Emulsification using a Mechanism of Ultrasonic Atomization Inside Gas or Vapor Cavities and Associated Systems and Devices

Patent Number: 9,498,651

Oleg Sapozhnikov, Mike Bailey, Larry Crum, Vera Khokhlova, Yak-Nam Wang

More Info

Patent

22 Nov 2016

The present technology is directed to methods of soft tissue emulsification using a mechanism of ultrasonic atomization inside gas or vapor cavities, and associated systems and devices. In several embodiments, for example, a method of non-invasively treating tissue includes pulsing ultrasound energy from the ultrasound source toward the target site in tissue. The ultrasound source is configured to emit high intensity focused ultrasound (HIFU) waves. The target site comprises a pressure-release interface of a gas or vapor cavity located within the tissue. The method continues by generating shock waves in the tissue to induce a lesion in the tissue at the target site. The method additionally includes characterizing the lesion based on a degree of at least one of a mechanical or thermal ablation of the tissue.

Noninvasive Disintegration of Peyronie's Plaque with Focused Ultrasound

Record of Invention Number: 47233

Hunter Wessells, Mike Bailey, Mahri Haider, Tatiana Khokhlova, Frank Lee, Adam Maxwell, George Schade, Yak-Nam Wang

Disclosure

23 Feb 2015

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
Close

 

Close