AES Section Meeting Reports

Pacific Northwest - September 14, 2016

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The PNW Section inaugurated their 2016-17 meeting season with a presentation on medical ultrasound technology by Dr. Jens Quistgaard of Mirabilis Medical, Inc of Bothell, WA. Jens described what medical ultrasound is, how it is implemented, and compared diagnostic imaging with therapeutic uses including destroying tumors with several thousand watts/cm*2. He pointed out the same physical behavior of ultrasound waves to audible sound we are familiar with.

To start the evening, PNW Committee members Dr. Mike Matesky (Opus 4 Studios) and Rick Chinn (Uneeda Audio) unveiled a new AES PNW free-standing banner sign they are donating to the Section, with graphics collaborated on by the two, and with Committeeperson Lawrence Schwedler's wife, designer Randi Ganulin.

Incoming Chair Dan Mortensen conducted some Section business, and introduced the guest speaker. Jens U. Quistgaard is currently President and CEO of Mirabilis Medical Inc., which is developing a non-invasive ultrasound therapy for treatment of uterine fibroids. He was formerly President and CEO of LipoSonix, Inc., a founder of SonoSite, Inc., and Chief Scientist at ATL Ultrasound (now part of Philips Medical Systems). Dr. Quistgaard holds a BS degree in Mathematics and Computational Sciences from Stanford University, and MS and PhD degrees in Electrical Engineering from the University of Washington. He is a Director of Life Science Washington, Vice Chairman of the Washington State Medical Device Innovation Partnership Zone, and a member of the Electrical Engineering Advisory Board and College of Engineering Visiting Committee at the University of Washington.

Jens noted that the laws of physics for ultrasound work just like they do for longer audio wavelengths. Waves are generated, adhere to formulas for velocity and wavelength, can reflect, can be absorbed, and can be focused. Ultrasound is used at low power for diagnostic imaging, such as a fetus in the womb, and at very high power can "cook" parts of a tumor which can be absorbed by the body's natural defenses. Diagnostic imaging is pretty mature, but therapeutic uses less so.

Ultrasonic generators are typically arrays of piezoelectric transducers chosen for specific uses, and the operating frequency may be adjusted as well for specific imaging needs. Jens also described beam-forming by both electronic and mechanical means, and other enhancements for diagnostic imaging. The FDA adult power limit of 720mW/cm*2 was mentioned.

Jens' company is currently working on "HIFU" therapeutic uses - High Intensity Focused Ultrasound, which can use several thousand watts/cm*2 to heat portions of certain tumors non-invasively. The body's own defense mechanism removes the dead tissue. The initial work is on uterine fibroids, although he also discussed its use as an alternative to low-volume liposuction surgery. This treatment is not yet FDA approved or commercially available, and tests continue in Germany. Discussion continued with other aspects of such high power, including cavitation, localized boiling, and an effect called acoustic streaming, where fluids are caused to move.

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