UCLA researchers in the Department of Bioengineering, Electrical Engineering, and Head and Neck Surgery have developed a novel ultrasound-based imaging technique that can be used to analyze tumor margins during surgery.
Accurate determination of tumor margins is essential during operations; under-resection results in disease recurrence, whereas over-resection may significantly decrease patient quality of life. However, current intraoperative analyses are largely based on physical examination of tissue and re-excision rates in the US are approximately 25%. While more detailed imaging such as MRI, CT, and ultrasound are useful prior to operations, they are difficult to apply during surgery. Development of techniques that can determine surgical boundaries will serve an important market and significantly improve surgical outcomes.
Professor Grundfest and coworkers have developed a new non-invasive imaging technique termed vibroacoustography (VA), that differentiates materials of different types. VA uses two intersecting ultrasound tones of different frequencies to generate a beat frequency, which can be measured and is dependent on the elasticity and viscosity of the tissue of interest. Because tumor tissue is 1.5-13x stiffer than healthy tissue, tumor margins can be determined by spatially mapping tissue viscoelasticity. This technology is label-free, low-energy, and offers real-time analysis, enabling use during surgery. VA can be used to identify boundaries between tumor and normal tissue that exhibits abnormal viscoelastic properties, including prostate, breast, and pancreas.
This technology provides potential advantages over currently available methods including high spatial resolution and 3D mapping capabilities as it provides sensitive, quantitative measurements, does not require use of fluorescent labels or other exogenous dyes, and is relatively low-energy and used non-invasively. Another advantage of this technology is no radiation is required for its use. The system is designed for use during head and neck surgery or other surgical procedures where the operative field is limited by the body’s anatomy. The technology allows for real-time operation, and the small hand-held probe and the compact system design allow for intraoperative use, which produces real-time images with real-time irrigation and physiologic monitoring.
Device has been fabricated and used to successfully distinguish a 3-layer model material of gelatin and agar. Additionally, clinical specimens have been measured ex vivo.