Better Detection of Thyroid Cancer.

Should be attainable through a new technique being developed at the Mayo Clinic. Ultrasound is currently the most sensitive tool for detecting thyroid nodules and the most cost-effective imaging method for evaluating the thyroid gland. However, the overwhelming majority of nodules discovered by ultrasound (as high as 95 percent) are benign. Often the ultrasound and other imaging results are ambiguous and cannot differentiate between malignant and benign thyroid nodules. The only way to definitively rule out a cancer diagnosis is through fine needle aspiration and biopsy. More than half these biopsies prove benign. While that may be reassuring to the people who undergo the biopsies, it would be better if they could receive that reassurance without having an expensive, invasive, and (as it turned out) unnecessary procedure.

Azra Alizad of Mayo Clinic College of Medicine has developed a novel non-invasive imaging technique called vibro-acoustography (VA) for identifying thyroid nodules in excised human thyroids imbedded in tissue gel. In this method, ultrasound is used to vibrate tissue at low frequencies, and the resulting vibrations can be detected by a sensitive microphone. Harder tissues normally produce a significantly different acoustic field than softer tissues, and< detecting the difference may reveal a more definitive diagnosis. Malignant lesions are stiffer than benign lesions; therefore it is reasonable to expect that VA will be a better tool for detection and differentiation of thyroid nodules than the conventional ultrasound imaging.

While the technique is not yet tested for actually detecting thyroid cancers in clinical trials, vibro-acoustography is currently undergoing clinical evaluation for detecting breast cancer lesions in people. If successful, this inexpensive and non-invasive imaging tool would represent a major advance in our ability to provide care for people with potential cancer. Alizad presents his new results this week at the meeting of the Acoustical Society of America (ASA) in New Orleans. (Paper 3pBB3, http://www.acoustics.org/press/)