The future of early breast cancer detection?
A new imaging technology could one day provide a valuable alternative to mammography and even eventually replace it for diagnosis of breast cancer. The technique, called real-time scanning thermoacoustic tomography, was developed in the laboratory of Dr. Lihong Wang, researcher with the Texas Engineering Experiment Station. Although breast cancer remains a leading cause of cancer deaths among women, the cure rate is greatly improved by early detection. Mammography has long been the best tool available for early detection. But is mammography the most accurate way to detect tumors? What if tumors could be detected sooner? Could more tumors be detected without ionizing radiation? Could unnecessary biopsies and lumpectomies be prevented by using better imaging technology? Wang, professor of biomedical engineering and electrical engineering at Texas A&M University, is exploring the answers to these questions at his Optical Imaging Laboratory. The lab is developing non-ionizing radio-frequency imaging for the early detection of various cancers. "The efficacy of mammography is not ideal. Sometimes you miss an early tumor, and roughly three-quarters of needle biopsies are benign," said Wang. The danger of ionizing radiation from mammograms is a matter of relative risk, says Wang. One in 2,000 patients per exam actually gets breast cancer from mammography. "You don't want to be that 1 in 2,000," said Wang. Radio frequency imaging is potentially more sensitive and specific in cancer detection than other medical diagnostics such as mammography and magnetic resonance imaging (MRI). Both MRI and mammography provide high-resolution imaging, but they do not provide the high contrast needed to distinguish between cancerous and normal tissue. Wang's method uses radio frequency and ultrasound technology in combination as an imaging tool that has a much greater contrast than mammography. It offers high resolution of objects as small as 0.5 millimeters, and the increased contrast results in greater sensitivity and specificity in the diagnosis-cancerous tumors can be detected and distinguished from benign. The technique uses radio frequency to illuminate the tissue being imaged. High-resolution ultrasound is then used to detect acoustic waves that radiate when the radio frequency is absorbed by the tissue. Cancerous breast tissue has been found to absorb two to five times more of the radio frequency waves than surrounding normal breast tissue. The difference in absorption rates results in a high level of contrast in the resulting image. The effect is attributed to bound water and sodium within malignant cells. Similarly, dense tumors can be distinguished from fluid-filled cysts. "I hope there will be enough radio-frequency contrast between normal tissue, cancerous tumors and benign tumors that X-ray mammography would not be needed," explained Wang. And what about all those needle biopsies on benign tumors? Wang says that while the effectiveness of the technology will still have to be proven, he has hopes that cancers will be able to be detected with high specificity without biopsies. "It would be ideal if a needle biopsy wasn't needed," said Wang. Wang has been working with M.D. Anderson Cancer Center to develop the technique. Wang is currently imaging mastectomy specimens supplied by M.D. Anderson as an intermediary step to clinical trials. So far the tests are going very well. Wang expects to complete the tests on the mastectomy samples by the end of the summer, at which point the researchers will be seeking grants to begin clinical studies at M.D. Anderson. Wang said his hope is to replace mammography, but he doubts that will happen right away. "Doctors are comfortable with mammography," said Wang. "but if we prove that this technique is more effective, they will accept it." Wang also suggests that the diagnostic equipment could be bundled into a conventional ultrasound machine, making it more practical for clinics and hospitals to buy. This technology is protected under U.S. Patent No. 6,567,688, issued May 20, 2003. The A&M System Technology Licensing Office is currently seeking one or more industrial partners to facilitate commercialization of the new method. For more information about licensing this technology, please contact Page Heller at firstname.lastname@example.org or 979-847-8682. Please reference TAMUS Project #1504.