- University of Pittsburgh
University of Pittsburgh researchers have found the combined PET/CT scanner is the most powerful imaging tool available for localizing, evaluating and therapeutic monitoring of head and neck cancer and may be equally useful for other cancers that are difficult to pinpoint.
Results of a study showing PET/CT has a distinct advantage over PET or CT alone were presented today at the annual meeting of the Society of Nuclear Medicine. According to the researchers, the prototype of the combined PET/CT machine at the University of Pittsburgh Medical Center is able to effectively localize cancerous activity in the head and neck, an area of the body that presents substantial challenges to other imaging methods because of densely packed tissue structures and the frequent involvement of lymph nodes.
Separately, computed tomography (CT) and positron emission tomography (PET) do not provide images with the necessary combination of clear structural definition and metabolic activity that is achieved with the PET/CT. “The PET/CT tells us the exact size, shape and location of the cancer and provides a specific target for surgery or other treatment,” said Carolyn Cidis Meltzer, M.D., associate professor of radiology and psychiatry and medical director of the UPMC PET Facility. “The PET/CT can also be used to help us develop the best course of treatment for an individual, then monitor that individual’s progress during treatment.”
Head and neck cancers often have already involved lymph nodes when first discovered and can spread rapidly if they are not found and treated quickly. Images from the combined PET/CT scanner are particularly useful in allowing a radiologist to see cancerous activity at a metabolic level and pinpoint its exact location in the tissue so a biopsy can be performed and proper treatment begun. Tumors among the skeletal muscle, salivary glands and lymphoid tissue in the head and neck area are difficult to separate from healthy tissue in standard PET images, which look like blotches of color amidst fuzzy structures. With CT, unless they are clearly swollen, cancerous lymph nodes may look normal.
Size matters when radiologists evaluate lymph nodes for signs of cancer. Seen by CT, lymph nodes under one centimeter are considered normal and not biopsied. The PET/CT, developed in part by David Townsend, Ph.D., senior PET physicist, professor of radiology at the University of Pittsburgh School of Medicine, and a co-director of the University of Pittsburgh PET facility, works by combining PET technology, in which the scanner reads cellular metabolism of glucose, and CT, which builds a clear cross section of tissue structures using x-rays. “Because head and neck cancer starts small and spreads rapidly, the PET/CT will provide doctors with a means for earlier diagnosis and treatment to potentially save lives,” said Dr. Townsend. “With PET/CT an accurate diagnosis of cancer could be provided months earlier than with any other imaging method.”
The groundbreaking research done by Drs. Townsend and Meltzer in Pittsburgh led the FDA to approve the PET/CT, known commercially as the Biograph, earlier this year for use as a diagnostic and therapeutic tool for cancer treatment. Other authors that contributed to the research are Carl H. Snyderman, Melanie B. Fukui, Daphne A. Bascom, Subash Chander, Jonas T. Johnson, Eugene N. Myers, Marsha A. Martinelli and Paul E. Kinahan.