Can PET scan replace needle biopsy?
Ruth Oratz, M.D., F.A.C.P.: PET [positron emission tomography] scan is a relatively new form of imaging, which looks at the metabolic activity of cells. Cancer cells, in general, are more active than normal cells in the body. PET scan uses a radioactively labeled form of glucose. Cancer cells pick up this glucose very avidly with great affinity, and on PET scan, malignant cells light up more brightly than normal cells. PET scans can be helpful in identifying areas of increased metabolic activity where there might be deposits of tumor cells, whether in a primary site, in the regional lymph nodes or in another area, such as a metastatic site. However, and this is a big however, PET scan is sensitive but not necessarily specific for cancer cells. Other conditions may cause increased metabolic uptake of glucose; for example, infections or inflammation. Furthermore, the amount of uptake may vary, depending on the nature of the metabolic process. I think a PET scan as a very rough road map.
