PET scanning or Positron Emission Tomography, is a procedure that produces a 3D image indicating where the body is using oxygen to burn glucose. In PET, the physician injects a small amount of a tagged sugar molecule into the patient and places the patient in the PET scanner. The PET scanner consists of thousands of small radiation detectors that measure the radiation that is being emitted by the sugar molecule within the patient. Thus, the PET scanner makes 3D images that show where the tagged sugar molecule went in the body. A lesion that is actively using this sugar molecule more than a surrounding area can point to inflammatory or malignant change. This can guide further diagnostic studies as well as point to prognosis.