FDG PET for malignancy evaluation

Nuclear imaging for malignancy exploits the differences in the way the tumor functions relative to normal tissue.  The majority of malignancies have excessively high energy demands and meet these by metabolizing glucose.  Thus, the glucose uptake by most tumors is markedly elevated compared to background (normal) tissue. 

The glucose uptake in the body can be measured and imaged by administering a small dose of a glucose analog labeled with a radiation emitter (fluoro-deoxy glucose or FDG) intravenously and then placing the patient into a scanner (which is a radiation detector).  Areas of malignancy will be manifest as sites of increased uptake of FDG.  The FDG administered is a “tracer.”  It will distribute in a manner similar to glucose but will have no impact on the body:  it does not change organ function, is not recognized as a foreign substance and will cause no apparent side effects (other than the uncertain impact that people receive from low doses of radiation).  In effect, only a “trace” dose is given.