Fluoro Deoxy Glucose or FDG is one of the most widely used radiopharmaceuticals in positron emission tomography imaging. One of the reasons for the widespread use of FDG is based on the principle of metabolic trapping. This concept expresses the use of a radioactive tracer in the direct evaluation of metabolic functions within the body. PET imaging of the whole body using FDG improves the diagnosis and staging of cancer, the selection of appropriate treatment and the evaluation of the therapeutic response. Although cancer usually starts in one organ, it is a systemic disease and its most devastating consequences are metastases to other organs. FDG often allows rapid diagnosis and Quantitative determination of metastases.