The primary clinical application of FDG-PET is in the evaluation of patients with lung cancer and includes diagnosis, staging and restaging of non-small cell lung cancer. PET has a very high accuracy (sensitivity = 97%, specificity = 78%) for characterizing nodules that are indeterminate by chest radiograph and computed tomography. The major utility of PET in the evaluation of patients with lung cancer is the staging of the entire body. PET is more accurate than the conventional imaging modalities of CT and bone scans in the detection of metastatic disease. PET is accurate in the staging of the mediastinum, adrenal glands, and the skeletal system. PET is not as accurate in the detection of brain metastases because of their small size and the normal cortical accumulation.