Positron emission tomography (PET) is a new diagnostic procedure which allows to image tissue metabolism in vivo. Utilizing increased substrate metabolism or transport as a marker of malignant disease, primary as well as metastatic or recurrent lung cancer can be detected. This allows for improved differential diagnosis of pulmonary nodules or staging of non small cell lung cancer as has been documented in several studies. New applications of PET may include non-invasive evaluation of tissue proliferation or hypoxia to predict individual prognosis or treatment response.