The purpose of this study was to investigate the utility of 18fluorodeoxyglucose (FDG) coincidence detection position emission tomography (CDET) in the evaluation of metastatic mediastinal lymph nodes in patients with potentially operable non-small-cell lung cancer (NSCLC). A prospective study was performed in thirty patients with newly suspected NSCLC. Thoracic computed tomography (CT), FDG CDET, and invasive surgical staging were performed in patients. Blinded prospective interpretation was performed for each test and compared to pathological staging obtained by mediastinoscopy and/or by thoracotomy. Patients were followed for six months to detect occult metastases. The sensitivity and specificity of CDET for the detection of mediaStinal lymph nodes were 75% and 94.4% respectively. The corresponding value for CT were 50% and 80.9%. Three patients with N1 disease were classified as N0 by CDET. With regard to definitive surgical node staging, CDET could identify nodal disease in 26 patients and CT only in 18 patients (n = 30). FDG full-ring positron emission tomography (PET) is the most accurate non-invasive method for the detection and staging of lung cancer. In addition, FDG CDET shows high accuracy for the detectability of pulmonary lesions with a diameter at least 2 cm and the evaluation of lymph node in NSCLC.