PURPOSE: To assess the role of positron emission tomographic (PET) imaging with 18-fluoro-2-deoxyglucose (18FDG) in detecting thoracic lymph node metastases in patients with bronchogenic carcinoma. MATERIALS AND METHODS: Over a 2-year period, any patient presenting to our institution with newly diagnosed bronchogenic carcinoma who was to have thoracic nodes sampled was considered eligible. All PET studies were performed prior to nodal sampling and areas of increased uptake were mapped according to the American Thoracic Society classification. Studies were correlated with CT and pathology. Sensitivity and specificity for predicting nodal metastases was calculated. RESULTS: Forty-two patients had 62 nodal stations (40 hilar/lobar, 22 mediastinal) sampled. The sensitivity and specificity for hilar/lobar lymph node station metastases using PET imaging was 73% and 76%, respectively. With CT, the sensitivity and specificity were 27% and 86%. The sensitivity and specificity using PET imaging for mediastinal node station metastases was 92% and 100%, respectively, while with CT the figures were 58% and 80%. The sensitivity and specificity for combined thoracic nodal station metastases using PET imaging was 83% and 82%, respectively, while with CT it was 43% and 85%. There was a strong statistical relationship between positive PET imaging and lymph node abnormalities. CONCLUSIONS: 18FDG-PET imaging is accurate in detecting thoracic lymph node metastases in patients with bronchogenic carcinoma. Normal results of PET studies virtually preclude the need for mediastinal nodal sampling prior to surgery, whereas abnormal results of studies most likely represent mediastinal metastases. Treatment can be based on the extent of disease suggested by PET imaging.