FDG PET of pleural effusions in patients with non-small cell lung cancer

OBJECTIVE, We determined the ability of F-18-fluorodeoxyglucose (FDG) posit ron emission tomography (PET) to differentiate benign and malignant pleural effusions in patients with non-small cell lung cancer. MATERIALS AND METHODS. Over a B-year period, we reviewed all patients with primary non-small cell lung cancer and a pleural effusion on staging CT who underwent FDG PET. We examined 25 patients (18 men and seven women; age ra nge, 37-86 years: mean age, 65 years). FDG PET revealed positive findings i f pleural activity was greater than background mediastinal activity; FDG PE T revealed negative findings if pleural activity was the same as or less th an background mediastinal activity. Results of FDG PET were correlated with pathologic diagnosis determined with thoracentesis or pleural biopsy. RESULTS, All patients had effusions on the same side as the primary tumor. Twenty-two patients had a malignant pleural effusion confirmed with thorace ntesis (n = 19) or biopsy (n = 3). FDG PET revealed positive findings in 21 patients and negative findings in one. Three patients had no evidence of m alignancy in the pleural space determined with cytologic findings (n = 2) o r biopsy results (n = 1). FDG PET uptake revealed positive findings in one of these patients and negative findings in two. Therefore, of 22 patients w ith positive findings on FDG PET, 21 had pleural metastases, and of three p atients with negative findings on FDG PET, one had metastases. The sensitiv ity, specificity, positive predictive value, negative predictive value, and accuracy of FDG PET for detecting pleural metastases were 95%, 67%, 95%, 6 7%, and 92%, respectively. CONCLUSION, This study suggests that FDG PET may be useful in improving sta ging evaluation in patients with non-small cell lung cancer and a pleural e ffusion. Increased pleural FDG uptake usually indicates pleural metastases, however, because the number of benign effusions studied was small, the rel evance of negative findings on FDG PET in this setting is uncertain.