Objective: To determine the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) using fluorine- 18‑deoxyglucose ([18F]-FDG) for the evaluation of a solitary pulmonary nodule (SPN). Methods: Prospective analysis of 53 consecutive patients submitted to PET/CT between March 2005 and May 2007 for the evaluation of an SPN. Of those, 32 met the criteria for inclusion in the present study. The lesions were evaluated for location, size, radiotracer uptake and maximum standardized uptake value (SUV). The FDG-PET/CT results were correlated with other predictors of malignancy (age, gender, smoking status, nodule size and nodule location). The definitive diagnosis was established through histopathology or through clinical/radiological follow-up for at least one year. Results: Fourteen malignant SPNs were found. Through analysis of the receiver operating characteristic curve, we established an SUV of 2.5 as the most appropriate cut-off point, since it correctly identified 13 of the 14 malignant SPNs. The results below that point revealed one false positive for neoplasia out of a total of 14. The semiquantitative method presented a sensitivity of 92.9%, specificity of 72.2%, positive predictive value of 72.2%, negative predictive value of 92.9% and accuracy of 81.2%. The multivariate analysis showed a statistically significant association with SPN malignancy only for nodule location in the upper lobes (p = 0.048) and SUV (p = 0.007). Conclusions: The results obtained suggest that the SUV of [18F]-FDG is a useful predictor of neoplasia in SPN, with a high negative predictive value, which allows malignancy to be safely ruled out, showing its relevance in the diagnostic approach to pulmonary nodules.

Keywords: Positron-emission tomography; Coin lesion, pulmonary; Lung neoplasms.