LIKELIHOOD OF MALIGNANCY IN A SOLITARY PULMONARY NODULE - COMPARISON OF BAYESIAN-ANALYSIS AND RESULTS OF FDG-PET SCAN

Objective: To compare the probability of cancer in a solitary pulmonar y nodule using standard criteria with Bayesian analysis and result of 2-[F-18] fluoro-2-deoxy-D-glucose-positron emission tomographic (FDG-P ET) scan. Setting: A university hospital and a teaching Veteran Affair s Medical Center. Methods: Retrospective analysis of 52 patients who h ad under gone both CT scan of the chest and a FDG-PET scan for evaluat ion of a solitary pulmonary nodule. FDG-PET scan was classified as abn ormal or normal. Utilizing Bayesian analysis, the probability of cance r using ''standard criteria'' available in the literature, based on pa tient's age, history of previous malignancy, smoking history, size and edge of nodule, and presence or absence of calcification were calcula ted and compared to the probability of cancer based on an abnormal or normal FDG-PET scan. Histologic study of the nodules was the gold stan dard. Results: The likelihood ratios for malignancy in a solitary pulm onary nodule with an abnormal FDG-PET scan was 7.11 (95% confidence in terval [Cl], 6.36 to 7.96), suggesting a high probability for malignan cy, and 0.06 (95% CI, 0.05 to 0.07) when the PET scan was normal, sugg esting a high probability for benign nodule. FDG-PET scan as a single test alone was more accurate than the standard criteria and standard c riteria plus PET scan in correctly classifying nodules as malignant or benign. Conclusion: FDG-PET scan as a single test was a better predic tor of malignancy in solitary pulmonary nodules than the standard crit eria using Bayesian analysis. FDG-PET scan can be a useful adjunct tes t in the evaluation of solitary pulmonary nodules.