26. Incidental findings should be included in the analysis of cost-effectiveness for evaluation of pulmonary nodules by FDG-PET

Background: In cost-effective analysis regarding to utilization of FDG-PET on lung nodules, most studies focused on lung lesions themselves (benign vs. malignant) and possible metastases if primary lesion is malignant. However, in a patient with pulmonary nodules, abnormal sites of increased FDG uptake on a whole-body PET scan may either the primary tumor or lesions unrelated to lung malignancy. The incidence of detection of the unsuspected lesions, which often changes the management of these patients, should also be included in the cost-effective analysis.

Methods: We retrospectively analyzed 213 cases referred for evaluation of pulmonary nodules. 89 of them proved to have lung malignancy and were excluded in our study. None of the remaining 124 patients had prior clinical or radiographic evidence of other abnormalities before undergoing FDG-PET. All unsuspected lesions were verified either histologically or by the clinical course of the disease.

Results: Among the 124 patients without lung cancer, FDG-PET revealed unsuspected abnormality in eight patients. These include other malignancy (colon cancer × 3, lymphoma × 1) and benign lesions (sarcoidosis × 3, cystic kidney × 1). None of the 124 patients studied had additional pathology found during follow-up.

Conclusion: The routine uses of FDG-PET for characterizing the lung lesions significantly increases the chances detecting unexpected other pathology. The incidental FDG-PET findings of unsuspected lesions, especially those unrelated to lung cancers, no doubt have a major impact on the management of these patients and may prove to be cost-effective.