Clinical use of combined positron emission tomography and computed tomography in thymoma recurrence

The aim of this study is to evaluate the efficacy of hybrid fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) for surveillance and follow-up of thymoma patients to detect recurrent disease. A retrospective chart review was performed on 37 thymoma patients who underwent FDG-PET/CT-scans during postoperative follow-up. The following information was obtained: clinical indication for FDG-PET/CT, the results of the FDG-PET/CT, particularly with regard to the additional diagnostic imaging information, the localization of the disease and subsequent clinical patient management. A total of 51 CT-scans were performed on 37 patients providing sensitivity and specificity for thymoma recurrence of 71% and 85%, respectively. Forty-five FDG-PET/CT-scans were performed on the same group of patients with an overall sensitivity and specificity of 82% and 95%, respectively. Notably, FDG-PET/CT sensitivity when employed for diagnosis of thymoma recurrence in the anterior mediastinum has reached 100% (CT has shown only 55% sensitivity for the detection of anterior mediastinal thymoma recurrence). Our preliminary study demonstrates that during follow-up after thymoma excision, FDG-PET/CT is superior to computed tomography alone in the detection and localization of mediastinal recurrence. In particular, the combined structural and metabolic information of FDG-PET/CT enhances the diagnostic confidence in lesion characterization.