Metabolic Characterization of Anterior Mediastinal Masses by 18F-FDG PET/CT

To evaluate the role of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the diagnosis of anterior mediastinal masses.Methods: The oncological 18F-FDG PET/CT images of 41 patients (17 women, 24 men; age: 16-83 years, mean age: 50.5±19.5 years) who attended the nuclear medicine department between November 2016 and September 2017 were retrospectively evaluated for the metabolic characterization of their anterior mediastinal masses.Results: Based on our results, the lesions of 4 patients were benign [maximum standard uptake value (SUVmax) <3] and that of 2 patients were non-tumoral (i.e., tuberculosis and sarcoidosis). The mean dimensions and the SUVmax levels of the malignant lesions were 6.4±3.7 cm and 11.9±9.6, respectively. The pathological results for the malign tumors were thymus tumors (n=8), lymphoma (n=8), lung cancer (n=11), carcinoid metastasis (n=2), thyroid carcinoma (n=2), germ cell carcinoma (n=1), schwannoma (n=1), and sarcoma (n=1). The degree of 18F-FDG accumulation could precisely identify the malign and benign tumors.Conclusion: Thus, contrary to the known causes, it is possible that anterior mediastinal masses originate from structures other than the anterior mediastinal structures. In this study, the lymphoma and lung carcinoma pathology were more frequent than thymic lesions.