Role of F-18 FDG PET/CT for differential diagnosis of anterior mediastinal mass: Comparison with computed tomography

Objectives The role of F-18 FDG PET/CT was not well documented in diagnosis of anterior mediastinal mass. The aims of this study are to evaluate the role of F-18 FDG PET/CT for differentiation between benign and malignancy of the anterior mediastinal mass and compare diagnostic value between PET/CT and thoracic CT.

Methods From March 2005 to July 2010, 35 newly diagnosed patients with anterior mediastinal mass (male=14, mean age: 44.2±18.4 years) underwent PET/CT and contrast enhanced CT were enrolled in this study. The thoracic CT scans were interpreted by experienced radiologist. Size and SUVmax of anterior mediastinal mass were obtained and compared with CT findings. Final diagnosis of all anterior mediastinal masses was determined by histological confirmation.

Results There were 17 benign lesions (8 thymoma, 4 mature teratoma, 3 chronic inflammatory lesion and 2 goiter) and 18 malignant lesions (8 lymphoma, 3 thymic carcinoma, 2 germ cell tumor, 2 non-small cell lung cancer, 1 small cell lung cancer, 1 leukemic infiltration and 1 paraganglioma. Patients with malignant anterior mediastinal mass showed significantly higher SUVmax (12.1±6.2) and larger size (7.7±2.3cm) than those of patients with benign (4.9±2.7, p=0.000; 5.5±1.8cm, p=0.003). In ROC analysis, cut-off value of SUVmax 5.8 showed high sensitivity (94.4%) and specificity (88.2%) for differentiating malignant anterior mediastinal mass and that of size 8.1cm showed sensitivity (50%) and specificity (100%). The sensitivity (94.4%), specificity (88.2%) and accuracy (91.4%) of F-18 FDG PET/CT were higher than sensitivity (88.9%), specificity (58.8%) and accuracy (74.3%) of thoracic CT.

Conclusions The SUVmax of F-18 FDG PET/CT can be used to differentiate benign and malignant lesions in patients with anterior mediastinal mass