The Role of 18F-FDG PET/CT Integrated Imaging in Distinguishing Malignant from Benign Pleural Effusion

Objective The aim of our study was to evaluate the role of F-18-FDG PET/CT integrated imaging in differentiating malignant from benign pleural effusion. Methods A total of 176 patients with pleural effusion who underwent F-18-FDG PET/CT examination to differentiate malignancy from benignancy were retrospectively researched. The images of CT imaging, F-18-FDG PET imaging and F-18-FDG PET/CT integrated imaging were visually analyzed. The suspected malignant effusion was characterized by the presence of nodular or irregular pleural thickening on CT imaging. Whereas on PET imaging, pleural (18)FFDG uptake higher than mediastinal activity was interpreted as malignant effusion. Images of F-18-FDG PET/CT integrated imaging were interpreted by combining the morphologic feature of pleura on CT imaging with the degree and form of pleural F-18-FDG uptake on PET imaging. Results One hundred and eight patients had malignant effusion, including 86 with pleural metastasis and 22 with pleural mesothelioma, whereas 68 patients had benign effusion. The sensitivities of CT imaging, F-18-FDG PET imaging and F-18-FDG PET/CT integrated imaging in detecting malignant effusion were 75.0%, 91.7% and 93.5%, respectively, which were 69.8%, 91.9% and 93.0% in distinguishing metastatic effusion. The sensitivity of F-18-FDG PET/CT integrated imaging in detecting malignant effusion was higher than that of CT imaging (p = 0.000). For metastatic effusion, F-18-FDG PET imaging had higher sensitivity (p = 0.000) and better diagnostic consistency with F-18-FDG PET/CT integrated imaging compared with CT imaging (Kappa = 0.917 and Kappa = 0.295, respectively). The specificities of CT imaging, F-18-FDG PET imaging and F-18-FDG PET/CT integrated imaging were 94.1%, 63.2% and 92.6% in detecting benign effusion. The specificities of CT imaging and 18F-FDG PET/CT integrated imaging were higher than that of F-18-FDG PET imaging (p = 0.000 and p = 0.000, respectively), and CT imaging had better diagnostic consistency with F-18-FDG PET/CT integrated imaging compared with F-18-FDG PET imaging (Kappa = 0.881 and Kappa = 0.240, respectively). Conclusion F-18-FDG PET/CT integrated imaging is a more reliable modality in distinguishing malignant from benign pleural effusion than F-18-FDG PET imaging and CT imaging alone. For image interpretation of F-18-FDG PET/CT integrated imaging, the PET and CT portions play a major diagnostic role in identifying metastatic effusion and benign effusion, respectively.