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

OBJECTIVE: The aim of our study was to evaluate the role of (18)F-FDG PET/CT integrated imaging in differentiating malignant from benign pleural effusion. METHODS: A total of 176 patients with pleural effusion who underwent (18)F-FDG PET/CT examination to differentiate malignancy from benignancy were retrospectively researched. The images of CT imaging, (18)F-FDG PET imaging and (18)F-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)F-FDG uptake higher than mediastinal activity was interpreted as malignant effusion. Images of (18)F-FDG PET/CT integrated imaging were interpreted by combining the morphologic feature of pleura on CT imaging with the degree and form of pleural (18)F-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, (18)F-FDG PET imaging and (18)F-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 (18)F-FDG PET/CT integrated imaging in detecting malignant effusion was higher than that of CT imaging (p = 0.000). For metastatic effusion, (18)F-FDG PET imaging had higher sensitivity (p = 0.000) and better diagnostic consistency with (18)F-FDG PET/CT integrated imaging compared with CT imaging (Kappa = 0.917 and Kappa = 0.295, respectively). The specificities of CT imaging, (18)F-FDG PET imaging and (18)F-FDG PET/CT integrated imaging were 94.1%, 63.2% and 92.6% in detecting benign effusion. The specificities of CT imaging and (18)F-FDG PET/CT integrated imaging were higher than that of (18)F-FDG PET imaging (p = 0.000 and p = 0.000, respectively), and CT imaging had better diagnostic consistency with (18)F-FDG PET/CT integrated imaging compared with (18)F-FDG PET imaging (Kappa = 0.881 and Kappa = 0.240, respectively). CONCLUSION: (18)F-FDG PET/CT integrated imaging is a more reliable modality in distinguishing malignant from benign pleural effusion than (18)F-FDG PET imaging and CT imaging alone. For image interpretation of (18)F-FDG PET/CT integrated imaging, the PET and CT portions play a major diagnostic role in identifying metastatic effusion and benign effusion, respectively.