Comparison of imaging features of ¹⁸F-FDG PET/CT in malignant pleural effusion and tuberculosis pleural effusion

Objective: To compare the imaging features of ¹⁸F-FDG PET/CT in malignant pleural effusion (MPE) and tuberculosis pleural effusion (TPE). Methods: From January 2012 to December 2014, 93 patients (52 males, 41 females, and average age (66.7 ± 12.7) years) with unexplained pleural effusion who underwent ¹⁸F-FDG PET/CT were retrospectively studied. MPE and TPE were confirmed by histology, cytology or clinical follow-up. Lesion SUV_max and T/NT were calculated. Both lesion size and density (in Hounsfield units) of pleural abnormalities on CT images were measured. The difference of images between MPE and TPE was analyzed. Diagnostic efficiency of ¹⁸F-FDG PET/CT for detecting MPE and TPE were estimated. Two-sample t test and χ² test were used to analyze the data. Results: The lesion SUV_max of 66 patients with MPE and 27 patients with TPE was higher than that in normal tissues (7.72 ± 6.50, 8.43 ± 4.92; t = 7.81 and 7.15, both P < 0.01), but there was no statistical difference between the TPE and MPE (t = 0.56, P > 0.05). T/NT was not significantly different between MPE and TPE (5.40 ± 4.29, 5.20 ± 2.73 respectively, t = -0.22, P > 0.05) either. The uptake features of ¹⁸F-FDG were different between MPE and TPE (χ² = 29.3, F < 0.01). When the nodular ¹⁸F-FDG uptake increase in pleura was taken as the malignancy, diffuse ¹⁸F-FDG uptake increase in pleura as tuberculosis, the sensitivity, specificity, positive predictive value, and negative predictive value of ¹⁸F-FDG PET/CT were 78.8% (52/66), 81.5% (22/27), 91.2% (52/57), 61.1%(22/36), respectively, for differentiation of MPE from TPE. Primary cancers were found in 43 patients. When the nodular uptake increase in pleura, or primary cancer associated with increased pleural uptake found by PET was taken as the malignancy, the above mentioned parameters were 95.5% (63/66), 81.5% (22/27), 92.6% (63/68), 88.0% (22/25), respectively. Conclusions: The ¹⁸F-FDG uptake in MPE and TPE is higher than that in normal tissues. ¹⁸F-FDG PET/GT is helpful in the search for the primary tumor of MPE. Qualitative method of ¹⁸F-FDG PET/CT has a good value in the differentiation of MPE from TPE. (authors)