Differentiation of Exudative and Transudative Pleural Effusion: MR Appearances

ABSTRACT

PURPOSE: The purpose of this study is to determine whether MR images after intravenous administration of Gd-DTPA can differentiate exudative and transudative pleural effusion. MATERIALS AND METHODS: We studied 18 patients with ten exudative and eignt transudative pleural effusions diagnosed clinically and by thoracentesis. We analysed the relationship between T1 value(normalized to fat) and the ratio of effusion/serum protein of pleuraleffusion. We also assessed the contrast enhancement of exudative and transudative pleural effusion on T1 weighted SE images taken at 15 and 30 minutes after administration of Gd-DTPA. RESULTS: The relationship between the effusion/serum protein ratio and T1 value(normalized to fat) was statistically not significant(r=0.27, P=0.381).On precontrast spin-echo T1W1, mean signal intensity of the transudate was 0.18 (+/-0.04) and that of the exudatewas 0.24(+/-0.07), values which were not significant differences(P>0.05). Postcontrast mean signal intensities of transudates at 15 and 30 were 0.20+/- 0.06 and 0.26+/-0.08, respectively, values which were not significantly higherthan that of precontrast mean signal intensity(P<0.05). Postcontrast mean signal intensity values of exudative pleural effusions at 15 and 30 mimutes(0.32+/-0.06 and 0.39+/-0.06, respectively) were, on the other hand, significantly higher than that of precontrast mean signal intensity(P<0.05). CONCLUSION: Postcontrast T1-weighted SE images at 15 and 30 minutes can be helpful in the differentiation of transudative and exudative pleural effusion.