USEFULNESS OF MR SIGNAL INTENSITY IN DISTINGUISHING BENIGN FROM MALIGNANT PLEURAL DISEASE

OBJECTIVE. The aim of this study was to analyze the potential usefulne ss of MR signal intensity in differentiating malignant from benign ple ural disease. SUBJECTS AND METHODS. Forty-five patients with pleural l esions identified on CT scans were subsequently examined by MR imaging at 0.5 T.T1-weighted, proton density-weighted, T2-weighted, and enhan ced T1-weighted spin-echo images were obtained. For 34 patients, a dia gnosis of malignant (n = 18) or benign (n = 16) disease was establishe d. The morphologic features of the pleural lesions and MR signal inten sity on T1-weighted, proton density-weighted, T2-weighted, and enhance d T1-weighted images were evaluated, and the ratio of lesion to muscle signal intensity was computed. RESULTS. Assessment of morphologic fea tures by MR imaging and CT was not significantly different. High signa l intensity on proton density-weighted and T2-weighted images was obse rved in all malignant lesions and in two benign lesions (sensitivity, 100%; specificity, 87%; negative predictive value, 100%), The ratio of lesion to muscle signal intensity on T1-weighted, proton density-weig hted, T2-weighted, and enhanced T1-weighted images discriminated betwe en malignant and benign lesions (p <.0001). For the subgroup of lesion s misinterpreted by CT (n = 6), the evaluation of MR signal intensity on long-TR images made it possible to differentiate malignant from ben ign conditions. CONCLUSION. MR signal intensity is a valuable addition al feature for differentiating malignant from benign pleural disease. Signal hypointensity with long-TR sequences is a reliable predictive s ign of benign pleural disease.