The role of FDG PET-CT imaging in differantial diagnosis of malignant and benign pleural masses evaluation

We retrospectively evaluated the contribution of F-18 FluorodeoxyglucosePositron Emission Tomography-Computed Tomography (FDG PET-CT) in differentialdiagnosis of between malignant and benign pleural lesions in patients with suspectedmalignant pleural mesothelioma (MPM). Fifty patients (32 females, 18 males; age range24-79 years) with pleural thickening, fluid, plaques or calcification on previous CT scanwere examined with FDG PET-CT. PET-CT imaging was performed at 1 h after FDGinjection. In 12 patients delayed imaging of the thorax was performed at 2 h afterinjection. FDG uptake was evaluated visually and semiquantitatively using standardizeduptake value (SUV). FDG PET-CT findings were compared with histopathologicdiagnosis. Thirty nine patients had increased FDG uptake in pleural lesions but PET-CTresults were negative in 11 patients. When compared with histopathologic results inFDG positive group 34 patients had MPM, 5 had benign pathology; in FDG negativegroup 8 patients had benign pathology, 3 had MPM. Of patients with delayed imaging 9showed increased SUV but 3 had decreased SUV on delayed images. Increased SUVgroup had 4 MPM, 5 benign pathology (3 chronic granulomatous inflamation, 2 benignasbestotic plaque). Decreased SUV group all had benign pathology (fibrosis, chronicinflammation, myofibrosis). The sensitivity, specificity and accuracy of FDG PET-CTwere 92%, 62% and 84%, respectively. PET-CT revealed distant metastases in 4patients with MPM. FDG PET-CT is a useful imaging modality in differential diagnosisof malignant and benign pleural lesions. Delayed imaging seems to be useful if there isa decrease in SUV suggestive of benign pathology but does not seem to have acontribution to differential diagnosis if SUV is increased.Key words: FDG PET-CT, Pleural thickening, Malignant pleuralmesothelioma, SUV.