THE ROLE OF 18F-FDG PET-CT IN DIAGNOSIS AND PREDICTION OF PROGNOSIS IN MALIGNANT PLEURAL MESOTHELIOMA/MALIGN PLEVRAL MEZOTELYOMA AYIRICI TANISI VE PROGNOZUNDA 18F-FDG PET/BT'NIN ROLU

Objective: The purpose of this study is to evaluate the performance of 18F-FDG PET/CT in the differential diagnosis of malignant and benign pleural disease as well as its prognostic value in the malignant pleural mesothelioma (MPM). Methods: Fifty-eight patients who underwent 18F-FDG PET/CT due to diffuse or nodular pleural thickening determined on conventional CT were retrospectively analyzed.18F-FDG PET/CT scans were evaluated visually and semiquantitatively using maximum standardized uptake value (SUVmax). Mediastinal blood pool SUVmax was used as a threshold value for defining positive/negative accumulation of tracer. 18F-FDG PET/CT findings were compared with histopathological and survival data. Patients were followed up clinically/radiologically. Results: Thirty-eight of fifty-eight patients (65.5%) had FDG (+) pleural lesions; 28/38 patients (73.6%) were diagnosed MPM and 10/38 patients (26.4%) were determined benign pleural disesase histopathologically. 20/58 scans (34.5%) were negative, and 18 of them were assumed benign based on two years follow-up, whereas 2 patients were diagnosed MPM by biopsy due to radiologic progression. Sensitivity, specificity, accuracy, positive predictive, and negative predictive values were 93%, 64%, 79%, 73%, and 90% respectively. Median overall survival was found to be 14.5 months. Higher SUVmax level (SUVmax>7.4) was associated with shorter survival (13 vs. 24 months)(p=0.032). Conclusion: 18F-FDG-PET/CT is a sensitive imaging method for differential diagnosis of malignant/benign pleural lesions, indicates the target of biopsy, and effects the management of patients. SUVmax of MPM has a potential role for predicting the prognosis. Amaç: Bu çalismanin amaci, malign ve benign plevral hastaligin ayirici tanisinda 18F-FDG PET/BT'nin performansi ve malign plevral mezotelyomadaki (MPM) prognostik degerini inceemektir. Yöntem: Konvansiyonel BT'de saptanan diffüz ya da nodüler plevral kalinlasma nedeniyle 18F-FDG PET/BT çekilen 58 hasta retrospektif olarak incelendi. 18F-FDG PET/BT taramalari, maksimum standartlastirilmis uptake degeri (SUVmax) kullanilarak görsel ve yari kantitatif olarak degerlendirildi. Pozitif/negatif tutulum ayriminda esik degeri olarak mediastinal kan havuzu SUVmax degerleri kullanildi. 18F-FDG PET/BT bulgulari, histopatolojik bulgular ve sagkalim verileri ile karsilastirildi. Hastalar klinik ve radyolojik olarak takip edildi. Bulgular: 58 hastanin 38'inde (%65,5) plevral lezyonlar FDG pozitifti; 28/3