Comperative evaluation of PET/CT with mediastinoskopy or thoracotomy in lung mass and pleural malignancies

We aimed to examine PET/CT of patients with lung tumors and pleural malignancies after mediastinoscopy and thoracotomy and to compare the pathology results of them. This study includes 49 patients who underwent PET/CT because of mediastinal or pulmonary mass, solitary pulmonary nodules and pleural thickening than operated for diagnosis, treatment and / or staging according to positivity on PET/CT between May 2012-May 2014. Patients who received preoperative RT or chemotherapy were excluded. PET/CT was obtained prior to surgery in all patients and results were compared with pathological results. PET/CT SUV max value 2.5 and 4.8 was accepted as cut-off value; sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PET/CT were compared in lung, mediastinum and pleura malignancies. Differential success of PET/CT for benign and malignant pathologies and the relationship between SUV max values and pathological results were statistically evaluated. Ages of 49 patients in the study were between 35-89, mean age was 59.3. 31 of the patients were men and 18 were women and mean ages were 56.4-61.1 years respectively. Fasting blood glucose levels were between 88-148 mg /dL. Malignancy detected in 33 of operated patients, 16 patients had benign pathology. 49% of the lesions was in right, 35% was in left hemithorax and 6% was located in mediastinum. Nine of the patients had adenocarcinoma, 6 had squamous cell carcinoma, 3 had adenosquamous cell carcinoma, but the other of the 15 patients had different pathological results. 6 of the patients with mediastinal mas that high-level involvement in PET/CT only 3 were with true malignancy, the other 3 were benign. 45 patients had SUV max values >2.5 and 31 of them were positive for malignancy but 14 had benign pathology. 35 patients had SUV max values>4.8 and 29 of them were positive for malignancy but 6 had benign pathology. PET/CT is important to determine biopsy localization; mediastinal lesions with high level of involvement for malignancy in PET/CT have only 50% positive for malignancy in mediastinoscopy; so mediastinoscopy is gold standard diagnostic process for mediastinal pathologies whereas PET/CT has high false positivity rate. In our region, due to the high prevalence of granulomatous disease, PET/CT has high rate of false positives. PET/CT SUV max cut-off value of 2.5 was found to be statistically unsignificant in detecting malignant pathologies with p = 0.54. However, SUV max cut-off value of 4.8 was found to be statistically significant in detecting malignant pathologies with p=0.0008 SUV max values vary from one center to a center and leads to incorrect results. In order to obtain more accurate results, SUV max values should be standardized. Keywords: Mediasten, PET CT, Thoracotomy