F-18 FDG PET/CT in primary and metastatic pleural involvement -

Aim: The aim was to determine the contribution of FDG PET/CT to differential diagnosis of pleural involvements. Material and Methods: Images of the patients who were refereed for PET/CT evaluation with suspicion of mesothelioma were respectively analysed. They were classified according to final histopathologic diagnosis. Involvement patterns, SUVmax of the lesions, mediastinal and extrathoracic lymph node, peritoneum involvement, distant metastasis were evaluated. Results: Findings of 25 patients were analysed. According to final diagnosis; eight patients were mesothelioma, 9 patients were lung cancer, a patient was colon cancer, other 2 patients were diagnosed as renal cell cancer and metastasis of lymphoma. In 5 patients; involvements were inflammatory. SUV max values of inflammatory cases (5.6±2.4) and cases with malign involvement (9.1±2.3) and pleural involvement patterns of benign and malignant cases were significantly different (p=0.001, p=0,01). SUV max of mesotheliomas, metastatic lesions were not statistically different (p=0.367). There were no significant differences between the pleural involvement patterns of pleural mesothelioma and metastatic pleural involvements (p=0,14). Mediastinal LAP’s were detected in 8 metastatic and in 6 mesothelioma cases. There was not any mediastinal LAP in benign cases. Peritoneal involvement was determined in 8 patients with pleural metastases, in 4 patients with mesothelioma. Bone marrow involvement, chest wall invasion was determined in one each mesothelioma cases. Contralateral lung lesion was determined in 1 metastatic patient. Invasion of chest wall was seen in 2, bone marrow involvement in 1, bone metastasis was detected in 4 patients. Two patients with metastatic involvement had hepatic metastasis, 4 had surrenal metastasis. Conclusion: SUV max values of benign lesions were significantly lower than malign involvements. Involvement patterns could be useful for differentiating benign from malign pleural involvements, when evaluated together with the SUVmax. There was not any difference between mesothelioma and metastatic involvements according to patterns, SUVmax values. PET/CT could determine the thoracic/extra-thoracic primary tumor. This would reduce the burden, cost of diagnostic process. Whole-body evaluation contributes a more accurate staging of malignant cases.