Analysis of false positive positron emission tomography with 2-fluoro (18-F)-2-deoxy-D glucose as a tracer in patients with suspected lung cancer

Accurate diagnosis of lung cancer is a critical factor determining operability in patients with non-small cell lung cancer (NSCLC). Positron emission tomography with 2-fluoro (18F)- 2-deoxy-D glucose as a tracer (FDG-PET) has been reported to be effective in detecting tumor and involvement in mediastinal and hilar lymph nodes. In this study, we analyzed the accuracy of FDG-PET in pulmonary lesions which were suspected as lung cancer and mediastinal lymph node involvements. Forty patients with pulmonary lesions which were suspected as lung cancer underwent preoperative analysis including thoracic computerized tomography (CT), and wholebody FDG-PET were evaluated retrospectively. All patients underwent surgical resection of primary tumors and hilar and/or mediastinal lymph nodes between 2009 and 2010. A total of 40 resected and histologically examined pulmonary specimens were used for analysis which were all reported as FDG-PET positive and suspected lung cancer preoperatively. Thoracotomy was performed for treatment or diagnosis. Thirtyfour of them were NSCLC, one of them was schwannoma, three of the patients were tuberculosis, one had chronic and active nonspesific infection, and the last one had severe dysplasia and granulomatous reaction. In this study, the sensitivity and the specificity of FDG-PET was calculated as 86 and 68%, respectively. FDG-PET illuminates the physicians in diagnosis of lung cancer and staging of mediastinal or hilar lymph nodes. However, as a differantial diagnosis, active pulmonary tuberculosis and other granulomatous or inflamatory diseases should be thought in FDG-PET positive patients before desicion to thoracotomy.