FDG-PET imaging of benign pulmonary diseases

The usefulness of fluorodeoxyglucose (FDG) -positron emission tomography (PET) has been established for the diagnosis of cancer. However, we often experience false positive as well as false negative cases in clinical practice. Examining those will be useful to understand more adequate use of FDG-PET. So we evaluated all the PET/CT results (n=467) conducted from April 2003 to March 2008 and selected 54 cases diagnosed eventually as benign pulmonary diseases. As a whole, the PET positive rate in the benign disease was 48.1% (26/54). In contrast, 149 cases with primary lung cancer examined in the same period yielded the positive rate of 86.6% (129/146). We analyzed the changes of PET positive rate by the shape or the size of the shadow, and by the disease. And we summarized false positive results from FDG-PET study and classified them into seven categories (inflammation, interstitial lung disease, pneumoconiosis, radiation pneumonia, granulomatous disease, large vessel vasculitis, mediastinal disease).