FDG-PET Imaging in Infection and Inflammation

Early diagnosis or exclusion of infection/inflammation is of utmost importance for the optimal management of patients with infection/inflammation. Currently available imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) provide excellent structural resolution for changes related to infection and inflammation disorders. However these modalities are of limited value in detecting early metabolic changes that occur in disease processes. Various functional nuclear medicine techniques, like labeled leukocyte imaging, Gallium scan, bone scan etc. have been tried in last three decades with variable success. Whole body imaging with FDG-PET for the diagnosis, staging, monitoring response to treatment, and detecting recurrent malignant diseases has been well established. The introduction of PET-CT has added a major dimension to FDG-PET imaging. In spite of great successes achieved by FDG-PET imaging in the evaluation of malignant disorders, the test is not specific for cancer. Soon after the introduction of FDG-PET for human studies, it was noted that lesions with substantial inflammatory cells also appears positive on FDG-PET. Benign processes such as infection, inflammation, and granulomatous diseases appear to have increased glycolysis and are therefore readily visualized by FDG-PET imaging. Therefore, the role of FDG-PET could be further enhanced in situations where, infection and inflammation is the focus of the investigation. In the present review we will discuss the various indications where FDG-PET can be useful.