The diagnostic role of 18-fluorodeoxyglucocose–positron emission tomography/computed tomography in occult bacteremia searching underlying primary disease

18-Fluoro-2-deoxy-D-glucose(FDG) is a structural analog of 2-deoxyglucose and accumulates in malignant tissues but also at sites of infection and inflammation. For this reason, FDG PET or PET/CT has great advantage in understanding of underlying pathology in assessment of FUO (Fever of unknown origin). However, till today, there are limited studies about the role of FDG PET or PET/CT in evaluation of FUO. Conventional diagnostic methods are still not adequate to reveal underlying reason in approximately 50% of patients with FUO especially in cases presenting with diagnostic challenges i.e. involvement of two or more organ systems with seemingly no correlation. We report a case of two years old Indian female child who presented with fever of one month duration, CT and MRI reported nonspecific findings. She underwent Whole body 18 FDG PET/CT for further evaluation, which revealed FDG avid rim lesion with central photopenic defect suspicious of pyogenic abscess in high parietal cortex along with bilateral lung nodules. This confirmed the diagnosis of a brain abscess secondary to pulmonary infection. We emphasize the utility of 18 FDG PET/CT as imaging modality, highlight the diagnostic difficulties using current serological and radiological measures, and propose managing FUO with 18 FDG PET/CT in cases empirically prior to more invasive measures.