Indirect signs of infection with fluorodesoxyglucose positron emission tomography in patients referred for a proven or suspected infectious disease

Introduction. Indirect signs of infection could improve the performance of fluorodesoxyglucose (FDG) positron emission tomography (PET) in the detection of infectious diseases. Methods. This retrospective study included patients referred for a FDG-PET exam for a proven or suspected infection. The primary endpoint was the presence or absence of an active infection at the time of the exam. Maximal and mean activity values (standardized uptake values, SUVmax and SUVmean) were investigated in the bone marrow, spleen and left adrenal gland. Results. Fifty-nine patients were included (23 for a suspected infection and 36 for suspected complications of an already documented infection). Finally, 43 patients had an active infection. Only the left adrenal SUVmax was significantly different between patients with and without infection (2.12 +/- 0.53 versus 1.79 +/- 0.46; P = 0.019), as well as the left adrenal gland slice surface (3.00 +/- 1.40 cm(2) versus 2.23 +/- 1.14 cm(2); P = 0.024). The criterion of a >= 1.79 adrenal SUVmax provided a sensitivity of 80% and a specificity of 69% for the diagnosis of infection. Among the 23 patients for whom no hypermetabolic focus was reported on PET images, 15 had an adrenal SUVmax >= 1.79, and 10 of them had a definite infection. Conclusion. FDG uptake of the left adrenal gland could be a useful parameter for the diagnosis of infection, especially when the conventional PET analysis is negative. (C) 2016 Elsevier Masson SAS. All rights reserved.