Role of FDG-PET and PET/CT in the diagnosis of prolonged febrile states.

Purpose: The role of FDG-PET and PET/CT in patients whose main symptom is prolonged fever has not yet been defined. We addressed this topic in a retrospective study.

Methods: A total of 124 patients (referred between May 2001 and December 2004) with fever of unknown origin or prolonged fever due to a suspected infection of a joint or vascular prosthesis were included in the study. The patients underwent either FDG-PET or FDG-PET/CT scanning. Sixty-seven patients had a negative focal FDG-PET finding; in this group the method was regarded as unhelpful in determining a diagnosis, and no further investigation was pursued. We tried to obtain clinical confirmation for all patients with positive PET findings.

Results: Fifty-seven (46%) patients had positive FDG-PET findings. In six of them no further clinical information was available. Fifty-one patients with positive PET findings and 118 patients in total were subsequently evaluated. Systemic connective tissue disease was confirmed in 17 patients, lymphoma in three patients, inflammatory bowel disease in two patients, vascular prosthesis infection in seven patients, infection of a hip or knee replacement in seven patients, mycotic aneurysm in two patients, abscess in four patients and AIDS in one patient. In eight (16%) patients the finding was falsely positive.

Conclusion: FDG-PET or PET/CT contributed to establishing a final diagnosis in 84% of the 51 patients with positive PET findings and in 36% of all 118 evaluated patients with prolonged fever.