Whole-body magnetic resonance imaging in the evaluation of children with fever without a focus

Background: Fever without a focus is defined as a temperature of 38° C or higher as the single presenting symptom. After extensive investigation, a large percentage (12-67%) of cases remain undiagnosed.

Objective: To assess the diagnostic value of whole-body magnetic resonance imaging (WB-MRI) in children with fever without a focus.

Materials and methods: A retrospective study was performed to identify children who underwent WB-MRI for fever without a focus. Ninety-two children, 50 boys, with a mean age of 6.1 years were included. A multidisciplinary team of physicians completed in consensus a medical record review that included: 1) immune status, 2) underlying chronic conditions, 3) hospitalization status at onset of fever, and 4) results of tissue, body fluid cultures and biopsies. Original MRI reports were evaluated. WB-MRI studies were categorized into helpful WB-MRI and not helpful WB-MRI.

Results: A final diagnosis for the cause of the fever was available for 68/92 cases (73.9%), which were determined to be infectious in 33/68 (48.5%), oncological in 3/68 (4.4%), rheumatological etiologies in 23/68 (33.8%) and miscellaneous in 9/68 (13.2%) cases. WB-MRI was found to be helpful in 62/92 cases (67.4%) and not helpful in 30/92 cases (32.6%). WB-MRI was 10.2 times less likely to be helpful in immunosuppressed children and almost 5.7 times less likely to be helpful in cases of prolonged fever (>3 weeks) at the time of MRI (P≤0.01).

Conclusion: WB-MRI provides helpful information in approximately 2/3 of children with fever without a focus. In most cases, it was helpful to exclude the need of further investigation.