Ces radiol. 2021, 75(1):52-57 | DOI: 10.55095/CesRadiol2021/005

Significance of ¹⁸F-FDG-PET/MRI in the diagnosis of the Fever of Unclear OriginOriginal article

Tomáš Rohan, Petr Hložanka, Marek Dostál, Andrea Šprláková-Puková

Klinika radiologie a nukleární medicíny LF MU a FN, Brno

Aim: To evaluate the contribution of ¹⁸F-FDG-PET/MRI in the diagnosis of Fever of Unknown Origin (FUO).

Methods: The study included 57 consecutive patients in the period 7/2016 to 12/2019 who underwent ¹⁸F-FDG-PET/MRI (Signa, GE) for FUO. Contrary to the official definition of FUO, the indication criteria have been extended to all patients with unclear temperatures above 37 °C. The sensitivity, specificity, predictive values and AUC of the PET/MRI finding in relation to the etiology of FUO were evaluated. A five-point Likert scale was used to semiquantitatively assess the probability of a cause of FUO based on PET/MRI finding (Likert 1 - PET/MRI finding is not a cause of FUO, Likert 5 - PET/MRI finding is a certain cause of FUO). The Likert 3 to 5 finding was evaluated as positive PET/MRI. Furthermore, clinical (fever, arthralgia, weight loss, night sweats) and laboratory (CRP, leukocytes) parameters were monitored, which were correlated with the positivity rate of PET/MRI.

Results: ¹⁸F-FDG-PET/MRI achieved a sensitivity of 93%, specificity 65%, positive and negative predictive values of 78 and 87%, AUC 0.82 when determining the etiology of FUO. The cause of fever of unclear origin was determined in 27 patients (57%), of whom 17 (36%) had non-infectious inflammatory disease, 8 (17%) infectious inflammatory disease and 2 (4%) neoplasm. In 20 (43%) patients, FUO remained without a known etiology, while in 14 (30%) of them the symptoms resolved spontaneously and in 6 (13%) patients they persisted without explanation even after one year of follow-up. The increased level of CRP at the time of ¹⁸F-FDG-PET/MRI examination showed up to 100% sensitivity and 100% negative predictive value for true positive PET/MRI, the specificity reached only 55%.

Conclusion: Based on this pilot study, ¹⁸F-FDG-PET/MRI is a suitable alternative to ¹⁸F-FDG-PET/CT in the search for the etiology of the fever of unclear origin.

Keywords: fever of unknown origin, magnetic resonance imaging, positron-emission tomography

Grants and funding:

Podpořeno MZ ČR - RVO (FNBr, 65269705) a MUNI/A/1342/2020.

Accepted: January 31, 2021; Published: March 1, 2021  Show citation