Evaluation of predictor variables of diagnostic [18F] FDG-PET/CT in fever of unknown origin.

BACKGROUND: Fever of unknown origin (FUO) is defined as an illness having fever which lasts at least 3 weeks of duration and is higher than 38.3 ºC on several measurements. The causes are infections, malignancies, noninfectious inflammatory diseases and miscellaneous. If [18F]FDG-PET/CT helps the final diagnosis, it is called contributory. The aim of the study is to evaluate the predictor variables effecting a contributory PET/CT for the diagnosis.

METHODS: This is a retrospective cohort study conducted between June 2006 and May 2015 including 76 patients. The evaluated predictor variables are age, sex, ESR, CRP, fibrinogen, ferritin, albumin, haemoglobin level, platelet count, total leukocyte count, neutrophil percentage, lymphocyte percentage, ALP, LDH, ALAT, ASAT, GGT, total bilirubin, CK, RF, ANA, urinanalysis, chest radiography, abdominal US, lymphadenopathy, duration of fever, comorbid diseases and previous therapies.

RESULTS: ESR (P=0.001), CRP (P=0.001), fibrinogen (P=0.009), lymphopenia (P<0.001), neutrophilia (P<0.001), ferritin (P<0.001), leukocytosis (P=0.003), duration of fever before PET/CT (<3 months) were found to be statistically significant for positive contribution of PET/CT results to the diagnosis. CONCLUSİONS: [18F]FDG-PET/CT is helpful and contributory for the diagnosis of FUO in patients having higher levels of CRP, ESR, ferritin, fibrinogen, leukocytosis, neutrophilia and shorter durations of fever (<3 months).