Clinical value of 18F-FDG coincidence imaging for patients with fever of unknown origin

Objective The aim of this study was to assess the clinical value of 18F-fluorodeoxyglu-cose (FDG) coincidence imaging in the diagnosis of fever of unknown origin (FUO).Methods Fifty-eight patients with FUO (temperature>38.3℃,fever more than 3 weeks) underwent SPECT imaging with 18F-FDG.Region of interest (ROI) was drawn over the lesions (L) and contralateral or adjacent normal tissue (B).The radioactivity ratio L/B was calculated for both benign and malignant pathologies and compared by t test.Results In 48 patients(83%),at least one site of abnormal 18F-FDG accumulation on SPECT was found,which led to the final diagnosis of malignant disease in 20 patients, and infectious or other benign disease in 23 patients.Five patients remained unknown.Four in 10(17%)cases with negative 18F-FDG SPECT were later proven as infectious disease(2 with urinary tract infection,2 with lymphadenitis);3 were found to have connective tissue and collagen disease (1 with rheumatism,1 with adult onset still's disease.1 with systemic lupus erythematosus);while the last 3 remained unknown.The L/B ratio of benign foci was 1.93±0.39,and that of malignant foci wa8 3.58±1.01(statistically significant difference with t=6.955.P<0.001).Conclusion 18F-FDG coincidence imaging is valuable in the diagnosis for FUO. Key words: Fever of unknown origin; Coincidence:Deoxyglucose