Diagnosis Value Of ¹⁸F-FDG PET/CT In Patients With Fever Of Unknown Origin Accompanied By Enlarged Lymph Nodes

Objective:To evaluate the clinical application value of ¹⁸F-FDG PET/CT and Dual-time point ¹⁸F-FDG PET/CT in patients with FUO accompanied by enlarged lymphonodes,so as to provide new ideas for clinical diagnosis.Methods:A retrospective study was conducted on the patients with FUO accompanied by enlarged lymphonodes refferred for ¹⁸F-FDG PET/CT or Dual-time point ¹⁸F-FDG PET/CT,who were admitted to the Infectious Diseases Department of the First Affiliated Hospital of China Medical University from July 2012 to June 2022.The essential data of patients,serum biochemical（including white blood cell count,neutrophils,lymphocytes,C-reactive protein,procalcitonin,lactate dehydrogenase）,Dual-time point ¹⁸F-FDG PET/CT early phase SUVmax,delayed phase SUVmax were collected.The data were collated and statistically analyzed with SPSS26.0.The data conforming to the normal distribution were tested by two independent samples t-test between the two groups,One-way ANOVA used for the comparison of three or more independent sample data,and the data that did not conform to the normal distribution was used by nonparametric test.ROC curve was drawn,and Youden index was used to determined the cut-off point and calculate the sensitivity and specificity.Results:A total of 156 patients were included according to the criteria,122 patients were made a clear diagnosis before discharge,including 43 cases of infectious diseases（27.6%）,35 cases of non-infectious inflammatory diseases（22.4%）,28 cases of malignancies（17.9%）,16 cases of other diseases（10.3%）,and 34 cases were unknown（21.8%）.The diagnostic sensitivity and diagnostic rate were 98.7%,64.6%,respectively.There was no significant difference in White blood cell counts,neutrophils,lymphocytes,C-reaction protein,procalcitonin,lactate dehydrogenase between the evaluation of diagnostic results（true positive,false positive）of ¹⁸F-FDG PET/CT and Dual-time point¹⁸F-FDG PET/CT（P>0.05）.A clear diagnosis was made in 27 of the 33 patients with Dual-time point ¹⁸F-FDG PET/CT before discharge,including 10 cases of infectious diseases（30.3%）,7 cases of non-infectious inflammatory diseases（21.2%）,10 cases of malignancies（30.3%）,6 cases were unknown（18.2%）.The diagnostic sensitivity and diagnostic rate were 100.0%,63.0%,respectively.D-SUVmax had significant difference between benign and malignant lesions（P<0.05）.There was no significant difference in early phase and delayed phase SUVmax,D-SUVmax,and RI-SUVmax among infectious diseases,non-infectious inflammatory diseases,and malignancies（P>0.05）.D-SUVmax was the best indicator to judge benign and malignant lesions,with sensitivity of 81.3%,specificity of 50%,and cut-off point of 1.35.Conclusion:The sensitivity and diagnostic rate of ¹⁸F-FDG PET/CT in patients with FUO accompanied by enlarged lymphonodes are very high.Combined with White blood cell counts,neutrophils,lymphocytes,C-reaction protein,procalcitonin,lactate dehydrogenase were not helpful in the diagnosis of ¹⁸F-FDG PET/CT and Dual-time point ¹⁸F-FDG PET/CT.The D-SUVmax of Dual-time point ¹⁸F-FDG PET/CT can better judge the benign and malignant diseases and have better sensitivity.