The Value Of ¹⁸F-FDG-PET/CT In The Clinical Application Of Classic FUO

Part 1The value of ¹⁸F-FDG-PET/CT in the etiological diagnosis of classic FUO.Objective The purpose of this study was to investigate the etiological distribution of classic fever?Fever of unknown origin,FUO?,to evaluate the value of¹⁸F-FDG-PET/CT in the etiological diagnosis of classic FUO,and to analyze the prognosis of the patients.Methods A retrospective analysis of 136 patients?60 males and 76 females,mean age 57±18 years?who were admitted to the General Hospital of Tianjin Medical University for fever from October 2016 to March 2018 was conducted.The systematic and comprehensive examination should include at least 3 major routine tests,fecal occult blood test,liver function,renal function,electrolyte,blood culture,chest X-ray and abdominal B ultrasound.All patients underwent PET/CT.Definitive final diagnosis is obtained through histology,internationally accepted criteria for the diagnosis of diseases,or through no less than 6 months of clinical follow-up?including responses to specific drug treatments and changes in imaging?.In order to understand the etiological distribution of classic FUO,the number of patients with definite diagnosis and the proportion of various etiological factors were analyzed.By comparing the results of ¹⁸F-FDG-PET/CT examination and the final diagnosis of the patients,the results of PET/CT were divided into four groups:true positive,true negative,false positive and false negative.The sensitivity,specificity,diagnostic accuracy,positive predictive value and negative predictive value of ¹⁸F-FDG-PET/CT in etiological diagnosis of FUO were calculated.Results Among 136 patients,92 cases?67.6%?had final etiology and 44 cases?32.4%?did not.Among 92 patients with definite etiology,38 cases?41.3%?were non-infectious inflammatory diseases,23 cases?25.0%?were infectious diseases,18cases?19.6%?were malignant tumors,13 cases?14.1%?were other diseases.The sensitivity,specificity,accuracy,PPV and NPV of ¹⁸F-FDG PET/CT were 90.2%,54.5%,78.7%,80.5%,and 72.7%,respectively.Among the causes of classic FUO,non-infectious inflammatory lesions account for the largest proportion.Conclusion Among the causes of classic FUO,non-infectious inflammatory lesions account for the largest proportion.¹⁸F-FDG-PET/CT is helpful in the etiological diagnosis of FUO patients.The sensitivity of ¹⁸F-FDG-PET/CT is high,and the negative results are also helpful for the elimination of malignant lesions.Part2Study on the opportunity and condition of ¹⁸F-FDG-PET/CT in patients with classic FUOObjective A preliminary study on the timing and conditions of ¹⁸F-FDG-PET/CT selection in patients with classic FUO.To screen the clinical parameters related to PET/CT,which is helpful to clarify the etiology of classic FUO,as a reference for clinicians,so that patients can benefit from PET/CT examination.Methods The clinical features of 135 patients were analyzed retrospectively to explore the clinical characteristics of patients whose ¹⁸F-FDG PET/CT examination is helpful to the etiological diagnosis of classic FUO.Using binary Logistic regression model,forced input method,adding all independent variables,single-step intercept,Using the binary Logistic regression model,the forced input method,adding all independent variables,single step intercept,referring to previous studies and the clinical characteristics of the patients,the following parameters were selected for inclusion in the regression model:sex,age,high fever?maximum body temperature>39.1??,CRP??0.8mg/dL?,leukocyte count?>9.5×10^9?,anemia?Male hemoglobin<130g/L,female hemoglobin<115 g/L?,LDH increased?>250UL?,Fer increased?>204ng/mL?,lymph node enlarged,glucocorticoid use before PET/CT examination.According to the results of univariate regression analysis and multivariate regression analysis,the opportunity and condition of rational use of¹⁸F-FDG PET/CT in classic FUO patients were analyzed and discussed.Results In the binary Logistic regression model,Univariate regression analysis showed that the clinical parameters related to the diagnostic efficacy of ¹⁸F-FDG PET/CT were increased Fer?P=0.021?and no glucocorticoid therapy before examination?P=0.037?.The results of multivariate regression analysis exhibited that when patients experienced the following clinical indications:high fever?P=0.010?,elevated Fer?P=0.035?,preoperatively untreated by glucocorticoids?P=0.006?,¹⁸F-FDG PET/CT trend to be more helpful in diagnosing.The results were statistically significant?P<0.05?.ConclusionOf patients with high fever,elevated Fer,and untreated by glucocorticoid preoperatively,¹⁸F-FDG PET/CT was more helpful in examining and identifying the cause of classic FUO.These patients are more likely to benefit from PET/CT,and these clinical parameters can be used as a reference for clinicians to screen patients for ¹⁸F-FDG-PET/CT.Part3A preliminary study on the relevant clinical factors of the prognosis of classic FUO patientsObjective To explore the relationship between the clinical factors,the results of¹⁸F-FDG PET/CT and the prognosis of classic FUO patients.Methods The clinical characteristics of 135 patients were analyzed retrospectively,and the patients were followed up for not less than 6 months to obtain the outcome of the patient.Based on the patient's survival at the end of the follow-up,the outcome of the patient was initially divided into two groups:survival and death.Descriptive statistics were used to analyze the prognosis of various etiological factors.Descriptive statistics were used to analyze the relationship between the results of PET/CT and the prognosis of the patients.Binary Logistic regression analysis was used to screen the clinical factors related to the prognosis of patients with non-malignant lesions and PET/CT-positive patients.Binary Logistic regression was used to study the prognostic factors of patients with non-malignant lesions.The independent variable sex,age,anemia,leukocyte count,LDH level,fever,PET/CT positive or not were added into the model.According to the results of univariate regression analysis and multivariate regression analysis,the clinical parameters related to the prognosis of patients with FUO caused by non-malignant lesions were obtained.A binary Logistic regression model was used to study the prognostic factors of FUO patients with PET/CT positive.Independent variables such as Sex,age,anemia or not,white blood cell count elevated or not,LDH level elevated or not,high fever or not,CRP level elevated or not?Fer level elevated or not were added.According to the results of univariate regression analysis and multivariate regression analysis,the clinical parameters related to the prognosis of FUO patients with positive results of PET/CT were obtained.Results Of the 135 patients with classic FUO,20 died at the end of the follow-up.Of the 20 patients died,14?70.0%?were malignant and 6?30.0%?were non-malignant.The mortality rate of malignant lesions was 77.8%,and that of non-malignant lesions was 5.1%.The difference was statistically significant according to Chi-square test?x²=59.613,P<0.001?.Of the 44 patients who had no definite cause of fever,2 died?4.5%?,37?84.1%?had no fever symptoms,18?40.9%?had self-limited fever.The mortality of FUO patients without definite cause of fever was 4.5%,and that of patients with definite cause of fever was 19.8%.According to Chi-square test,the difference was statistically significant?x²=5.455,P=0.020?.Among the 135 patients,33 patients?24.4%?had negative PET/CT results,only one patient?3.0%?died at the end of follow-up,and the other 32 patients with negative PET/CT results had a better prognosis,self-limited fever was found in 10patients?30.3%of PET/CT-negative patients?.The results of PET/CT were positive in 102 cases,and 19 cases?17.6%?died of PET/CT positive at the end of follow-up.There was no significant difference in mortality between PET/CT positive and negative patients by Chi-square test?x²=3.650,P=0.056?.In the study of prognostic factors in patients with non-malignant FUO,the results of binary Logistic regression analysis showed that LDH was increased?P=0.031?and age?P=0.010?was the risk factor of death,and it was correlated with the prognosis of the patients.The results were statistically significant?P<0.05?.For every 1-year increase in age,the risk of death increased by 1.155 times,and the mortality of patients with elevated LDH was 11.4 times higher than that of those without LDH.The ROC curve showed a mean age limit of 64.5 years for poor prognosis.In the study of prognostic factors in PET/CT-positive patients,the results of binary Logistic regression analysis showed that male?P=0.021?,older age?P=0.004?and elevated LDH?P=0.011?were the risk factors of death.The results were statistically significant?P<0.05?.Male patients are 4.371 times more likely to die than women;for every 1 year increase in age,patients are 1.063 times more likely to die;patients with elevated LDH are 6.533 times more likely to die than those with no increase in LDH.The ROC curve showed a mean age limit of 62.5 years for poor prognosis.Conclusion Among the causes of classical FUO,the mortality of patients with malignant lesions was much higher than that of patients with non-malignant lesions,and the prognosis was the worst.The patients who had no definite cause of fever had lower mortality and better prognosis,and 40.9%of the patients were self-limited fever.Aging and elevated LDH are independent predictors of poor prognosis in patients with non-malignant lesions.Male,age,increased LDH were independent predictors of poor prognosis in PET/CT-positive patients with typical FUO.