The Application Of ¹⁸F-FDG PET/CT In The Diagnosis And Postoperative Evaluation Of Digestive Tract Tumors

Objective:To discuss the application of 18F-FDG PET/CT in the diagnosis and evaluate the therapeutic effect of postoperative digestive tract tumors.Methods:Retrospective analyze 49 patients with suspected gastrointestinal tumor in our hospital and 48 patients with postoperative tumor reexamination from September 2017 to February 2019.All patients underwent 18F-FDG PET/CT before or after surgery,and the final diagnoses of all patients were obtained by colonoscopy or postoperative pathology.All patients(97 patients)underwent conventional PET/CT early scans,and some who required time-lapse imaging had delayed scan after(53 patients)3～4 hours.Analyze the best SUVmax cutoff and delayed imaging of the patient’s SUVchange rate for differential diagnosis of primary and secondary digestive tract tumor,also for differential diagnosis of benign and malignant postoperative tumors.In patients with delayed imaging,the early-imaging SUVmax can be marked as SUVearly and the delay-imaging SUVmax could be marked as SUVdelayed,Then caculate the change of SUVmax(SUVchange rate),SUVchange rate=(SUVdelayed-SUVearly)/SUVearlyx100%.Discuss the optimal diagnostic cutoff of SUVmax and SUVchange rate in benign and malignant lesions of the digestive tract tumors,calculate the sensitivity,specificity,accuracy,positive predictive value and negative predictive value of SUVmax optimal diagnostic cutoff and SUV change rate in the diagnosis of digestive tract lesions.Then,evaluate the optimal diagnostic cutoff value of SUVmax and SUV change rate of 18F-FDG PET/CT examination in the diagnosis of digestive tract malignant lesions.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of CT images in all cases were calculated and these values were compared with the values of PET/CT.Statistical method:use SPSS statistical sofeware 20.0 for data analysis.Results:1.The optimal diagnostic cutoff of SUVmax for benign and malignant lesions of the digestive system was 4.5,and the optimal diagnostic cutoff of SUVmax for benign and malignant lesions after surgery was 3.2,At this time,the sensitivity,specificity and accuracy of each diagnosis were the highest.2.In patients with delayed imaging,the SUVdelayed was significantly higher than the SUVearly in malignant lesions of the digestive tract,the difference had the statistic significance(P<0.05).The SUVdelayed was roughly similar to the SUVearly m benign disease,the difference hadn’t the statistic significance(P<0.05).3.When the SUVchange rate was 10.7%,the sensitivity,specificity and accuracy in the diagnosis of benign and malignant lesions of the digestive system were high,which could be used as a reference in the diagnosis of benign and malignant lesions of the digestive tract.4.Sensitivity and accuracy of the 18F-FDG PET/CT scan in the diagnosis of malignant lesions were significantly higher than that of CT,and the difference was statistically significant(P<0.05).Conclusions:18F-FDG PET/CT is of great significance in the diagnosis and postoperative evaluation of digestive tract tumors.In particular,SUVmax cutoff and SUVchange rate provide important diagnostic evidences in the differential diagnosis of benign and malignant lesions.