Application Of ¹⁸F-FDG PET/CT Combined With CT Thin Layer Scanning For Differentiation Of Malignant And Benign Solitary Pulmonary Nodules

Objective:To explore the diagnostic value of PET/CT and CT thin layer scanning in differentiation of malignant and benign solitary pulmonary nodules alone and combinedly,as to improve the diagnosis rate of early lung cancer and extend the survival of lung cancer patients.Method:A total of 104 patients diagnosed of SPN?solitary pulmonary nodule,SPN?from March 2018 to July 2019 undergoing ¹⁸F-FDG(¹⁸F-fluorodeoxyglucose,¹⁸F-FDG)PET/CT?positron emission tomography/computed tomography?and CT?computed tomography,CT?thin layer scanning in our hospital were retrospectively analyzed.Three experienced PET/CT diagnostic physicians?including one senior physician,one deputy chief physician,and one chief physician?read the films,and analyzed the images of CT thin layer scanning,PET/CT,and CT thin layer scanning combined PET/CT in all cases.The characteristics of CT images were used for benign and malignant interpretation of SPN.The benign and malignant results of SPN in all cases were obtained through the collection of final pathological data and follow-up.Patients were grouped according to whether the SPN is benign or malignant,the sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of CT thin layer scanning,PET/CT,and CT thin layer scanning combined with PET/CT for the benign and malignant judgment of SPN were statistically calculated using SPSS19.0 software.The quantitative analysis of SUV_max value of ROC curve were used for differential diagnosis of benign SPN and malignant SPN.In this study,the morphological characteristics of CT thin layer scanning:lobulation sign,glitch sign,pleural depression sign,vascular bundle sign,and vacuole sign,were compared between benign and malignant SPN groups.Results:In this study,98 cases of the 104 SPN were confirmed by surgery or CT-guided biopsy and pathology of the 104 SPN,among which 85 were malignant,13 were benign.The other 6 cases were confirmed as benign by clinical follow-up.When using CT thin layer scanning alone to diagnose benign and malignant SPN,the sensitivity was 83.5%,the specificity 57.9%,and the accuracy 78.8%;the positive predictive value was 69.8%;the negative predictive value was 44.0%.The sensitivity of PET/CT alone to diagnose benign and malignant SPN was 82.3%,the specificity 73.6%,the accuracy 80.7%;the positive predictive value was 93.0%;the negative predictive value was 73.6%.The sensitivity of PET/CT combined with CT thin layer scanning in the diagnosis of benign and malignant SPN was 86.5%,the specificity 85.7%,and the accuracy 86.5%;the positive predictive value was 98.8%;the negative predictive value was 31.5%.The sensitivity,specificity,and accuracy of PET/CT combined with CT thin layer scanning in the diagnosis of benign and malignant SPN were higher than those of CT thin layer scanning or PET/CT alone.In malignant lesions,the proportion of the presence of lobular sign was 90.5%,burr sign 72.9%,pleural pit sign 50.5%,vacuole sign 32.9%,and vascular bundle sign 56.4%.In benign lesions,the proportion of the presence of lobular sign was52.6%,burr sign 52.6%,pleural depression sign 34.5%,vacuole sign 21.0%,and vascular bundle sign 36.8%.There was statistical significant difference in the presence of lobular sign between the benign and malignant groups?P=0.000?.The average SUV_max of the benign group SPN was 2.9±3.1?range 0.6-14.4?;the average SUV_max of the benign group was 7.038±5.5?range 0.6-27.6?.The SUV_max value of the malignant nodule group was higher than that of the benign group,and the difference was statistically significant?P=0.033?.Based on the quantitative analysis of the ROC curve,the best SUV_max cutoff value for identifying benign and malignant SPNs was 3.25.The diagnostic sensitivity was 75.0%,the specificity 84.2%,and the area under the curve AUC was 0.805.Conclusion:1.¹⁸F-FDG PET/CT imaging combined with CT thin layer scanning has higher diagnostic efficacy than PET/CT and CT thin layer scanning alone for SPN diagnosis.2.Malignant SPN has higher SUV_maxax than benign SPN.Using SUV_max of 3.25as the cutoff value for SPN has the highest efficiency in benign and malignant diagnosis.3.The presence of lobular sign in CT thin layer scanning has diagnostic significance for malignant SPN.