| Objective:The aim of this study was to compare the metabolic distribution characteristics and CT morphological features of benign and malignant solitary pulmonary nodules,and to explore the qualitative diagnostic value of relative activity distribution of 18F-FDG PET/CT in the diagnosis of solitary pulmonary nodules.Methods:The study was analyzed the patients received 18F-FDG PET/CT from 26 July 2013 to 26 December 2017 in（hospital）and included 178patients（97 males（54.49%））,81 females（45.51%）;age range 3385（58.71±12.24）years.The clinical and imaging data included name,gender,age,symptoms,history of smocking,nodule diameter,nodule location,nodule morphology,nodule edge,nodule lobulation,nodule spiculation,nodule vascular convergence,nodule pleural indentation,the maximum standardized uptake value（SUVmax）of imaging agent concentration of SPN lesions on18F-FDG PET/CT and the relative activity distribution.All patients confirmed by surgery,pathology and followed-up study.All SPNs were divided into benign group and malignant group for univariate analysis.According to the degree of pathological differentiation of adenocarcinoma and squamous cell carcinoma,the diameter of nodules,the shape of nodules and the location of nodules,we compared the SUVmax and RAD among the above groups,respectively.To compare the diagnostic efficacy of 18F-FDG PET/CT imaging indicators of SUVmax≥2.5 and RAD<1 on the diagnosis of malignant SPN in all samples.The receiver operating characteristic curves was applied to analysis the efficacy of the indexs according to the diameter of SPN group.Results:1.The average SUVmax of benign SPN was 2.3 and the average RAD was（1.010554±0.011411）.The average SUVmax of malignant SPN was 6.8and the average RAD value was（0.987834±0.013699）.2.There were statistically significant differences in age,history of smocking,nodule size,nodule location,nodule morphology,RAD,SUVmax,nodule size,edge,lobulation,speculation and vascular convergence sign（All P<0.05）by the univariate analysis between benign and malignant SPN.There weren’t statistically significant differences in gender（P=0.762）,nodule morphology（P=0.136）,nodule location（P=0.895）and pleural indentation sign（P=0.251）by the univariate analysis between benign and malignant SPN.3.There was statistically significant differences in SUVmax（χ2=43.755,P=0.001）by statistic analysis according to the degree of pathological differentiation,and wasn’t statistically significant differences in RAD（χ2=3.808,P=0.283）by statistic analysis according to the degree of pathological differentiation.According to the size of nodules,the results showed that there was statistically significant difference in SUVmax between small diameter group and medium diameter group,small diameter group and large diameter group and middle diameter groupandlargediametergroup（Z=-4.972,P=0.001;Z=-5.991,P=0.001;Z=-4.149,P=0.001）.There were statistically significant differences in RAD between small diameter group and medium diameter group,small diameter group and large diameter group（P=0.020,P=0.001）,but there wasn’t a statistically significant difference in RAD between medium diameter group and large diameter group（P=0.059）.4.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of RAD for the diagnosis of malignant SPN were 91.7%,89.5%,91.0%,94.9%and 83.6%respectively,compared with those with SUVmax≥2.5（87.6%,56.1%,76.40%,80.9%and 68.1%）.5.The area under the curve（AUC）for diagnosis of malignant SPN by RAD was 0.909（95%confidence interval,0.857-0.909）,which was higher than 0.792（95%confidence interval,0.715-0.868）when SUVmax≥2.5 was used as the diagnostic criteria.According to the size of nodules,the results showed that the AUC for diagnosis of malignant SPN in small diameter group by RAD and SUVmax was 0.980（95%confidence interval,0.919-1.000）and0.700（95%confidenceinterval,0.361-1.000）respectively.The AUC for diagnosis of malignant SPN in medium diameter group by RAD and SUVmax was 0.948（95%confidence interval,0.896-1.000）and 0.766（95%confidence interval,0.634-0.898）respectively.The AUC for diagnosis of malignant SPN in large diameter group by RAD and SUVmax was 0.853（95%confidence interval,0.751-0.956）and 0.762（95%confidence interval,0.641-0.883）respectively.Conclusion:1.The age,smoking of history,nodule diameter,nodule edge,nodule lobulation,spiculation and vascular bundles sign are the independent risk factors for the diagnosis of benign and malignant SPN by univariate analysis.2.The relative activity distribution has a higher value than SUVmax in differential diagnosis of benign and malignant SPN.3.There was a statistically significant difference in SUVmax of different diameter groups.SUVmax tended to increase with the increase of nodule diameter.There was no statistically significant difference in RAD between medium diameter group and large diameter group.However,there was a statistically significant difference in RAD between small diameter group and middle diameter group and small diameter group and large diameter group.4.There were statistically significant differences in SUVmax between groups with different degrees of differentiation,but there was no statistically significant difference between RAD groups. |
