The Study Of Spectral Imaging Combined With Virtual Un-enhanced Technique In Accessing And Diagnosing Pathological Classification Of Lung Adenocarcinoma With Pure Ground-glass Opacity

Part One Feasibility study of spectral CT virtual un-enhanced technique to evaluate pulmonary adenocarcinoma with pure ground-glass opacityObjective:To investigate the image quality of the new virtual un-enhanced images(VUE)of the Revolution CT on lung adenocarcinoma presenting as pure ground glass nodule(pGGN)compared with true un-enhanced images(TUE).Materials and Methods:Forty-eight patients underwent conventional un-enhanced CT scan with 120 kVp and contrast-enhanced CT with automatic spectral imaging protocol selection(GSI-Assist)mode during the arterial phase(AP)and venous phase(VP)were prospectively collected.VUE based on initial data were generated from spectral CT scan.CT attenuation value of the lesion and various sites(including thoracic aorta,pulmonary artery,subcutaneous fat and erector spinae),chest subcutaneous fat SD value,maximum diameter of the lesion,subjective score of image quality and lesion displaying clarity,as well as CT signs of the lesion were compared between the TUE and VUE images.Contrast-to-noise ratio(CNR)of the pulmonary artery and thoracic aorta and the lesion net CT attenuation value of the arteriovenous phase relative to TUE and AP-VUE,VP-VUE were calculated respectively.The effective radiation dose(ED)of the dual-phase enhanced spectral scanning and conventional three-phase scanning were recorded,and the percentage of the effective radiation dose(ED)reduction was calculated.Statistical analysis was performed with One-way ANOVA,Kruskal-Wallis H test,Mann-Whitney U test,LSD-t test and two independent samples t test.Results:There were no significant differences in CT attenuation value of the lesion and various sites,chest subcutaneous fat SD value,maximum diameter of the lesion and CNR of the pulmonary artery and thoracic aorta between the TUE and VUE images(?2=2.596?5.688,F=0.206?2.564,all P>0.05).There was no significant difference in the lesion net CT attenuation value of the arteriovenous phase relative to TUE and AP-VUE,VP-VUE(?2=0.737,1.042,both P>0.05).Similar characteristic appearances of the lesion were observed in the TUE and VUE images.The subjective scores of AP-VUE images were lower than TUE images(Z=-4.993,P<0.001),while there was no significant difference between VP-VUE and TUE images(Z=-1.271,P=0.204).There was no significant difference in the subjective scores of the lesion displaying clarity between VP-VUE and TUE images(?2=4.585,P=0.101).The dose-length product(DLP)and the effective radiation dose(ED)of conventional three-phase scanning were 858.38±84.06 mGy·cm and 12.01±1.17m Sv,respectively,of which were 637.44±74.87 mGy·cm and 8.92±1.04 mSv from the dual-phase enhanced spectral scanning.There were significant difference in the effective radiation dose(ED)between the two scanning schemes(t=13.597,P<0.001).The effective radiation dose(ED)was reduced by 25.73%in the dual-phase enhanced spectral scanning.Conclusion:The VUE images derived from Revolution CT can provide reliable diagnostic information for lung adenocarcinoma presenting as pGGN,specifically,VP-VUE has similar image quality to TUE,which has the potential to replace TUE,replacing TUE images will lower radiation exposure by 25.73%.Part Two Combined spectral CT quantitative analysis and morphological parameters in distinguishing pathological subtypes of pulmonary adenocarcinoma with pure ground-glass opacityObjective:To explore the differential diagnostic value of spectral CT quantitative analysis parameters combined with morphological parameters for pathological subtypes of lung adenocarcinoma presenting as pure ground glass nodule(pGGN).Materials and Methods:Sixty-five patients with surgical-pathological confirmed lung adenocarcinoma with pure ground-glass opacity underwent conventional un-enhanced CT scan with 120 kVp and spectral CT dual-phase contrast enhanced scan and were classified into group A[15 cases of adenocarcinoma in situ(AIS)and 21 cases of minimally invasive adenocarcinoma(MIA)]and group B[29 cases of-invasive adenocarcinoma(IAC)]respectively.Conventional morphological parameters including maximum diameter,mean CT attenuation value,volume and mass in un-enhanced image were recorded.Spectral CT quantitative parameters during the arterial phase(AP)and venous phase(VP)including iodine concentration(IC),normalized iodine concentration(NIC),water concentration(WC)and spectral curve slope of k1?k6(where k1?k3 represent the slope of 40?70 keV,70?100 keV,100?140 keV in arterial phase,k4?k6 represent the slope correspondingly in venous phase).Two independent samples t test and Mann-Whitney U test were used for analyses while the areas under the ROC curve was calculated to evaluate the diagnostic efficiency.Results:Morphology quantitative analysis showed that there were significant differences in maximum diameter,mean CT attenuation value,volume,and mass between group A(AIS+MIA)and group B(IAC)(t=-4.364,Z=-2.773?-4.329(all P<0.05),with highest diagnostic efficiency in mass(threshold value of 290.81mg,AUC of 0.814,sensitivity of 75.9%,specificity of 72.2%,positive predictive value of 68.7%,negative predictive value of 78.7%,and accuracy rate of 73.8%,respectively).Spectral CT quantitative analysis showed that there were significant differences in k1,WC-AP,and WC-VP between group A(AIS+MIA)and group B(IAC)(t=-3.446?-5.392,all P<0.05).Among the quantitative parameters,WC-AP and WC-VP had higher diagnostic efficiency,with threshold value of 361.40mg/cm3,374.95mg/cm3,AUC of 0.828 and 0.843,sensitivity of 75.9%and 79.3%,specificity of 86.1%and 83.3%,positive predictive value of 81.4%and 79.3%,negative predictive value of 81.5%and 83.3%,and accuracy rate of 81.5%,respectively.Multi-parameter combination(mass,WC-AP,WC-VP)for the pathological subtype differential analysis of lung adenocarcinoma with pure ground-glass opacity can increase the diagnostic efficacy(AUC of 0.898,sensitivity of 82.8%,the specificity of 86.1%,positive predictive value of 82.7%,negative predictive value of 86.1%,and accuracy rate of 84.6%,respectively).Conclusion:The WC-AP,WC-VP of spectral CT quantitative parameters could used for pGGN lung adenocarcinoma pathological subtypes,and combination parameter mass could increase the diagnostic sensitivity,specificity,and accuracy.