Part One:To Explore The Clinical Application Value Of The Detector-derived Dual-layer Spectral Computed Tomography In Non-small Cell Lung Cancer Part Two:CT Imaging Features Of Bronchiolar Adenoma

Part one:To explore the clinical application value of the detector-derived dual-layer spectral computed tomography in non-small cell lung cancerPart Ⅰ:A feasibility study of detector-derived dual-layer spectral computed tomography virtual non-contrast imaging in evaluating and diagnosing non-small cell lung cancerObjective To evaluate the image quality of detector-derived dual-layer spectral computed tomography(DLCT)virtual images non-contrast(VNC)and virtual monoenergetic imaging(VMI),and explore the feasibility of using VNC instead of the true non-contrast(TNC)images in non-small cell lung cancer(NSCLC).Methods We prospectively collected 92 patients with NSCLC confirmed by histopathology from Cancer Hospital,Chinese Academy of Medical Sciences,who underwent DLCT chest scanning with the mode of TNC、arterial phase(AP)and venous phase(VP).VNC images and VMI(40keV-100keV level)were reconstructed based on initial data,and all images were evaluated subjectively and objectively.The subjective evaluation included images quality score and CT morphological characteristics of NSCLC lesions(lobulation,spiculation,bubble lucency and pleural indentation)observation.Objective evaluation included measurement of NSCLC lesion size,CT value,noise,signalto-noise ratio(SNR)and contrast-to-noise ratio(CNR)of NSCLC lesion,thoracic aorta,lung tissue,scapular muscle and fat in all images.The dose-length product(DLP)of the three phases of the plain scan,AP scan and VP scan were recorded to calculate the effective radiation dose.Results The subjective scores of two-phase VNC images,70keV and 100keV level VMI images were higher than 4.VMI(70keV)(AP)and VMI(100keV)(AP)can reduce artifacts of high contrast concentration in the axillary and subclavian veins of conventional AP images.The subjective scores of VMI(40keV)images in AP and VP were lower than that of conventional images.CT morphological features of NSCLC lesions were consistent in conventional images,VNC images and VMI both in AP and VP.The difference between the longest diameter and the maximum short diameter of NSCLC target lesions on TNC images and two-phase VNC images was 0.002～0.003 cm.The absolute values of the difference in CT values of thoracic aorta and scapular muscle between the two-phase VNC images and TNC images were all less than 5HU,and the absolute values of the difference in CT values of NSCLC target lesions,lung tissue and fat between the two-phase VNC images and TNC images were all less than 10HU.The difference in CT values of NSCLC target lesions within ±15HU was 87.0%and 78.3%,respectively.The difference in CT values in the thoracic aorta,lung tissue,scapular muscle and fat was more than 95.0%within ±15 HU.There was no statistical significance in NSCLC lesions’ noise,CNR and thoracic aorta’s noise between VNC(AP)images and TNC images(p>0.05),there was no statistical significance in NSCLC lesions’ SNR between VNC(VP)images and TNC images(p>0.05).The noise of other tissues in the two-phase VNC images was smaller than that in the TNC images,and those SNR and CNR in the two-phase VNC images were larger than those in the TNC images,their difference was statistically significant(p<0.05).The above results show that two-phase VNC images can meet basic diagnostic requirements.The CT value and SNR of NSCLC lesions increased gradually with the decrease of VMI level,and reached the maximum value at VMI(40keV).VMI(40keV)and VMI(70keV)showed higher SNR in VP images than in AP images,and the difference was statistically significant(p<0.01).The noise of NSCLC target lesions in arteriovenous stage VMI(40keV)was higher than that in conventional images,and the difference was statistically significant(p<0.01).The effective radiation dose was reduced by 31.2%by subtracting the chest TNC image scan.Conclusions The VNC image and VMI of DLCT with a better image quality of NSCLC applications to some extent.The VNC images can provide adequate and reliable information for NSCLC detection and diagnosis,and reduce the radiation dose and the scan time of patients.Part Ⅱ:The value of quantitative parameters of detectorderived dual-layer spectral computed tomography in predicting epidermal growth factor receptor mutation among patients with non-small cell lung cancerObjective To analyze the relationship between detector-derived dual-layer spectral computed tomography(DLCT)and epidermal growth factor receptor(EGFR)mutation status in patients with non-small cell lung cancer(NSCLC).Methods Based on the first part of the study,the clinical,imaging and pathological data of 92 patients with NSCLC,who underwent chest scanning of DLCT with the mode of arterial phase(AP)and venous phase(VP),and tumor tissue samples tested for EGFR mutation were prospectively collected.Quantitative parameters of dual phase chest DLCT scanning,including iodine concentration(IC),virtual non-contrast(VNC),iodine no water(INW),the slope of the spectral attenuation curves(XHU),effective atomic number(Zeff).We evaluated the correlation between quantitative parameters and EGFR mutations.Results The positive rates were 75.0%(69/92)for EGFR of NSCLC,all of which were exons 18-21 mutations.Univariate analysis revealed that arterial enhancement fraction(AEF)and normalized arterial enhancement fraction(NAEF)had no significant difference between the two groups(p>0.05).Zeff(AP),λHU(AP),VMI(40keV)and VMI(100keV)were not significantly different between the two groups(p>0.05).The quantitative parameters of IC,NIC,INW and ED both in AP and VP,as well as Zeff and,HU in VP of the EGFR mutant group were significantly higher than those in the EGFR wild group(p<0.05).ROC curve analysis of those quantitative parameters with significant differences between the two groups,the highest specificity of predicting EGFR mutation status was INW(VP)of 95.65%,and the AUC value was 0.855(95%CI:0.768,0.942).In multivariate analysis,INW(AP)and NIC(VP)were significantly associated with EGFR mutation,p<0.05.Multivariate analysis of candidate variables from general clinical data and CT image features combined with quantitative parameters showed that NIC(VP)was an independent factor for predicting EGFR mutation status in NSCLC patients,with a sensitivity of 79.71%,a specificity of 86.96%,an accuracy of 81.52%and AUC of 0.897(95%CI:0.816～0.951).Conclusion Quantitative parameters of DLCT are helpful to predict the mutation status of EGFR in NSCLC.NIC(VP)value is significantly correlated with EGFR mutation,which can provide valuable reference information for the treatment selection of lung cancer patients.Part two:CT imaging features of bronchiolar adenomaObjective To investigate the CT characteristics of bronchiolar adenoma(BA)in order to improve the understanding of the disease and to increase the accuracy of preoperative diagnosis.Methods The clinical,imaging and pathological data of 69 patients with BA confirmed by surgical resection and pathology at Cancer Hospital,Peking Union Medical College,Chinese Academy of Medical Sciences from December 2018 to November 2020 were retrospectively reviewed.The type,the location and the size of the lesions,the distance from the lesion to the adjacent pleura,as well as the morphological characteristics including lobulation,spiculation,bubble lucency and pleural indentation were analyzed and recorded.The follow-up CT data were also reviewed.Results Among 69 BAs,pre-operation chest CT displayed visible lesion in 25 cases,and showed negative in 44 cases.According to the lesion density,the 25 BAs on CT images were classified into solid type(n=8),ground-glass type(n=8),cystic type(n=6)and cyst type(n=3).There were 15 lesions in the right lung(1 in the upper,2 in the middle and 12 in the lower lobe)and 10 lesions in the left lung(5 in the upper and 5 in the lower lobe.Ten lesions were found adjacent to the pleura.As for the other 15 cases,the distance between the lesion and the adjacent pleura was(1017)mm.Calcification was displayed in one cystic type BA case.The maximum diameter of 25 BAs were 4.4-30.3 mm,with the median value of 9.6 mm.The lobulation,spiculation,bubble lucency,and pleural indentation of lesions were detected in 20,11,12,and 6 cases.In total there were 11 patients received the preoperative follow-up CT,and 4 cases showed enlargement in diameter(including 2 cases of solid type,1 of ground-glass type and 1 of cystic type).The growth rate was 0.43-2.14 mm/year,with the median value of 1.67 mm/year.Imaging signs including spiculation(n=1),bubble lucency(n=1)and lobulation(n=1)were newly discovered on the preoperative follow-up CT.Postoperative follow-up CT was performed in 13 cases,without any recurrence or metastasis found.Conclusion CT imaging features of BA usually display as a single pulmonary solid or ground-glass nodule,and also can be presented as cystic or cyst type in several cases.Lesions can appear the lobulation,spiculation and bubble lucency,with calcification rarely found.A few of BA cases can enlarge during follow-up.