Evaluation Of Coronary Artery Calcification Score Based On Non-gated Chest LDCT Screening For Lung Cancer

Part 1 Preliminary Study on Thoracic Aorta and Coronary Artery Calcification Based on Low-dose Chest CT Screening of Lung Cancer?Objective?To investigate the epidemiological characteristics of thoracic aorta and coronary calcification,and to analyze the effects of common risk factors on thoracic aorta and coronary calcification.?Methods and meterials?Low dose chest CT was performed in 2393 asymptomatic subjects who underwent lung cancer screening from September 2014 to August 2015.The chi-square test was used to analyze the distribution of thoracic aorta and coronary calcification in different age and gender.Logistic regression analysis was used to investigate the effects of some risk factors on thoracic aorta and coronary calcification.?Results?In total 2393 subjects,the positive rate of aortic calcification was 24.73%.Among them,the positive rate of calcification was the highest in the arch,followed by descending aorta,and the lowest in the ascending aorta.The positive rate of aortic calcification was8.82%,and the positive rate of calcification was higher in the left coronary artery than right coronary artery.The positive rate of thoracic aorta and coronary calcification were increasing with age,and the positive rate of calcification was higher in male than female(P<0.05).The positive rate of calcification was higher in smokers than non-smokers,and the positive rate of calcification was higher in smokers(?30 capsules)than the smokers(<30capsules)(P <0.05).The age,smoking and chronic bronchitis were associated with thoracic aorta and coronary calcification.The OR values were 4.758?1.426?1.597 and 2.653?1.413?2.338,respectively.?Conclusion?The positive rate of thoracic aorta and coronary calcification were increasing with age,and the positive rate is higher in male than female.The detection of calcification of coronary arteries and thoracic aorta by lung cancer screening using low dose chest CT had important significance which related to coronary heart disease.Part 2 Consistency Study of CACS Based on Different Iterative Reconstructions of Non-gated Chest LDCT with ECG-gated CT?Objective?To investigate the feasibility and better iterative reconstruction technique of coronary artery calcification score in the screening of cardiovascular disease risk by non-gated LDCT scan of the chest.?Materials and methods?102 patients who required coronary artery CTA examination due to diseases were enrolled in this prospective study.ECG-gated CT and non-gated low-dose CT(Non-gated LDCT)scan of the chest were performed and the latter was reconstructed by i Dose and IMR,which were labeled as A and B groups respectively,and ECG-gated CT labeled as group C.Subjective evaluation,objective evaluation,coronary calcification score(CACS)and risk stratification of three groups were compared.The subjective scores of each group were compared using Friedman M test,and kappa values is used to compare the concordance of two observers' subjective scores.The objective evaluation of each group were compared by ANOVA analysis.The consistency of CACS measurements in each group was examined by ICC values.Agatston score risk categories(1–100,101–400,> 400)was assessed with kappa values.?Results?The median scores of group A,group B and group C were 3,4 and 4 respectively,and there was no significant difference between group B and group C(P >0.05).The image noise in group C was 18.96±3.59 HU and the contrast noise ratio(CNR)was 7.91±1.73.The image noise of group A and B were lower than that of group C,and CNR is higher than C group,and noise reduction and improvement of CNR in group B were stronger than group A(P <0.05).The median CACS of group A,group B and group C were 117.48?131.42 and 221.45,respectively.The ICC value of CACS in group A ?B and group C was both 0.977.The kappa values of group A with group C were 0.545,and the kappa values of group B with group C were 0.602.12.75% of the subjects who were in high risk of group C were classified as moderate risk in group A;11.76% of the subjects who were in high risk of group C were classified as moderate risk in group B.16.67% of the subjects who were in moderate risk of group C were classified as low risk in group A;and 13.73% of the subjects who were in moderate risk of group C were classified as low risk in group B.?Conclusion?The consistency of CACS value between non-gated chest LDCT and ECG-gated CT scan CACS was good.IMR was superior to i Dose4 in improving the overall image quality,displaying coronary calcification plaque,measuring CACS and risk stratification.The subjects whose CACS detected by non-gated LDCT was in the moderate risk should be recommended to do the ECG-gated CT scan to assess the accurate CACS,and then to guide the primary prevention of cardiovascular disease.Part 3 New Categorization Algorithm of Coronary Artery Calcification Score for more Accurate Risk Assessment on Non-gated Chest Low-dose CT Screening Using IMR Technique?Objective?To investigate the new categorization algorithm of coronary artery calcification score(CACS)for more accurate risk assessment on non-gated low-dose chest CT(LDCT)using IMR technique for lung cancer screening.?Materials and methods?102 patients who required coronary artery CTA examination due to diseases were enrolled in this prospective study.ECG-gated nonenhanced CT and non-gated low-dose chest nonenhanced CT were performed and the latter was reconstructed by IMR.Agatston scores of non-gated low-dose chest nonenhanced CT and ECG-gated CT nonenhanced CT images were both measured by the Heart-Beat CS Agatston analysis software of the Philips workstation.The ROC curve was used to examine the diagnostic efficacy of non-gated low-dose chest nonenhanced CT,and take the truncated point with the largest youden index as the best cutoff point.Using kappa test to examine the traditional and new cutoff point in diagnosing risk stratification of the non-gated low-dose chest nonenhanced CT scan with risk stratification of ECG-gated nonenhanced CT.?Results?The CACS values measured by the non-gated low-dose chest CT nonenhanced scan were stratified by the traditional diagnostic threshold,and the CACS values measured by ECG-gated CT were tested according to the traditional boundary risk stratification,the kappa value was 0.602,P <0.05.The area under the ROC curve of medium-risk was 0.962,P <0.05,and the best diagnostic value was 87.44 in the CACS value measured by the non-gated low-dose chest CT nonenhanced scan.The area under of the ROC curve in high-risk group was 0.966,P <0.05,and the optimal diagnostic value was 255.26.The CACS values measured by the non-gated low-dose chest CT nonenhanced scan were stratified by the new diagnostic threshold,and the CACS values measured by ECG-gated CT were tested according to the traditional boundary risk stratification,the kappa value was 0.781,P <0.05.?Conclusions?This study showed that the consistency of CACS was high between non-gated chest LDCT and ECG-gated CT,but there is underestimation of risk stratification;therefore,this study developed a new standard of non-gated CACS value risk stratification,that is,low risk is 1 to 87,medium risk is 88 ~ 255,high risk is> 255,and the new standard of non-gating evaluation in risk stratification will be more accurate,especially for patients who are in high risk.