| Part one Analysis of elasticity characteristics of ascending aorta,descending aorta and pulmonary artery using 640slice-volume CTObjective:As the prevalence and development of coronary computed tomographic angiography?CCTA?,it is meaningful that CCTA can provide not only the structural details of artery,but also functional information of vessel elasticity.Our aim was to explore the elasticity characteristics of ascending aorta?AA?,descending aorta?DA?,main pulmonary artery?MPA?,left pulmonary artery?LPA?,right pulmonary artery?RPA?,and their relationship between each other using 640 slice-volume computed tomography?CT?.Furthermore,this study will also observe their relations with age.Methods:A total of 42 subjects who underwent CCTA on 640slice-volume CT and met the inclusion criteria were enrolled in this study.The subjects were divided into 2 groups:Group A,age?45;Group B,age>45.The aortic distensibility?AD?and aortic compliance?AC?of aorta and pulmonary artery?PA?of each group were compared.Results:1.The AD and AC of PA decreased in the following order:MPA,RPA,and LPA.2.The correlation coefficients of different elastic parameters between different vessels were found to be different.The correlation coefficient of AD between AA and DA,AA and MPA,DA and MPA,RPA and MPA,LPA and MPA,and RPA and LPA were 0.689,0.520,0.393,0.329,0.579,and 0.534?P<0.05?,respectively.The correlation coefficients of AC for the6 groups mentioned above were 0.351?P<0.05?,0.470?P<0.05?,0.249?P>0.05?,0.190?P>0.05?,0.441?P<0.05?,and 0.409?P<0.05?,respectively.3.There was an age-dependent decrease of AD and AC in AA,DA,MPA,LPA?P<0.05?,but no difference in RPA?P>0.05?.Conclusion:1.The elasticity characteristics of AA,DA,MPA,LPA,and RPA could be well shown by 640 slice-volume CT.The elasticity relativity was observed and was different between AA and DA,AA and MPA,LPA and MPA,LPA and RPA.2.The vascular elasticity of AA,DA,MPA and LPA is related to age,which should be taken into consideration in clinical trials and treatments for the elasticity-related cardiovascular diseases.Part two Application of 640 slice-volume CT wide-volume scanning mode in CTPAObjective:To explore the feasibility and application value of the retrospective ECG-gated 640 slice-volume CT wide-volume scanning mode in CTPA.Methods:Patients having undergone CTPA on 640 slice-volume CT in our hospital were selected and divided randomly into three groups?30 cases each?:traditional non ECG-gated helical scanning group?Non-gated group?;retrospective ECG-gated helical scanning group?Gated group?;retrospective ECG-gated wide-volume scanning mode group?Wide-volume group?.The age,sex,body mass index,heart rate,scanning time,scanning range,CTDIvol and DLP of each group were recorded,and the effective radiation dose?ED?was calculated according to the formula.The quality of CTPA image was scored by two experienced radiologists in a double-blind manner,recording respiratory and cardiac vascular motion artifacts for each group.Results:1.All patients successfully completed the scan.There were no significant differences in gender composition,age,body mass index,and scanning range between the three groups?P?0.05?.Scanning time:Non-gated group,Gated group and Wide-volume group were respectively?3.7±0.2?s,?11.5±1.6?s,?5.8±2.6?s,the difference was statistically significant?P<0.05?.2.The scoring of image:88 patients with CTPA image quality score?3points,accounting for 97.9%.The scores of the Gated group and the Wide-volume group were significantly better than those of the Non-gated group?P<0.05?.There was no significant difference between the Gated group and the Wide-volume group?P?0.05?.There were significant statistical differences in the pulsation artifacts of cardiac vascular motion between the three groups of CTPA images?P<0.05?,indicating that ECG-gated CTPA can effectively eliminate heart beat artifacts and improve image quality.There were no statistically significant differences in respiratory motion artifacts between the three groups of CTPA images?P?0.05?.3.Radiation dose:The effective radiation dose of the Non-gated group,Gated group and Wide-volume group was?4.0±1.1?mSv,?7.9±2.8?mSv,?5.3±1.8?mSv,and the difference was statistically significant?P<0.05?.Conclusion:Retrospective ECG-gated wide-volume scanning mode on640 slice-volume CT is a practicable method in CTPA,which can reduce the pulsation artifacts of cardiac vascular motion without significantly increasing the radiation dose of the patients,significantly improve the image quality of the pulmonary artery,and subsequent cardiac function analysis and pulmonary artery elasticity analysis could be performed.Part three Application of CT pulmonary artery elasticity in evaluating severity of acute pulmonary embolismObjective:This study was designed to investigate the characteristics of pulmonary artery elasticity in patients with acute pulmonary embolism?APE?and its value in assessing the severity and right heart function of APE.Methods:Patients who suspected APE and performing retrospective ECG-gated CTPA in our hospital were enrolled.CTPA was used as the diagnostic criteria for pulmonary embolism.Patients with APE were divided into low-risk group and high-risk group according to the serious risk of APE.A control group without pulmonary embolism matching the basic data with the APE patients was collected.The AD value and right ventricular end-diastolic volume?RVEDV?,right ventricular end-systolic volume?RVESV?,right-left ventricular end-diastolic volume ratio?RVEDV/LVEDV?,right-left ventricular end-systolic volume ratio?RVSDV/LVSDV?were compared between the three groups,as well as the maximum cross-sectional area of pulmonary artery?PAmax?,minimum cross-sectional area of pulmonary artery?PAmin?,the ratio of maximum cross-sectional area of pulmonary artery and ascending aorta?PA/AAmax?,the ratio of minimum cross-sectional area of pulmonary artery and ascending aorta?PA/AAmin?.The relationships between AD value and right heart morphology and functional parameters were discussed,the ROC curve was used to determine the sensitivity and specificity of the above parameters for the diagnosis of APE severity.Results:1.The AD values of the control group,low-risk group and high-risk group were respectively 7.877±2.637(×10-3mmHg-1),6.121±2.054(×10-3mmHg-1),4.333±1.776(×10-3mmHg-1),which were gradually reduced,and the differences were statistically significant?P<0.05?.2.There were statistically significant differences in the morphology and functional parameters of right heart between the three groups?P<0.05?.PAmax and PAmin were statistically different between the high-risk group and low-risk group,the control group and the high-risk group?P<0.05?.PA/AAmax and PA/AAmin were statistically different between the high-risk group and the low-risk group?P<0.05?.RVEDV and RVESV were statistically different between the control group and the high-risk group?P<0.05?.RVEDV/LVEDV,RVESV/LVESV were statistically different between the control group and the high-risk group,the low-risk group and the high-risk group?P<0.05?.3.The correlation analysis between AD value and the morphology and functional parameters of right heart showed that there was light to moderate negative correlation?r=-0.277-0.573?,except for PA/AAmax and PA/AAmin,in which PAmin had the best correlation with AD value?r=-0.573,P<0.05?.4.The area under the ROC curve of the AD value,PAmax,PAmin,PA/AAmax,PA/AAmin,RVEDV,RVEDV/LVEDV and RVESV/LVESV to identify the high-risk APE was all greater than 0.5.The area under the ROC curve of PAmin was 0.892,which was the best,and the critical value was568.5 with the sensitivity and specificity were 100%and 56.3%respectively.The area under the ROC curve of the AD value was 0.738,the critical value was 4.132,and the sensitivity and specificity were respectively 60%and93.8%.Conclusion:1.As the severity of APE increases,the AD value of pulmonary artery is reduced.2.The AD value as the index of pulmonary artery elasticity obtained by retrospective ECG-gated CTPA can accurately evaluate the severity of APE and right heart function,which is helpful to identify patients at high risk of APE,thus providing imaging evidence for disease assessment,treatment options and prognosis evaluation of APE. |
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