A Study Of The Relationship Of Coronary Collateral Circulation Formation And Reverse Attenuation Gradient Sign On CCTA

Part Ⅰ A Study of Performance of Collateral Circulation Involved Coronaries in CCTAObjectiveTo explore the differences of the formation of CT attenuated gradient in coronary computed tomography angiography(CCTA)among collateral-recipient vessel,collateral-donor vessel and those without collateral circulation.Materials and MethodsCCTA and digital subtraction angiography(DSA)data were retrospectively collected from PACS system in our hospital(from January 2013 to December 2016).The control group consisted of coronary arteries without collateral circulation formation(Rentrop grade 1-3)and the case group,which including Rentrop grade 1-3 in DSA,was further divided into two groups(donor vessel group and recipient vessel group)according to the blood supply relationship in collateral circulation.We measured and calculated the CT attenuation gradient of coronary arteries in each group with the help of CT post-processing workstation to compare ①the differences of CT attenuated gradient in different stenosis grade in 3 groups and ② the differences of optimal CT attenuated gradient regression curves of vessels in 3 groups.Results1.After excluding the cases with poor image quality,56 cases of Rentrop grade 1-3 in DSA were found in total(56 pairs of donor-recipient vessels)and 833 vessels of Rentrop grade 0 were remained.2.In the control group and donor vessel group,the liner regression constants of CT attenuate gradient in grade Ⅳ stenosis was statistic significant when compared to that of grade Ⅰ,Ⅱ and Ⅲ stenosis in each group.But there wasn’t significant among grade Ⅰ,Ⅱ and Ⅲ stenosis in each group.In recipient vessel group,the liner regression coefficient of grade Ⅲ stenosis was larger than that of grade Ⅳ stenosis,but it showed no statistically significance between them.The linear regression constants of CT attenuation gradient in grade Ⅲ or grade Ⅳ stenosis in control group and the donor vessel group were greater than that in recipient vessel group,and all of them(regardless of stenosis grade)showed statistically significant.3.Stratified by the degree of stenosis,the regression coefficient of CT attenuation gradient in control group showed statistically significance when comparing that of recipient vessel group in IV grade stenosis.Other degrees of stenosis of CT attenuation gradient of linear regression coefficient(absolute value)showed no statistical difference within or between groups.4.Judging the reverse attenuation gradient sign(RAG sign)with the criterion of liner regression coefficient,the probability of RAG sign in recipient vessel group(30.36%)was higher than the control group and donor vessel group(5.52%,10.71%,respectively).Judging the RAG sign with the criterion of fittest regression curves,the probability of RAG sign in recipient vessel group(62.5%)was higher than the control group and donor vessel group(9.96%,19.64%,respectively)too.Both methods showed statistically significant when comparing the probability of RAG sign in the recipient vessel group to that of the other two groups,while no statistically significant existed when comparing the probability of RAG sign in the donor vessel group and control group.Conclusion1.The formation of CT attenuated gradient of donor vessels in collateral circulation are the same as that of coronary arteries without collateral circulation.When in the same stenosis grade,the recipient vessels are less opacity compared to donor vessels in collateral circulation or coronary arteries without collateral circulation.2.A higher probability to find RAG sign in collateral recipient vessels though the method of finding the optimal regression curves.For high grade stenosis,we could not exclude the possibility of existing collateral circulation even if we could not find the RAG sign.Part Ⅱ A study of Influence Factors of RAG Sign in CCTAObjectiveTo explore the influence factors of RAG sign in CCTA.Materials and methodsCCTA and DSA data of 56 patients with Rentrop gradel-3 studied in Part I.According to DSA,we divided the data from three aspects,namely,the Rentrop grade of collateral circulation,the degree of stenosis of recipient vessels and the stenosis sites of recipient vessels and compared the probability of RAG sign in each group with the Chi-square test.Results1.The number of cases in Rentrop grade 1-3 was 29,16 and 11 respectively,and the probability of RAG sign was 75.9%,68.8%and 45.5%,respectively.No statistically significance can be found among them.2.There were 14 non-total occlusion vessels and the percentage of RAG sign was 64.3%.While 42 chronic total occlusion vessels had a percentage of 69%at the present of RAG sign.Statistically significance lay between two groups.3.20 cases occluded at the proximal of the vessels,15 at the middle and 21 at the distal.The probability of RAG sign was 55%、46.7%and 90.5%,respectively.When comparing between groups,the proximal group and middle group showed no significance,while the distal group revealed significance when comparing to the other two.ConclusionThe abundance of collateral circulation has no obvious effect on the occurrence of RAG sign in CCTA.Yet,it is more likely to find the RAG sign in the recipient vessel if stenosis occurs at the distal segment of the vessel or it is completely obstructed.