Evaluation Of Myocardial Bridge-mural Coronary Artery With DSCT In Coronary Artery Angiography

Purpose To investigate the depiction rate of myocardial bridge(MB) and mural coronary artery(MCA) with dual-source computed tomography(DSCT) and clinical significance thereof;To study the value of DSCT in the diagnosis of MB-MCA;To investigate the correlation between the percentage of systolic compression of the mural coronary artery and the length and depth of the myocardial bridge with dual-source computed tomography(DSCT).Methods Except some patients whose images could not be evaluated,450 continuous datasets of the patients who were suspected as with coronary artery disease(CHD) and underwent dual-source computed tomography were assembled, and they were performed by 2 radiologists with multiple planner reformation(MPR) independently;the anatomical relationship between the coronary artery and myocardium were observed.When consistency was obtained among the independent results,the diagnosis of MB-MCA could be confirmed.Maximum intensity projection (MIP),curved planar reformation(CPR) and volume rendering(VR) were used conjunctively to observe morphological changes of the coronary arteries,such as atherosclerotic plaques and compression.The length of MCA and depth of MB were measured from CPR and MPR images respectively,the results were expressed as(?)±s.From all the patients with MB-MCA and whose MCA were encased by the myocardium completely,30 patients were choosed randomly,their datasets were reconstructed seriatim by every 5%R-R interval,the whole cardiac cycle were reconstructed by 20 phases,the diameter of the mural coronary arteries of every phase was reviewed and measured,the phases were found out where the diameters were maximal and minimal,the systolic compression rate was calculated,Pearson correlation analysis was used to analyze the relation between length,depth,and degree of systolic compression of the mural coronary artery.Results A total of 192 sites of MB-MCA were found in 163(163/192,36.2%) of the 450 patients,153 of the 192 sites of MB-MCA were located on the LAD (153/192,79.7%),22(22/192,11.5%) on diagonal branch,13(13/192,6.8%) on obtuse marginal,3(3/192,1.6%) on RCA and 1(1/192,0.5%) on ramus.139 of the 163 patients were found to be with only one MB-MCA,18 with two sites,and 6 with three or more sites.Coronary atherosclerosis was found proximal to the myocardial bridge in 107 of the 192 sites(55.7%),proximal and distal to the myocardial bridge in 3 of the 192 sites(1.6%),no atherosclerosis was found just on the distal of the myocardial bridge.The length of MCA was 20.0 mm±10.1mm,and the depth of MB which part of a coronary artery was completely surrounded by myocardium was 2.1mm±0.9mm.72 sites of the whole 192 were completely surrounded by myocardium.Among the 30 MCA sites choosed from these 72 sites randomly,the minimal diameters were found in 27 sites(90.0%) from 30%to 35%R-R reconstruction interval,and the maximal diameters were found in 23(76.7%) sites from 70%to 75%R-R intervals and in 27(90.0%) sites from 70%to 80%R-R intervals.A significant correlation was not found between systolic compression and the length of the MB(r=0.096,P=0.613) but was found with the depth of the MB(r=0.675,P＜0.01) of the mural coronary artery.Conclusion The prevalence of MB-MCA in this study is 36.2%.DSCT coronary angiography is a non-invasive,efficient method in the diagnosis of MB-MCA.The minimal and maximal diameters of the mural coronary artery usually emerged in 30%～35%R-R reconstruction interval and 70%～80%R-R reconstruction interval respectively on DSCTCA.The degree of systolic compression of MCA significantly correlates with MB depth but not length.Application With the advanced dual source CT,this study showed the anatomical relationship between the mural coronary artery and myocardium intuitively and clearly.We proposed a new non-invasive,efficient method for the diagnosis of MB-MCA,and we analyzed the several most important reasons for the differential depiction rate of the conventional coronary angiography(0.5%—4.5%) and autopsy studies(15%—85%).We observed and summarized the diameter variability regularity of MCA during the whole cardiac cycle to profit from the high temporal resolution of DSCT.We investigated the functional correlation between MCA and MB originally,it would be very voluble in revealing the true clinical meaning of MB-MCA.