腺苷负荷动态CT心肌灌注定量评价冠状动脉微循环的实验研究

目的 观察腺苷对心肌灌注的影响,对比腺苷负荷前后心肌灌注变化,并得出定量指标。方法 对10只中华小型猪依次行静息态及负荷态动态CT心肌灌注成像（CT-MPI）,测量左心室心肌17个节段、右冠状动脉（RCA）、左前降支（LAD）及回旋支（LCx）3支血管支配心肌,基底部、中间部、心尖部（包括心尖）3个区域及心肌各壁所属节段心肌血流量（MBF）、心肌血容量（MBV）、达峰时间（TTP）及组织通过时间（TTT）。将心肌节段分为静息组和负荷组,比较组间MBF、MBV、TTP及TTT差异。通过腺苷负荷后心肌血流灌注量化指标改变,观察腺苷对冠状动脉微循环的负荷效能。结果 静息组MBF、MBV、TTP及TTT分别为（199.82±66.24）ml/（100 ml·min）、（15.71±5.58）ml/100 ml、（6.38±2.03）s及（13.39±4.91）s;负荷组分别为（278.87±123.24）ml/（100 ml·min）、（20.91±7.66）ml/100 ml、（5.83±1.68）s及（12.53±4.49）s。相比静态组,负荷组MBF、MBV显著升高、TTP缩短（t=8.757、7.738、3.367,P均<0.05）,2组TTT差异无统计学意义（t=1.743,P>0.05）。结论 腺苷可增加心肌小型猪血流灌注、缩短灌注TTP;结合动态CT-MPI,可定量分析负荷前后心肌灌注变化及程度。正常心肌组织灌注储备不受腺苷影响。

Quantitative evaluation of coronary microcirculation by adenosine loading dynamic CT perfusion

Objective To observe the effect of adenosine on myocardial perfusion and compare changes in myocardial perfusion before and after adenosine load, so as to obtain quantitative perfusion indicators of myocardium.Methods Ten healthy Chinese miniature pigs underwent dynamic CT myocardial perfusion imaging (CT-MPI) in resting and loaded states, respectively. Myocardial blood flow (MBF), myocardial blood volume (MBV), time to peak (TTP) and tissue transit time (TTT) of all 17 segments were measured and analyzed among three vessels (right coronary artery[RCA], left anterior descending branch[LAD] and left circumflex artery[LCx]) supporting myocardium as well as basal-middle-apical (including apical) regions. Then quantitative perfusion indicators of all myocardial wall segments were divided into resting group and loaded group. MBF, MBV, TTP and TTT were compared between groups. The changes of quantitative indexes after myocardial perfusion adenosine loading were observed to evaluate the loading efficiency of adenosine on coronary microcirculation.Results MBF, MBV, TTP and TTT in resting group was (199.82±66.24) ml/(100 ml·min), (15.71±5.58)ml/100 ml, (6.38±2.03)s and (13.39±4.91)s, while in loaded group was (278.87±123.24)ml/(100 ml·min), (20.91±7.66)ml/100 ml, (5.83±1.68)s and (12.53±4.49)s, respectively. Compared with those in resting group, MBF and MBV increased while TTP decreased significantly in loaded group (t=8.757, 7.738, -3.367, all P<0.05). There was no statistical difference of TTT between 2 groups (t=-1.743, P>0.05).Conclusion Adenosine can increase myocardial perfusion and shorten TPP in pigs. Combined with dynamic CT-MPI, changes of myocardial perfusion before and after adenosine loading can be quantitatively analyzed. Normal myocardial perfusion reserve is not affected by adenosine.