摘要目的:探讨基于第3代双源CT动态心肌灌注成像（CT-MPI）定量的正常心肌血流量（MBF）与负荷后心率增量的关系。方法:回顾性分析2016年10月至2019年11月于上海交通大学附属第六人民医院行动态CT-MPI及冠状动脉CTA（CCTA）检查的冠状动脉正常或冠状动脉轻微狭窄（定义为任一心外膜血管直径狭窄<25%）441例患者的CT-MPI图像，根据纳入和排除标准最终纳入研究231例患者。根据17节段模型在每个节段绘制ROI，采用混合去卷积法和最大斜率模型计算出每个节段的MBF及整体MBF。同时记录负荷后心率的增量及图像质量的相关参数。根据负荷后心率增量将患者分为4组，即心率增量≤9次/min组、10~19次/min组、20~29次/min组及≥30次/min组。非正态分布计量资料相关性分析采用Spearman相关性检验，采用Kruskal-Wallis检验比较多组间差异，事后比较采用Dunn-Bonferroni检验以区分两组间差异。采用Mann-Whitney U检验比不同节段的两组间差异。 结果:纳入的所有患者的整体MBF为157（140，182）ml·100 ml?1·min?1。负荷后整体MBF与心率增量呈正相关（ r=0.350， P<0.001）。心率增量不同亚组（≤9次/min亚组37例、10~19次/min亚组107例、20~29次/min亚组66例及≥30次/min亚组21例）的MBF分别为（142±26）、155（137，177）、（171±31）及（187±42）ml·100 ml?1·min?1。不同心率增量亚组的绝对整体MBF差异具有统计学意义（ H=30.000， P<0.001）。心率增量≤9次/min亚组的整体MBF显著低于心率增量10~19次/min亚组的整体MBF（调整后 P=0.029）；当心率增量≥20次/min时MBF的差异无统计学意义（调整后 P>0.05）。第3节段MBF（基底部下室间隔段）显著低于其他节段的MBF［分别为136（117，148）和161（142，191）ml·100 ml?1·min?1， U=104 539.000， P<0.001］。 结论:整体MBF值与负荷后心率增加的程度呈正相关。心率增量≥10次/min的患者整体MBF更高。

abstractsObjective:To investigate the relationship between normal range of myocardial blood flow (MBF) and heart rate (HR) increments after stress based on the third generation dual-source CT dynamic myocardial perfusion imaging (CT-MPI).Methods:Retrospective analysis was performed on the CT-MPI images of 441 patients with normal coronary artery or with minimal coronary stenosis (defined as diameter stenosis<25% at any epicardial vessel) who underwent dynamic CT-MPI and coronary computed tomography angiography (CCTA) between October 2016 and November 2019 in our institute. Two hundred and thirty-one patients were finally included in the study. The ROI was manually placed on a segment base according to the 17-segment model. The model (hybrid deconvolution and maximum slope) was used to calculate the global MBF and MBF of each segment. The HR increments after stress and parameters related to image quality were also recorded. Patients were divided into four subgroups according to HR increments after stress(≤9 beats/min subgroup, 10-19 beats/min subgroup, 20-29 beats/min subgroup and ≥30 beats/min subgroup). Spearman test was used for correlation analysis of quantitative variables that were not normally distributed. Kruskal-Wallis test was used for multiple comparisons among subgroups. A Dunn-Bonferroni test for post hoc comparisons was used to identify differences between pairs of groups. Mann-Whitney U test was used for comparison between MBF of different segments. Results:The median global MBF of all patients was 157(140, 182)ml·100 ml?1·min?1. Global MBF was positively correlated with the degree of HR increase after stress. The mean or median MBF of different subgroups (≤9 beats/min subgroup, between 10 to 19 beats/min subgroup, between 20 to 29 beats/min subgroup and ≥30 beats/min subgroup) were (142±26), 155 (137, 177), (171±31) and (187±42) ml·100 ml?1·min?1, respectively. The global MBF of subgroups with different HR increments showed statistically significant difference ( H=30.000, P<0.001). The global MBF of the subgroup with HR increment ≤9 beats/min was significantly lower than that of the subgroup with HR increment between 10 to 19 beats/min (adjusted P=0.029). However, when the HR increment≥20 beats/min,the difference became insignificant (adjusted P>0.05). The median MBF of basal inferoseptal segment was significantly lower than MBF of other segments [136 (117,148) ml·100 ml?1·min?1 vs. 161 (142,191) ml·100 ml?1·min?1, U=104 539.000, P<0.001]. Conclusions:Global MBF is positively correlated with the degree of HR increase after stress. Significantly higher global MBF is seen in patients with HR increment of ≥10 beats/min.