^(11)C-乙酸盐心脏PET/CT成像动力学参数与成像时长关系研究

Relationship Between Pharmacokinetic Parameters and Imaging Duration in Dynamic^(11)C⁃Acetate Cardiac PET/CT

目的评估成像时间对动态^(11)C-乙酸盐(^(11)C-acetate,^(11)C-AC)正电子发射断层显像(positron emission tomography,PET)检查心肌组织^(11)C-AC药代动力学参数计算结果的影响,探究临床缩短成像时间的可行性。方法本研究为回顾性分析,研究对象为北京协和医院接受^(11)C-AC PET/CT心脏成像检查的46名受试者(来自于一项评估饮酒男性心肌组织和代谢特征的临床研究)。每名受试者注射740 MBq^(11)C-AC后均进行40 min动态^(11)C-AC PET/CT扫描。以从左心室血池中获取^(11)C-AC的时间活度曲线作为输入函数,40 min(53帧)图像数据拟合得到的^(11)C-AC药代动力学参数(K_(1)值、k_(2)值)为参考标准,从最后一帧依次减少纳入的动态图像帧数,计算不同成像时长动态数据对应的^(11)C-AC药代动力学参数,与参考标准进行相关性与变化趋势一致性分析并进行差异性比较,以所有心肌节段中线性回归模型拟合优度评价指标R^(2)均大于0.9时对应的时间为最短成像时间。结果当成像时间≥17 min(37帧)时所有心肌节段中的^(11)C-AC药代动力学参数K_(1)与k_(2)值同参考标准的相关性均较好(R^(2)均>0.9),心肌整体平均结果中K_(1)值、k_(2)值与参考标准拟合的线性回归模型的回归系数分别分布于0.982~1.007和0.783~1.000。当成像时间为17 min(37帧)时,左前降支、右冠状动脉以及左回旋支灌注区域的K_(1)值、k_(2)值与参考标准均具有显著差异(P均<0.001),其中左前降支灌注区域相对差异(relative difference,RD)最高[K_(1)值:(3.93±1.98)%;k_(2)值:(13.79±6.40)%],右冠状动脉灌注区域RD最低[K_(1)值:(2.84±1.89)%;k_(2)值:(9.74±5.62)%]。结论对于饮酒或健康的男性人群,心脏^(11)C-AC PET/CT成像检查时,缩短成像时间至17 min(37帧)可获得与标准时间相一致的示踪剂药代动力学参数,为临床优化图像采集时间提供了一定的参考依据。

Objective To evaluate the effect of imaging time on the pharmacokinetic parameters calcu⁃lation of dynamic^(11)C⁃acetate cardiac positron emission tomography(PET)scan and to investigate the feasibility of shortening the imaging time in clinical practice.Methods This study was a retrospective analysis and 46 subjects who underwent^(11)C⁃acetate PET/CT cardiac imaging at Peking Union Medical College Hospital(from a clinical study assessing myocardial tissue and metabolic characteristics in men with alcohol consumption)were included.Each subject was injected with 740 MBq^(11)C⁃acetate before a 40⁃minute PET/CT scan,and time⁃ac⁃tivity curve in the left ventricle was collected as input function.Pharmacokinetic parameters(K_(1)and k_(2))calcu⁃lated from the 40⁃minute dynamic data(53 frames)was regarded as the reference standard.The number of in⁃cluded dynamic image frames was sequentially reduced from the last frame,and the corresponding pharmacoki⁃netic parameters of^(11)C⁃acetate were calculated.Correlation,consistent analysis of trends and the relative differ⁃ences on pharmacokinetic parameters between shortened data and reference standard were evaluated.The shortest acceptable scan time was determined based on the criterion that the R^(2)of linear regression models was higher than 0.9 in all myocardial segments.Results The R^(2)between^(11)C⁃acetate pharmacokinetic parameters and the reference standard was higher than 0.9 in all myocardial segments at scan time≥17 min(37 frames)for both K_(1)and k_(2).The regression coefficients of K_(1)values calculated from the shortened data and the reference standard in myocardium were distributed in the range of 0.982-1.007,and the regression coefficients of k_(2)val⁃ues calculated from the shortened data and the reference standard were distributed in the range of 0.783-1.000.When the scan time was reduced to 17 min(37 frames),the K_(1)and k_(2)values of left anterior descend⁃ing branch,right coronary artery and left circumflex branch perfusion regions were significantly different from the reference standard(all P<0.05).Left anterior descending branch perfusion region had the highest relative difference(RD)[K_(1):(3.93±1.98)%;k_(2):(13.79±6.40)%],while right coronary perfusion region had the lowest RD[K_(1):(2.84±1.89)%;k_(2):(9.74±5.62)%].Conclusions For the male population with al⁃cohol consumption or are healthy,shortening the scan time to 17 min(37 frames)during dynamic^(11)C⁃acetate PET/CT cardiac imaging can obtain tracer pharmacokinetic parameters consistent with the reference standard,which can provide references for optimizing clinical image acquisition time.