MR TECHNIQUES FOR MEASUREMENT OF CORONARY ARTERY FLOW

据估计，有150万人死于冠状动脉疾病 每年有52万人死于心肌梗塞。尽管 冠状动脉造影术在诊断冠心病中的广泛应用 冠状动脉疾病的生理意义的评估 冠状动脉造影术确定的冠状动脉病变仍然非常主观。 冠状动脉血流储备(CFR)的测量，定义为 高热静息冠脉血流，一直是提倡的一种方法 能够提供有关生理意义的信息的 一种狭窄。然而，现有的测量CFR的技术都有 严重缺陷限制了CFR测量在 临床环境。 使用磁共振(MR)成像的流量测量技术具有 有可能提供有关冠脉血流和CFR的信息。 基于相位差(PD)速度法的磁共振技术已经被 在身体的其他几个区域用于评估血液流动。然而， 在小血管中，局部放电技术受到部分容量和其他因素的影响 在流量测定中引入误差的影响。 我们已经开发了一种测量冠状动脉血的替代策略 流量测量使用一种称为复差(CD)流量测量的MR技术。 仿真和模型实验表明，CD方法的计算量较小 与相位差(PD)流动相比，对小血管中的伪影敏感 测量技术。从幻影、动物、 人类志愿者表示，CD和PD技术能够 提供活体CFR测量。我们建议调查警署和 我们最近开发的CD技术作为潜在的非侵入性方法 评估冠脉流量和冠脉血流储备。首先，我们将发展 两种新的能够获取数据的磁共振图像采集策略 用于活体冠状动脉流量测量。这两笔新收购 策略基于对分段的视图共享渐变的修改 回波捕获以及分段回波平面捕获。那我们 将测试绝对流量和流量比的准确度和精密度 使用计算机控制的这些序列获得的测量结果 计算机控制的运动状态下的流动模体。第三，我们将 使用开胸冠状动脉动物模型评估这些技术 这将提供速度、流速、动脉大小、心律失常和 与人类预期的运动相当的运动。最后，我们将进行 30例单支冠状动脉病变患者的临床研究 在动物模型中验证的技术可在 人类和可以显示异常的人类冠状动脉血流储备 对病人进行测量。

Coronary artery disease is responsible for an estimated 1.5 million myocardial infarctions and 520 thousand deaths per year. Despite the widespread clinical use of coronary angiography for the diagnosis of coronary artery disease, assessment of the physiologic significance of a coronary lesion identified with angiography remains very subjective. Measurement of the coronary flow reserve (CFR), defined as the ratio of hyperremic to resting coronary blood flow, has been advocated as a method capable of providing information regarding the physiologic significance of a stenosis. However, existing techniques for measuring CFR all have significant drawbacks that limit the usefulness of CFR measurements in the clinical environment. Flow measurement techniques using magnetic resonance (MR) imaging have the potential to provide information regarding coronary blood flow and CFR. MR techniques based on the phase-difference (PD) velocity method have been used in several other regions of the body to assess blood flow. However, in small vessels the PD technique is affected by partial volume and other effects which introduce errors in the flow determination. We have developed an alternative strategy for measuring coronary blood flow using a MR technique called complex difference (CD) flow measurement. Simulations and phantom experiments show that the CD method is less sensitive to artifacts in small vessels than phase difference (PD) flow measurement techniques. Preliminary data obtained from phantoms, animals, and human volunteers suggest that the CD and PD techniques are capable of providing CFR measurements in vivo. We propose to investigate the PD and our recently developed CD techniques as potential non-invasive methods for assessing coronary flow and coronary flow reserve. First we will develop two new MR image acquisition strategies that are capable of obtaining data for coronary flow measurements in vivo. The two new acquisition strategies are based on modifications to a segmented, view shared gradient echo acquisition as well as a segmented echo-planar acquisition. Then we will test the accuracy and precision of absolute flow and flow ratio measurements obtained with these sequences using a computer controlled flow phantom on a computer-controlled motion state. Third, we will evaluate these techniques using an open-chest coronary artery animal model that will provide velocities, flow rates, arterial sizes, arrhythmias, and motion comparable to those expected in humans. Finally, we will conduct a study in 30 patients with single vessel coronary artery disease to show that the techniques validated in the animal model are reproducible in humans and can demonstrate abnormal human coronary flow reserve measurements in patients.