MR TECHNIQUES FOR MEASUREMENT OF CORONARY ARTERY FLOW

据估计， 心肌梗死和每年52万人死亡。 尽管 冠状动脉造影在临床上广泛用于诊断 冠状动脉疾病，评估的生理意义， 冠状动脉血管造影术确定的病变仍然非常主观。 测量冠状动脉血流储备（CFR），定义为 静息冠状动脉血流量，一直主张作为一种方法 能够提供关于以下生理意义的信息： 狭窄 然而，用于测量CFR的现有技术都具有以下缺点： 限制CFR测量的有用性的显著缺点 临床环境 使用磁共振（MR）成像的流量测量技术具有 可能提供关于冠状动脉血流和CFR的信息。 基于相位差（PD）速度方法的MR技术已经被 用于身体的其他几个部位来评估血流。 然而，在这方面， 在小血管中，PD技术受部分容积和其他 在流量测定中引入误差的影响。 我们已经开发出一种测量冠状动脉血的替代策略 使用称为复差（CD）流量测量的MR技术测量流量。 仿真和体模实验表明，CD方法 对小血管中伪影的敏感性高于相位差（PD）血流 测量技术 从幻影、动物、 和人类志愿者表明，CD和PD技术能够 提供体内CFR测量。 我们建议调查PD， 我们最近开发的CD技术作为潜在的非侵入性方法， 评估冠状动脉血流和冠状动脉血流储备。 首先，我们将开发 两种新的MR图像采集策略，能够获得数据 用于体内冠状动脉流量测量。 两个新的收购 策略基于对分段视图共享梯度的修改 回波采集以及分段回波平面采集。 然后我们 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 计算机控制运动状态下的流动体模。 三是 使用开胸冠状动脉动物模型评价这些技术 这将提供速度，流速，动脉大小，心律失常， 与人类预期的运动相当。 最后，我们将进行 一项对30名单支冠状动脉疾病患者的研究显示， 在动物模型中验证的技术在 并且可以显示异常的人冠状动脉血流储备 患者的测量。

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.