Improved Estimation of Ischemic Burden with Cardiac MRI

改进的心脏MRI对缺血负荷的估计 摘要：冠状动脉疾病(CAD)是影响2000多万美国人的主要医疗问题 每年给我国造成的损失估计为828亿美元。心肌灌注成像是一种成熟的工具，可以 检测并确定CAD的特征。灌注缺损区大小，也被称为缺血负荷，是一个有前途的生物标志物 不仅对分诊患者进行导尿，还可在纵向研究中确定治疗效果 并预测未来的心脏事件。虽然到目前为止，这些和大多数其他研究都使用了单光子发射 计算机断层扫描(SPECT)成像、磁共振成像(MRI)可能更适合于 评估缺血负荷。与无电离的SPECT相比，MRI具有更高的面内空间分辨率 辐射和在总检查时间的一小部分。MRI还提供了晚期Gd增强的黄金标准 (LGE)用于识别梗死心肌组织的显像法。通过减去梗死组织的大小 使用MR应力灌注成像计算的灌注缺损区大小，更准确地估计缺血 负担是可能的。然而，使用标准灌注mri获得的分辨率和切片覆盖率是有限的。 而且通常涉及跳过获得的切片之间的大片心肌组织。不可避免的 在拥有完整切片覆盖和保持高时间分辨率之间进行权衡可能会导致 未发现的血流灌注缺陷区。当心电门控信号较差时，权衡问题会加剧 而当对心率不规则的患者进行成像时，例如在房颤患者中，常见的 冠心病患者的病情。非门控心脏灌注核磁共振是最近流行的一种方法，可以缓解这种情况。 通过以非常高的时间分辨率连续采集数据来进行权衡，而与心电信号无关。穷 或者不一致的心电门控也会影响需要多次额外屏气和长时间屏气的LGE成像 与传统分段收购相比，收购时间更短。倒置之间的R-R间期不一致 脉冲导致纵向磁化的不完全恢复和健康组织的不正确消退 LGE成像。不受限制的自由呼吸收购也比传统收购更简单，传统收购要求 屏气和心电选通信号要求。更简单和更健壮的协议可以带来更广泛的 心脏MRI技术在CAD管理中的应用。具体目标是(1)开发新的同步 多切片技术与先进的重建方法，对运动具有健壮性。(二)从严从严 将新的磁共振方法与现有的磁共振技术进行比较。(3)通过比较来验证新的框架 在一项先导性研究中使用SPECT计算缺血负荷。我们的团队有互补的经验来 成功地执行这个项目的所有方面。我们研究的成功将带来一场改变游戏规则的 解决计算缺血负荷的关键障碍并更准确地表征 使用MRI的CAD，即使对于心律失常的患者，允许更广泛地使用无辐射心脏 灌注和LGE-MRI检查。 好了！

Improved estimation of ischemic burden with cardiac MRI Summary: Coronary artery disease (CAD) is a major healthcare problem that affects over 20 million Americans and costs our nation an estimated $82.8 billion each year. Myocardial perfusion imaging is a proven tool to detect and characterize CAD. Perfusion defect size, also termed ischemic burden, is a promising biomarker not only for triaging patients for catheterization but also in longitudinal studies to determine the efficacy of therapy and to predict future cardiac events. While these and most other studies to date used Single Photon Emission Computed Tomography (SPECT) imaging, Magnetic Resonance Imaging (MRI) may be more suitable for estimating ischemic burden. MRI offers superior in-plane spatial resolution than SPECT without the ionizing radiation and in a fraction of the total exam time. MRI also offers a gold standard Late Gadolinium Enhancement (LGE) imaging method for identifying infarcted myocardial tissue. By subtracting the infarcted tissue size from the perfusion defect size computed using MR stress perfusion images, a more accurate estimation of ischemic burden is possible. However, the resolution and slice coverage obtained with standard perfusion MRI is limited and often involves skipping large regions of myocardial tissue between the slices acquired. The inevitable tradeoff between having complete slice coverage and preserving high temporal resolution potentially leads to missed regions of perfusion deficit. The tradeoff problem is exacerbated when the ECG gating signal is poor and when imaging patients with irregular heart rate, for example in patients with atrial fibrillation, a common condition in patients with CAD. Ungated cardiac perfusion MRI is a recently popular approach that mitigates this tradeoff by continuously acquiring data with very high temporal resolution irrespective of the ECG signal. Poor or inconsistent ECG gating can also affect LGE imaging requiring several additional breath holds and long acquisition times with conventional segmented acquisitions. Inconsistent R-R interval between the inversion pulses leads to incomplete recovery of longitudinal magnetization and improper nulling of the healthy tissue in LGE imaging. Ungated free-breathing acquisitions are also simpler than conventional acquisitions which impose breath-holding and ECG gating signal requirements. A simpler and more robust protocol can lead to wider adoption of cardiac MRI techniques for CAD management. Specific aims are (1) To develop novel simultaneous multi-slice techniques with advanced reconstruction methods that are robust to the motion. (2) To rigorously compare the new MR methods with existing MR technology. (3) To validate the new framework by comparing ischemic burden computed using SPECT in a pilot study. Our team has complementary experience to successfully execute all aspects of this project. The success of our study will deliver a game-changing technology that addresses critical barriers to computing ischemic burden and more accurately characterizes CAD using MRI, even for patients with arrhythmias allowing for more widespread use of radiation-free cardiac perfusion and LGE-MRI. !