Improved cardiac T1 reactivity measures for gadolinium-free MRI assessment of ischemic heart disease

摘要：缺血性心脏病(IHD)，也称为冠状动脉疾病，是一个主要的医疗保健问题 这影响了2000多万美国人，每年给我们国家造成的损失估计为828亿美元。心肌 血流灌注成像是一种已被证实的检测和表征IHD的工具。在计算单光子发射时 断层扫描(SPECT)成像在美国被广泛使用，MRI提供更高分辨率的灌注图像 没有电离辐射。然而，灌注磁共振成像需要注射基于Gd的造影剂来 确定血流灌注缺损区。Gd对肾功能不佳的患者来说是有问题的，他们是 排除在这些心脏磁共振血流灌注研究之外。心脏T1标测最近显示出很有希望 在不使用Gd的情况下识别和表征冠状动脉疾病。T1映射在 在药物诱导的应激状态下，在心脏的静息状态下，计算T1差值为 被称为T1反应性的百分比。通过反映血容量的变化，T1反应性已显示为 有望识别心肌中的缺血区。T1反应性是一个很有前途的生物标志物，不仅 对患者进行导尿分流，也进行纵向研究，以确定治疗的效果和 预测未来的心脏事件。然而，现有协议在可靠地检测T1变化方面并不是最优的 压力。在压力和运动不足的情况下，患者也很难长时间屏气。 补偿会导致T1 MAP质量较差。药理应激的有限时间窗可以限制 切片覆盖率。为了充分评估非对比T1方法的潜力，我们计划开发一种 稳健的T1映射方法，通过开发稳健的运动来优化T1映射协议 补偿方法，在有限的时间窗口内获得全心覆盖，显著 缩短屏气时间。该项目的具体目标是(1)优化T1映射协议和 开发一种适用于大呼吸运动的稳健图像配准方法(2)以开发新的图像配准方法 同步多切片采集方法和先进的深度学习技术，实现快速、完整的数据采集 心脏T1图，以及(3)通过将新的快速T1图与当前的Gd-1进行比较来验证新的快速T1图- 基于灌注法的IHD检测。我们的团队和机构拥有深厚的心脏磁共振经验， 成功执行该项目的所有方面所需的技术。我们项目的成功将带来一个 疑似IHD患者的改变游戏规则的MRI技术：快速、全心覆盖T1标测 没有使用Gd，以及准确表征新的性能的验证研究 方法。

Summary: Ischemic heart disease (IHD), also called coronary artery disease, 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 IHD. While Single Photon Emission Computed Tomography (SPECT) imaging is widely used in the U.S., MRI offers higher resolution perfusion images without ionizing radiation. However, perfusion MRI requires injecting gadolinium-based contrast agents to identify regions of perfusion deficit. Gadolinium is problematic in patients with poor kidney function, who are excluded from these cardiac MR perfusion studies. Cardiac T1 mapping recently has shown promise to identify and characterize coronary artery disease without the use of gadolinium. T1 mapping is performed in a pharmacologically induced stress state and again in the resting state of the heart to compute T1 differences as a percentage known as T1 reactivity. By reflecting blood volume changes, T1 reactivity has shown to be promising to identify ischemic regions in the myocardium. T1 reactivity 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. However, existing protocols are sub-optimal to reliably detect T1 changes at stress. It is also difficult for patients to hold their breath for long durations at stress and inadequate motion compensation leads to poor T1 map quality. The limited time window of pharmacological stress can limit the slice coverage. In order to fully evaluate the potential of the non-contrast T1 approach, we plan to develop a robust T1 mapping method that optimizes the T1 mapping protocol, by developing a robust motion compensation method and obtaining whole heart coverage within the limited time window and significantly reduce the breath-hold duration. Specific aims of the project are (1) to optimize T1 mapping protocol and develop a robust image registration method for large breathing motion at stress (2) to develop novel simultaneous multi-slice acquisition methods and state-of-the-art deep learning techniques for rapid, whole- heart T1 mapping, and (3) to validate the new rapid T1 mapping by comparing it to the current gadolinium- based perfusion method for IHD detection. Our team and institution have deep cardiac MRI experience and the technology needed to successfully execute all aspects of this project. The success of our project will deliver a game-changing MRI technology for patients with suspected IHD: rapid, whole-heart coverage T1 mapping without the use of gadolinium, and validation studies that accurately characterize the performance of the new method.