A comprehensive valvular heart disease assessment with stress cardiac MRI

项目概要/摘要 二尖瓣反流（MR）是一个日益严重的公共卫生问题，随着人口老龄化，其患病率 预计将大幅上升。对于MR诊断和严重程度评估，超声心动图技术具有 长期以来一直是护理标准。然而，基于这种技术的评估在以下两方面都有局限性： 技术挑战和治疗建议。因此，MR的最佳管理，特别是 确定手术时机仍然是复杂的，并且可以从提供定量信息的工具中受益。 本项目的总体目标是开发和验证一种应力 心血管MRI方案，可以为MR患者制定更明确的治疗计划。 心血管MRI（CMR）是一种成熟的成像技术，可提供最全面的 心血管系统的评估。基于CMR的流量定量的再现性已被证明 要比超声心动图优越上级。尽管有这些优点，CMR的附加临床价值， MR患者尚未确定。最近，有证据表明，基于CMR的评估 对MR患者的临床结局具有更好的预测能力，因此可以在确定 针对这些患者的治疗方案。然而，现有的CMR技术具有显著的局限性， 排除了它们在常规临床护理中的应用。例如，使用传统的2D相位的流量量化， 对比MRI（PC-MRI）对成像平面的位置敏感，无法测量跨瓣 直接流动，需要屏住呼吸，并且容易出现心律不齐。最近，4D血流成像， 由于其体积覆盖和三方向编码，已经获得了显着的兴趣，但采集 对于使用现有协议的4D流动成像而言，时间可能过长，特别是对于整个心脏覆盖。 此外，现有的4D流动成像协议仅在静止条件下执行成像，这不能完全地在静止条件下执行成像。 表征仅在压力测试下未被掩盖的功能损害。 在这项工作中，我们将开发和验证一个全面的CMR协议，（i）提供ferumoxytol- 具有全心脏覆盖的增强的4D流动成像，（ii）需要来自MRI技术人员的最小规划， (iii)在临床上可行的采集时间内进行，（iv）不需要屏气或常规心脏检查 心律，（v）不需要导航器门控，（vi）允许在运动应激期间成像，暴露功能 损伤，和（vii）另外提供心脏功能量化，以解释和解释应激诱导的 在MR患者中观察到功能障碍。在目标1和2中，我们将开发和优化协议。在 目的3和4，我们将在55名健康受试者和55名 我们假设，开发的协议导致更可靠的评估 与单独TTE相比，MR的可能性更高，并为更大规模的临床研究奠定了基础， 参数来预测临床结果。

Project Summary/Abstract Mitral valve regurgitation (MR) is a growing public health concern, and with an aging population, its prevalence is expected to rise steeply. For MR diagnosis and severity assessment, echocardiographic techniques have long been the standard of care. Assessment based on such techniques, however, has limitations, both in terms of technical challenges and treatment recommendations. As a result, optimal management of MR, especially determining the timing of surgery, remains complex and stands to benefit from tools that provide quantitative and comprehensive characterization of MR. The overall goal of this project is to develop and validate a stress cardiovascular MRI protocol that can lead to a more definitive treatment plan for MR patients. Cardiovascular MRI (CMR) is a well-established imaging technique that provides the most comprehensive evaluation of the cardiovascular system. The reproducibility of CMR-based flow quantification has been shown to be superior to that of echocardiography. Despite these advantages, the additive clinical value of CMR for MR patients has not been established. More recently, evidence has emerged that CMR-based assessment has better predictive power for clinical outcomes for MR patients and thus could play a central role in determining management plans for such patients. Existing CMR techniques, however, have significant limitations, precluding their use in routine clinical care. For example, the flow quantification using traditional 2D phase- contrast MRI (PC-MRI) is sensitive to the placement of the imaging plane, cannot measure the transvalvular flow directly, requires breath-holding, and is susceptible to irregular cardiac rhythm. Recently, 4D flow imaging, due to its volumetric coverage and three-directional encoding, has gained significant interest, but acquisition for 4D flow imaging using existing protocols can be prohibitively long, especially for whole-heart coverage. Also, existing 4D flow imaging protocols only perform imaging under resting conditions, which cannot fully characterize functional impairment that is only unmasked under stress testing. In this work, we will develop and validate a comprehensive CMR protocol that (i) provides ferumoxytol- enhanced 4D flow imaging with whole-heart coverage, (ii) requires minimal planning from the MRI technologist, (iii) is performed in clinically feasible acquisition time, (iv) does not require breath-holds or regular cardiac rhythm, (v) does not require navigator gating, (vi) allows imaging during exercise stress, exposing functional impairment, and (vii) additionally provides cardiac function quantification to explain and interpret stress-induced functional impairment observed in MR patients. In Aims 1 and 2, we will develop and optimize the protocol. In Aims 3 and 4, we will validate the accuracy and reproducibility of the protocol in 55 healthy subjects and 55 patients diagnosed with MR. We hypothesize that the developed protocol leads to a more reliable assessment of MR than possible with TTE alone and set the stage for larger clinical studies where the power of CMR parameters to predict clinical outcomes is demonstrated.