Comprehensive quantitative magnetic resonance imaging in assessment of aortic valve disease

项目总结/摘要 无症状性主动脉瓣狭窄（AS）患者的死亡风险很高。处理 主动脉瓣置换术（AVR）是一种有效的治疗方法，但需要及时识别适当的 条件目前用于确定症状状态的方法是高度主观的，并且通常不能 表明在发生不可逆心脏损伤之前进行干预。同样地，将处于风险中的无症状患者 未经治疗也可能导致他们发展为AS的不良心肌后遗症。评价心脏 心室形态、整体和局部心脏功能、主动脉顺应性以及心肌组织 组合物将提供对AS患者心脏健康的全面评估， 跟踪慢性持续性主动脉瓣压力超负荷导致的LV重塑。 在这个项目中，我们建议开发三种类型的磁共振成像（MRI）方法 用于全面和定量地提供对心脏健康的期望评价。（1）3D CINE MRI用于结构和功能评价; 2）4D flow MRI用于心肌局部功能和血液 血流评估;以及3）用于组织表征的3D定量参数标测，检测心肌 纤维化它们是高度加速的自由呼吸全心脏和主动脉成像技术， 非常适合这种需要快速采集、自由呼吸策略和无 造影剂给药要求。 从定量MRI测量，如左心室射血分数（LVEF），LV肥大， 左室舒张和收缩功能障碍、心肌纤维化、主动脉僵硬度和扩张性及其相关性 将分析症状的严重程度，预测症状进展的最佳生物标志物将是 鉴定 这项全面的定量MRI方案用于评价心肌组织成分， 严重主动脉瓣狭窄患者的主动脉功能和主动脉异常将更准确地评估 AS的影响。更准确地说，定量MR参数可以帮助预测症状的发展， 严重主动脉瓣狭窄患者症状严重程度的进展，并改善当前患者的选择 主动脉瓣置换术的策略。该项目的成功将对医疗保健产生重大影响。 考虑到严重主动脉瓣狭窄的临床重要性，以及目前的方法无法可靠地 预测症状的发展或进展。

PROJECT SUMMARY/ABSTRACT Patients with asymptomatic aortic valve stenosis (AS) patients have a high mortality risk. Treatment by aortic valve replacement (AVR) is an effective therapy but requires timely identification of the appropriate condition. The current approach for determining symptomatic status is highly subjective and often fails to indicate intervention before irreversible cardiac damage occurs. Similarly, leaving at-risk asymptomatic patients untreated may also result in their developing the adverse myocardial sequellae of AS. Evaluation of cardiac ventricular morphology, global and regional cardiac function, aortic compliance, as well as myocardial tissue composition would provide a comprehensive assessment of the heart health in patients with AS that could track the remodeling of the LV as a result of chronic sustained aortic valve pressure overload. In this project, we propose to develop three categories of magnetic resonance imaging (MRI) approaches for comprehensively and quantitatively providing the desired evaluation on the heart health. They are: 1) 3D CINE MRI for structural and functional evaluation; 2) 4D flow MRI for myocardial regional function and blood flow assessment; and 3) 3D quantitative parametric mapping for tissue characterization, detecting myocardial fibrosis. They are highly accelerated free-breathing whole heart and aorta imaging techniques, which are well suitable for this fragile AS patient population who needs rapid acquisition, free breathing strategies, and no requirement of contrast administration. From the quantitative MRI measurements such as left ventricular ejection fraction (LVEF), LV hypertrophy, LV diastolic and systolic dysfunction, myocardial fibrosis, and aortic stiffness and distensibility, their association with severity of symptoms will be analyzed and best biomarkers for predicting symptomatic progression will be identified. This comprehensive quantitative MRI protocol for evaluation of myocardial tissue composition and function, and aortic abnormalities in patients with severe aortic valve stenosis will more accurately assess the effects of AS. More precisely, quantitative MR parameters may help predict development of symptoms and progression of symptom severity in patients with critical aortic stenosis, and improve current patient selection strategies for aortic valve replacement. Success of this project will have a strong impact on the health care system given the clinical importance of severe aortic stenosis, and the inability of current methods to reliably predict the development or progression of symptoms.