全心脏高分辨率联合T1和T1ρ定量磁共振成像技术研究及其在心肌梗死诊断中的应用

延迟强化心脏磁共振成像是目前对心肌梗死最具特异性和敏感性的诊断方法。然而延迟强化成像需要注射钆造影剂，不适用于肾功能障碍病人。非强化心肌参数T1和T1ρ均展示了区分梗死和健康心肌的潜力，但是目前仍缺乏研究比较二者诊断心肌梗死的能力。心肌参数测量通常需要在病人的一次屏气中采集多个对比度图像，有限的屏气时间限制了成像范围和空间分辨率，影响诊断。并且现有技术无法在一次扫描中同时测量T1和T1ρ，如果分别测量，两者之间的配准误差会影响比较结果。本项目将开发自由呼吸的全心脏高分辨率T1和T1ρ同时测量技术，利用图像导航矫正呼吸运动实现高采集效率，结合4-5倍稀疏采样，将扫描时间降低到临床可接受的5分钟内。基于开发出的新技术，本项目将开展临床研究，系统比较T1、T1ρ以及联合T1和T1ρ这三种参数图对心肌梗死病人的诊断效果，探究内源性对比的心肌T1/T1ρ参数图取代外源性对比的延迟强化成像的可行性。

Late gadolinium enhanced cardiac magnetic resonance imaging (LGE CMR) has been widely used in clinical practice for diagnosis of myocardial infarction (MI) due to its superior specificity and sensitivity. However, LGE CMR requires injection of gadolinium-based contrast agents, which is contradictive to patients with kidney dysfunction. Native myocardial T1 and T1ρ mapping by CMR has respectively shown the potential for differentiating infarcted and heathy myocardium. However, studies comparing the performance of the two parameters in diagnosing MI are still lacking. In addition, current myocardial mapping techniques commonly acquire a series of different contrast-weighted images under a single breath-hold, which limits the achievable imaging coverage and spatial resolution, affecting the clinical diagnosis. Furthermore, there is currently no available technique for simultaneous T1 and T1ρ quantification in a single scan. If measured separately, the possible mis-registration between T1 and T1ρ maps will influence their comparison..In this project, we will develop a free-breathing whole-heart high-resolution joint T1 and T1ρ mapping technique, where an image navigator (iNAV) will be used to measure and correct respiratory motion to achieve high respiratory acquisition efficiency. With 4x-5x undersampling for further acceleration, the scan time of the proposed CMR sequence will be reduced to a clinically acceptable 5 minutes. The developed technique will be used to image MI patients in a clinical study to systematically compare the diagnostic performance of the three sets of parametric maps: T1; T1ρ; joint T1 and T1ρ, as well as to investigate the feasibility of replacing exogenous contrast LGE CMR with endogenous contrast T1/T1ρ mapping.