Self-Navigated Multi-Contrast And Quantitative Whole Heart 3D Magnetic Resonance Imaging

心血管疾病（CVD）仍然是世界范围内主要的单一死因，尽管在预防和诊断和治疗方面取得了进展。CVD死亡的两个主要原因是由于斑块破裂和随后的血栓形成引起的突然冠状动脉粥样硬化血栓形成以及由于不利的心肌重塑和随后的梗死扩展引起的心肌梗死（MI）后的心力衰竭。冠状动脉粥样硬化的检测和不良心肌重塑的预测仍然具有挑战性的当前成像技术。尽管X射线冠状动脉造影术是检测冠状动脉狭窄的金标准，但其对于冠状动脉斑块的检测和表征的价值有限。多层螺旋CT（MSCT）是一种检测冠状动脉狭窄的优秀非侵入性替代方法，具有一定的冠状动脉斑块可视化和特征化能力，但其诊断用途仅限于无冠状动脉钙化的患者。正电子电子断层扫描（PET）对于心肌灌注和活力评估具有良好的诊断灵敏度，最近也被证明具有冠状动脉斑块可视化的潜力，但存在空间分辨率低和辐射暴露的问题，并且尚未广泛使用。超声心动图是评价左室功能和室壁运动异常的临床金标准。它便宜且易于使用，但严重依赖于操作员。由于上述限制，需要开发一种替代的和非侵入性的成像测试，其允许在没有上述限制的情况下进行全面的心脏评估。根据磁共振学会（SCMR）专家共识声明，磁共振成像（MRI）被认为是评估心脏解剖结构、左心室（LF）功能（CINE-MRI）、心肌活力（LGE-MRI）和灌注（MR-灌注）的金标准，因为其具有出色的软组织对比度、高空间分辨率和无电离辐射。最近的临床研究也证明了其对定量心肌组织表征（T1和T2弛豫时间标测）的有用性及其区分健康和患病组织的能力。然而，当前MRI采集方案的关键限制是所有成像序列（例如，CINE、LGE、T1和T2标测、冠状动脉MR血管造影（MRA）等）在不同的几何方向上，在不同的屏气位置或使用时间效率低的导航器门控方法顺序地采集。这带来了若干挑战：（1）放射技师需要高的专业知识来执行复杂的检查，（2）患者必须执行多次（> 30次）屏气，这对于患病患者来说是非常具有挑战性的，（3）检查的持续时间长，导致高的操作成本，以及（4）由于屏气位置、扫描几何形状和非各向同性空间分辨率的不同，数据融合是困难的。我们假设，基于图像的呼吸自导航结合图像加速技术将解决上述挑战，并允许提高自由呼吸（无屏气）三维（3D）多对比定量全心心脏MRI的可靠性和图像质量。所提出的方法将实现无创全面心脏检查，改善患者体验，提高诊断率和改善成本效益，从而改善NHS白色文件所概述的心血管疾病的治疗和结局。

Cardiovascular disease (CVD) remains the leading single cause of death worldwide despite improvements in prevention and advances in diagnosis and treatment. The two major causes for CVD death are sudden coronary atherothrombosis due to plaque rupture and subsequent thrombus formation and heart failure following myocardial infarction (MI) due to adverse myocardial remodeling and subsequent infarct expansion. Detection of coronary atherosclerosis and prediction of adverse myocardial remodeling remain challenging with current imaging techniques. While x-ray coronary angiography is the gold standard for the detection of coronary stenosis it has limited value for the detection and characterization of coronary plaque. Multislice computed tomography (MSCT) is an excellent non-invasive alternative for the detection of coronary stenosis and has some ability to visualize and characterize coronary plaque but its diagnostic use is limited to patients without coronary calcification. Positron electron tomography (PET) has good diagnostic sensitivity for myocardial perfusion and viability assessment and recently also has been shown to have potential for coronary plaque visualization but suffers from low spatial resolution and radiation exposure and is not widely available. Echocardiography is the clinical gold standard for the assessment of left ventricular function and wall motion abnormalities. It is cheap and easy to use but is heavily operator dependent. Due to the above limitations there is a need for the development of an alternative and non-invasive imaging test that allows for comprehensive cardiac assessment without the above restrictions. Magnetic resonance imaging (MRI) is considered the gold standard for the assessment of cardiac anatomy, left ventricular (LF) function (CINE-MRI), myocardial viability (LGE-MRI) and perfusion (MR-perfusion) due to its excellent soft tissue contrast, high spatial resolution and lack of ionizing radiation according to a Society for Magnetic Resonance (SCMR) expert consensus statement. Recent clinical research studies also have demonstrated its usefulness for quantitative myocardial tissue characterization (T1 and T2 relaxation time mapping) and its ability to differentiate between healthy and diseased tissue. However, a key limitation of the current MRI acquisition scheme is that all imaging sequences (e.g. CINE, LGE, T1 and T2 mapping, coronary MR angiography (MRA), etc.) are acquired sequentially, in different geometric orientations, at different breath-hold positions or using time inefficient navigator gating methods. This imposes several challenges: (1) radiographers need high expertise to perform the complex examination, (2) patients have to perform multiple (>30) breathholds which can be very challenging in sick patients, (3) the duration of the examination is long leading to high operational costs and (4) data fusion is difficult because of the different breathhold positions, scan geometries and non-isotropic spatial resolution. We hypothesize that image based respiratory self-navigation combined with image acceleration techniques will address the above challenges and allow improving the reliability and image quality of free-breathing (no breathholds) three-dimensional (3D) multi-contrast quantitative whole heart cardiac MRI. The proposed approach will enable non-invasive comprehensive cardiac examination with improved patient experience, higher diagnostic yield and improved cost effectiveness thereby improving the treatment and outcome of cardiovascular disease as outlined by the NHS white paper.