Multidimensional and Multiparametric Quantitative Cardiac MRI from Continuous Free-Breathing Acquisition

心血管疾病（CVD）是西方世界发病率和死亡率的主要单一原因，每年在英国造成65000多人死亡。改善心血管疾病的治疗和结果是国民保健服务的主要优先事项之一，到2025年将心血管疾病相关死亡率降低25%是联合国提出的主要挑战之一。磁共振成像（MRI）是一种非常有前途的无创工具，用于心血管疾病的早期风险评估、治疗指导和治疗监测。MRI已被证明可以提供心脏解剖的精细描述，被认为是评估心室容量和功能的金标准。最近，磁弛豫特性的定量制图（例如T1和T2弛豫时间）已经被开发出来，以标准化心肌组织特性的定量测量，从而实现病变和健康组织的非侵入性表征和分化。临床研究表明，参数化制图技术在量化弥漫性心肌纤维化（T1图）和评估心肌水肿和炎症（T2图）方面具有潜力。因此，磁共振参数映射提供了早期疾病检测和监测的希望，随着时间的推移或对治疗的反应，将磁共振范式从可视化转变为量化。目前MRI方案的局限性在于，所有这些图像（如心脏解剖、功能、T1图和T2图）都是顺序获取的，通常具有不同的分辨率、不同的几何方向和不同的屏气位置。该方案需要患者的配合，因为采集通常在多次屏气下进行，需要经验丰富的放射技师计划和执行不同的采集，并导致扫描时间长。此外，患者通常无法在同一呼吸体位屏气。因此，在不同的呼吸条件下获得的图像不能直接融合，从而影响心脏MRI的诊断、准确性和可重复性。本项目提出的方法将通过允许在整个心脏和呼吸周期内同时获取具有多个参数（例如心脏解剖，功能，T1图和T2图）的MR图像来克服这些问题。从而在提供解剖和功能信息的同时，提供多种组织参数的定量信息，从而实现高效（单次扫描，扫描时间更短，可预测），准确，简化（无需规划，患者更舒适），全面评估心血管疾病。

Cardiovascular disease (CVD) is the leading single cause of morbidity and mortality in the Western world, causing over 65.000 deaths every year in England. Improving the treatment and outcome of cardiovascular disease is one of the main priorities of the National Health Service (NHS) and a reduction of 25% in mortality associated to cardiovascular disease by the year 2025 is one of the major challenges proposed by the United Nations. Magnetic Resonance Imaging (MRI) is a very promising non-invasive tool for early risk assessment, guidance of therapy and treatment monitoring of CVD. MRI has been shown to provide exquisite depiction of cardiac anatomy and is considered the gold standard to assess ventricular volumes and function. More recently, quantitative mapping of magnetic relaxation properties (known as e.g. T1 and T2 relaxation times) have been developed to standardise the quantitative measurement of myocardial tissue properties, enabling non-invasive characterisation and differentiation of diseased and healthy tissue. Clinical research studies have shown the potential of parametric mapping techniques for quantification of diffuse myocardial fibrosis (T1 map) and the assessment of myocardial oedema and inflammation (T2 map). Thus, MR parameter mapping offer the promise of early disease detection and monitoring over time or in response to therapy, changing the MR paradigm from visualisation to quantification.The limitation of the current MRI scheme is that all these images (e.g. cardiac anatomy, function, T1 map and T2 map) are acquired sequentially, usually with different resolution, different geometric orientations and at different breath-hold positions. This scheme requires patient cooperation as acquisitions are usually performed under multiple breath holds, requires experienced radiographers to plan and perform the different acquisitions, and results in long scan times. Moreover patients are usually unable to hold their breath at the same respiratory position. Thus images acquired at different breath-holds cannot be directly fused thereby affecting diagnosis, accuracy and reproducibility of cardiac MRI. The method proposed in this project will overcome these problems by allowing the simultaneous acquisition of MR images with multiple parameters (e.g. cardiac anatomy, function, T1 map and T2 map), throughout the whole cardiac and respiratory cycles, from a single free-breathing acquisition. Thus providing anatomic and functional information simultaneously with quantitative information of multiple tissue parameters for an efficient (single scan, shorter and predictable scan time), accurate, simplified (less planning required and more comfortable for the patients) and comprehensive assessment of cardiovascular disease.