Sparse sampling and constrained reconstruction for accelerated contrast enhanced magnetic resonance imaging

磁共振成像(MRI)是一种强大的手段，但仍然有限。旨在捕捉生理变化的时间分辨扫描因扫描时间过长而严重受阻。尤其是动态增强(DCE)磁共振成像，其目的是显示注射的造影剂通过血管系统时的流动情况。这项技术具有重要的临床价值，但仅由于获取的限制而很少实施。硬件的进步继续减少了扫描时间，但回报却在递减。迫切需要新的加速成像方法。我的研究计划由这项发现基金建立，将开发、验证和翻译用于高速动态核磁共振的新方法。 我的研究项目将探索稀疏采样和约束重建--统称为压缩传感(CS)--以实现更快的MRI。这些技术利用了众所周知的JPEG文件格式：图像可以使用其原始数据的一小部分来存储。CS假设，由于图像可以有效地存储，因此没有必要获取所有原始数据。这使得能够从比通常所需的更少的样本中形成图像，从而更快地成像。随着维度的增加，压缩变得更加有效，使得4D成像(即动态3D)成为加速的有力候选者。我的初步工作已经证明，DCE MRI能够适应极端的加速：加速比传统方法高出一个数量级是可行的。尽管其潜力很大，但针对CS的最佳方法尚不成熟。此外，高分辨率动态扫描的效用还没有被探索：相同的源数据将允许提取多个生理信息。目前，还没有MRI供应商生产CS-这是由于技术障碍，而不是实用程序。很明显，CS将在医学成像中发挥重要作用，但目前有效的技术阻碍了广泛采用。 本申请中详细说明的项目将构成以学员为重点的研究计划的基础，该计划的长期目标是开发、实施和商业化用于磁共振成像的先进数据采样和重建技术。这项建议的具体目标是： 目的1：设计用于加速4D成像的新的采集和重建算法。 目标2：制定一项全面的DCE考试。 目标3：实现这些技术的在线重建。 该项目的第一个目标将侧重于优化既适用于常规图像重建(尽管时间分辨率较低)又适用于约束重建(适用于高保真图像)的数据采集方法。该项目的第二个目标将利用目标1提供的极大改善的图像质量来提取多个临床数据。这在目前的DCE扫描中是不可能的，并且有可能彻底改变对比度增强成像的临床执行方式。第三个目标将努力将AIMS 1和AIMS 2定义的技术与MRI扫描仪紧密结合，以实现快速图像重建。这一目标经常被忽视，但对促进临床验证和加快商业化至关重要。 综上所述，这项应用提出了加速磁共振成像的技术创新。拟议的发明的应用远远超出了我们最初的临床应用(DCE)。学员参与、工业和临床合作以及商业化将是我研究计划的中心主题。

Magnetic resonance imaging (MRI) is a powerful modality but remains limited. Time-resolved scans, which aim to capture changing physiology, are severely hindered by long scan times. This is particularly true for dynamic contrast enhanced (DCE) MRI, which aims to visualize the flow of an injected contrast agent as it passes through the vasculature. This technique has significant clinical value yet is rarely performed due solely to acquisition limitations. Hardware advances continue to reduce scan times, but with diminishing returns. New methods for accelerated imaging are urgently needed. My research program established by this Discovery Grant will develop, validate, and translate novel methods for highly accelerated dynamic MRI. My research program will explore sparse sampling and constrained reconstruction—together termed compressed sensing (CS)—for faster MRI. These techniques exploit what is well known from the JPEG file format: images can be stored using a fraction of their original data. CS posits that since images can effectively stored, there is no need to acquire all of the original data. This enables image formation from fewer samples than are typically required—thus faster imaging. Compression becomes more effective as dimensions are added, making 4D imaging (i.e., dynamic 3D) a strong candidate for acceleration. My preliminary work has demonstrated that DCE MRI is amenable to extreme speed-ups: acceleration an order of magnitude beyond conventional methods is feasible. Despite its potential, optimal methods for CS are poorly established. Furthermore, the utility of high-resolution dynamic scans has not been explored: the same source data will allow extraction of multiple pieces of physiological information. Currently, no MRI vendor has productized CS—this is due to technological barriers, not utility. It is clear that CS will play a vital role in medical imaging but effective techniques currently preclude widespread adoption. The projects detailed in this application will form the basis of a trainee focused research program with a long-term goal to develop, implement, and commercialize advanced data sampling and reconstruction technologies for MRI. Specific aims of this proposal are: Aim 1: design novel acquisition and reconstruction algorithms for accelerated 4D imaging. Aim 2: develop a comprehensive DCE exam. Aim 3: implement on-line reconstruction of these techniques. The first aim of this project will focus on optimizing data acquisition methods that are amenable to both conventional image reconstruction (albeit with low temporal resolution) and to constrained reconstruction (for high fidelity images). The second aim of this project will exploit the vastly improved image quality available from Aim 1 to extract multiple pieces of clinical data. This is not possible from current DCE scans and has the potential to revolutionize how contrast enhanced imaging is performed clinically. The third aim will strive to tightly integrate the techniques defined by Aims 1 and 2 with the MRI scanner to enable rapid image reconstruction. This objective is often overlooked yet is crucial to facilitate clinical validation and to expedite commercialization. In summary, this application proposes technological innovations to accelerate MRI. Applications of the proposed inventions reach far beyond our initial clinical application (DCE). Trainee involvement, industrial and clinical collaborations, and commercialization will be central themes in my research program.