Hyperpolarized 129Xe MRI: Development of hardware, software and its PET-based validation.

非侵入性体内吸入超极化129 MRI被证明是有用的可视化的通气肺区域，获得有关肺泡大小的区域信息，观察之间的氧交换的氙“溶解”在肺组织和红细胞，也成像的氙频率的脑供血。然而，即使经过20年的超极化129 MRI的发展，这种成像方式的基本局限性仍然无法解决。这种限制的一个很好的例子是129 μ m图像的低信噪比（SNR），这阻碍了对SNR高度敏感的许多新的采集方案的开发，例如各向同性体素静态通气成像、加速的多b值扩散加权MRI、肺组织和血液内的129 μ m气体和129 μ m的加速同时收集、129 μ m脑灌注成像、和129纳米生物传感器成像。129 Ω图像的低SNR主要有三个原因：由于图像采集时间有限，加上非最佳图像重建算法，目前存在的图像采集方法效率低下; MRI发射/接收线圈的灵敏度低;以及129 Ω超极化水平低，加上小批量生产。 通过利用基本的MRI原理，拟议的研究计划将解决几十年来悬而未决的129个MRI问题。这在加拿大是独一无二的，充分反映了我在129年MRI领域的进步。我在过去二十年中积累的丰富专业知识，沿着我在开发先进硬件方面的经验，将使我的研究团队能够克服该领域目前的技术挑战。该研究计划是开发、测试和验证新型129 MRI成像方法并将其与金标准灌注成像模式（PET）进行比较的绝佳平台。我的研究小组在2019年的一次实验中证明了这种测量的可行性。该项目的成功将向129名研究人员（加拿大的6个研究中心和许多国外研究中心）、行业（MRI硬件制造商）和临床医生证明肺和脑129 MRI成像的有用性。为什么这件事现在比以往任何时候都重要？129肺部MRI功能非常强大，是唯一一种用于肺部结构和功能测量的无辐射成像工具，由于Covid-19对肺部的损害，现在和将来都需要进行深入的研究和开发。该计划将为准确的肺损伤评估，治疗指导和治疗结果评估提供新的工具。此外，该研究计划还为HQP提供医学成像，MRI脉冲序列开发和硬件工程，深度学习，量子和热力学建模等领域的培训。

Non-invasive in-vivo inhaled hyperpolarized 129Xe MRI was proven to be useful for visualizing of the ventilated lung regions, obtaining regional information about the lung alveolar sizes, observing the oxygen-like exchange between a xenon "dissolved" in the lung tissue and red blood cells and also imaging of the brain blood supply on the xenon frequency. However, even after 20 years of developing hyperpolarized 129Xe MRI, the fundamental limitations specific to this imaging modality remain unresolvable. A good example of such limitation is the low signal-to-noise ratio (SNR) of 129Xe images, which impedes the development of many novel acquisition schemes that are highly sensitive to the SNR, such as isotropic voxel static ventilation imaging, accelerated multiple b-value diffusion-weighting MRI, accelerated simultaneous collection of 129Xe gas and 129Xe within lung tissue and blood, 129Xe brain perfusion imaging, and 129Xe biosensor imaging. There are three main reasons for low SNR of 129Xe images: the inefficient image acquisition methods that currently exist, due to the limited image acquisition time combined with non-optimal image reconstruction algorithms; low-sensitivity of the MRI transmit/receive coils; and the low level of 129Xe hyperpolarization in combination with the small volume production. By utilizing fundamental MRI principles, the proposed research program will solve decades of unresolved 129Xe MRI problems. This is unique for Canada and fully reflects my progress in the 129Xe MRI field. My extensive expertise, built over the last two decades, in developing acquisition methods along with my experience in building advanced hardware will allow my research team to overcome the current technological challenges in the field. This research plan is an excellent platform to develop, test and validate novel 129Xe MRI imaging methods and compare them to the gold standard perfusion imaging modality (PET). The feasibility of such measurements has been demonstrated by my research group in a single experiment in 2019. The success of this program will demonstrate the usefulness of lung and brain 129Xe MRI imaging to 129Xe researchers (6 sites in Canada and many abroad), industry (MRI hardware makers) and clinicians. Why does this matter now, more than ever? 129Xe lung MRI is extremely powerful and it is the only radiation free imaging tool for lung structure & function measurements, whose urgent need has emerged because of the damage Covid-19 does to the lung, requiring intensive research and development now and in the future. The proposed program will provide new tools for accurate lung damage assessment, therapy guidance, and treatment outcome evaluation. Furthermore, this research plan provides training for HQP in the fields of medical imaging, MRI pulse sequence development and hardware engineering, Deep Learning, quantum and thermodynamic modelling.