Approaches for hyperpolarized noble gas magnetic resonance imaging of rodent lungs

近年来，超极化稀有气体(HNG)，特别是氦-3和氙气-129极大地扩展了磁共振(MR)成像的能力，尤其是在可视化人类肺解剖和功能方面。HNG磁共振成像具有几个重要的优点：(I)安全，(Ii)高空间和时间分辨率，(Iii)功能信息。HNG的另一个新特征是，在磁场强度大大低于大多数传统MR成像系统的情况下，可以获得最佳的图像质量。低磁场可以降低磁共振的复杂性和成本，允许新的“开磁”几何结构来减少幽闭恐惧症，并允许探索体位对肺生理的影响。此外，低场下显著增加的横向弛豫时间为测量基本的远程气体扩散和肺部快速氧合变化提供了独特的机会，这在高场下是不可能的。这项研究的目标是：i)优化低场MR成像系统；ii)开发测量的低场HNG参数与肺的解剖和生理特性(表面积、气道大小、炎症和氧合)之间的关系的数学模型；iii)开发和验证对肺部疾病啮齿动物模型敏感的新的低场HNG成像方法。这项拟议的研究将在西安大略大学(罗巴茨研究所)的低场超极化磁共振成像实验室进行，该实验室部分由NSERC发现之前的资金建立。这项研究计划将汇集低场超极化磁共振成像实验室在体内生产和提供HNG、硬件和软件开发以及数学建模方面的专业知识，以及UWO物理系在脉冲场MR硬件方面的专业知识，以及UWO医学和牙科学院在发展啮齿动物肺部疾病实验模型方面的专业知识。这项研究的意义很高，因为低场HNG MRI是全新的，因此将为基础和应用知识的产生提供重要的机会。

Hyperpolarized Noble Gases (HNG), specifically helium-3 and xenon-129, have significantly expanded the capability of Magnetic Resonance (MR) imaging in recent years, most notably for visualizing human lung anatomy and function. HNG MR imaging offers several important advantages: (i) safety, (ii) high spatial and temporal resolution and (iii) functional information. A further novel feature of HNG is that the optimal image quality is achieved at magnetic field strengths substantially lower than most conventional MR imaging systems. Low field can reduce MR complexity and costs, allow new "open magnet" geometries for reduced claustrophobia and permit exploration of the effects of posture on lung physiology. Furthermore, the substantially increased transverse relaxation times available at low fields provides a unique opportunity to measure fundamental long-range gas diffusion and rapid oxygenation changes in the lung not possible at high fields. The objectives of the proposed research are: i) to optimize a low field MR imaging system; ii) to develop mathematical models of the relationships between measured low field HNG parameters and the anatomical and physiological properties of the lung (surface area, airway sizes, inflammation and oxygenation); iii) to develop and validate new low field HNG MR imaging methods sensitive to rodent models of lung disease. The proposed research will take place at the low field hyperpolarized MR imaging laboratory at the University of Western Ontario (Robarts Research Institute) established in part with previous NSERC Discovery funding. The research plan will bring together the expertise of the low field hyperpolarized MR imaging laboratory in the production and delivery of HNG in vivo, hardware and software development and mathematical modeling with the expertise of the Physics Department at UWO in pulsed-field MR hardware and the expertise of the UWO School of Medicine and Dentistry in the development of experimental models of lung disease in rodents. The significance of the proposed research is high as low field HNG MRI is entirely novel and therefore will provide significant opportunities for knowledge generation, both basic and applied.