Advanced Quantitative Magnetic Properties Mapping of Tissue Microstructure

动机***超高场（UHF bbbb3特斯拉）MRI技术的出现，无论是硬件还是MRI序列物理，都以前所未有的精度引入了可视化人体组织结构体内变化的可能性。因此，MRI体素级微观结构的超高分辨率映射对于提供更细致的神经发育，大脑可塑性和细胞衰老的理解将具有重要影响***本提案旨在扩展基于定量磁化率和弛豫测量的脑组织微观结构MRI模型，以创建基于7特斯拉(T) MRI数据的中分辨率微观结构图。具体来说，通过使用50 - 150米各向同性体素大小的中间分辨率，目前可以通过7 T动物MRI实现，提议的工作将寻求创建髓磷脂双层，轴突和神经胶质细胞磁化特性的可重复评估。MRI测量将通过在成像体素内使用真实细胞几何和髓磷脂体积分数的计算模型与潜在的生物学特征相关。******总体目标***本方案旨在建立一种可重复、定量的微结构MRI方法来测量小鼠大脑神经胶质细胞中髓磷脂体积分数和铁蛋白铁的储存量。该MRI方法将被开发和验证，使用7 T MRI对铜（CPZ）喂养的小鼠作为一个高度可控的生物系统来估计髓磷脂体积分数和脑白质中铁蛋白铁的数量。******影响：***虽然传统的MRI对比可以可靠地描绘人脑组织的对比，但它们缺乏定量特异性。这与基础神经科学和发育神经科学中基础脑神经解剖学的MRI研究特别相关。一种非侵入性的、空间分辨的大脑关键微观结构特征的量化将显著增强MRI作为神经发育、神经科学和脑衰老研究的工具。同样重要的是，该计划将为高素质人员提供良好的培训机会，并为增加对小鼠脑组织微观结构组织的理解奠定基础，最终目标是将这些发现/方法转化为人类成像。*****

Motivation***The advent of ultra high field (UHF > 3 Tesla) MRI technologies, both hardware and MRI sequence physics, has introduced the possibility of visualizing in vivo changes in human tissue structure with an unprecedented level of accuracy. Accordingly, an ultra-high resolution mapping of MRI voxel-level microstructure would be highly impactful for providing a more nuanced understanding of neurodevelopment, brain plasticity and cellular aging***This proposal aims to extend quantitative magnetic susceptibility and relaxometry-based MRI models of brain tissue microstructure to create intermediate resolution microstructure maps, based on 7 Tesla (T) MRI data. Specifically, by using an intermediate resolution of 50 150 m isotropic voxel sizes, presently achievable with 7 T animal MRI, the proposed work will seek to create reproducible assessments of myelin bilayer, axon and neuroglia magnetic susceptibility properties. MRI measurements will be related to underlying biological features by using computational models of realistic cell geometries and myelin volume fraction within an imaging voxel. ******Overall Objective***This proposal aims to formulate a reproducible, quantitative microstructure MRI method to measure both myelin volume fraction and the amount of ferritin iron stored in neuroglial cells in mouse brain. The MRI method will be developed and validated using 7 T MRI of cuprizone (CPZ)-fed mice as a highly controllable biological system for estimating myelin volume fraction and the amount ferritin iron in brain white matter.******Impact: ***While traditional MRI contrasts can reliably depict contrast in human brain tissue, they lack quantitative specificity. This is particularly relevant for MRI studies of fundamental brain neuroanatomy in basic and developmental neuroscience. A non-invasive, spatially resolved quantification of critical microstructural features in the brain would significantly enhance MRI as a tool for neurodevelopmental, neuroscience and brain aging research. Equally important, the proposed program will provide excellent training opportunities for highly qualified personnel, as well as set the basis for increased understanding of the microstructural organization of mouse brain tissue, with the ultimate goal of translating these findings/methods to human imaging.*****