Advanced Quantitative Magnetic Properties Mapping of Tissue Microstructure

超高场（UHF > 3特斯拉）MRI技术的出现，无论是硬件还是MRI序列物理学，都引入了以前所未有的准确度可视化人体组织结构体内变化的可能性。因此，MRI体素级微结构的超高分辨率映射对于提供对神经发育、脑可塑性和细胞衰老的更细致的理解将是非常有影响的。该提议旨在扩展基于定量磁化率和弛豫测量的脑组织微结构的MRI模型，以基于7特斯拉（T）MRI数据创建中间分辨率微结构图。具体而言，通过使用50 - 150米的各向同性体素大小的中间分辨率，目前可实现7 T动物MRI，拟议的工作将寻求创建可重复的评估髓鞘双层，轴突和神经胶质细胞的磁化率特性。通过使用成像体素内的真实细胞几何形状和髓磷脂体积分数的计算模型，MRI测量将与潜在的生物学特征相关。总体而言，该建议旨在制定一个可重复的，定量的显微结构MRI方法来测量髓鞘体积分数和铁蛋白铁储存在神经胶质细胞在小鼠大脑中的量。MRI方法将开发和验证使用7 T MRI的cuprizone（CPZ）喂养的小鼠作为一个高度可控的生物系统，用于估计髓鞘体积分数和铁蛋白铁在脑白色matter.Impact的量：虽然传统的MRI对比可以可靠地描绘对比人脑组织，他们缺乏定量特异性。这对于基础和发育神经科学中的基础脑神经解剖学的MRI研究特别相关。非侵入性的，空间分辨定量的关键微结构特征在大脑中将显着增强MRI作为一种工具，神经发育，神经科学和脑老化的研究。同样重要的是，拟议的计划将为高素质的人员提供极好的培训机会，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。

MotivationThe 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 agingThis 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 ObjectiveThis 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.