Quantitative MT imaging development and application

描述（由申请人提供）： 该项目的总体目标是开发和优化磁共振成像（MRI）技术，用于组织中大分子含量和动力学的新的定量测量，与脑髓鞘的表征特别相关。申请人在先前的工作中已经证明，新的MRI技术可以用于量化生物系统中大分子和游离水质子池的大小，并提供这些不同组织子成分之间的磁化转移（MT）速率常数的定量测量。所提出的研究将进一步发展和优化该技术，将该技术与其他MT技术进行比较，并将使用最佳技术结合多组分T2测量来研究白色物质和脱髓鞘病变中发生的水沉淀和交换率的变化。该项目的具体目标如下： * 进一步开发选择性反转恢复（SIR），并优化SIR和脉冲饱和技术，以实现定量测量新组织特性的速度、可靠性和准确性。 * 比较SIR与脉冲饱和度，并在对模型生物聚合物的一系列测量中针对已知标准验证这两种方法。 * 评估生物聚合物和健康大鼠体内定量MT成像的优化方法。 * 评估定量MT成像对组织学显示的脱髓鞘、炎症和轴突丢失引起的脑物质变化的敏感性，产生的信息将进一步发展MRI在多发性硬化症中的应用。

DESCRIPTION (provided by applicant): The overall goal of this project is to develop and optimize a magnetic resonance imaging (MRI) technique for novel quantitative measurements of the macromolecular content and dynamics in tissues with special relevance to the characterization of brain myelin. The applicant has demonstrated in previous work that a novel MRI technique can be used to quantify (he ralio of the sizes of macromolecular and free water proton pools in biological systems, and provide a quantitative measure of the magnetization transfer (MT) rate constant between these different tissue subcomponents. The proposed studies will further develop and optimize this technique, will compare this technique to other MT techniques, and \vll use the optimum technique in combination with multi-component T2 measurements to investigate the changes in water cempartmeritation and exchange rates that occur in white matter and demyelinated lesions. The specific aims of the project are as follows: * to further develop selective inversion recovery (SIR) and to optimize both SIR and the pulsed saturation technique for speed, reliability, and accuracy for quantitatively measuring novel tissue properties. * to compare SIR to pulsed saturation and to validate both these methods against a known standard in a series of measurements on model biopolymers. * to evaluate optimized methods of quantitative MT imaging in biopolymers and in vivo in healthy rats. * to evaluate the sensitivity of quantitative MT imaging to changes in brain matter due to demyelination, inflamation, and axonal loss as revealed by histology, producing information that will further develop applications of MRI in multiple sclerosis.