Characterizing MRI parameters of iron-loaded tissues

描述(由申请人提供)： 该项目的总体目标是定量了解组织铁水平和核磁共振(核磁共振)特性之间的关系，以便开发一种严格测量大脑、肝脏和其他器官中铁的方法。铁是一种生理上至关重要的物质，但它也可能是有毒的，并与各种组织中的许多病理状态有关。正如最近NIDDK研讨会的报告中总结的那样，目前唯一建立的、经过校准的组织铁储存非侵入性测量方法是使用超导量子干涉装置(SQUID)磁强计的生物磁感应强度测量，但成本、复杂性和技术要求限制了这项技术的使用。许多先前的研究表明，磁共振成像(MRI)可以检测到铁的负荷，但还没有建立明确的方案来准确地测量组织中的铁含量。虽然核磁共振可以很容易地检测依赖于组织铁含量的各种信号参数，但这些参数(例如T1、T2、T2*、T2‘、Delta/omega)与存储的铁的浓度和形式的确切依赖关系是复杂和不清楚的。这一问题只能通过将铁代谢的研究与基本的核弛豫机制的研究和先进的MRI测量方案的开发相结合来解决。我们在范德比尔特的团队是唯一有资格采用这种方法的人。我们建议将铁超载动物模型的研究、先进的核磁共振技术和高分辨率的SQUID敏感性成像结合起来。这些实验与计算机模拟相结合，将允许对单个动物的生物磁学和核磁共振数据进行详细、定量的比较，这些动物的组织铁含量可以在每次实验结束时定量测定

DESCRIPTION (provided by applicant): The overall aims of this project are to understand quantitatively the relationships between tissue iron levels and nuclear magnetic resonance (NMR) properties in order to develop a method for rigorously measuring iron in the brain, liver, and other organs. Iron is a physiologically vital substance, but it also can be toxic and has been associated with numerous pathological states in various tissues. As summarized in the report of a recent NIDDK workshop, the only established, calibrated method for non-invasive measurement of tissue iron stores is currently biomagnetic susceptometry using Superconducting Quantum Interference Device (SQUID) magnetometers, but the cost, complexity, and technical demands limit access to this technique. Many previous studies have indicated that magnetic resonance imaging (MRI) can detect iron loading, but no clear protocol has been established to measure iron content in tissue accurately. While NMR can readily detect a variety of signal parameters that depend upon the iron content of tissue, the exact dependence of these parameters (e.g. T1, T2, T2*, T2', delta/omega on the concentration and form of the stored iron is complex and unclear. This problem can be addressed only by combining studies of iron metabolism with studies of fundamental nuclear relaxation mechanisms and the development of advanced MRI measurement protocols. Our group at Vanderbilt is uniquely qualified for such an approach. We propose to combine the study of an animal model of iron overload, advanced NMR techniques, and high-resolution SQUID susceptibility imaging. These experiments, in combination with computer simulations, will allow the detailed, quantitative comparison of biomagnetic and NMR data from individual animals whose tissue iron content can be determined quantitatively at the end of each experiment