Quantitative MRS using phased arrays

描述（由申请人提供）：磁共振波谱（MRS）最引人注目的潜在用途之一是作为关键内源性化合物的无创生化分析。小规模研究表明，定量MRS (qMRS)（其结果以浓度形式报告）可以监测与癌症、狼疮、慢性疼痛综合征、慢性疲劳综合征、肝硬化和心肌病等疾病的诊断和治疗监测相关的生物标志物。鲁棒qMRS需要对信号激励、采集和处理过程中引入的众多尺度因子进行补偿。现有的补偿这些比例因素的方法需要极大的努力，除了最细致的研究地点外，对所有地方都是不切实际的。现有的方法也依赖于有问题的假设和/或导致痛苦的信噪比降低。因此，几乎所有的MRS结果都以任意单位或比率的形式呈现，这可能是模糊的或误导性的。要补偿的最繁重的比例因素是RF线圈负载条件和线圈接收灵敏度的变化。我们开发了一种减轻qMRS负担的方法。使用单通道表面线圈，我们之前已经证明这种方法适用于人类体内使用，并自动补偿线圈负载条件。在这个项目中，我们将把这种方法转化为最先进的多通道相控阵线圈，并增强算法，包括对射频线圈接收灵敏度的补偿。我们对增强算法的详细推导表明，它可以在不修改的情况下使用现成的相控阵实现。所有需要的是一个低成本的，独立的光电设备，完全独立于磁铁系统的软件和硬件。该装置的两个功能是将稳定的、预校准的人工信号注入磁铁内置的体线圈中，并测量体线圈中的相对电流。这些功能将允许qMRS与利用加速图像采集协议的化学移位成像序列集成。该项目的成功完成将使我们能够使用未经修改的相控阵和标准脉冲序列，提供高效、准确、定量、无创的人脑关键内源性化合物浓度图，没有信噪比损失，与以任意单位报告结果的方法相比，几乎没有增加采集时间。

DESCRIPTION (provided by applicant): One of the most compelling potential uses of magnetic resonance spectroscopy (MRS) is as a noninvasive biochemical assay for key endogenous compounds. Small-scale studies suggest that quantitative MRS (qMRS), in which the results are reported as concentrations, can monitor biomarkers associated with diagnosis and treatment monitoring for diseases such as cancer, lupus, chronic pain syndrome, chronic fatigue syndrome, liver cirrhosis and cardiomyopathy. Robust qMRS requires compensation for the numerous scale factors introduced during signal excitation, acquisition and processing. Existing methods that compensate for these scale factors require acute diligence and are impractical for all but the most meticulous research sites. Existing methods also rely on questionable assumptions and/or lead to painful reductions in signal to noise ratios. As a result, nearly all MRS results are presented in terms of arbitrary units or as ratios, which can be ambiguous or misleading. Among the most onerous scale factors to compensate for are variations in RF coil loading conditions and coil reception sensitivity. We have developed a method that eases the burden of qMRS. Using single-channel surface coils we have previously demonstrated that this method is suitable for in vivo use in humans and automatically compensates for coil loading conditions. In this project we will translate the method to state-of-the-art, multi-channel phased array coils and enhance the algorithm to include compensation for RF coil reception sensitivity. Our detailed derivation of the enhanced algorithm shows that it can be implemented using off-the-shelf phased arrays without modification. All that is needed is a low-cost, discrete electro-optical device that operates completely independently from the magnet system software and hardware. The two functions of this device are to inject a stable, precalibrated artificial signal into the magnet's built-in body coil and to measure relative electrical current flow in the body coil. These features will allow qMRS to be integrated with chemical shift imaging sequences that take advantage of accelerated image acquisition protocols. Successful completion of this project will allow us to provide efficient, accurate, quantitative, noninvasive concentration maps of key endogenous compounds in human brains using unmodified phased-arrays and standard pulse sequences with no signal-to-noise ratio penalties, and virtually no increase in acquisition times compared to methods that report the results as arbitrary units.