Olsrud Johan, Nilsson Anders, Mannfolk Peter, Waites Anthony, Ståhlberg Freddy
MR Department, Center for Medical Imaging and Physiology, Lund University Hospital, SE-221 85 Lund, Sweden.
Magn Reson Imaging. 2008 Feb;26(2):279-86. doi: 10.1016/j.mri.2007.06.010. Epub 2007 Aug 28.
Clinical applications of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) depend heavily on robust paradigms, imaging methods and analysis procedures. In this work, as a means to optimize and perform quality assurance of the entire imaging and analysis chain, a phantom that provides a well known and reproducible signal change similar to a block type fMRI experiment is presented. It consists of two gel compartments with slightly different T2 that dynamically enter and leave the imaged volume. The homogeneous gel in combination with a cylindrical geometry results in a well-defined T2 difference causing a signal difference between the two compartments in T2-weighted MR images. From time series data obtained with the phantom, maps of percent signal change (PSC) and t-values are calculated. As an example of image parameter optimisation, the phantom is demonstrated to be useful for accurate determination of the influence of echo time (TE) on BOLD fMRI results, taking the t-value as a measure of sensitivity. In addition, the phantom is proposed as a tool for quality assurance (QA) since reproducible time series and t-maps are obtained in a series of independent repeat experiments. The phantom is relatively simple to build and can therefore be used by any clinical fMRI center.
血氧水平依赖（BOLD）功能磁共振成像（fMRI）的临床应用在很大程度上依赖于稳健的范式、成像方法和分析程序。在这项工作中，作为优化和执行整个成像与分析链质量保证的一种手段，我们展示了一种体模，它能提供与块式fMRI实验类似的已知且可重复的信号变化。它由两个T2稍有不同的凝胶隔室组成，这两个隔室动态地进入和离开成像体积。均匀的凝胶与圆柱形几何形状相结合，产生了明确的T2差异，导致在T2加权磁共振图像中两个隔室之间出现信号差异。根据用该体模获得的时间序列数据，计算信号变化百分比（PSC）图和t值图。作为图像参数优化的一个例子，该体模被证明可用于准确确定回波时间（TE）对BOLD fMRI结果的影响，将t值作为灵敏度的度量。此外，由于在一系列独立的重复实验中获得了可重复的时间序列和t图，该体模被提议作为质量保证（QA）的工具。该体模构建相对简单，因此任何临床fMRI中心都可以使用。
