Song Xiaolei, Chan Kannie W Y, McMahon Michael T
Division of MR Research, The Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins School of Medicine, Baltimore, MD, USA.
Methods Mol Biol. 2011;771:171-87. doi: 10.1007/978-1-61779-219-9_9.
There has been a tremendous amount of interest in developing new MR contrast agents for cellular and molecular imaging applications such as the visualization of tumors, highlighting areas of angiogenesis, highlighting of contrast agent-labeled therapeutic stem cells, and highlighting of contrast agent-labeled drug delivery vehicles. The contrast properties of paramagnetic and super-paramagnetic relaxation-based agents have allowed MR imaging to be used as a tool for all of the above applications. However, a new class of MR contrast agents, chemical exchange saturation transfer (CEST) agents, provides additional features such as (1) the ability to highlight multiple biological events at once within an image through the distinguishability of the different CEST contrast agents, (2) the ability to toggle the contrast "off-to-on" by applying a saturation pulse, and (3) potentially providing more information about the environment surrounding the contrast agent such as the pH or concentration of metabolites. In this chapter, we will focus on the methods which can be used in terms of acquisition schemes and hardware to screen these agents through MR imaging.
在开发用于细胞和分子成像应用的新型磁共振（MR）造影剂方面，已经引发了极大的兴趣，这些应用包括肿瘤可视化、突出血管生成区域、突出造影剂标记的治疗性干细胞以及突出造影剂标记的药物递送载体。基于顺磁性和超顺磁性弛豫的造影剂的对比特性，使得MR成像能够用作上述所有应用的工具。然而，一类新型的MR造影剂，即化学交换饱和转移（CEST）造影剂，具有其他特性，例如：（1）能够通过不同CEST造影剂的可区分性，在一幅图像中同时突出多种生物学事件；（2）能够通过施加饱和脉冲将对比度“从关闭切换到开启”；（3）有可能提供更多关于造影剂周围环境的信息，例如pH值或代谢物浓度。在本章中，我们将重点关注在采集方案和硬件方面可用于通过MR成像筛选这些造影剂的方法。
