Magnetic resonance imaging (MRI) contrast agents have become an important tool in clinical medicine. The most common agents are Gd(3+)-based complexes that shorten bulk water T(1) by rapid exchange of a single inner-sphere water molecule with bulk solvent water. Current gadolinium agents lack tissue specificity and typically do not respond to their chemical environment. Recently, it has been demonstrated that MR contrast may be altered by an entirely different mechanism based on chemical exchange saturation transfer (CEST). CEST contrast can originate from exchange of endogenous amide or hydroxyl protons or from exchangeable sites on exogenous CEST agents. This has opened the door for the discovery of new classes of responsive agents ranging from MR gene reporter molecules to small molecules that sense their tissue environment and respond to biological events.

中文翻译：

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用于磁共振成像的化学交换饱和转移造影剂。


磁共振成像（MRI）造影剂已成为临床医学的重要工具。最常见的试剂是基于 Gd(3+) 的复合物，它通过单个内球水分子与本体溶剂水的快速交换来缩短本体水 T(1)。目前的钆制剂缺乏组织特异性，并且通常对其化学环境不产生反应。最近，已经证明，MR 对比度可以通过基于化学交换饱和转移 (CEST) 的完全不同的机制来改变。 CEST 对比可源自内源酰胺或羟基质子的交换或外源 CEST 试剂上的可交换位点。这为发现新型反应剂打开了大门，从 MR 基因报告分子到感知组织环境并对生物事件做出反应的小分子。