Contrast-enhanced magnetic resonance imaging is an essential tool for disease diagnosis and management; all marketed clinical magnetic resonance imaging (MRI) contrast agents (CAs) are gadolinium (Gd) chelates and most are extracellular fluid (ECF) agents. After intravenous injection, these agents rapidly distribute to the extracellular space and are also characterized by low serum protein binding and predominant renal clearance. Gd is an abiotic element with no biological recycling processes; low levels of Gd have been detected in the central nervous system and bone long after administration. These observations have prompted interest in the development of new MRI contrast agents based on biotic elements such as iron (Fe); Fe-HBED (HBED = N,N′-bis(2-hydroxyphenyl)ethylenediamine-N,N′-diacetic acid), a coordinatively saturated iron chelate, is an attractive MRI CA platform suitable for modification to adjust relaxivity and biodistribution. Compared to the parent Fe-HBED, the Fe-HBED analogs reported here have lower serum protein binding and higher relaxivity as well as lower relative liver enhancement in mice, comparable to that of a representative gadolinium-based contrast agent (GBCA). Fe-HBED analogs are therefore a promising class of non-Gd ECF MRI CA.

中文翻译：

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Fe-HBED类似物：用于磁共振成像的有前途的一类铁螯合造影剂。

增强磁共振成像是疾病诊断和管理的重要工具。所有市售的临床磁共振成像（MRI）造影剂（CA）都是g（Gd）螯合物，大多数是细胞外液（ECF）剂。静脉注射后，这些药物迅速分布到细胞外空间，其特征还在于血清蛋白结合率低和主要的肾脏清除率。Gd是一种非生物元素，没有生物循环过程；用药很长时间后，在中枢神经系统和骨骼中检测到低水平的Gd。这些发现促使人们对基于生物元素（如铁）的新型MRI造影剂的开发产生兴趣。Fe-HBED（HBED =  N，N'-双（2-羟苯基）乙二胺-N，N'-二乙酸）是配位饱和的铁螯合物，是一种有吸引力的MRI CA平台，适用于修饰以调节松弛度和生物分布。与亲本Fe-HBED相比，此处报道的Fe-HBED类似物在小鼠中具有较低的血清蛋​​白结合力和较高的弛豫性以及较低的相对肝脏增强能力，与代表性的ado基造影剂（GBCA）相当。因此，Fe-HBED类似物是有前途的非Gd ECF MRI CA类。