Development of contrast agents that image tumor-specific protease for Overhauser effect-enhaced MRI

Overhauser增强MRI（OMRI）是一种双共振技术，它使用氮氧自由基等顺磁试剂通过称为Overhauser效应的过程增强核自旋的信号强度。在这项研究中，树枝状聚（L-赖氨酸）聚合物修饰与稳定的硝酰基自由基通过底物肽的蛋白酶特异性表达在肿瘤中。蛋白酶对肽的切割影响了自由基的OMRI信号。该系统可作为OMRI功能性肿瘤成像技术的基础。

Overhauser-enhanced MRI (OMRI) is a double resonance technique that uses the presence of paramagnetic agents such as nitroxyl radicals to enhance the signal intensity from nuclear spins by a process known as the Overhauser effect. In this study, dendritic poly(L-lysine) polymers were modified with stable nitroxyl radicals through substrate peptides of a protease specifically expressed in tumors. Cleavage of the peptides by the protease affected the OMRI signal from the radicals. This system could be the basis of a functional tumor imaging technique by OMRI.