衰老早期的组织学没有明显的病理学改变，因此用临床影像学方法来观察相关过程有相当的困难。本项目申请将开发一类新型靶向型磁共振成像造影剂的纳米四氧化三铁粒子，在组织细胞凋亡Caspase蛋白酶的作用下，可以在动物活体内选择性缩合为顺磁超纳米分子，并在9.4T高场条件下具备高灵敏度的检出能力。因此，可以通过这种全新的检测技术，对衰老早期脑组织内不同区域的起始衰老蛋白酶和作用衰老蛋白酶的分布进行准确的定量，从而实现磁共振成像在器官宏观尺度对衰老早期过程的直接观察与研究。

No significant tissue structure alternation is presented in early aging, thus make it difficult to observe the direct changes associated with early aging with clinical imaging methods. Here, we proposed a novel method based on a family of targeted iron oxide nano-particles. Under the catalysis of a family of cell apoptosis enzyme, Caspase3/7 or Caspase9, the nano-particles can further condense into paramagnetic supra-particles, can obtain a high level of sensitivity at 9.4T high field. By applying the novel method, MRI could be used to directly observe the associate changes at early aging, and to quantify the concentrations of initiator and active Caspase enzymes in different regions of the brain.