Time Domian Electron Paramagnetic Resonance Imaging

项目摘要：a）用于人类应用的新型脉冲序列：我们实验室开发的EPR成像系统常规用于癌症小鼠模型（异种移植和原位模型）中肿瘤氧状态的临床前成像。按比例放大共振结构，以实现对pO 2的较大物体成像。为了在人体研究中实施，有必要开发一种使用低RF水平的信号形成方法，以符合FDA法规。开发了一种称为“弗兰克脉冲序列”的RF激励方案，与传统的50瓦功率相比，可以利用毫瓦的RF功率水平生成信号。这是可能的，通过开发一个RF模块，提供与相位的伪随机排序的激励脉冲和一个谐振结构，隔离的激励和信号接收。我们现在正在集成无线植入式射频线圈/氧气传感探头组件的系统，以进行长期氧气评估。已经开发了一种微型无线RF线圈（直径4 mm），其在生物相容性聚合物中嵌入顺磁性固体，可以植入体内，以测试在植入点监测组织氧的可行性。植入的射频无线线圈没有导线，但可以用外部线圈进行探测，该外部线圈可以激励无线线圈和顺磁探头。因此，该组件可以长期植入期望的部位，并且可以在数周/数月的时间段内监测氧气变化。初步研究表明，检测灵敏度提高了5-7倍。体内研究正在进行中。B）随着肿瘤氧动力学成像技术的进步，EPR成像技术有可能用于：a）监测放射后肿瘤的再氧合; B）肿瘤氧合与肿瘤移植物糖酵解之间的关系。

Project Summary: a) a) Novel Pulse sequences for human applications: The EPR imaging system developed in our lab is in routine use for pre-clinical imaging of tumor oxygen status in mouse models of cancer, both as xenografts and orthotopic models. Scaling up of resonant structures to enable imaging larger objects for pO2. For implementation in human studies, it is necessary to develop a signal formation method using low RF levels to comply with FDA regulations. An RF excitation scheme called "Frank Pulse Sequence" was developed whereby signals can be generated with RF power levels of milliwatt compared to the conventional power of 50 Watts. This was possible by the development of an RF module which delivers pulses of excitation with pseudo-random ordering of the phase and a resonant structure which isolates the excitation and signal reception. We are now in the process of integrating the system for Wireless implantable RF coil/oxygen sensing probe assembly for long term oxygen assessment. A miniature wireless RF coil (4 mm dia) with an embedded paramagnetic solid in a biocompatible polymer has been developed which can be implanted in vivo to test the feasibility of monitoring tissue oxygen at the point of implantation. The implanted RF wireless coil has no leads but can be probed with an external coil which can excite the wireless coil and the paramagnetic probe. Thus this assembly can be implanted chronically at desired sites and oxygen changes can be monitored over periods of weeks/months. Preliminary studies show that a 5-7 fold enhanced sensitivity of detection has been realized. In vivo studies are underway. b) With the improvements in imaging of tumor oxygen dynamics, it was possible to use EPR imaging to: a) monitor the post radiation tumor reoxygenation and b: relationship between tumor oxygenation and glycolysis in tumor xenografts.