Time Domian Electron Paramagnetic Resonance Imaging

项目概述：a) a)人类应用的新型脉冲序列：我们实验室开发的EPR成像系统常规用于肿瘤小鼠模型的临床前成像，包括异种移植和原位模型。放大共振结构，使pO2成像更大的物体。为了在人体研究中实施，有必要开发一种使用低射频电平的信号形成方法，以符合FDA的规定。一种称为“弗兰克脉冲序列”的射频激励方案被开发出来，与传统的50瓦功率相比，可以用毫瓦的射频功率水平产生信号。这可以通过开发射频模块来实现，该模块提供具有伪随机相位顺序的激励脉冲和隔离激励和信号接收的谐振结构。我们现在正在整合无线植入式射频线圈/氧传感探头组件系统，用于长期氧评估。在生物相容性聚合物中嵌入顺磁性固体的微型无线射频线圈（直径4毫米）已被开发出来，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引线，但可以通过外部线圈进行探测，该外部线圈可以激发无线线圈和顺磁探头。因此，该组件可以长期植入所需的部位，并且可以在数周/数月的时间内监测氧气的变化。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提高，利用EPR成像可以：a)监测放射后肿瘤再氧合，b：肿瘤氧合与异种移植肿瘤糖酵解的关系。

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.