Time Domian Electron Paramagnetic Resonance Imaging

项目1：时间域电子顺磁共振成像：在氧含量为0%(缺氧)到21%(常氧)的规定条件下，使用包含三基对比剂Oxo 63、Oxo 31和Oxo 71的体模样品，验证了通过时域电子顺磁共振成像(EPRI)进行的氧成像的有效性。对这些样品进行的成像实验显示了与氧含量相一致的光谱响应。随后，对成像研究中的实验条件，如梯度大小、视场、成像时间和图像分辨率等进行了研究，得出了体内成像实验的最佳条件。对荷瘤小鼠等活体动物的研究表明，肿瘤和正常器官如肾脏、心脏、肝脏等积累了大量造影剂，造影剂分布的图像提供了足够的图像强度来提取生理信息。在仪器方面，扫描仪现在已经具备了使用时间分辨率为纳秒的整形射频脉冲提供均匀射频激励的能力。此外，现在已经开发了数据采集系统，以提供快速数据采集的能力，使得在不到5分钟内采集空间分辨率低于毫米的三维图像成为可能。有了这些能力，可以进行高时间和空间分辨率的活体实验。提取空间共同注册功能信息的数据分析程序现在正在测试中，以便可以进行常规的活体研究。

Project 1: Time Domian Electron Paramagnetic Resonance Imaging:The validation of oxygen imaging by Time Domain Electron Paramagnetic Resonance Imaging (EPRI) has been validated using phantom samples containing the trityl contrast agents Oxo 63, Oxo 31, and Oxo 71 under defined conditions of oxygen content in the range of 0% oxygen (anoxia) to 21 % oxygen (normoxia). Imaging experiments carried out on these samples showed spectral responses, which were in agreement with the oxygen content. Subsequently, experimental conditions in imaging studies such as the gradient magnitudes, field of view, imaging times and image resolution were studied and optimal conditions were arrived at for in vivo imaging experiments. Studies on live animals such as tumor bearing mice suggest that tumors and normal organs such as kidneys, heart, liver etc accumulate significant levels of the contrast agent and images of the contrast agent distribution provides enough image intensity to extract physiological information.With respect to instrumentation, the scanner has been now provided with capabilities to provide uniform RF excitation using shaped RF pulses with nanosecond time resolution. Additionally, data acquisition system has now been developed to provide capabilities for rapid data acquisition making it now possible to collect three-dimensional images with sub-mm spatial resolution in less than 5 minutes.With these capabilities, in vivo experiments can be carried out with high temporal and spatial resolution. Data analyses procedures to extract spatially co-registered functional information are now being tested so that routine in vivo studies can be performed.