Time Domian Electron Paramagnetic Resonance Imaging

仪器：我们已经成功地集成了10 mT的EPRI和7 T的MRI的共振器组件，利用这两种模式之间300 MHz的共用射频。有了这一能力，我们开发了动物处理和扫描协议，允许顺序EPRI和MRI，而不必在扫描之间移动对象。这对研究的成功至关重要，因为EPRI扫描仪和核磁共振扫描仪位于10号楼的两个角落。所做的研究证明了这些实验的可行性，并且图像可以共同配准。此外，MRI方案在实验和计算上都进行了优化，以得出与EPRI生成的pO2图相关联的血流相关属性。正在设计一种新的谐振器组件，用于EPRI的工作频率为300 MHz，用于MRI的工作频率为128 MHz，以允许使用3T MRI进行类似的研究，该MRI现已在同一楼层的EPRI扫描仪附近提供。这将允许我们扩大研究，因为它提供了额外的MRI时间，这是目前的限制因素。我们还为EPRI建造了一个直径为7厘米的更大尺寸的谐振器，这将使我们能够获得关于EPRI在更大尺寸上的可行性的信息，以了解与射频加热和图像保真度相关的问题。这些信息对评估这项人类使用的技术将是有价值的。该磁体在最近完成的大口径磁体/梯度磁体上进行了测试，并成功地获得了定义对象的图像。我们还通过采用更灵敏的数字化仪，进一步改进了信号采集系统。在采集软件方面，进行了重大改进，以最大限度地减少控制软件的开销，从而能够在较短的时间间隔内采集图像。图像重建软件还经过优化，可以通过适当的用户界面处理大数据集，以便图像在采集后可以立即重建，从而可以立即对CAN条件进行任何更改。我们现在正在进行具有纵向成像能力的多模式肿瘤成像的体内常规研究，使我们能够在两周内检查同一动物，并检查治疗可能对氧合、血流和代谢状态的影响。

Instrumentation: We have successfully integrated a common resonator assembly for EPRI at 10 mT and MRI at 7 T taking advantage of a common RF of 300 MHz between the two modalities. With this capability, we have developed animal handling and scanning protocols to permit sequential EPRI and MRI without having to move the object between scans. This is critical for the success of the study since the EPRI scanner and MRI scanner are at two corners of Building 10. The studies done demonstrate the feasibility of these experiments and that the images can be co-registered. Additionally MRI protocols were optimized both experimentally and computationally to derive blood flow related properties to correlate with the EPRI generated pO2 maps. A new resonator assembly is being designed to operate at 300 MHz for EPRI and at 128 MHz for MRI to permit similar studies using a 3 T MRI now available in near proximity to the EPRI scanner on the same floor. This will allow us to expand the studies since it gives additional MRI time, which is currently the limiting factor. We also completed construction of a larger size resonator for EPRI with a diameter of 7 cm which will allow us to acquire information on the feasibility of EPRI on larger sizes to learn issues related to RF heating and image fidelity. This information will be valuable in evaluating this technique for human use. This magnet was tested in the recently completed large bore size magnet/gradients and images from defined objects were successfully obtained. We have also made additional improvements in the signal acquisition system by incorporating more sensitive digitizers. In terms of acquisition software, significant improvements were made to minimize overheads in the control software making it possible to acquire images in shorter time intervals. The image reconstruction software is also optimized to handle large data sets with appropriate user interfaces so that images can be readily reconstructed immediately after acquisition so that any changes in the can conditions can be made instantly. We are now conducting routine in vivo studies on multimodality tumor imaging with longitudinal imaging capabilities allowing us to examine the same animal over a two week period and examijne the impact treatments may have on oxygenation, blood flow, metabolic status.