Magnetic Particle Imaging (MPI) for Functional Brain Imaging in Humans

 描述（由申请人提供）：在这项计划资助中，我们提出了几项工程开发，以推进磁粒子成像（MPI）取代MRI作为人类神经科学的下一代功能性脑成像工具。我们召集了一组技术专家来解决无数已识别和未识别的障碍，我们采用模拟和台式实验来表征和测试这些技术障碍的解决方案，并通过台式测试成像仪的特定子部分来验证解决方案。最后，我们模拟了计划中的设备的整体性能，并评估其对人类功能性脑成像的益处。 MPI是一项年轻但极具前景的技术，它利用氧化铁纳米颗粒的非线性磁响应来定位它们在体内的存在。MPI直接检测纳米颗粒的磁化强度，而不是使用对磁共振弛豫时间的二次效应。因此，虽然MPI和MRI共享许多技术，但MPI方法不以任何方式使用MR现象。 我们的计划是通过监测局部氧化铁浓度（从而监测局部脑血容量，CBV）来检测脑毛细血管网络中氧化铁浓度的激活诱导和静息状态变化。这种CBV对比源在动物和人类fMRI研究中得到了很好的证明，这些研究使用相同的氧化铁试剂通过MRI检测CBV变化。但是，通过开发MPI作为检测方式，我们发现神经元激活的对比度噪声比（CNR）可能增加120倍。 这种天文探测的好处使改进MRI技术所设想的任何潜在好处都相形见绌。例如，考虑到BOLD CNR与磁体强度的平方成比例，CNR的这种增加将相当于30特斯拉MRI扫描仪，这显然是不可行的。我们设想灵敏度的布恩将对神经科学产生即时的革命性影响。它将消除执行组平均以查看激活或网络的需要，从而将分析带到影响临床医学所需的个体水平。通过将基本检测方法提高100倍，我们希望彻底改变适用于健康和疾病的人类大脑的非侵入性功能成像方法。

 DESCRIPTION (provided by applicant): In this planning grant we propose several engineering developments to advance Magnetic Particle Imaging (MPI) to replace MRI as the next-generation functional brain imaging tool for human neuroscience. We assemble a group of technology experts to solve a myriad of identified and unidentified barriers, we employ simulation and bench-top experiments to characterize and test solutions for these technical obstacles and validate solutions by bench testing specific sub-sections of the imager. Finally we simulate the overall performance of the planned device and assess its benefit for human functional brain imaging. MPI is a young but extremely promising technology that uses the nonlinear magnetic response of iron- oxide nanoparticles to localize their presence in the body. MPI directly detects the nanoparticle's magnetization rather than using secondary effects on the Magnetic Resonance relaxation times. Thus, while MPI and MRI share many technologies, the MPI method does not use the MR phenomena in any way. Our plan is to detect the activation-induced and resting-state changes in the iron-oxide concentration in the cerebral capillary network by monitoring the local iron oxide concentration (and thus local Cerebral Blood Volume, CBV). This CBV-contrast source is well-proven in animal and human fMRI studies which detect CBV changes by MRI using the same iron-oxide agents. But, by developing MPI as the detection modality, we show that there is a potential 120-fold increase in the contrast-to-noise ratio (CNR) of neuronal activation. This astronomical detection benefit dwarfs any potential benefit envisioned by improving MRI technology. For example, given that the BOLD CNR scales with the square of the magnet strength, this increase in CNR would be equivalent to a 30 Tesla MRI scanner, which is clearly infeasible. We envision the sensitivity boon will have an instantaneous and revolutionary impact on neuroscience. It will eliminate the need to perform group averaging to see an activation or networks, bringing analysis to the individual level needed to impact clinical medicine. By improving the basic detection methodology by 100 fold, we hope to revolutionize non-invasive functional imaging methods applicable to the human brain in health and disease.