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

 描述(由申请人提供)：在这份规划拨款中，我们提出了几项工程开发，以推进磁粒子成像(MPI)，以取代MRI，成为人类神经科学的下一代脑功能成像工具。我们召集了一组技术专家来解决无数已识别和未知的障碍，我们使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，并通过对成像仪的特定部分进行台式测试来验证解决方案。最后，我们模拟了计划中的设备的整体性能，并评估了其对人类功能脑成像的益处。MPI是一项年轻但非常有前途的技术，它利用氧化铁纳米颗粒的非线性磁反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，而不是利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(从而检测局部脑血容量，CBV)来检测激活诱导和静息状态下大脑毛细血管网络中氧化铁浓度的变化。这种CBV对比源在动物和人类的fMRI研究中得到了很好的证实，这些研究使用相同的氧化铁剂通过MRI检测CBV的变化。但是，通过发展MPI作为检测手段，我们发现神经元激活的对比度噪声比(CNR)潜在地增加了120倍。这一天文数字的检测收益使改进MRI技术所预见的任何潜在收益相形见绌。例如，假设粗体的CNR与磁体强度的平方成比例，CNR的这种增加将相当于一台30特斯拉的MRI扫描仪，这显然是不可行的。我们预计，敏感性的恩惠将对神经科学产生即时和革命性的影响。它将不再需要执行组平均来查看激活或网络，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改进100倍，我们希望彻底改变适用于健康和疾病人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.