Design Optimization of Combined Magnetoencephalography and Susceptometry

描述（由申请人提供）：人脑活动涉及神经元活动和代谢、血流量和血氧水平时空变化的复杂相互作用。这些过程在大脑的神经血管单元中具有功能联系，这些神经血管单元由神经元、星形胶质细胞和血管平滑肌细胞组成。神经血管耦合受损与中风、高血压、癫痫、阿尔茨海默病和帕金森病有关，是人类大脑功能网络水平动力学的生物医学研究热点。目前的无创神经血管成像策略主要集中在功能磁共振成像（fMRI）和脑电图（EEG）的结合，以及近红外光谱（NIRS）和脑电图或脑磁图（MEG）的结合。然而，现有的多模态神经成像方法存在一些基本的局限性。fMRI的时间分辨率约为0.5 Hz，限制了研究神经血管耦合动力学的时间精度。近红外光谱克服了功能磁共振成像的速率限制，但只对大脑皮层的外部区域敏感。受试者排除是MRI的一个问题，对某些金属植入物的个体是不安全的，对幽闭恐惧症患者的耐受性很差。迫切需要工程进步来提供空间分辨率，高速，匹配的神经和血液动力学生理学成像。该项目的目标是开发一种新的神经成像技术来满足这些需求。该系统采用了一种创新的方法来整合超导量子干涉器件（SQUID）的两种功能：生物磁强计测量磁化率和脑磁图（MEG）。脑磁图测量神经活动的基础是检测活跃神经元产生的磁场。SQUID敏感性测量检测血液中脱氧血红蛋白水平的变化，类似于fMRI，但时间采样更快。另一个好处是，该系统能够对磁性纳米颗粒进行高精度动态成像，这为靶向癌症治疗开辟了新的应用。由于该系统使用了超低磁场，它也可以用于研究植入电极阵列的癫痫患者的神经血管功能，以及植入深部脑刺激装置的帕金森病患者的神经血管功能。本项目旨在优化所提出的meg -电纳测量系统的空间分辨率和采样率，并对meg -电纳测量与EEG-fMRI进行对比分析。该项目的技术创新有可能在多模态神经成像中提供前所未有的精度和分辨率，从而在正常和病理生理条件下实现神经血管脑动力学的根本性突破。1

DESCRIPTION (provided by applicant): Human brain activity invokes a complex interplay of neuron activity and spatiotemporal variations in metabolism, blood flow and blood oxygen level. These processes are functionally connected in neurovascular units of the brain, which are composed of integrated networks of neurons, astrocytes, and vascular smooth muscle cells. Impaired neurovascular coupling is implicated in stroke, hypertension, epilepsy, Alzheimer and Parkinson diseases and is the subject of intense biomedical research on network-level dynamics of human brain function. Current strategies for noninvasive neurovascular imaging focus on combined functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) and to a lesser degree on combined near-infrared spectroscopy (NIRS) and EEG or magnetoencephalography (MEG). There are however some fundamental limitations to existing multimodal neuroimaging approaches. The temporal resolution of fMRI, on the order of 0.5 Hz, limits the temporal precision of investigations into the dynamics of neurovascular coupling. NIRS overcomes the rate limitation of fMRI but is only sensitive to the outer regions of the cerebral cortex. Subject exclusion is a concern with MRI, which is unsafe for individuals with certain metal implants and is poorly tolerated by individuals with claustrophobia. Engineering advances are urgently needed to deliver spatially resolved, high-speed, matched imaging of neural and hemodynamic physiology. The objective of this project is to develop a new neuroimaging technology that meets these needs. The proposed system uses an innovative approach to integrating two capabilities of the superconducting quantum interference device (SQUID): biomagnetometer measurement of magnetic susceptibility and magnetoencephalography (MEG). Measuring neural activity with MEG is based on detecting the magnetic fields produced by active neurons. SQUID susceptibility measurement detects changes in the level of deoxygenated hemoglobin in the blood, similarly to fMRI, but with faster temporal sampling. An added benefit is that the proposed system is capable of high-precision dynamic imaging of magnetic nanoparticles, which opens up novel applications for targeted cancer therapies. Since the proposed system uses ultra-low field magnetics it may also be used to study neurovascular function in epilepsy for patients with implanted electrode arrays and in Parkinson disease for patients with implanted deep brain stimulation devices. This project specifically aims to optimize the spatial resolution and sampling rate of the proposed MEG-susceptometry system and to perform a comparative analysis between MEG-susceptometry and EEG-fMRI. The technological innovations from this project have the potential of delivering unprecedented precision and resolution in multimodal neuroimaging that will enable fundamental breakthroughs in neurovascular brain dynamics in normal and pathophysiological conditions. 1