MB-SWIFT as a novel approach for simultaneous functional imaging of the brain and spinal cord

摘要 我们的目标是建立一种新的MRI方法来同时从大脑获取功能磁共振(FMRI)数据 和脊髓。与标准的MRI读数不同，我们的方法不需要专门的垫片程序， 因为它是基于最新开发的名为多带扫描成像的零回波时间MRI脉冲序列 使用傅立叶变换(MB-SWIFT)，它对磁场不均匀具有固有的弹性。 对中枢神经系统(CNS)功能的全面评估将从中受益匪浅 成像方式，特别是在脊髓损伤、神经退行性疾病、疼痛等研究领域 和衰老。到目前为止，中枢神经系统的功能神经成像一直是一个尚未开发的研究领域，因为有几个 技术挑战，其中最大的挑战是需要有效地填补足够大的视场以覆盖 包括大脑和脊髓。已经提出了每切片动态垫片方法的解决方案。然而， 它们受到涡流稳定时间的限制，大大延长了实验过程，并且 它们仅适用于颈段(但不包括下段)脊髓。此外，动态垫片允许 只对大脑和脊髓进行低效的顺序采集，而不是同时采集，造成额外的 中枢神经系统功能磁共振成像面临的挑战。正如我们的初步数据所证明的那样，MB-SWIFT可以成像两个视场 (FOV)在大脑和腰髓的遥远位置以真正同时的方式(即，在1毫秒内 彼此)，从而允许对CNS进行前所未有的功能成像，这是标准的 功能磁共振成像的成像方式。目前的项目是在大鼠身上进行的概念验证研究，旨在首先 优化MB-SWIFT协议，包括双射频线圈和双视野捕获，然后演示 在没有专用垫片解决方案的情况下，MB-SWIFT的CNS功能磁共振成像可提供强大的功能磁共振成像结果。 此外，我们还将优化MB-SWIFT的辐条顺序和后处理流水线，以处理生理 噪声，并证明MB-SWIFT提供脊髓神经元活动的替代标记物。终于 我们将建立基于任务和静息状态的功能磁共振成像的对象间、对象内和站点间的重复性 使用双视野MB-SWIFT从中枢神经系统提取结果。一旦完成，该研究将提供一个 为临床前研究提供了宝贵的工具，并将为人类的翻译奠定基础。

ABSTRACT Our goal is to establish a novel MRI approach to acquire functional MRI (fMRI) data simultaneously from brain and spinal cord. Unlike standard MRI readouts, our approach does not require a dedicated shimming procedure, as it is based on the newly developed zero echo time MRI pulse sequence entitled Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) which is inherently resilient to magnetic field inhomogeneities. Comprehensive evaluations of the central nervous system (CNS) function will tremendously benefit from this imaging modality, particularly in areas of research such as spinal cord injury, neurodegenerative diseases, pain and aging. Thus far, functional neuroimaging of the CNS has been an untapped area of research due to several technical challenges, the biggest of which is the need to efficiently shim a field of view large enough to cover both brain and spinal cord. Solutions of per-slice dynamic shimming approaches have been proposed. However, they are limited by the settling-time of eddy currents, they considerably prolong the experimental session, and they have been applied only to cover cervical (but not lower) spinal cord. Furthermore, dynamic shimming allows only inefficient sequential rather than simultaneous acquisitions of brain and spinal cord, posing additional challenges for CNS fMRI. As proven by our preliminary data, MB-SWIFT can instead image two fields of view (FOVs) at distant locations in brain and lumbar spinal cord in a true simultaneous fashion (i.e., within 1 ms of each other), thus allowing unprecedented functional imaging of the CNS that is unattainable with standard imaging modalities for fMRI. The current project is a proof-of-concept study conducted in rats, designed to first optimize the MB-SWIFT protocol including the dual RF coil and the dual FOV acquisition, then to demonstrate that fMRI of CNS with MB-SWIFT provides robust fMRI outcomes in absence of dedicated shimming solutions. Moreover, we will optimize spoke order of MB-SWIFT and post-processing pipeline for handling physiological noise, and demonstrate that MB-SWIFT provides surrogate markers of neuronal activity in spinal cord. Finally we will establish inter-subject, intra-subject and inter-site reproducibility of task-based and resting-state fMRI outcomes extracted from the CNS with dual FOV MB-SWIFT. Once completed, the study will provide an invaluable tool for pre-clinical research, and will set the stage for translation to humans.