An acquisition and reconstruction framework to enable mesoscale human fMRI on clinical 3 Tesla scanners

一种采集和重建框架，可在临床 3 Tesla 扫描仪上实现中尺度人体 fMRI

• 批准号: 10481056
• 负责人: Kawin Setsompop
• 金额: $ 85.32万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10481056
• 关键词: 3-Dimensional; Address; Adoption; Animal Model; Animals; Benchmarking; Blood Vessels; Blood Volume; Blood flow; Brain; Brain imaging; Caliber; Cell Nucleus; Clinical; Communities; Consensus; Cortical Column; Coupling; Data; Data Set; Development; Dropout; Excision; Functional Imaging; Functional Magnetic Resonance Imaging; Goals; Human; Image; Imaging technology; Knowledge; Magnetic Resonance Imaging; Measurement; Measures; Medical center; Methods; Microscopic; Motor; Motor Cortex; Neurons; Noise; Outcome; Oxygen; Preparation; Protocols documentation; Research; Research Personnel; Resolution; Rest; Sampling; Scanning; Signal Transduction; Specificity; Speed; Techniques; Technology; Testing; Time; Weight; base; blood oxygen level dependent; blood oxygenation level dependent response; brain circuitry; cerebral blood volume; contrast imaging; experimental study; human imaging; image reconstruction; imaging approach; imaging modality; imaging study; improved; next generation; novel; optical imaging; preconditioning; reconstruction; relating to nervous system; response; simulation; spatiotemporal; targeted imaging; temporal measurement; tool; usability; volunteer

PROJECT SUMMARY/ABSTRACT Functional MRI (fMRI) is the most widely-used tool to noninvasively measure brain function and has produced much of our current knowledge about the functional organization of the human brain. However, all fMRI methods measure neuronal activity indirectly by tracking the associated local changes in blood flow, volume and oxygenation, which limit their spatiotemporal specificity to the underlying neuronal activity. While this is often viewed as the fundamental limitation of fMRI, recent optical imaging studies in animal models have shown a tight coupling between microvascular diameter changes and neural activity. These data indicate that human fMRI— as it is performed today—has vast untapped potential that can only be reaped if our measurements can be made sensitive exclusively to changes in these smallest blood vessels. Recent human studies have demonstrated that fMRI based on tracking changes in cerebral blood volume (CBV) with high sensitivity to microvascular diameter changes indeed provide improved neural specificity compared to the conventional blood-oxygenation-level- dependent (BOLD) method. Since the advent of fMRI, BOLD has been the most used fMRI contrast due to its robustness and high sensitivity, yet consensus is building that CBV provides far more faithful measurements of neural activity. Adoption of this powerful non-BOLD fMRI approach has been lacking due to its low sensitivity. To address this, we will develop new imaging methods to dramatically increase sensitivity of CBV-based fMRI. The key to our approach is the recognition that it is now possible, with advanced acquisition methods that we have recently developed, to separate “contrast encoding” in fMRI from image encoding. Because the standard image encoding with EPI in fMRI inherently introduces T2* weighting (and thus BOLD contrast), emerging non-BOLD techniques must inefficiently acquire two sets of data for every measurement to remove the unwanted BOLD contamination in post-processing. The need to acquire two sets of images, along with the necessary post-processing, plus the T2* signal loss combine to cause up to 4× SNR-efficiency loss. Our method, based on our distortion- and blurring-free Echo-Planar Time-resolved Imaging (EPTI) technology, overcomes this SNR loss by eliminating the unwanted BOLD weighting. We call our new framework “Mz fMRI” as it provides a means to generate fMRI contrast based purely on longitudinal magnetization (Mz), applicable to various non- BOLD fMRI methods. We will provide a proof of concept of this powerful framework by integrating EPTI with “VASO” to create an efficient CBV-fMRI without distortion, blurring, or the need for BOLD removal. Our simulations indicate that our approach will deliver sufficient sensitivity for sub-millimeter CBV-fMRI at 3T, and will perform better than existing CBV methods at 7T; the availability of these powerful methods at 3T will open non-BOLD fMRI up to the entire fMRI community, boosting neuronal specificity and enabling broad application of mesoscale fMRI—such as studies of cortical columns and layers and small subcortical nuclei— and thereby opening new possibilities for mapping whole-brain circuitry.

项目摘要/摘要 功能性MRI（fMRI）是无创测量大脑功能的最广泛使用的工具，并已产生 我们当前关于人脑功能组织的知识。但是，所有fMRI方法 通过跟踪血流，体积和体积和 氧合，将其空间时间特异性限制在潜在的神经元活性中。虽然这常常 被视为fMRI的基本局限性，动物模型中最近的光学成像研究表明 微血管直径变化和神经活动之间的耦合。这些数据表明人fMRI- 正如今天的那样，只有可以进行测量，才能收获巨大的未开发潜力 敏感的仅在这些最小的血管中改变。最近的人类研究表明 FMRI基于跟踪大脑血容量（CBV）的变化，对微血管直径高灵敏度 与常规的血氧水平相比，变化确实提供了改善的神经特异性。 依赖（粗体）方法。自fMRI冒险以来，BOLD一直是最常用的fMRI对比度 鲁棒性和高灵敏度，但共识正在建立，即CBV提供了更加忠实的测量 神经活动。由于其低灵敏度，因此缺乏这种强大的非智能磁场方法的采用。 为了解决这个问题，我们将开发新的成像方法，以显着提高基于CBV的fMRI的灵敏度。 我们方法的关键是认识到现在可以使用高级采集方法 我们最近开发了fMRI中的“对比度编码”与图像编码分开。因为 用fMRI中的EPI编码的标准图像固有地引入了T2*权重（因此是粗体对比度）， 新兴的非折叠技术必须降低每次测量的两组数据才能删除 后期处理中不必要的粗体污染。需要获取两组图像，以及 必要的后处理，以及T2*信号损失组合，最多可导致4×SNR效率损失。我们的方法， 基于我们的失真和模糊的回声平面时间分辨成像（EPTI）技术 通过消除不需要的大胆加权，这种SNR损失。我们称我们的新框架为“ MZ fMRI”，因为 一种纯粹基于纵向磁化（MZ）的fMRI对比的方法，适用于各种非 - 大胆的fMRI方法。我们将通过将EPTI与 “ VASO”创建有效的CBV-FMRI而不会失真，模糊或需要大胆去除。 我们的模拟表明我们的方法将对亚毫米毫米CBV-FMRI产生足够的敏感性 3T，并且在7T时的表现将比现有的CBV方法更好；这些功能强大的方法在3T上的可用性将 向整个FMRI社区开放非Bold FMRI，提高神经元特异性并实现广泛 中尺度fMRI的应用 - 例如对皮质柱和层以及小皮层核的研究 - 从而为绘制全脑电路绘制新的可能性。