Advanced Neuroimaging through Novel Encoding Strategies and Hardware Design

项目摘要/摘要 最近的大规模研究使用核磁共振成像来更深入地了解我们的大脑是如何工作的。 健康和疾病。人类连接组项目(HCP)和英国生物库倡议使用Echo平面成像 (EPI)检查功能磁共振成像(FMRI)和弥散磁共振成像(DMRI)显示的大脑连接性。尽管计划免疫 为神经科学提供必要的快速编码，它受到严重失真伪影的困扰 影响B0场均匀度较差的区域，如颞叶和额叶。同时 多层(SMS)成像通常用于更高效的采样，高多波段(MB)因子几乎不会留下 用于面内加速的现有捕获方法中的编码能力。这使得图像失真保持不变 不加控制会阻碍大脑中调节决策、情绪和语义记忆的区域。此外， 神经成像方案通常使用低效的结构成像扫描，这会消耗很大一部分 分配的时间，这本来可以用于额外的fMRI和dMRI采样。 我们提出了协同硬件、收购和重建战略，以在以下领域提供倍增收益 图像失真，同时减轻EPI中的信号空洞和与T2*相关的体素模糊。我们将设计和建造一个 通道AC/DC组合接收和填隙脑阵列提供2倍以上均匀的B0场和 改进的并行成像能力。在脉冲序列方面，我们将为以下对象开发“Wave-caipi”轨迹 EPI，并优化利用我们的AC/DC阵列的编码能力，将面内加速提高到5倍。 这将与动态垫片的增益相乘，从而将失真降低10倍， 同时保留执行2倍短信加速的能力。即使在极端的甲基溴系数(例如8倍)下，我们也会 通过快速的功能磁共振成像，仍然可以将目标难以成像区域的失真降低到原来的1/3。我们还将发展 用交替相位编码方向采集EPI的2个镜头，并结合B0 MAP在重建中消除高分辨率dMRI中的失真。我们将在这些技术的基础上 并开发了一套基于EPI的全脑T1和T2参数的定量结构成像扫描 在90秒内以1 mm的各向同性分辨率绘制高几何保真度的地图。这些将使纵向 研究并为fMRI和dMRI的获取留出更多时间。 最后，我们将通过聚焦于腹内侧前额叶来验证fmri和dmri的改进。 大脑皮层和大脑奖励迂回，由于它们靠近空气/组织，都被置于具有挑战性的区域 接口。我们将比较开发的快速T1加权和T2加权捕获与常规T1- MPRAGE和T2-FSE通过执行形态测量分析进行扫描。我们将努力传播我们的 为下一代神经成像项目提供动力的开发，只需插入我们的线圈并安装 我们的序列。

Project Summary/Abstract Recent large-scale studies have employed MRI to gain a deeper understanding of how our brain works in health and disease. Human Connectome Project (HCP) and UK Biobank initiatives use Echo Planar Imaging (EPI) to examine brain connectivity as revealed by functional (fMRI) and diffusion MRI (dMRI). Although EPI empowers neuroscience with the necessary fast encoding, it is plagued by distortion artifacts that severely affect regions with poor B0 field homogeneity, such as the temporal and frontal lobes. While Simultaneous MultiSlice (SMS) imaging is routinely used for more efficient sampling, high MultiBand (MB) factors leave little encoding power in existing acquisition methods for in-plane acceleration. This lets the image distortion remain unchecked to hamper brain regions that regulate decision-making, emotions and semantic memory. Further, neuroimaging protocols often employ inefficient structural imaging scans that consume a large portion of the allotted time, which could have been used for additional fMRI and dMRI sampling. We propose synergistic hardware, acquisition and reconstruction strategies to provide multiplicative gains in image distortion, while mitigating signal voids and T2*-related voxel blurring in EPI. We will design and build a 64-channel “AC/DC” combined receive and shim brain array to provide >2× more uniform B0 field and improved parallel imaging capability. On the pulse sequence side, we will develop “wave-CAIPI” trajectories for EPI and optimally utilize the encoding power of our AC/DC array to push the in-plane acceleration to 5-fold. This will combine multiplicatively with the gain from dynamic shimming to yield >10-fold distortion reduction, while retaining the ability to perform 2-fold SMS acceleration. Even at extreme MB factors (e.g. 8-fold), we will still allow for a >3× reduction in distortion to target hard-to-image regions with fast fMRI. We will also develop “BUDA” acquisition to sample 2-shots of EPI with alternating phase encoding directions, and incorporate a B0 map in the reconstruction to eliminate distortion in high-resolution dMRI. We will build on these technologies and develop a suite of EPI-based quantitative structural imaging scans for whole-brain T1 and T2 parameter mapping with high geometric fidelity at 1mm isotropic resolution in 90 sec. These will empower longitudinal studies and leave more time for fMRI and dMRI acquisitions. Finally, we will validate the improvements in fMRI and dMRI by focusing on the ventromedial prefrontal cortex and the brain reward circuity, both placed in challenging regions due to their proximity to air/tissue interfaces. We will compare the developed rapid T1- and T2-weighted acquisitions against conventional T1- MPRAGE and T2-FSE scans by performing morphometric analysis. We will strive to disseminate our developments to fuel the next generation of neuroimaging projects, simply by plugging in our coil and installing our sequences.