ULTRAHIGH FIELD TECHNOLOGY FOR FUNCTIONAL IMAGING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 在越来越细微的范围内研究大脑功能结构的愿望一直是推动 开发高场强磁共振扫描仪(3特斯拉及以上)。这一努力的一个主要目标是将 将功能磁共振实验的仪器分辨率提高到我们可以探索功能磁共振的生物空间极限的水平。AS 目前使用的是3 mm的各向同性分辨率，功能成像甚至不能声称可以分辨皮质带状结构。 需要一个数量级的改进来容易地解决大脑皮层的下一个较低水平： 层状和柱状结构。虽然朝着这一目标取得了相当大的进展，但一个主要问题是 困扰着这些形状复杂的3D结构研究的是fMRI采集的2D性质。整体而言 因此，本研究的目标是开发3D各向同性功能磁共振成像编码方法，以降低功能磁共振成像的空间分辨率 同时避免了困扰研究的“炸薯条”形状的体素。使用大纵横比体素(通常向上 到在切片方向上长10倍)，所需的层状或柱状结构被部分体积效应稀释 除了在皮质的小区域，那里发生了偶然的排列。 由于空间分辨率受到固有敏感性和有限的空间编码能力的限制，我们将开发 高度并行的检测策略，以解决这些问题，并提供真正的3D单次激发体积功能磁共振成像 各向同性分辨率。我们通过开发高灵敏度96通道接收器来解决灵敏度和编码问题。 7特斯拉唯一用于脑功能成像的阵列系统。此外，我们还将开发模拟模式混合策略，以 形成检测元件的正交化线性组合，最大限度地提高灵敏度和编码能力 适用于具有少量RF通道的系统(如临床系统上的32个通道)。我们 开发单次激发方法以减少使用高速回波的多激发方法中的时间不稳定性。 体积轨迹和螺旋线堆叠轨迹。对于最高分辨率的研究，我们将利用并行技术开发变焦EVI 空间定制的2D和3D激励的传输加速。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The desire to study the structure of brain function at a finer and finer scale has been a major impetus for the development of high field strength MR scanners (3 Tesla and above). A major goal of this effort is to bring the instrumental resolution of the fMRI experiment to the level where we can explore the biological spatial limits of fMRI. As currently practiced with 3mm isotropic resolution, functional imaging cannot even claim to resolve the cortical ribbon. An order of magnitude improvement is needed to readily resolve the next lower level of the cerebral cortex: that of laminar and columnar structures. While considerable progress has been made toward this goal, a major problem plaguing the study of these complexly shaped 3D structures has been the 2D nature of the fMRI acquisition. The overall goal of this study is therefore to develop 3D isotropic fMRI encoding methods to reduce the spatial resolution of fMRI while avoiding the "french fry" shaped voxels which have plagued studies. With large aspect ratio voxels (commonly up to 10 fold longer in the slice direction), desired laminar or columnar structures are diluted by partial volume effects except in small regions of the cortex where a fortuitous alignment occurs. Because spatial resolution is limited by both intrinsic sensitivity and limited spatial encoding capability, we will develop highly parallel detection strategies to address these issues and provide true 3D single-shot volumetric fMRI with high isotropic resolution. We address the sensitivity and encoding issues by developing a high sensitivity 96 channel receive- only array system for functional brain imaging at 7 Tesla. Additionally we will develop analog mode-mixing strategies to form orthogonalized linear combinations of detection elements which maximize the sensitivity and encoding ability suitable for systems with a small number of RF channels (such as the 32 channels found on clinical systems). We develop single-shot methods to reduce the temporal instabilities in multi-shot methods using highly accelerated echo- volumnar and stack-of-spirals trajectories. For the highest resolution studies we will develop zoomed EVI utilizing parallel transmission acceleration of spatially tailored 2D and 3D excitations.