High-Res Multishot DTI by Real-Time Navigation

描述（由申请人提供）： 扩散张量（DT）MRI提供了关于组织中水分子微观流动性的独特信息，这是任何其他医学成像技术都无法获得的。弥散加权成像（DWI）已成为检测脑卒中细胞水肿区域的有力常规工具。DT-MRI通常用于检查大脑中各种白质疾病的有髓神经束。 然而，传统的DT-MRI技术是非常敏感的磁化率伪影，并不能实现很高的空间分辨率。对于高分辨率DT-MRI技术存在实质性的需求，该技术在诸如视神经、脑干、外周神经和脊髓以及心脏和一些其他器官的困难区域中工作。多激发DT-MRI技术可用于提高空间分辨率并克服磁化率伪影，但对大扩散梯度期间由于微观运动而引起的相位误差非常敏感。 该项目将完成开发，并对一种用于稳健高分辨率多次激发DT-MRI的新技术进行详细评价。该技术的新颖之处在于，它结合单个扩散加权来获得扩散制备磁化的两个分量，从而消除了由于扩散加权横向磁化中的残留相而引起的不均匀扩散加权。导航回波提供数据质量的测量，并允许通过动态数据重新采集减少伪影。为简洁起见，我们将该技术称为2D或3D nav-CADPaW-EPI（使用多次激发EPI的扩散准备和加权磁化的导航复合采集）。在成功开发、优化和测试脉冲序列后，我们将详细研究脑、脑干、视神经和脊髓中DT测量结果的准确性、可重复性和解剖学一致性。该技术也可以应用于任何解剖区域的敏感性伪影是严重的。本项目中开发和测试的技术应最终提高检测视神经和脊髓中早期MS病变的能力，并为均匀覆盖整个大脑和神经系统的白色物质纤维束成像提供更精细的细节。

DESCRIPTION (provided by applicant): Diffusion Tensor (DT) MRI provides unique information about the microscopic mobility of the water molecules in tissues that cannot be obtained with any other medical imaging technique. Diffusion weighted imaging (DWI) has become a powerful routine tool for detecting regions of cell edema in cerebral stroke. DT-MRI is generally used to examine the tracts of myelinated nerves for various white-matter diseases in the brain. However, conventional DT-MRI techniques are very sensitive to magnetic susceptibility artifacts, and cannot achieve very high spatial resolution. There is a substantial need for high-resolution DT-MRI techniques that work in difficult areas such as the optic nerves, brainstem, peripheral nerves, and spinal cord, as well as in the heart and some other organs. Multi-shot DT-MRI techniques could be used to increase spatial resolution and overcome susceptibility artifacts, but are very sensitive to phase errors due to microscopic motions during the large diffusion gradients. This project will complete the development and perform a detailed evaluation of a novel technique for robust high resolution multi-shot DT-MRI. The technique is novel in that it acquires both components of the diffusion prepared magnetization in conjunction with a single diffusion weighting and thereby eliminates non-uniform diffusion weighting due to residual phase in the diffusion weighted transverse magnetization. A navigator echo provides a measure of data quality and allows artifact reduction by dynamic data re-acquisition. For brevity, we refer to the technique as 2D or 3D nav-CADPaW-EPI (navigated composite acquisition of diffusion prepared and weighted magnetization using multi-shot EPI). After successful development, optimization, and testing of the pulse sequence, we will perform a detailed study of the accuracy, repeatability, and anatomic consistency of the resulting DT measurements in the brain, brain stem, optic nerve, and spinal cord. The technique can also be applied to any anatomic region where the susceptibility artifact is severe. The technique developed and tested in this project should ultimately improve the ability to detect early MS lesions in the optic nerve and spinal cord and provide finer detail for white matter tractography uniformly over the entire brain and nervous system.