Advanced Techniques for Rapid and Artifact-Resistant MR Diffusion Imaging

描述(申请人提供)：在过去的十年中，磁共振扩散成像已经发展成为评估卒中、组织纤维结构和特征性组织水扩散的非常有用的工具。然而，与其他常用的MR图像对比相比，最新的MR扩散成像显示出明显的不足。广泛使用的2D单次激发扩散成像技术往往产生质量较差的图像，通常存在图像几何失真和信噪比(SNR)较低的问题。特别是，扭曲的图像几何结构排除了与不同对比度或不同成像模式的图像进行直接比较的可能性。为了寻找更好的MR扩散成像脉冲序列，已经提出了许多方法，如缩小视场成像、线和平板扫描扩散成像(LSDI和SSDI)、单激发平行扩散成像和分段多激发扩散成像。虽然所有这些方法都在一定程度上减少了扩散图像中经常出现的过度失真，但这种改进总是以增加扫描时间和/或降低SNR为代价的。在目前的工作中，主要的动机是通过将图像采集扩展到3D来极大地缓解信噪比问题。到目前为止，这种对3D的扩展一直受到扫描时间延长和运动伪影倾向的阻碍。这项拟议的研究引入了新的方法，有望克服这些缺点。其具体目标是：1)为通常较慢但非常抗伪像的LSDI和SSDI序列开发3D中信噪比中立的并行化。2)将多镜头分割的2D图像沿三维方向并行化，开发具有3D导航仪校正运动相关相位误差的3D扩散成像。3)开发新的加速方案，以将3D扩散成像扫描时间保持在实际限度内，同时还减少失真伪影。4)在幻影、正常志愿者和神经上皮性肿瘤患者中测试这些进展，这些患者为了外科治疗计划而接受临床扫描。 与公众健康相关：磁共振成像测量和成像分子扩散的能力提供了一种新的图像对比度来源，并已被证明在评估与中风相关的损害以及神经和肌肉的纤维结构方面非常有用。虽然3D扩散成像将显示出比2D成像显著的优势，但到目前为止，它一直受到技术问题的阻碍，例如采集时间长和运动伪影。本申请旨在解决这些问题，以实现稳健和实用的3D扩散成像。

DESCRIPTION (provided by applicant): Over the last decade MR diffusion imaging has evolved into an immensely useful tool to assess stroke, tissue fiber architecture, and characteristic tissue water diffusion. Nevertheless, compared with other commonly applied MR image contrasts, state-of-the art MR diffusion imaging exhibits significant deficiencies. The widely used 2D single-shot diffusion imaging techniques tend to produce images of inferior quality, often suffering from distorted image geometry and poor signal-to-noise ratio (SNR). In particular, distorted image geometries preclude direct comparisons with images of different contrast or different imaging modalities. In the quest for better MR diffusion imaging pulse sequences, numerous approaches have been suggested, like reduced field-of-view imaging, line and slab scan diffusion imaging (LSDI and SSDI), single-shot parallel diffusion imaging, and segmented multi-shot diffusion imaging. While all of these methods reduce to some extent the excessive distortions often present in diffusion images, such improvements invariably come at the expense of increased scan time and/or reduced SNR. In the present work, the main incentive is to greatly alleviate the SNR problem by extending the image acquisition to 3D. Until now, this extension to 3D has been hampered by prolonged scan times and proneness for motion artifacts. The proposed research introduces novel methods, which promise to overcome these disadvantages. The specific aims are: 1) To develop SNR-neutral parallelization in 3D for the typically slower, but very artifact- resistant LSDI and SSDI sequences. 2) To parallelize multi-shot segmented 2D along the third dimension and to develop 3D diffusion imaging with 3D navigator correction of motion-related phase errors. 3) To develop novel acceleration schemes to keep 3D diffusion imaging scan times within practical limits, while also reducing distortion artifacts. 4) To test these developments in phantoms, in normal volunteers, and in neuroepithelial tumor patients, who undergo clinical scans with the purpose of surgical treatment planning. PUBLIC HEALTH RELEVANCE: The capability of magnetic resonance imaging to measure and image molecular diffusion has provided a new source of image contrast and has proven extremely useful in assessing stroke-related damage and the fiber architecture of nerves and muscles. While 3D diffusion imaging would present significant advantages over 2D imaging, it has up to now been impeded by technical problems, such as long acquisition times and motion artifacts. The present application aims at solving these problems, to enable robust and practical 3D diffusion imaging.