Advanced Techniques for Rapid and Artifact-Resistant MR Diffusion Imaging

描述（由申请人提供）：在过去十年中，MR扩散成像已发展成为评估卒中、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，最先进的MR扩散成像表现出显著的缺陷。广泛使用的2D单次激发扩散成像技术倾向于产生质量差的图像，通常遭受失真的图像几何形状和差的信噪比（SNR）。特别地，失真的图像几何形状妨碍与不同对比度或不同成像模态的图像的直接比较。在寻求更好的MR扩散成像脉冲序列时，已经提出了许多方法，如缩小视野成像、线和板扫描扩散成像（LSDI和SSDI）、单次激发平行扩散成像和分段多次激发扩散成像。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。在目前的工作中，主要的动机是通过将图像采集扩展到3D来大大缓解SNR问题。到目前为止，这种向3D的扩展一直受到扫描时间延长和运动伪影倾向的阻碍。拟议的研究引入了新的方法，有望克服这些缺点。具体目标是：1）针对通常较慢但非常抗伪影的LSDI和SSDI序列开发3D中的SNR中性并行化。2)沿第三维平行化多激发分段2D沿着，并开发具有运动相关相位误差的3D导航器校正的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制范围内，同时减少失真伪影。4)为了测试这些发展的幻影，在正常志愿者，并在神经上皮肿瘤患者，谁接受临床扫描的目的是手术治疗计划。 公共卫生相关性：磁共振成像测量和成像分子扩散的能力提供了一个新的图像对比度来源，并已被证明在评估中风相关的损伤和神经和肌肉的纤维结构非常有用。虽然3D扩散成像将呈现比2D成像显著的优势，但是到目前为止，它受到技术问题的阻碍，例如长采集时间和运动伪影。本申请旨在解决这些问题，以实现稳健且实用的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.