High Resolution DTI Using 3D Single-Shot Acquisition

描述(申请人提供)：扩散张量成像(DTI)提供有关中枢和周围神经系统中白质束组织的信息。DTI已成功应用于脑束成像，在脑白质病变的早期诊断中具有潜在的应用价值。在多发性硬化症等疾病中，弥散张量的早期变化可能先于常规MRI扫描上可见的白质变化。然而，目前DTI技术的局限性阻碍了它在大脑的大部分以及脊髓、视神经和周围神经中的使用，在这些地方，MS的早期变化可能是明显的。扩散张量成像需要长时间的数据采集，因此容易受到场不均匀和患者运动引起的图像伪影的影响。随着成像速度的加快，这些伪影会减少。单次激发扩散张量成像方法已经发展到以更快的速度成像，从而以牺牲图像分辨率为代价来减少运动和不均匀伪影。已经开发了多激发方法以获得更高的分辨率，但这些方法容易受到多个采集之间的相位不一致引起的伪影的影响。我们发展了一种新的DTI技术，三维单次激发激发回波采集弥散加权成像(3DSS-DWSTEPI)，它在有限的成像体积上通过单次激发采集获得扩散信息。据我们所知，这是首次关于单次获得三维体的报道。该技术有可能克服当前使用的DTI技术的局限性。与二维成像相比，三维成像可以获得更高的信噪比，并且在切片边界没有信号损失。使用体积选择性激发来创建交错的三维子体积将允许以最佳回声序列长度进行更快的成像。在本项目中，提出了实时导航来监控任何可能降低DTI测量精度的过度运动相关误差，并拒绝/重新获取特定数据。这项拟议的技术有可能使目前DTI方法无法访问的重要区域，如脊髓、外周神经、视神经和大脑区域的DTI成为可能，从而使多发性硬化症等脑白质疾病的早期诊断成为可能。

DESCRIPTION (provided by applicant): Diffusion tensor imaging (DTI) provides information about the organization of white matter tracts in the central and peripheral nervous systems. DTI has been successfully applied to tractography of the brain, and has potential usefulness in early diagnosis of white matter disorders. Early changes in diffusion tensors may precede white matter changes visible on conventional MRI scans in diseases such as multiple sclerosis. However, limitations in current DTI techniques have prevented its use in much of the brain and in the spinal cord, optic nerves, and peripheral nerves, where early changes of MS may be manifest. Diffusion tensor imaging requires long data acquisitions and is therefore susceptible to image artifacts arising from field inhomogeneity and patient motion. These artifacts are reduced with faster imaging. Single- shot diffusion tensor imaging methods have been developed to image with greater speed, thus reducing motion and inhomogeneity artifacts, at the cost of image resolution. Multi-shot methods have been developed to attain higher resolution, but these methods are subject to artifacts caused by phase inconsistencies between multiple acquisitions. We have developed a novel DTI technique, three-dimensional single shot diffusion weighted imaging with stimulated echo acquisition (3D ss-DWSTEPI) which obtains diffusion information in a single shot acquisition over a limited imaging volume. To our knowledge, this is the first report on singleshot acquisition of three dimensional volume. This technique has the potential to overcome limitations of currently used DTI techniques. Three-dimensional imaging can give improved SNR and no loss of signal at the slice boundary in comparison with two-dimensional imaging. The use of volume-selective excitation to create interleaved three-dimensional subvolumes will allow faster imaging with optimal echo train lengths. In this project, realtime navigation is proposed to monitor any excessive motion related error which may reduce DTI measurement accuracy, and reject/reacquire the specific data. The proposed technique has the potential to make DTI possible in important areas such as the spinal cord, peripheral nerves, optic nerves, and regions of the brain not currently accessible by current DTI methods, allowing earlier diagnosis of white matter diseases such as multiple sclerosis.