High Resolution Diffusion-Weighted Magnetic Resonance Imaging at 300-Micron Level

扩散加权成像(DWI)和扩散张量成像(DTI)是重要的磁共振成像技术 具有显著临床实用价值的成像(MRI)工具。但是，当前可用于DWI的空间分辨率为 通常约为每像素2 mm，这大大低于解剖学的亚毫米级分辨率 核磁共振检查。这种低空间分辨率严重限制了扩散磁共振成像在研究白质方面的能力。 例如，结构和完整性。DWI和DTI的超高场强及其新兴应用 儿童神经成像、小动物神经成像、手术计划和神经纤维束成像 产生了对1)更高的图像空间分辨率和2)更大数量的扩散梯度的强烈需求 方向。这项提案的总体目标是开发和改进先进的成像技术 和新的扩散分析模型。为此，我们建议采用一系列新技术 包括运动导航多镜头序列，多线圈并行成像，在高(3T)和超高 高磁场强度(7T)。固有的优点是多炮序列允许改进 数据采集方案具有较好的信噪比和较小的伪影，也缓解了数据采集的快速性问题 信号衰减；并行成像提供了一种缩短总扫描时间并进一步减少 图像伪影，而超高场以牺牲潜力为代价提供更强的SNR和T2*敏感度 手工艺品。尽管这些技术的协同在高分辨率DWI和DTI方面具有巨大的潜力， 许多技术挑战依然存在。本研究的具体目标是通过以下方式应对这些挑战：1) 开发具有3D运动导航和高效体积成像的多镜头DW序列；2) 开发多镜头并行图像采集技术和快速图像重建算法 可以在临床环境中高效、快速地对数千张图像进行后处理，最终；3)测量 高阶扩散张量参数用于解析多峰白质结构。这些高级 这些技术不仅可以更好地可视化和量化体内的水质子扩散过程 在几百微米的尺度上，还会显著提高图像的质量和速度 收购。这些技术最终将对扩散加权图像产生更好的诊断潜力， 最终，更准确地量化复杂的组织扩散特性。

Diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) are important magnetic resonance imaging (MRI) tools with significant clinical utility. However, current available spatial resolution for DWI is typically around 2mm per pixel, which is substantially lower than the submilimeter resolution of anatomical MRI. Such low spatial resolution severely limits the ability of diffusion MRI in investigating white matter structure and integrity, for example. Ultra high field strengths and emerging applications of DWI and DTI in pediatric neuroimaging, small animal neuroimaging, surgical planning and neural fiber tractography have created a strong demand for 1) higher image spatial resolution and 2) larger number of diffusion gradient directions. The overall goal of this proposal is to develop and refine advanced image formation techniques and novel diffusion analysis models. Towards this end, we propose to employ an array of novel techniques including motion navigated multi-shot sequences, parallel imaging with multiple coils, at high (3T) and ultra high magnetic field strengths (7T). Inherent advantages are that multi-shot sequences allow for improved data acquistion schemes with better SNR and reduced artifacts, which also alleviates the problem of rapid signal decay; parallel imaging provides a method for shortening the total scan time and further reducing image artifacts, while ultra high field offers stronger SNR and T2* sensitivity at the expense of potential artifacts. Although the synergy of these techniques holds great potential for high resolution DWI and DTI, many technical challenges remain. The specific aims of this research are to meet these challenges by: 1) developing multi-shot DW sequences with efficient volumetric imaging with 3D motion navigation and ; 2) developing multi-shot parallel imaging acquistion techniques and fast image reconstruction algorithms that can efficiently and rapidly post-process thousands of images in a clinical setting, and finally; 3) measuring higher order diffusion tensor parameters to resolve multi-modal white matter structures. These advanced techniques will not only allow better visualization and quantitation of in vivo water proton diffusion processes on the scale of a few hundred microns, but will also significantly improve the quality and speed of the image acquistions. These techniques will eventually result better diagnostic potential for diffusion-weighted images, and, ultimately, more accurate quantification of complex tissue diffusion properties.