Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
Magn Reson Med. 2024 Oct;92(4):1568-1583. doi: 10.1002/mrm.30149. Epub 2024 May 20.
To improve the spatial resolution and repeatability of a non-contrast MRI technique for simultaneous time resolved 3D angiography and perfusion imaging by developing an efficient 3D cone trajectory design.
A novel parameterized 3D cone trajectory design incorporating the 3D golden angle was integrated into 4D combined angiography and perfusion using radial imaging and arterial spin labeling (CAPRIA) to achieve higher spatial resolution and sampling efficiency for both dynamic angiography and perfusion imaging with flexible spatiotemporal resolution. Numerical simulations and physical phantom scanning were used to optimize the cone design. Eight healthy volunteers were scanned to compare the original radial trajectory in 4D CAPRIA with our newly designed cone trajectory. A locally low rank reconstruction method was used to leverage the complementary k-space sampling across time.
The improved sampling in the periphery of k-space obtained with the optimized 3D cone trajectory resulted in improved spatial resolution compared with the radial trajectory in phantom scans. Improved vessel sharpness and perfusion visualization were also achieved in vivo. Less dephasing was observed in the angiograms because of the short TE of our cone trajectory and the improved k-space sampling efficiency also resulted in higher repeatability compared to the original radial approach.
The proposed 3D cone trajectory combined with 3D golden angle ordering resulted in improved spatial resolution and image quality for both angiography and perfusion imaging and could potentially benefit other applications that require an efficient sampling scheme with flexible spatial and temporal resolution.
通过开发一种高效的 3D 锥形轨迹设计，提高非对比 MRI 技术用于同时进行时间分辨 3D 血管造影和灌注成像的空间分辨率和可重复性。
将一种新的参数化 3D 锥形轨迹设计（包含 3D 黄金角）整合到 4D 联合血管造影和灌注成像中，使用径向成像和动脉自旋标记（CAPRIA）实现更高的空间分辨率和更灵活的时空分辨率的动态血管造影和灌注成像的采样效率。数值模拟和物理体模扫描用于优化锥形设计。对 8 名健康志愿者进行扫描，以比较 4D CAPRIA 中的原始径向轨迹和我们新设计的锥形轨迹。使用局部低秩重建方法来利用跨时间的互补 k 空间采样。
与体模扫描中的径向轨迹相比，优化后的 3D 锥形轨迹在 k 空间外围获得的改进采样导致空间分辨率提高。在体内也实现了更好的血管清晰度和灌注可视化。由于我们的锥形轨迹的短 TE，血管造影中观察到的去相位较少，并且由于改进的 k 空间采样效率，与原始的径向方法相比，也实现了更高的可重复性。
所提出的 3D 锥形轨迹与 3D 黄金角排序相结合，可提高血管造影和灌注成像的空间分辨率和图像质量，并且可能有益于其他需要灵活时空分辨率的高效采样方案的应用。
