Levine Evan, Daniel Bruce, Vasanawala Shreyas, Hargreaves Brian, Saranathan Manojkumar
Lucas Center, Departments of Electrical Engineering and Radiology, Stanford University, Stanford, California, USA.
Magn Reson Med. 2017 May;77(5):1774-1785. doi: 10.1002/mrm.26254. Epub 2016 Apr 21.
To enable robust, high spatio-temporal-resolution three-dimensional Cartesian MRI using a scheme incorporating a novel variable density random k-space sampling trajectory allowing flexible and retrospective selection of the temporal footprint with compressed sensing (CS).
A complementary Poisson-disc k-space sampling trajectory was designed to allow view sharing and varying combinations of reduced view sharing with CS from the same prospective acquisition. These schemes were used for two-point Dixon-based dynamic contrast-enhanced MRI (DCE-MRI) of the breast and abdomen. Results were validated in vivo with a novel approach using variable-flip-angle data, which was retrospectively accelerated using the same methods but offered a ground truth.
In breast DCE-MRI, the temporal footprint could be reduced 2.3-fold retrospectively without introducing noticeable artifacts, improving depiction of rapidly enhancing lesions. Further, experiments with variable-flip-angle data showed that reducing view sharing improved accuracy in reconstruction and T mapping. In abdominal MRI, 2.3-fold and 3.6-fold reductions in temporal footprint allowed reduced motion artifacts.
The complementary-Poisson-disc k-space sampling trajectory allowed a retrospective spatiotemporal resolution tradeoff using CS and view sharing, imparting robustness to motion and contrast enhancement. The technique was also validated using a novel approach of fully acquired variable-flip-angle acquisition. Magn Reson Med 77:1774-1785, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
采用一种结合新型可变密度随机k空间采样轨迹的方案，实现稳健、高时空分辨率的三维笛卡尔磁共振成像（MRI），该方案允许通过压缩感知（CS）灵活且回顾性地选择时间覆盖范围。
设计了一种互补泊松盘k空间采样轨迹，以允许视图共享以及在同一前瞻性采集中减少视图共享与CS的不同组合。这些方案用于基于两点狄克逊的乳腺和腹部动态对比增强MRI（DCE-MRI）。使用可变翻转角数据的新方法在体内对结果进行了验证，该数据使用相同方法进行回顾性加速，但提供了真实情况。
在乳腺DCE-MRI中，时间覆盖范围可回顾性地减少2.3倍，而不会引入明显伪影，从而改善了对快速强化病变的描绘。此外，可变翻转角数据实验表明，减少视图共享可提高重建和T映射的准确性。在腹部MRI中，时间覆盖范围减少2.3倍和3.6倍可减少运动伪影。
互补泊松盘k空间采样轨迹允许使用CS和视图共享进行回顾性时空分辨率权衡，增强了对运动和对比增强的稳健性。该技术还通过完全采集的可变翻转角采集的新方法得到了验证。《磁共振医学》77:1774 - 1785, 2017。© 2016国际磁共振医学学会。
