Department of Radiology, Neuroradiology Section, Stanford Healthcare, 300 Pasteur Drive - S047, 94305, Stanford, CA, USA.
Institute for Biomedical Engineering, ETH Zürich, Gloriastrasse 35, 8092, Zürich, Switzerland.
Clin Neuroradiol. 2020 Sep;30(3):535-544. doi: 10.1007/s00062-019-00817-w. Epub 2019 Aug 2.
To determine the optimal combination of low b‑values to generate perfusion information from intravoxel incoherent motion (IVIM) in patients with acute ischemic stroke (AIS) considering the time constraints for these patients.
A retrospective cohort study of AIS patients with IVIM MRI was performed. A two-step voxel-by-voxel postprocessing was used to derive IVIM perfusion fraction maps with different combinations of b values. Signal values within regions of ischemic core, non-infarcted ischemic hemisphere, and contralateral hemisphere were measured on IVIM (f, D, fD, D) parameter maps. Bland-Altman analysis and the Dice similarity coefficient were used to determine quantitative and spatial agreements between the reference standard IVIM (IVIM with 6 b values of 0, 50, 100, 150, 200, 1000 s/mm) and other combinations of b values. Significance level was set at p < 0.05.
There were 58 patients (36 males, 61.3%; mean age 70.2 ± 13.4 years) included. Considering all IVIM parameters, the combination of b values of 0, 50, 200, 1000 was the most consistent with our reference standard on Bland-Altman analysis. The best voxel-based overlaps of ischemic regions were on IVIM D, while there were good voxel-based overlaps on IVIM f.
The IVIM with these four b values collects diffusion and perfusion information from a single short MRI sequence, which may have important implications for the imaging of AIS patients.
考虑到急性缺血性脑卒中（AIS）患者的时间限制，确定从体素内不相干运动（IVIM）生成灌注信息的低 b 值的最佳组合。
对接受 IVIM MRI 的 AIS 患者进行回顾性队列研究。采用两步体素后处理方法，从不同 b 值组合中得出 IVIM 灌注分数图。在 IVIM 参数图（f、D、fD、D）上测量缺血核心区、未梗死缺血半球和对侧半球的信号值。采用 Bland-Altman 分析和 Dice 相似系数来确定参考标准 IVIM（6 个 b 值为 0、50、100、150、200、1000 s/mm 的 IVIM）与其他 b 值组合之间的定量和空间一致性。显著性水平设为 p<0.05。
共纳入 58 例患者（36 例男性，61.3%；平均年龄 70.2±13.4 岁）。考虑所有 IVIM 参数，b 值为 0、50、200、1000 的组合在 Bland-Altman 分析中与我们的参考标准最一致。在 IVIM D 上，缺血区域的基于体素的重叠最好，而在 IVIM f 上，有很好的基于体素的重叠。
这四个 b 值的 IVIM 从单个短 MRI 序列中收集扩散和灌注信息，这可能对 AIS 患者的成像具有重要意义。
