Department of Radiology and Functional and Molecular Imaging Key Lab of Shaanxi Province, Tangdu Hospital, Air Force Medical University (Fourth Military Medical University), Xi'an, 710038, Shaanxi, People's Republic of China.
MR Research China, GE Healthcare China, Beijing, 100176, China.
BMC Med Imaging. 2020 Feb 10;20(1):14. doi: 10.1186/s12880-020-0419-0.
Our study aims to reveal whether the low b-values distribution, high b-values upper limit, and the number of excitation (NEX) influence the accuracy of the intravoxel incoherent motion (IVIM) parameter derived from multi-b-value diffusion-weighted imaging (DWI) in the brain.
This prospective study was approved by the local Ethics Committee and informed consent was obtained from each participant. The five consecutive multi-b DWI with different b-value protocols (0-3500 s/mm) were performed in 22 male healthy volunteers on a 3.0-T MRI system. The IVIM parameters from normal white matter (WM) and gray matter (GM) including slow diffusion coefficient (D), fast perfusion coefficient (D*) and perfusion fraction (f) were compared for differences among defined groups with different IVIM protocols by one-way ANOVA.
The D* and f value of WM or GM in groups with less low b-values distribution (less than or equal to 5 b-values) were significantly lower than ones in any other group with more low b-values distribution (all P < 0.05), but no significant differences among groups with more low b-values distribution (P > 0.05). In addition, no significant differences in the D, D* and f value of WM or GM were found between group with one and more NEX of low b-values distribution (all P > 0.05). IVIM parameters in normal WM and GM strongly depended on the choice of the high b-value upper limit.
Metrics of IVIM parameters can be affected by low and high b value distribution. Eight low b-values distribution with high b-value upper limit of 800-1000 s/mm may be the relatively proper set when performing brain IVIM studies.
本研究旨在探讨低 b 值分布、高 b 值上限和激发次数（NEX）是否会影响多 b 值扩散加权成像（DWI）脑内体素内不相干运动（IVIM）参数的准确性。
本前瞻性研究获得了当地伦理委员会的批准，并获得了每位参与者的知情同意。在 3.0T MRI 系统上对 22 名男性健康志愿者进行了 5 次连续的多 b 值 DWI，b 值方案不同（0-3500 s/mm）。通过单因素方差分析比较了不同 IVIM 方案定义组之间正常白质（WM）和灰质（GM）中 IVIM 参数（慢扩散系数 D、快灌注系数 D*和灌注分数 f）的差异。
低 b 值分布（小于或等于 5 个 b 值）较少的组的 WM 或 GM 的 D和 f 值显著低于其他低 b 值分布较多的组（均 P<0.05），但低 b 值分布较多的组之间无显著差异（P>0.05）。此外，低 b 值分布 NEX 为 1 次和更多次的 WM 或 GM 的 D、D和 f 值之间无显著差异（均 P>0.05）。正常 WM 和 GM 的 IVIM 参数强烈依赖于高 b 值上限的选择。
IVIM 参数的指标可能受到低 b 值和高 b 值分布的影响。在进行脑 IVIM 研究时，8 个低 b 值分布（高 b 值上限为 800-1000 s/mm）可能是比较合适的设置。
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