Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
GE Global Research, Niskayuna, New York, USA.
J Magn Reson Imaging. 2020 Jan;51(1):296-310. doi: 10.1002/jmri.26792. Epub 2019 May 20.
Distortion-free, high-resolution diffusion imaging using DIADEM (Distortion-free Imaging: A Double Encoding Method), proposed recently, has great potential for clinical applications. However, it can suffer from prolonged scan times and its reliability for quantitative diffusion imaging has not been evaluated.
To investigate the clinical feasibility of DIADEM-based high-resolution diffusion imaging on a novel compact 3T (C3T) by evaluating the reliability of quantitative diffusion measurements and utilizing both the high-performance gradients (80 mT/m, 700 T/m/s) and the sequence optimization with the navigator acquisition window reduction and simultaneous multislice (multiband) imaging.
Prospective feasibility study.
PHANTOM/SUBJECTS: Diffusion quality control phantom scans to evaluate the reliability of quantitative diffusion measurements; 36 normal control scans for B -field mapping; six healthy and two patient subject scans with a brain tumor for comparisons of diffusion and anatomical imaging.
FIELD STRENGTH/SEQUENCE: 3T; the standard single-shot echo-planar-imaging (EPI), multishot DIADEM diffusion, and anatomical (2D-FSE [fast-spin-echo], 2D-FLAIR [fluid-attenuated-inversion-recovery], and 3D-MPRAGE [magnetization prepared rapid acquisition gradient echo]) imaging.
The scan time reduction, the reliability of quantitative diffusion measurements, and the clinical efficacy for high-resolution diffusion imaging in healthy control and brain tumor volunteers.
Bland-Altman analysis.
The scan time for high in-plane (0.86 mm ) resolution, distortion-free, and whole brain diffusion imaging were reduced from 10 to 5 minutes with the sequence optimizations. All of the mean apparent diffusion coefficient (ADC) values in phantom were within the 95% confidence interval in the Bland-Altman plot. The proposed acquisition with a total off-resonance coverage of 597.2 Hz wider than the expected bandwidth of 500 Hz in human brain could yield a distortion-free image without foldover artifacts. Compared with EPI, therefore, this approach allowed direct image matching with the anatomical images and enabled improved delineation of the tumor boundaries.
The proposed high-resolution diffusion imaging approach is clinically feasible on C3T due to a combination of hardware and sequence improvements.
3 TECHNICAL EFFICACY: Stage 1 J. Magn. Reson. Imaging 2020;51:296-310.
最近提出的无失真、高分辨率弥散成像技术 DIADEM（无失真成像：双编码方法）具有很大的临床应用潜力。然而，它可能会受到扫描时间延长的影响，其定量弥散成像的可靠性尚未得到评估。
通过评估定量弥散测量的可靠性，并利用高性能梯度（80 mT/m，700 T/m/s）和序列优化，结合导航采集窗口减少和同时多切片（多频带）成像，研究新型紧凑型 3T（C3T）上基于 DIADEM 的高分辨率弥散成像的临床可行性。
前瞻性可行性研究。
体模/受试者：扩散质量控制体模扫描，以评估定量扩散测量的可靠性；36 例正常对照扫描用于 B 场映射；6 例健康志愿者和 2 例脑肿瘤患者扫描，用于扩散和解剖成像比较。
磁场强度/序列：3T；标准单次回波平面成像（EPI）、多 shot DIADEM 弥散和解剖（2D-FSE [快速自旋回波]、2D-FLAIR [液体衰减反转恢复]和 3D-MPRAGE [磁化准备快速获取梯度回波]）成像。
扫描时间的缩短、定量扩散测量的可靠性以及健康对照和脑肿瘤志愿者高分辨率弥散成像的临床效果。
Bland-Altman 分析。
通过序列优化，高分辨率（0.86mm）、无失真、全脑弥散成像的扫描时间从 10 分钟缩短至 5 分钟。在 Bland-Altman 图中，所有体模的平均表观扩散系数（ADC）值均在 95%置信区间内。与 EPI 相比，该方法可以获得无折叠伪影的无失真图像，因为其总离频覆盖范围为 597.2Hz，宽于人脑预期带宽 500Hz。因此，该方法可以与解剖图像直接匹配，并能够改善肿瘤边界的描绘。
由于硬件和序列改进的结合，新型高分辨率弥散成像方法在 C3T 上具有临床可行性。
3 技术功效：1 级 J. Magn. Reson. Imaging 2020；51：296-310。
