Department of Diagnostic Imaging, St Jude Children's Research Hospital, Memphis, Tennessee, USA.
J Magn Reson Imaging. 2021 Sep;54(3):997-1008. doi: 10.1002/jmri.27636. Epub 2021 Apr 15.
In archived diffusion tensor imaging (DTI) studies, a reversed-phase encoding (PE) scan required to correct the distortion in single-shot echo-planar imaging (EPI) may not have been acquired. Furthermore, DTI tractography is adversely affected by incorrect white matter segmentation due to leukoencephalopathy (LE). All these issues need to be addressed.
To propose and evaluate a modified DTI processing pipeline with DIstortion COrrection using pseudo T -weighted images (DICOT) to overcome limitations in existing acquisition protocols.
Retrospective feasibility.
DICOT was assessed in simulated data and 84 acute lymphoblastic leukemia (ALL) patients with reversed PE acquired. The pipeline was then tested in 522 scans from 261 ALL patients without a reversed PE acquired.
FIELD STRENGTH/SEQUENCE: A 3 T; diffusion-weighted EPI; 3D magnetization prepared rapid acquisition gradient echo (MPRAGE).
Repeated measures analysis of variance and Tukey post hoc tests were performed to compare fractional anisotropy (FA) values obtained by different methods.
FA and corresponding absolute error maps were obtained using TOPUP, DICOT, INVERSION (Inverse contrast Normalization for VERy Simple registratION) and NO CORR (no correction). Each method was assessed by comparing to TOPUP. The pipeline in the ALL patients was evaluated based on the failure rate of the distortion correction using the global correlation values.
Using DICOT reduced the mean absolute errors by an average of 32% in FA in simulation datasets. In 84 patients, the error reductions were approximately 15% in FA with DICOT, while it was 5% with INVERSION. No significant differences between the TOPUP and DICOT were observed in FA with P = 0.090/0.894(AP/PA). Only 15 of 516 examinations requiring any additional manual intervention.
This modified pipeline produced better results than the INVERSION. Furthermore, robust performance was demonstrated in archived patient scans acquired without an inverse PE necessary for TOPUP correction.
3 TECHNICAL EFFICACY: Stage 2.
在存档的扩散张量成像（DTI）研究中，可能没有采集到用于纠正单次回波平面成像（EPI）中失真的反转相位编码（PE）扫描。此外，由于脑白质病（LE），DTI 束追踪受到不正确的白质分割的不利影响。所有这些问题都需要解决。
提出并评估一种改良的 DTI 处理管道，使用伪 T 加权图像（DICOT）进行失真校正，以克服现有采集方案的局限性。
回顾性可行性。
在模拟数据中评估了 DICOT，并对 84 例采集到反转 PE 的急性淋巴细胞白血病（ALL）患者进行了评估。然后，在 261 例未采集反转 PE 的 ALL 患者的 522 例扫描中测试了该管道。
磁场强度/序列：3T；扩散加权 EPI；3D 磁化准备快速获取梯度回波（MPRAGE）。
采用重复测量方差分析和 Tukey 事后检验比较不同方法获得的分数各向异性（FA）值。
使用 TOPUP、DICOT、INVERSION（用于 VERy Simple registratION 的逆对比归一化）和 NO CORR（无校正）获得 FA 和相应的绝对误差图。每种方法都与 TOPUP 进行比较进行评估。基于全局相关值，评估 ALL 患者的管道中失真校正的失败率。
在模拟数据集上，使用 DICOT 平均可将 FA 的平均绝对误差降低 32%。在 84 例患者中，DICOT 下 FA 的误差降低约 15%，而 INVERSION 下为 5%。在 FA 中，TOPUP 和 DICOT 之间没有显著差异，P=0.090/0.894（AP/PA）。只有 516 次检查中的 15 次需要任何额外的手动干预。
与 INVERSION 相比，该改良管道产生了更好的结果。此外，在没有用于 TOPUP 校正的反转 PE 的情况下，对存档的患者扫描进行了稳健的性能演示。
3 技术功效：2 级。
