Hewlett Miriam, Oran Omer, Liu Junmin, Drangova Maria
Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.
Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada.
Magn Reson Med. 2025 Apr;93(4):1642-1656. doi: 10.1002/mrm.30385. Epub 2024 Dec 3.
To perform prospective motion correction (PMC) for improved and susceptibility mapping using a purely navigator-based approach.
Spherical navigators (SNAVs) were combined with an additional FID readout for simultaneous measurement of motion and zeroth-order field shifts. The resulting FIDSNAVs were interleaved for PMC of a multi-echo gradient echo sequence with retrospective correction. Experiments were performed on a 3T scanner with a 32-channel head coil. Performance was assessed in five volunteers with motion prompts derived from real unintentional motion trajectories.
At short TEs, PMC alone was sufficient to achieve good image quality; at longer TEs, retrospective correction was often just as important for artifact reduction as motion correction. Both PMC and retrospective correction reduced error in and susceptibility maps for all participants. Residual artifacts were observed in the most severe motion case.
Combining SNAVs with an additional FID readout enables simultaneous motion and field correction with no additional hardware requirements, improving the fidelity of quantitative mapping in the presence of motion.
使用纯基于导航器的方法进行前瞻性运动校正（PMC）以改善成像和磁化率映射。
将球形导航器（SNAV）与额外的FID读出相结合，用于同时测量运动和零阶场偏移。所得的FIDSNAV进行交错排列，用于具有回顾性校正的多回波梯度回波序列的PMC。在配备32通道头部线圈的3T扫描仪上进行实验。在五名志愿者中进行了性能评估，其运动提示来自真实的非故意运动轨迹。
在短回波时间（TE）时，仅PMC就足以实现良好的图像质量；在较长TE时，回顾性校正对于减少伪影通常与运动校正同样重要。PMC和回顾性校正均降低了所有参与者的成像和磁化率映射中的误差。在最严重的运动情况下观察到残留伪影。
将SNAV与额外的FID读出相结合可实现同时的运动和场校正，无需额外的硬件要求，从而在存在运动的情况下提高定量映射的保真度。
