Phoenix Children's Hospital, Phoenix, Arizona.
Barrow Neurological Institute, Phoenix, Arizona.
Magn Reson Med. 2019 Apr;81(4):2501-2513. doi: 10.1002/mrm.27583. Epub 2018 Nov 16.
B eddy currents are a subtle but important source of artifacts in spiral MRI. This study illustrates the importance of addressing these artifacts and presents a system response-based eddy current correction strategy using B eddy current phase measurements on a phantom.
B and linear eddy current system response measurements were estimated from phantom-based measurement and used to predict residual eddy current effects in spiral acquisitions. The measurements were evaluated across multiple systems and gradient sets. The corresponding eddy current corrections were studied in both axial spiral-in/out TSE and sagittal spiral-out MPRAGE volunteer data.
Correction of B eddy currents using the proposed method mitigated blurriness in the axial spiral-in/out images and artifacts in the sagittal spiral-out images. The system response measurement was found to yield repeatable results over time with some variation in the B eddy current responses measured between different systems.
The proposed eddy current correction framework was effective in mitigating the effects of residual B and linear eddy currents. Any spiral acquisition should take residual eddy currents into account. This is particularly important in spiral-in/out acquisitions.
涡流是螺旋 MRI 中一种微妙但重要的伪影来源。本研究说明了解决这些伪影的重要性，并提出了一种基于涡流相位测量的系统响应涡流校正策略，该策略在体模上进行。
通过基于体模的测量来估计带宽和线性涡流系统响应测量值，并用于预测螺旋采集中的残余涡流效应。在多个系统和梯度集上评估了这些测量值。在轴向螺旋进出 TSE 和矢状螺旋输出 MPRAGE 志愿者数据中研究了相应的涡流校正。
使用所提出的方法校正 B 涡流减轻了轴向螺旋进出图像的模糊度和矢状螺旋输出图像的伪影。随着时间的推移，系统响应测量结果发现具有可重复性，而在不同系统之间测量的 B 涡流响应存在一些变化。
所提出的涡流校正框架有效地减轻了残余 B 和线性涡流的影响。任何螺旋采集都应考虑残余涡流。在螺旋进出采集时尤其重要。
