Bydder M, Atkinson D, Larkman D J, Hill D L G, Hajnal J V
Robert Steiner MRI Unit, Imaging Sciences Department, Clinical Sciences Centre, Imperial College, Hammersmith Hospital, London, UK.
Magn Reson Med. 2003 Mar;49(3):493-500. doi: 10.1002/mrm.10388.
The additional data acquired when using multiple receiver coils is commonly used to improve SNR or reduce acquisition times. It may also be used to remove image artifacts by selectively replacing corrupt data. In the present study, a correction scheme is presented based on simultaneous acquisition of spatial harmonics (SMASH) that enables detection and correction of motion artifacts caused by 2D translations. Newly measured data is compared with predictions from previously measured data by making negative and positive spatial harmonics. Differences are attributed to motion occurring in the interval between the acquisition of separate phase encode lines and correction parameters are determined. Two types of rigid body motion are considered: 1) object and coil array move, and 2) object only moves, since each causes different phase errors in k-space. Simulation, phantom, and volunteer experiments demonstrate the validity of the technique.
使用多个接收线圈时获取的额外数据通常用于提高信噪比或缩短采集时间。它还可用于通过选择性地替换损坏的数据来去除图像伪影。在本研究中，提出了一种基于空间谐波同步采集（SMASH）的校正方案，该方案能够检测和校正由二维平移引起的运动伪影。通过生成负空间谐波和正空间谐波，将新测量的数据与先前测量数据的预测值进行比较。差异归因于在单独的相位编码线采集之间的时间间隔内发生的运动，并确定校正参数。考虑了两种类型的刚体运动：1）物体和线圈阵列移动，以及2）仅物体移动，因为每种情况在k空间中会导致不同的相位误差。模拟、体模和志愿者实验证明了该技术的有效性。
