Hennel F, Nédélec J F
FORENAP, MR Centre, Rouffach, France.
Magn Reson Med. 1995 Oct;34(4):520-4. doi: 10.1002/mrm.1910340406.
A version of interleaved echo-planar imaging (EPI) is presented in which only one polarity of the readout gradient is used for signal acquisition to avoid ghosting artifacts. Two possible forms of the phase encoding gradient, blipped and constant, are discussed. With the constant phase encoding, interleaving of partial trajectories in the Fourier domain (k-space) is controlled automatically by the echo train delay. The constant phase encoding gradient introduces a shear distortion of the k-space grid. A modification of the reconstruction procedure is given which corrects for this effect. The method provides a 128 x 128 image in 1 s on a clinical system with standard gradients.
本文介绍了一种交错回波平面成像（EPI）版本，其中仅使用读出梯度的一个极性进行信号采集，以避免重影伪影。讨论了相位编码梯度的两种可能形式，即快速跳变和恒定形式。对于恒定相位编码，傅里叶域（k空间）中部分轨迹的交错由回波链延迟自动控制。恒定相位编码梯度会引入k空间网格的切变失真。给出了一种重建过程的修正方法，用于校正这种效应。该方法在具有标准梯度的临床系统上1秒内可提供128×128的图像。
