Cho M H, Kim W S, Cho Z H
Department of Electrical Science, Korea Advanced Institute of Science, Seoul.
Magn Reson Imaging. 1990;8(4):395-405. doi: 10.1016/0730-725x(90)90047-6.
The flow effects appear as a change of phase as well as signal intensity in NMR imaging. Since the flow of blood and CSF (cerebrospinal fluid) is pulsatile due to the heart pumping, their velocities are not constant during NMR imaging. This type of velocity fluctuation such as the blood or CSF flow induces irregular flow-dependent phase shifts, which have been one of the main causes of flow artifacts in NMR imaging. In order to reduce the flow artifacts, especially the CSF flow artifacts, a new cardiac cycle ordered phase encoding method is proposed and has been studied. This proposed technique utilizes the cardiac cycle as a precursor for the phase encoding gradients similar to the ROPE (respiratory ordered phase encoding) technique which has been used for respiratory motion artifact reduction. The basic concept and its applications are discussed together with the experimental results obtained with human volunteers using the KAIS 2.0 2.0 T whole-body NMR imaging system.
在核磁共振成像中，流动效应表现为相位变化以及信号强度变化。由于心脏泵血，血液和脑脊液（CSF）的流动是脉动的，在核磁共振成像过程中它们的速度并不恒定。这种速度波动，如血液或脑脊液流动，会引起不规则的与流动相关的相移，这一直是核磁共振成像中流动伪影的主要原因之一。为了减少流动伪影，特别是脑脊液流动伪影，提出并研究了一种新的心动周期有序相位编码方法。该技术利用心动周期作为相位编码梯度的前体，类似于用于减少呼吸运动伪影的ROPE（呼吸有序相位编码）技术。结合使用KAIS 2.0 2.0T全身核磁共振成像系统对人类志愿者进行实验所获得的结果，讨论了其基本概念及其应用。
