Hennig J
Department of Radiology, Section of Medical Physics, University Clinic of Freiburg, Hugstetterstrasse 55, D-79106 Freiburg, Germany.
Eur Radiol. 1999;9(6):1020-31. doi: 10.1007/s003300050788.
The k-space algorithm offers a comprehensive way for classification and understanding of the imaging properties of all commonly used MR sequences. This presentation describes the basic concepts of k-space and its most relevant properties for MR imaging. The ramifications of k-space sampling is discussed for the most commonly used groups of MR sequences including gradient-echo techniques, echo-planar imaging, spin echo, and rapid acquisition relation enhanced imaging (e. g., turbo spin echo, fast spin echo). In addition, the basic problems and properties of sequences based on non-rectilinear k-space sampling, such as spiral imaging, are discussed. Their artifact behavior is significantly different from rectilinear scans, which project all imperfections along the phase-encoding directions, whereas the artifact produced by spirals are more complex and not always easily recognizable as such. An understanding of the k-space sampling offers important insight into the basic properties of a given sequence regarding signal-to-noise ratio, image distortion, resolution and contrast. It is demonstrated that the ultimate limitation in imaging speed is given by the loss of signal-to-noise ratio inherent to faster data sampling.
k空间算法为分类和理解所有常用MR序列的成像特性提供了一种全面的方法。本报告描述了k空间的基本概念及其与MR成像最相关的特性。讨论了k空间采样对最常用的MR序列组的影响，包括梯度回波技术、回波平面成像、自旋回波和快速采集弛豫增强成像（如涡轮自旋回波、快速自旋回波）。此外，还讨论了基于非直线k空间采样的序列（如螺旋成像）的基本问题和特性。它们的伪影行为与直线扫描有显著不同，直线扫描会将所有缺陷沿相位编码方向投影，而螺旋产生的伪影则更为复杂，且不总是那么容易识别。了解k空间采样有助于深入了解给定序列在信噪比、图像失真、分辨率和对比度方面的基本特性。结果表明，成像速度的最终限制是由更快的数据采样所固有的信噪比损失所决定的。
