Recent advances in parallel imaging for MRI.
Recent advances in parallel imaging for MRI.
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DOI：
10.1016/j.pnmrs.2017.04.002
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发表时间：
2017-08
影响因子：
6.1
通讯作者：
Seiberlich N
中科院分区：
文献类型：
--
作者：
Hamilton J;Franson D;Seiberlich N
磁共振成像（MRI）是现代医学的重要技术。然而，其主要缺点之一是在空间中定位MR信号以生成图像所需的长扫描时间。本文综述了并行成像的一些基本原理和最新进展，这是一类缩短扫描时间的图像重建技术。首先，涵盖了MRI数据采集的基本原理，包括k空间、欠采样和混叠的概念。它表明，扫描时间可以减少采样在k空间中的相位编码线的数量较少，但是，如果没有进一步的处理，所得到的图像将退化的混叠伪影。几乎所有现代临床扫描仪都从多个独立的接收器线圈阵列获取数据。并行成像方法利用这些线圈阵列的属性来分离图像域中的混叠像素或使用附近采集的k空间点的知识来估计缺失的k空间数据。三个平行的成像方法-SENSE，GRAPPA和SPIRIT-详细描述，因为它们是临床上使用的，并形成更先进的方法的基础。这些技术可以扩展到非笛卡尔采样模式，其中收集的k空间点不落在矩形网格上。非笛卡尔采集具有几个有益的特性，最重要的是不相干混叠伪影的出现。接下来介绍同时多切片成像的最新进展，其使用并行成像来解开已经一次采集的若干切片的图像。并行成像也可以用于加速3D MRI，其中扫描连续体积而不是连续切片。另一类相位约束并行成像方法利用图像幅度和相位两者来实现更好的重建性能。最后，一些应用程序的并行成像被用来加速磁共振波谱成像。
Magnetic Resonance Imaging (MRI) is an essential technology in modern medicine. However, one of its main drawbacks is the long scan time needed to localize the MR signal in space to generate an image. This review article summarizes some basic principles and recent developments in parallel imaging, a class of image reconstruction techniques for shortening scan time. First, the fundamentals of MRI data acquisition are covered, including the concepts of k-space, undersampling, and aliasing. It is demonstrated that scan time can be reduced by sampling a smaller number of phase encoding lines in k-space; however, without further processing, the resulting images will be degraded by aliasing artifacts. Nearly all modern clinical scanners acquire data from multiple independent receiver coil arrays. Parallel imaging methods exploit properties of these coil arrays to separate aliased pixels in the image domain or to estimate missing k-space data using knowledge of nearby acquired k-space points. Three parallel imaging methods—SENSE, GRAPPA, and SPIRiT—are described in detail, since they are employed clinically and form the foundation for more advanced methods. These techniques can be extended to non-Cartesian sampling patterns, where the collected k-space points do not fall on a rectangular grid. Non-Cartesian acquisitions have several beneficial properties, the most important being the appearance of incoherent aliasing artifacts. Recent advances in simultaneous multi-slice imaging are presented next, which use parallel imaging to disentangle images of several slices that have been acquired at once. Parallel imaging can also be employed to accelerate 3D MRI, in which a contiguous volume is scanned rather than sequential slices. Another class of phase-constrained parallel imaging methods takes advantage of both image magnitude and phase to achieve better reconstruction performance. Finally, some applications are presented of parallel imaging being used to accelerate MR Spectroscopic Imaging.
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影响因子：
3.3
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