Isotropic submillimeter fMRI in the human brain at 7 T: Combining reduced field-of-view imaging and partially parallel acquisitions
Isotropic submillimeter fMRI in the human brain at 7 T: Combining reduced field-of-view imaging and partially parallel acquisitions
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DOI：
10.1002/mrm.24156
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发表时间：
2012-11-01
影响因子：
3.3
通讯作者：
Turner, Robert
中科院分区：
文献类型：
--
作者：
Heidemann, Robin M.;Ivanov, Dimo;Turner, Robert
回波平面成像因其采集速度快而成为功能磁共振成像(FMRI)中应用最广泛的成像序列。然而，它容易出现局部失真、图像模糊和信号空洞。由于这些效应随着回波串长度和场强的增大而增大，因此在超高场下进行高分辨率回波平面成像是解决这些问题的关键。采用部分并行采集方法可以提高回波平面成像的成像质量。然而，部分并行捕获会受到混叠伪影和噪声增强的影响。另一种缩短回声序列长度的方法是减小视场(FOV)，同时保持相同的空间分辨率。然而，为了实现显著的加速，产生的FOV会变得非常小。当FOV选择不完整时，出现另一个问题，使得在减小的FOV之外存在来自区域的剩余信号混叠。本文提出了一种简化视场成像与部分并行捕获相结合的新方法。这种方法可以解决每种单独方法的上述问题，实现高质量的单次激发回波平面成像采集，具有亚毫米各向同性分辨率和良好的信噪比，用于超高场强的功能磁共振成像。这在7T的人脑功能磁共振成像中得到了证实，其各向同性分辨率为650微米。Magn Reson Med，2012。(C)2012年威利期刊公司。
Echo-planar imaging is the most widely used imaging sequence for functional magnetic resonance imaging (fMRI) due to its fast acquisition. However, it is prone to local distortions, image blurring, and signal voids. As these effects scale with echo train length and field strength, it is essential for high-resolution echo-planar imaging at ultrahigh field to address these problems. Partially parallel acquisition methods can be used to improve the image quality of echo-planar imaging. However, partially parallel acquisition can be affected by aliasing artifacts and noise enhancement. Another way to shorten the echo train length is to reduce the field-of-view (FOV) while maintaining the same spatial resolution. However, to achieve significant acceleration, the resulting FOV becomes very small. Another problem occurs when FOV selection is incomplete such that there is remaining signal aliased from the region outside the reduced FOV. In this article, a novel approach, a combination of reduced FOV imaging with partially parallel acquisition, is presented. This approach can address the problems described above of each individual method, enabling high-quality single-shot echo-planar imaging acquisition, with submillimeter isotropic resolution and good signal-to-noise ratio, for fMRI at ultrahigh field strength. This is demonstrated in fMRI of human brain at 7T with an isotropic resolution of 650 mu m. Magn Reson Med, 2012. (c) 2012 Wiley Periodicals, Inc.