Multifrequency interpolation for fast off-resonance correction
Multifrequency interpolation for fast off-resonance correction
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DOI：
10.1002/mrm.1910370523
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发表时间：
1997-05-01
影响因子：
3.3
通讯作者：
Macovski, A
中科院分区：
文献类型：
--
作者：
Man, LC;Pauly, JM;Macovski, A
场不均匀性或磁化率变化会导致使用非 2DFT k 空间读出轨迹获取的图像变得模糊。对于具有长读出时间的序列（例如螺旋成像），此问题更为明显。过去已经报道过基于获取的现场图的理论和实践校正方法。本文介绍了一种基于现有频率分段校正概念的新校正方法，但速度更快，理论上更准确，它包括在多个频率上重建数据以形成一组基础图像，然后将这些基础图像与从场图导出的空间变化线性系数相加。新算法应用于通过投影重建和螺旋序列获取的体模和活体图像，产生清晰聚焦的图像。
Field inhomogeneities or susceptibility variations produce blurring in images acquired using non-2DFT k-space readout trajectories, This problem is more pronounced for sequences with long readout times such as spiral imaging. Theoretical and practical correction methods based on an acquired field map have been reported in the past. This paper introduces a new correction method based on the existing concept of frequency segmented correction but which is faster and theoretically more accurate, It consists of reconstructing the data at several frequencies to form a set of base images that are then added together with spatially varying linear coefficients derived from the field map, The new algorithm is applied to phantom and in vivo images acquired with projection reconstruction and spiral sequences, yielding sharply focused images.