A HOMOGENEITY CORRECTION METHOD FOR MAGNETIC-RESONANCE-IMAGING WITH TIME-VARYING GRADIENTS
A HOMOGENEITY CORRECTION METHOD FOR MAGNETIC-RESONANCE-IMAGING WITH TIME-VARYING GRADIENTS
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DOI：
10.1109/42.108599
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发表时间：
1991-12-01
影响因子：
10.6
通讯作者：
MACOVSKI, A
中科院分区：
文献类型：
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作者：
NOLL, DC;MEYER, CH;MACOVSKI, A
当使用时变梯度进行成像时，非共振行为不仅会导致几何失真（如自旋-扭曲成像的情况），还会改变脉冲响应的形状并导致模糊。这种效应对于投影重建和螺旋卡帕空间扫描序列来说是众所周知的。我们在这里介绍了一种重建和均匀性校正方法，以纠正零阶的不均匀性的影响，利用先验知识的不均匀性。在该方法中，根据采集时间对数据进行分段，使用某种快速线性算法进行重建，校正不均匀性，然后叠加以产生均匀性校正图像。这种分段的方法相比，共轭相位重建的程度的校正和执行时间。我们应用这种方法在体内图像使用投影重建和螺旋扫描序列。
When time-varying gradients are used for imaging, the off-resonance behavior does not just cause geometric distortion as is the case with spin-warp imaging, but changes the shape of the impulse response and causes blurring. This effect is well known for projection reconstruction and spiral kappa-space scanning sequences. We introduce here a reconstruction and homogeneity correction method to correct for the zeroth order effects of inhomogeneity using a priori knowledge of the inhomogeneity. In this method, the data are segmented according to collection time, reconstructed using some fast, linear algorithm, corrected for inhomogeneity and then superimposed to yield a homogeneity corrected image. This segmented method is compared to a conjugate phase reconstruction in terms of degree of correction and execution time. We apply this method to in vivo images using projection-reconstruction and spiral-scan sequences.