Acquistion and Accuracy in Rapid NMR Imaging Methods
Acquistion and Accuracy in Rapid NMR Imaging Methods
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快速 NMR 成像方法的采集和准确性
DOI：
10.1002/mrm.1910020504
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发表时间：
1985
影响因子：
3.3
通讯作者：
D. Twieg
中科院分区：
文献类型：
--
作者：
D. Twieg
回声平面成像方法（EPI）及其变体可以在比傅里叶或投影重建方法更短的时间内获得足够的数据以形成图像。基于核磁共振成像中k -轨迹的采集公式，讨论了EPI和SEPI（一种使用正弦梯度波形的变体）对梯度波形和信号采样的基本要求。利用新的仿真方法，验证了EPI和SEPI的图像缺陷是由于不能满足这些要求而导致的。在快速成像中，忠实地再现理论上理想的梯度波形对梯度系统的响应提出了苛刻的要求。然而，如果使用适当的重建计算，则表明非理想梯度系统响应不会降低图像。推导了EPI和SEPI的传递函数和噪声功率谱，并使用这两个函数的比值来推导简单视觉解释任务的理想观测器信噪比。结果表明，在相同的核磁共振成像系统下，EPI和SEPI的理想观测器性能在某些视觉任务中存在显著差异。©1985学术出版社，Inc。
The echo‐planar imaging method (EPI) and its variants can acquire data sufficient to form an image in a much shorter time than the Fourier or projection‐reconstruction methods. Fundamental requirements on gradient waveforms and signal sampling are discussed for EPI and SEPI (a variant using sinusoidal gradient waveforms), based on the k‐trajectory formulation of acquisition in NMR imaging. Using a new simulation method, image defects in EPI and SEPI are demonstrated which result from failure to meet these requirements. Faithful rendition of theoretically ideal gradient waveforms places severe demands on gradient system response in rapid imaging. It is shown, however, that nonideal gradient system response need not degrade images if appropriate reconstruction computations are used. Transfer functions and noise power spectra are derived for EPI and SEPI, and the ratio of these two functions is used to derive ideal observer signal‐to‐noise ratios for simple visual interpretive tasks. It is shown that ideal observer performance can differ significantly between EPI and SEPI for some visual tasks, using the same NMR imaging system.© 1985 Academic Press,Inc.
影响因子：
3.8
作者：
TWIEG, DB
通讯作者：
TWIEG, DB