Sampling errors in projection reconstruction MRI.
Sampling errors in projection reconstruction MRI.
复制标题
投影重建 MRI 中的采样误差。
DOI：
10.1002/mrm.1910400317
复制
发表时间：
1998
影响因子：
3.3
通讯作者：
Joseph,PM
中科院分区：
文献类型：
--
作者：
Joseph,PM
在磁共振成像（MRI）中使用投影重建（PR）技术时，已报告了某些类型的伪影。如果样本之间的间距油墨空间过大，则会发生这些情况。有人认为，PR比二维傅立叶重建需要更精细的空间采样，并且通常的奈奎斯特准则是不够的。本文研究了这个问题，得出的结论是，奈奎斯特采样标准足以避免混叠效应，前提是使用带限插值的墨水空间。该程序的动机是分析PR技术，因为它通常在X射线计算机断层扫描中实施。一个相关的问题是构造一个滤波函数ink‐space，它为低空间频率提供适当的权重。结果表明，一个simplekfilter不满足这一要求，并推导出一个合适的过滤器的程序进行说明。两种不同尺寸的圆盘的模拟PR配置文件的方法进行了测试。结果表明，这两种新的方法的组合，使几乎完美的重建磁盘的大小所隐含的奈奎斯特限制。
Certain kinds of artifacts have been reported when projection reconstruction (PR) techniques are used in magnetic resonance imaging (MRI). These will occur if the spacing between samples ink‐space is too large. It has been suggested that PR requires finerk‐space sampling than does two‐dimensional Fourier reconstruction, and that the usual Nyquist criterion is inadequate. This paper examines this problem, with the conclusion that the Nyquist sampling criterion is adequate to avoid aliasing effects, provided that a band‐limited interpolation is used ink‐space. This procedure is motivated by analysis of the PR technique as it is commonly implemented in x‐ray computed tomography. A related problem is shown to be the construction of a filter function ink‐space that gives proper weight to the low spatial frequencies. It is shown that a simplekfilter does not satisfy this requirement, and a procedure for deriving a suitable filter is described. The methods are tested in simulated PR profiles of circular disks of two different sizes. It is shown that the combination of the two new methods gives virtually perfect reconstruction for disks up to the size implied by the Nyquist limit.