Efficient k-space sampling by density-weighted phase-encoding
Efficient k-space sampling by density-weighted phase-encoding
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DOI：
10.1002/mrm.10647
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发表时间：
2003-12-01
影响因子：
3.3
通讯作者：
von Kienlin, M
中科院分区：
文献类型：
--
作者：
Greiser, A;von Kienlin, M
采集加权提高了MRI实验的局部性。提出了一种基于k-空间采样密度变化的纯相位编码实验中捕获加权的方法。与以均匀增量对k空间进行采样的常规成像或累加加权不同，密度加权改变相邻采样点之间的距离Deltak以近似给定的径向加权函数。开发了一种快速、非迭代的算法，根据径向加权函数w(K)、期望扫描次数NA(Tot)和标称空间分辨率DelTax(Nom)计算一维、二维和三维的采样矩阵。密度加权相位编码结合了空间响应函数的改进形状和捕获加权的高信噪比以及扩展的视场。由小视场引起的混叠所产生的伪影能量大大降低。在仿真和实验中，将密度加权与均匀和累加加权相位编码的特性进行了比较。显示了人体心脏的密度加权(31)P 3D化学位移成像，显示了密度加权代谢成像的优越性能。(C)2003年Wiley-Liss，Inc.
Acquisition-weighting improves the localization of MRI experiments. An approach to acquisition-weighting in a purely phase-encoded experiment is presented that is based on a variation of the sampling density in k-space. In contrast to conventional imaging or to accumulation-weighting, where k-space is sampled with uniform increments, density-weighting varies the distance between neighboring sampling points Deltak to approximate a given radial weighting function. A fast, noniterative algorithm has been developed to calculate the sampling matrix in one, two, and three dimensions from a radial weighting function w(k), the desired number of scans NA(tot) and the nominal spatial resolution Deltax(nom). Density-weighted phase-encoding combines the improved shape of the spatial response function and the high SNR of acquisition-weighting with an extended field of view. The artifact energy that results from aliasing due to a small field of view is substantially reduced. The properties of density-weighting are compared to uniform and to accumulation-weighted phase-encoding in simulations and experiments. Density-weighted (31)P 3D chemical shift imaging of the human heart is shown which demonstrates the superior performance of density-weighted metabolic imaging. (C) 2003 Wiley-Liss, Inc.