Statistical noise analysis in GRAPPA using a parametrized noncentral Chi approximation model.
Statistical noise analysis in GRAPPA using a parametrized noncentral Chi approximation model.
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DOI：
10.1002/mrm.22701
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发表时间：
2011-04
影响因子：
3.3
通讯作者：
Hoge, W. Scott
中科院分区：
文献类型：
--
作者：
Aja-Fernandez, Santiago;Tristan-Vega, Antonio;Hoge, W. Scott
磁共振图像中噪声分布的表征是图像处理算法中的一个非常重要的问题。多年来，单线圈采集中假设的Rician噪声一直是信噪比估计、图像滤波或扩散张量估计的基石。随着并行协议的出现，如灵敏度编码或允许加速采集的广义自动校准部分并行采集，这种噪声模型不再成立。由于广义自校准部分并行采集重建产生的平方信号的组合，在每个接收线圈恢复，非中心的Chi统计先前已提出的噪声的分布模型。然而，我们在本文中证明，由于采集方案中的几个伪影，主要是每个线圈获得的信号之间存在的相关性，这是一个弱模型。或者，我们建议这样的相关性模型的自由度的信号，这在一个等效的nonaccelerated系统与少数独立的接收线圈，因此，一个较低的信噪比的数量减少。利用该模型，可以为图像中的所有像素假设非中心Chi分布，其有效线圈数和有效噪声方差可以从广义自动校准部分并行采集插值系数以封闭形式显式计算。对合成和体内数据集进行了广泛的实验，以显示模型的拟合优度。
The characterization of the distribution of noise in the magnitude MR image is a very important problem within image processing algorithms. The Rician noise assumed in single-coil acquisitions has been the keystone for signal-to-noise ratio estimation, image filtering, or diffusion tensor estimation for years. With the advent of parallel protocols such as sensitivity encoding or Generalized Autocalibrated Partially Parallel Acquisitions that allow accelerated acquisitions, this noise model no longer holds. Since Generalized Autocalibrated Partially Parallel Acquisitions reconstructions yield the combination of the squared signals recovered at each receiving coil, noncentral Chi statistics have been previously proposed to model the distribution of noise. However, we prove in this article that this is a weak model due to several artifacts in the acquisition scheme, mainly the correlation existing between the signals obtained at each coil. Alternatively, we propose to model such correlations with a reduction in the number of degrees of freedom of the signal, which translates in an equivalent nonaccelerated system with a minor number of independent receiving coils and, consequently, a lower signal-to-noise ratio. With this model, a noncentral Chi distribution can be assumed for all pixels in the image, whose effective number of coils and effective variance of noise can be explicitly computed in a closed form from the Generalized Autocalibrated Partially Parallel Acquisitions interpolation coefficients. Extensive experiments over both synthetic and in vivo data sets have been performed to show the goodness of fit of out model.
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影响因子：
3.8
作者：
MCGIBNEY, G;SMITH, MR
通讯作者：
SMITH, MR
影响因子：
10.6
作者：
BRUMMER, ME;MERSEREAU, RM;LEWINE, RRJ
通讯作者：
LEWINE, RRJ
影响因子：
10.6
作者：
Fillard, Pierre;Pennec, Xavier;Ayache, Nicholas
通讯作者：
Ayache, Nicholas
DOI：
10.1097/01.rmr.0000136558.09801.dd
发表时间：
2004-08-01
期刊：
Topics in magnetic resonance imaging : TMRI
影响因子：
--
作者：
Blaimer, Martin;Breuer, Felix;Jakob, Peter M
通讯作者：
Jakob, Peter M
影响因子：
3.3
作者：
Griswold, MA;Jakob, PM;Haase, A
通讯作者：
Haase, A