Koay Cheng Guan, Basser Peter J
National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
J Magn Reson. 2006 Apr;179(2):317-22. doi: 10.1016/j.jmr.2006.01.016. Epub 2006 Feb 20.
An analytically exact method is proposed to extract the signal intensity and the noise variance simultaneously from noisy magnitude MR signals. This method relies on a fixed point formula of signal-to-noise ratio (SNR) and a correction factor. The correction factor, which is a function of SNR, establishes a fundamental link between the variance of the magnitude MR signal and the variance of the underlying Gaussian noise in the two quadrature channels. A more general but very similar method is developed for parallel signal acquisitions with multiple receiver coils. In the context of MR imaging, the proposed method can be carried out on a pixel-by-pixel basis if the mean and the standard deviation of the magnitude signal are available.
提出了一种解析精确的方法，用于从有噪声的幅度磁共振（MR）信号中同时提取信号强度和噪声方差。该方法依赖于信噪比（SNR）的不动点公式和一个校正因子。校正因子是SNR的函数，它在幅度MR信号的方差与两个正交通道中潜在高斯噪声的方差之间建立了基本联系。针对使用多个接收线圈的并行信号采集，开发了一种更通用但非常相似的方法。在MR成像的背景下，如果幅度信号的均值和标准差可用，则所提出的方法可以逐像素地进行。
