Department of Physics and Astronomy, Faculty of Science, University of Western Ontario, London, Ontario, Canada.
Magn Reson Med. 2011 Oct;66(4):1192-7. doi: 10.1002/mrm.22893. Epub 2011 Apr 4.
Measuring signal-to-noise ratio (SNR) for parallel MRI reconstructions is difficult due to spatially dependent noise amplification. Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time, or rely on repeated image acquisitions. A new SNR estimation approach is proposed, a hybrid of the repeated image acquisitions method detailed in the National Electrical Manufacturers Association (NEMA) standard and the Monte Carlo based pseudo-multiple replica method, in which the difference between images reconstructed from the unaltered acquired data and that same data reconstructed after the addition of calibrated pseudo-noise is used to estimate the noise in the parallel MRI image reconstruction. This new noise estimation method can be used to rapidly compute the pixel-wise SNR of the image generated from any parallel MRI reconstruction of a single acquisition. SNR maps calculated with the new method are validated against existing SNR calculation techniques.
由于空间依赖的噪声放大，测量并行磁共振成像重建的信噪比（SNR）很困难。现有的测量并行 MRI SNR 的方法受到限制，因为它们不适用于所有重建，需要大量的计算时间，或者依赖于重复的图像采集。提出了一种新的 SNR 估计方法，它是对 NEMA 标准中详细描述的重复图像采集方法和基于蒙特卡罗的伪多副本方法的混合，其中使用从未修改的采集数据重建的图像与在添加校准的伪噪声后重建的相同数据之间的差异来估计并行 MRI 图像重建中的噪声。这种新的噪声估计方法可用于快速计算来自单个采集的任何并行 MRI 重建生成的图像的像素级 SNR。使用新方法计算的 SNR 图与现有的 SNR 计算技术进行了验证。
