偏差校正的DCT子空间非局部均值MRI图像去噪算法

A Bias Corrected MR Images Denoising Method Using DCT-based Nonlocal Means Filter

针对直接采用高斯白噪声去噪算法去除MRI图像中的莱斯(Rician)噪声仅能取得次优去噪效果这一问题,在DCT子空间非局部均值去噪算法基础上,提出一种偏差校正的DCT子空间非局部均值MRI图像去噪算法。首先分析MRI图像中Rician噪声的特性,给出在MRI模值平方图中估计噪声偏差的方法;然后使用偏差校正的DCT子空间非局部均值MRI图像去噪算法在MRI图像的模值平方图上进行去噪处理。在模拟MRI图像上进行实验,其结果表明,该算法在有效去除Rician噪声的同时,很好地保留了器官和软组织的细节纹理信息,取得了较好的去噪效果。

The noise in MRI image is a muhiplicative noise with non-zero mean and obeys Rician distribution. However, many ex- isting MRI image denoising algorithms directly apply methods which are right for additive white Gauss noise with zero mean. They de- noise sub-optimally. An optimal bias corrected MR images denoising approach is present based on non-local means filter in DCT sub- space. Firstly, the characteristics of Rician noise in image are analyzed and the method to estimate noise bias in the space of squared magnitude MRI image is discussed. Then, the proposed MRI image denoising algorithm is utilized to reduce the Rician noise. Valida- tion work is carried out on simulated images and the results demonstrate that the proposed method can denoise effectively and it can re- tain anatomical structures of organs and tissues while remove Rician noise in image,