A Wavelet-based Multiresolution Medical Image Registration Strategy Combining Mutual Information with Spatial Information
A Wavelet-based Multiresolution Medical Image Registration Strategy Combining Mutual Information with Spatial Information
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发表时间：
2006-01
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通讯作者：
R. Xu;Yen-Wei Chen
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作者：
R. Xu;Yen-Wei Chen
互信息是医学图像配准中广泛使用的一种度量，取得了较好的配准效果，但由于缺乏空间信息，会导致误配准。克服这个问题的工作之一是由（10）提出的，其中基于梯度的项与互信息相结合。本文对文献[10]中的方法进行了改进，提出了一种更适用于多分辨率方案的配准策略。与（10）不同的是，不同分辨率的图像及其对应的类梯度图像的计算都在小波变换下进行了整合。该方法分别从小波变换的低频系数和高频系数计算互信息和空间信息，并采用混合度量将互信息和空间信息联合收割机起来。当使用多分辨率方案时，所提出的配准策略可以比（10）中的方法运行得更快。另外，与现有的采用小波变换进行配准的方法相比，本文将小波变换应用于三维图像的配准，同时利用了高频系数和低频系数。实验结果表明，该方法在MR-MR和CT-MR配准问题中表现良好。
Mutual information is a widely-used metric in medical image registration, which achieves good results; however it can lead to misregistration because of the absence of spatial information. One of the works to overcome this problem is proposed by (10) in which a gradient-based term is combined with mutual information. In this paper, we improve the method in (10) and propose a registration strategy which is more suitable when multiresolution scheme is adopted. Different from (10), the calculations of both the images with different resolutions and their corresponding gradient-like images are inte- grated under the wavelet transform. Mutual information (MI) and spatial information (SI) are respectively calculated from the low-frequency coefficients and high-frequency co- efficients of wavelet transform on each resolution layer; and a hybrid metric is adopted to combine MI and SI together. The proposed registration strategy can run faster than the method in (10) when multiresolution scheme is used. Additionally, compared to the other existing works where wavelet transform is adopted for registration, we apply wavelet transform to the problem of 3D image registration and make use of both of the high fre- quency coefficients and low frequency coefficients. Experiments show that the proposed method behaves well in MR-MR and CT-MR registration problems.