现有的彩色医学图像配准方法一般是采用体外定位标记法，如 SPECT/CT彩色医学图像，但外标记支架与病体的固定检查比较繁琐，本文提出一种四元数彩色模型下，求取旋转角度与平移量等配准参数的方法。首先将彩色医学影像用四元数向量矩阵形式表达，在此基础上，提出 SPECT/CT医学图像四元数几何矩的计算方法，根据四元数图像质量分布情况，利用图像转动惯量的性质，求取两图像的相对旋转角度；再利用两图像的质心欧氏距离确定两图像的平移量，继而实现配准。该方法对彩色图像 SPECT/CT进行配准实验，获得了良好配准结果，实验证明该方法的有效性与可行性。

A new approach to the simultaneous registration of multiple medical images is proposed using shared chain mutual information (SCMI) as the matching measure. The presented method applies SCMI to measure the shared information between the multiple images. Registration is achieved by adjusting the relative position of the floating image until the SCMI between all the images is maximized. Using this measure, we registered three and four simulated magnetic resonance imaging (MRI) images using downhill simplex optimization to search for the optimal transformation parameters. Accuracy and validity of the proposed method for multiple-image registration are testified by comparing the results with that of two-image registration. Furthermore, the performance of the proposed method is validated by registering the real ultrasonic image sequence.