Improving the MI registration metric Narendhran Vijayakumar 04/25/2008

Mutual Information Advantages – Works well for multi-modality images Disadvantages – Spatial information not take into account 2

Spatial Information Using Gradient Information 1 – Gradient factor at each shift (x,y) is calculated – Multiplied with MI Mutual information of Regions 2 – Multidimensional MI 3 [1] Pluim et al., “Image Registration by Maximization of Combined Mutual Information and Gradient Information, IEEE trans. On Medical Imaging, Aug 2000 [2] Russakoff et al., “Image Similarity using Mutual information of Regions”, ECCV 2004

Clustering Reduce the gray levels – May affect image registration accuracy – Reduce the gray levels by clustering/grouping the data 3 4 [3] Knops et al., “Normalized mutual information based registration using k-means clustering and shading correction”, Medical Image Analysis, June 2006.

MI of Synthetic T1/T2 5

MI of T2FLAIR/DWEPI 6

MI of T2FLAIR/DIFFRAD 7