Different registration methods Narendhran Vijayakumar 01/25/2008

2 Different types registration methods Mutual information based registration method Cost function based registration method –Correlation and Sum of absolute difference functions Fourier Transform based registration method –Faster than any of the methods Independent Component Analysis –For non rigid body registration

3 Cost function based registration Registration is achieved by minimizing the cost function Cost = a * F(I1,I2) – b * G(I1,I2) where F(I1,I2) - Sum of absolute difference (SAD) G(I1,I2) - Correlation Coefficient (CC)

4 SAD and CC definition SAD is defined as CC is defined as 1 [1] Peter et al, Syntegra Image Automated registration algorithms, white paper 2003

5 Comparing MI and Cost function Test images - (Translational and Rotational parameters are known) MI based registrationCost function Translational error: 0.23±0.49mm Rotational error: 0.14±0.17 o Translational error: 0.23±0.49mm Rotational error:

6 Registering T2 FLAIR and Radial Diffusion weighted MI based registrationCost function Average translation X direction – 24.57mm Y direction – 6.08mm Average rotation Counter Clockwise – 0.23 o Clockwise – 0.25 o Average translation X direction – 22.46mm Y direction – 10.06mm Average rotation Counter Clockwise – 0 o Clockwise – 0 o

7 Performance Metrics Gold standard –Two experts individually determine which image is better registered Overlapping Images Phantom –Best way to test the algorithms RegRef Reg

8 Future Work Brightness –How different methods behave ? Determine the Scale parameter FFT based method