1. Quality Improvements for Multi-Modal Neuroimaging Mika Seppä Brain Research Unit / LTL AMI-Centre Helsinki University of Technology

2. MS/2007

3. 1. Registration 2. Resampling 3. Visualization 3 central stages:

4. MS/2007  Match metric  Single-modal registration –sum of squared differences  Multi-modal registration –mutual information 1. Registration

5. MS/2007 MI artifacts  Images aligned  Same pixel/voxel sizes  Registration bias  Local maxima  Continuous sampling –higher-order method offset (pixels) MI

6. MS/2007 2. Resampling  Very common operation –geom. correction, motion correction, group average etc. 15 x SNR = 10*log 10 (  s 2 /  e 2 )...

7. MS/2007 Two-stage resampling SNR (dB) Time (ms)

8. MS/2007 3. Visualization 0.1-5 fps 800 fps 120 fps

9. MS/2007

12. Seppä (2007). On continuous sampling and sub-sample accuracy in mutual-information registration. TKK Report, TKK- KYL-017. Seppä (2007). High-quality two-stage resampling for 3-D volumes in medical imaging. Medical Image Analysis, 11:346- 360. Seppä, Hämäläinen (2005). Visualizing human brain surface from T1-weighted MR images using texture-mapped triangle meshes. NeuroImage, 26:1-12. Hiltunen, Suortti, Arvela, Seppä, Joensuu, Hari (2005). Diffusion tensor imaging and tractography of distal peripheral nerves at 3 T. Clinical Neurophysiology, 116:2315-2323.

13. MS/2007