1. Functional Brain Signal Processing: EEG & fMRI Lesson 10 Kaushik Majumdar Indian Statistical Institute Bangalore Center kmajumdar@isibang.ac.in M.Tech. (CS), Semester III, Course B50

2. K Space Mezrich, 1995 K space in MR imaging Localization in terms of spatial frequency. Wave number K space is named after the wave number k. http://www.psy.vanderbilt.edu/courses/hon185/SpatialFrequency/Spat ialFrequency.html

3. 3D Magnetic Gradient X Y Z B(x) = B 0 + G.x B(y) = B 0 + G.y B(z) = B 0 + G.z B(x) = B 0 - G.x B(y) = B 0 - G.y B(z) = B 0 - G.z

4. Slice Location: Location Along Z axis For Hydrogen gyromagnetic ratio is 42.6 MHz/T. For a 2.5 T gradient magnetic field strength (say in a 3 T scanner) the RF pulse should be in a band 106.5 ± δ MHz. Kandel et al., 2000 Pooley, 2005

5. Frequency Encoding: Location Along X Axis Buxton, 2009

6. Phase Encoding: Location Along Y Axis Buxton, 2009

7. Magnetic Pulses Along X, Y and Z Axes Buxton, 2009

8. MR Signal Representation in K Space ƒ(x) is the variable magnetic field Mezrich, 1995

9. Trade Off Challenge in MR Imaging Simultaneous achieving of (1) high spatial resolution, (2) high temporal resolution, and (3) high SNR.

10. Talairach Coordinate System http://www.talairach.org

11. Talairach Coordinate (cont.) www.brainvoyager.com Talairach origin is at the intersection of posterior and superior margins of the anterior commissure (AC) on the midhemispheric plane.

12. Cerebral Dimension of Brain Templates Lancaster et al., 2007

13. References R. Mezrich, A perspective on K space, RSNA, 195: 297 – 315, 1995, available online at http://pages.stat.wisc.edu/~mchung/teaching/ MIA/reading/fourier.kspace.mezrich.1995.pdf http://pages.stat.wisc.edu/~mchung/teaching/ MIA/reading/fourier.kspace.mezrich.1995.pdf R. B. Buxton, Introduction to Functional Magnetic Resonance Imaging, 2e, Cambridge University Press, Cambridge, UK, 2009.

14. References (cont.) http://www.talairach.org J. L. Lancaster et al., Bias between MNI and Talairach coordinates analyzed using ICBM- 152 brain template, Hum. Brain Mapp., 28: 1194 – 1205, 2007.

15. THANK YOU This lecture is available at http://www.isibang.ac.in/~kaushikhttp://www.isibang.ac.in/~kaushik