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Calibration WG

Calibration WG. Overall goals:. 1. Develop and maintain scanner QA methods. Procedures on web site Paper in press: Friedman & Glover, JMRI. Develop and implement means for reducing intersite variations in fMRI sensitivity. Bonus Aim. Calibration WG.

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Calibration WG

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  1. Calibration WG Overall goals: 1. Develop and maintain scanner QA methods • Procedures on web site • Paper in press: Friedman & Glover, JMRI • Develop and implement means for reducing intersite variations in fMRI sensitivity

  2. Bonus Aim Calibration WG Proposed intersite calibration aims: 1. Further develop BH methods (GHG) Develop ASL methods (Tom Liu) 3. Examine smoothing equalization (Friedman et al., in review) 4. Develop new method based on SFNR (Lee Friedman)

  3. Update on BH • Theory and measurements developed Paper on BH kids/adults (Thomason, NI 2005) Paper on BH calib (Thomason, HBM in press) • Next steps

  4. Working Memory Children Adults low Spatial medium high low Verbal medium high M. Thomason

  5. Vascular res.   HR   CBF  hypoxia Basal metab.  O2, CO2, NO, H+  vasodilation   rCBF BH-induced BOLD signal Thomason, et. al, NI 2005

  6. Vascular BOLD Uniformity Thomason, et. al, NI 2005

  7. BH Task: Children vs. Adults Thomason, et. al, NI 2005

  8. BH Task: Children vs. Adults Thomason, et. al, NI 2005

  9. BOLD Signal rCBF [HbO2] OEF CMRO2 = OEF x rCBF x [HbO2] [Hb] M. Thomason et al., HBM 2006 Davis, PNAS (1998) Buxton, 2003

  10. BOLD Signal BH task Kastrup (1999) Hoge (1999) F = fBH/fa M. Thomason et al., HBM 2006

  11. BH Calibration Method • Use BH task (non-neuronal, no change in CMRO2) to normalize cognitive task • Reduces signal change related to vasoreactivity • Should reduce inter-subject variance

  12. WM/BH Study • Adult subjects performed - SWM task (Sternberg) - BH task • Compared intersubject variability in WM effect with/without BH calibration M. Thomason et al., HBM 2006

  13. Calibration: WM Raw Calib M. Thomason et al., HBM 2006

  14. Calibration: WM Raw ROI whole brain pixel- wise 1 Slice for all subjects M. Thomason et al., HBM 2006

  15. Calibration: WM Raw pixel- wise 1 Slice for 3 subjects M. Thomason et al., HBM 2006

  16. BH Calibration: Individual Subs No calib Calib 5 ≤ t ≤ 20 M. Thomason et al., HBM 2006

  17. Calibration: SWM 5 subjects, parietal M. Thomason et al., HBM 2006

  18. BH Calibration: Group Activation No cal Calib vol = 1.0 vol = 1.24 @ p .001 3.5 ≤ t ≤ 10 M. Thomason et al., HBM 2006

  19. Activation Response No cal Calib t-score average = 7.82 t-score average = 14.58 M. Thomason et al., HBM 2006

  20. Update on BH • Theory and measurements developed Paper published on BH kids/adults Paper in press BH calib • Next steps

  21. Update on BH • Theory and measurements developed Paper published on BH kids/adults Paper in press BH calib • Next steps

  22. Sl 10, aud Vascular Responsivity: BH • Variations in inspiration may modulate blood oxygenation

  23. Behavioral Effect Mitigation Approaches • Model breathing variations using GLM Signal = a * Resp + b * HR

  24. Vascular Responsivity: BH GHG111603

  25. Behavioral Effect Mitigation Approaches • Model breathing variations using GLM Signal = a * Resp + b * HR • Provide respiration feedback to maintain inspiration level constant

  26. BH Status • Program available to make calibrated timeseries- input = timeseries, BH scan, params • Developing feedback device piezo electric resp monitor from ADI LED meter, analog electronics. Est. cost $500

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