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DISCO- mcDESPOT

DISCO- mcDESPOT. Nov. 6, 2011 Jason Su. Methods. In vivo, 3T 2mm in-plane resolution 5mm slice resolution Rect 200us SPGR (13 angles from up to 18) and SSFP (13 angles up to 65) Left out B1 correction Running into issues with HIFI producing completely wrong T1

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DISCO- mcDESPOT

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  1. DISCO-mcDESPOT Nov. 6, 2011 Jason Su

  2. Methods • In vivo, 3T • 2mm in-plane resolution • 5mm slice resolution • Rect 200us SPGR (13 angles from up to 18) and SSFP (13 angles up to 65) • Left out B1 correction • Running into issues with HIFI producing completely wrong T1 • Still some work to do incorporating Ives’s Bloch-Siegert -> kappa map code into pipeline • Possible issue with collection • May need more samples on low end of SPGR signal curve, was enough for DESPOT1 but perhaps not mcDESPOT, only 1-2 points before Ernst angle

  3. Results • Performance is mixed for the different output maps • Overall good performance with T1 • Worse performance with T2, probably because bands caused by off-resonance affect high-freq. k-space • MWF % difference histogram is poor but looks decent, could be a dividing by small numbers issue • Stochastic nature of optimization makes interpretation difficult, i.e. how much variation is due to randomness or view sharing?

  4. MWF – offline.recon

  5. MWF – DISCO

  6. MWF – % Difference Mean: 11.3056 SD: 75.637

  7. Fast T1 – offline.recon

  8. Fast T1 – DISCO

  9. Fast T1 – % Difference Mean: -0.75528 SD: 11.4194

  10. Slow T1 – offline.recon

  11. Slow T1 – DISCO

  12. Slow T1 – % Difference Mean: -0.84407 SD: 10.024

  13. Fast T2 – offline.recon

  14. Fast T2 – DISCO

  15. Fast T2 – % Difference Mean: 1.9265 SD: 31.8879

  16. Slow T2 – offline.recon

  17. Slow T2 – DISCO

  18. Slow T2 – % Difference Mean: -0.34274 SD: 12.2981

  19. Off-Resonance – offline.recon

  20. Off-Resonance – DISCO

  21. Off-Resonance – % Difference Mean: 10.7222 SD: 105.1012

  22. Residence Time – offline.recon

  23. Residence Time – DISCO

  24. Residence Time – % Difference Mean: 0.0097232 SD: 16.17

  25. More Images • From the performance in T1 mapping, we know that our SPGRs are fairly high-fidelity • SSFPs are probably the source of error • The first flip angle is again problematic • In the future, should probably start with improving DESPOT-FM performance, much easier to look at

  26. SSFP fa5 – offline.recon

  27. SSFP fa5 – DISCO

  28. SSFP fa5 – % Difference

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