Steve Patterson1,
2, Chris Bowen, 12
1Dalhousie
University, Halifax, NS, Canada; 2Institute for Biodiagnostics
(Atlantic), NRC, Halifax, NS, Canada
Most pass-band SSFP fMRI studies employ the signal-optimizing flip angle (&[alpha] s), which maximizes on-resonant signal and produces a flat pass-band signal vs. off-resonance profile. In this work we derive an analytical expression for the BOLD contrast-optimizing flip angle (&[alpha] c). Using literature-reported relaxation times for grey matter, we found that &[alpha] c ≈ &[alpha] s + 20o for B0 from 1.5-7T. We tested our result against Monte Carlo simulations of SSFP fMRI BOLD contrast at 3T and found that the BOLD contrast-optimizing flip angle maximizes on-resonant BOLD contrast (23% increase from &[alpha] s) and produces a flat pass-band BOLD contrast vs. off-resonance profile.