Signal and noise characteristics of SSFP FMRI: a comparison with GRE at multiple field strengths.
Recent work has proposed the use of steady-state free precession (SSFP) as an alternative to the conventional methods for obtaining functional MRI (FMRI) data. The contrast mechanism in SSFP is likely to be related to conventional FMRI signals, but the details of the signal changes may differ in important ways. Functional contrast in SSFP has been proposed to result from several different mechanisms, which are likely to contribute in varying degrees depending on the specific parameters used in the experiment. In particular, the signal dynamics are likely to differ depending on whether the sequence is configured to scan in the SSFP transition band or passband. This work describes experiments that explore the source of SSFP FMRI signal changes by comparing SSFP data to conventional gradient-recalled echo (GRE) data. Data were acquired at a range of magnetic field strengths and repetition times, for both transition band and passband methods. The signal properties of SSFP and GRE differ significantly, confirming a different source of functional contrast in SSFP. In addition, the temporal noise properties are significantly different, with important implications for SSFP FMRI sequence optimisation.
Miller
Karla L
KL
Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, UK, and A.A. Martinos Center, Massachusetts General Hospital, Charlestown, USA. karla@fmrib.ox.ac.uk
Smith
Stephen M
SM
Jezzard
Peter
P
Wiggins
Graham C
GC
Wiggins
Christopher J
CJ
D000465:Algorithms; D003627:Data Interpretation, Statistical; D004574:Electromagnetic Fields; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation
D010100:Oxygen