Marta Bianciardi1,
Karleyton C. Evans2, Jonathan R. Polimeni3, Tian Y.
Song2, Boris Keil3, Christina Triantafyllou3,
Bruce R. Rosen3, David A. Boas3, Lawrence L. Wald3
1Department
of Radiology, A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard
Medical School, Charlestown, MA, United States; 2Department of
Psychiatry, Massachusetts General Hospital, Harvard Medical School,
Charlestown, MA, United States; 3Department of Radiology, A.A.
Martinos Center for Biomedical Imaging, Massachusetts General Hospital,
Harvard Medical School, Charlestown, MA, United States
Respiration generates fMRI signal instability in the brain by different mechanisms, including chest motion, and pulsatile motion of blood/CSF due to respiratory-pressure-wave. We investigated the relative contribution of these effects, their spatial distribution, and the performance of different correction methods by acquiring whole-brain high-spatial-resolution magnitude and phase fMRI resting-state data at 7Tesla. Our results indicate that the major sources of respiratory-related signal instability are: chest motion in phase-data, and pulsatile motion in magnitude-data. Optimized correction of respiratory effects in both magnitude- and phase-data was achieved by combining RETROICOR with a method for estimating off-resonance changes in phase-data.