A Real-Time Cardiac Synchronization Method for Reducing Flow-Induced Instabilities in SSFP fMRI of the Brainstem

Rob Hendrikus Tijssen¹, Thomas William Okell¹, Karla Loreen Miller¹

Low distortion and high signal-to-noise ration make Steady-state free precession (SSFP) FMRI an attractive pulse sequence for high resolution brainstem FMRI. Unfortunately the multi-shot character of the readout makes the sequence highly susceptible to flow-induced instabilities that correlate with the cardiac cycle. We present a readout method that achieves real-time cardiac synchronization without varying frame rate, based on GRAPPA and partial-Fourier reconstruction. This method significantly improves temporal stability in the brainstem.