Real-time cardiac synchronization with fixed volume frame rate for reducing physiological instabilities in 3D FMRI

► 3D readouts for FMRI are highly susceptible to physiological signal fluctuations. ► The fluctuations are shown to correlate predominantly with the cardiac cycle. ► Based on simulations a real-time cardiac synchronized readout was developed. ► The method employs parallel imaging to maintain a fixed volume acquisition time. ► Synchronization vastly improves the temporal stability in deep brain structures.