Semi-Randomized Trajectories to the Rescue: Reducing Artifacts from Fluctuating Physiological Signals in 3D Steady-State MRI

Rapid 3D steady-state sequences such as SWI are sensitive to semi-periodic physiological fluctuations (e.g., cardiac pulsation, breathing, and eye movement) resulting in repeating artifacts in the images. Randomization of the phase-encoding order reduces the above artifacts but results in apparent noise from slow global changes (like motion or eddy currents changes). We propose a new semi-randomized acquisition order that allows to set a cutoff frequency for artifact suppression; above which artifacts are suppressed, whereas artifacts from slower changes are unaffected. Simulations and SWI human brain scanning at 7T validate the method.