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

摘要: Although 2D echo-planar imaging (EPI) remains the dominant method for functional MRI (FMRI), 3D readouts are receiving more interest as these sequences have favorable signal-to-noise ratio (SNR) and enable at a high isotropic resolution. Spoiled gradient-echo (SPGR) balanced steady-state free-precession (bSSFP) rapid that typically acquired with highly segmented readouts, thus less sensitive to image distortion signal dropout. They therefore provide powerful alternative FMRI in areas strong susceptibility offsets, such deep gray matter structures brainstem. Unfortunately, multi-shot nature of readout makes physiological fluctuations, large instabilities observed inferior regions brain. In this work characterization source is given new presented reduce SPGR bSSFP. Rapidly single-slice data, which critically sampled respiratory cardiac waveforms, showed pulsation instabilities. Simulations further synchronizing cycle minimizes considerably. A real-time synchronization was developed, utilizes parallel-imaging techniques allow without alteration volume acquisition rate. The implemented significantly improves temporal stability affected by cardiac-related fluctuations. bSSFP data tSNR brainstem increased 45%, cost small reduction cortical areas. improved approximately 20% subcortical well when performed.