Fast, variable system delay correction for spiral MRI

PURPOSE: Time-varying system delays and eddy currents can substantially reduce the image quality of spiral images. A new method is proposed to estimate variable system delays for spiral-based trajectories. METHODS: This approach requires a minor modification of a conventional stack-of-spirals sequence and analyzes data collected on three overlapping orthogonal cylinders. RESULTS: Initial results are presented for acquired and synthesized phantom data and in vivo data. CONCLUSION: The proposed method includes gradient coupling effects, requires no phantom measurements or specialized hardware, is robust to off-resonance effects, and estimates independent continuous delays for each gradient channel over the data-sampling period.