MRI Scan Time Reduction by Asymmetric Spiral Sampling

This work compares two ways of spiral scanning in MRI, i.e., scanning with an odd or with an even number of k-space trajectories. Within each scan, the angles between adjacent trajectories are equal to each other. On the condition that prior correction for experimental phase distortion of the image be feasible, we show that an odd number of trajectories yields about twice as much information as that available from the nearest even number of trajectories. Consequently, using an odd number of trajectories rather than the traditional even number, can bring about image improvement and/or scan time reduction. Keywords— k-space, asymmetric sampling, spiral scanning, point-spread function.