3D Seiffert spiral k-space trajectories for a functional sodium (23Na) MRI protocol at 3T

Motivation: With advancing hardware, scan durations of 23Na-MRI have decreased, enabling novel applications that probe dynamic or functional processes; existing sequences, though, may not fully exploit the possible acceleration. Goal(s): Implement and demonstrate a highly efficient ultrashort echo time non-Cartesian sequence based on 3D Seiffert spirals, for temporally-resolved applications of 23Na-MRI. Approach: A possible acquisition protocol for functional brain 23Na-MRI at a temporal resolution of 47s was tested on a healthy volunteer at rest, at 3T. Results: Image quality and SNR are high considering the temporal resolution, with compressed sensing successfully reducing noise. Further work will optimise the sequence analytically, ensuring homogeneous k-space sampling. Impact: Dynamic 23Na-MRI at 3T is possible at sub-minute temporal resolution with a 3D Seiffert spiral k-space trajectory. Unlike for other sequences, efficient k-space coverage is achieved without downsides of unpleasant acoustic noise, or exciting mechanical resonances of scanner hardware.