Arc-ZTE: Incoherent k-space sampling in time using continuously-slewed gradients for flexible, dynamic, quiet Zero TE MRI

Motivation: Existing Zero TE methods are constrained due to gradient slew limits between spokes, which hinders their use in dynamic imaging applications. Goal(s): We aim to improve temporal k-space sampling in time by increasing the possible angular distance between consecutive spokes via continuously-slewed gradients, while still maintaining minimal gradient refocusing and minimal acoustic noise. Approach: We parameterize the k-space trajectory using sequential rotations of an arc in k-space, then optimize the rotation angles over metrics for sampling uniformity and refocusing. Results: We demonstrate a proof-of-concept of this trajectory and show improvement over radial ZTE in k-space coverage metrics and reconstructions for various temporal resolutions. Impact: By improving temporal k-space sampling for Zero-TE MRI, our work enables quiet, dynamic imaging with flexible temporal resolution. Potential applications include quiet DCE or respiratory motion-resolved imaging for neonates and other sound-sensitive populations.