Arc-ZTE: Continuously-Slewed Zero-TE Imaging With Incoherent Temporal Sampling for Near-Silent Dynamic MRI.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Medical Physics

Background:

• Dynamic MRI is crucial for assessing physiological processes.
• Conventional MRI sequences often produce high acoustic noise, limiting patient tolerance and image quality.
• Zero Echo Time (ZTE) imaging offers potential for faster acquisitions but requires optimized k-space trajectories.

Purpose of the Study:

• To develop a novel ZTE imaging technique, Arc-ZTE, for flexible, low-noise, high spatiotemporal resolution dynamic MRI.
• To evaluate Arc-ZTE's performance against existing radial ZTE schemes in terms of acoustic noise and k-space coverage.

Main Methods:

• Proposed Arc-ZTE, a technique using continuously-slewed readout gradients to create rotating arcs in k-space for incoherent sampling.
• Employed an optimization procedure to enhance temporal k-space coverage and minimize gradient refocusing.
• Assessed acoustic noise, k-space uniformity, and sampling incoherence using phantom and in vivo data.

Main Results:

• Arc-ZTE demonstrated stable k-space coverage and improved sampling incoherence compared to radial ZTE.
• While arc curvature increased noise (0.3-14.2 dB), Arc-ZTE remained significantly quieter (20-35 dB) than conventional 3D sequences.
• In vivo imaging successfully captured respiratory motion and contrast uptake dynamics at high temporal resolutions (0.5-1.1 s/frame).

Conclusions:

• Arc-ZTE facilitates flexible, time-resolved, near-silent dynamic MRI via incoherent temporal sampling.
• The technique allows retrospective adjustment of temporal resolution without trajectory redesign.
• Arc-ZTE has the potential to enhance dynamic imaging success rates in vulnerable patient groups, including neonates and young children.