Design and development of a novel flexible ultra-short echo time (FUSE) sequence

To present the validation of a new Flexible Ultra-Short Echo time (FUSE) pulse sequence using a short-T₂ phantom.

FUSE was developed to include a range of RF excitation pulses, trajectories, dimensionalities, and long-T₂ suppression techniques, enabling real-time interchangeability of acquisition parameters. Additionally, we developed an improved 3D deblurring algorithm to correct for off-resonance artifacts. Several experiments were conducted to validate the efficacy of FUSE, by comparing different approaches for off-resonance artifact correction, variations in RF pulse and trajectory combinations, and long-T₂ suppression techniques. All scans were performed on a 3 T system using an in-house short-T₂ phantom. The evaluation of results included qualitative comparisons and quantitative assessments of the SNR and contrast-to-noise ratio.

Using the capabilities of FUSE, we demonstrated that we could combine a shorter readout duration with our improved deblurring algorithm to effectively reduce off-resonance artifacts. Among the different RF and trajectory combinations, the spiral trajectory with the regular half-inc pulse achieves the highest SNRs. The dual-echo subtraction technique delivers better short-T₂ contrast and superior suppression of water and agar signals, whereas the off-resonance saturation method successfully suppresses water and lipid signals simultaneously.

In this work, we have validated the use of our new FUSE sequence using a short T₂ phantom, demonstrating that multiple UTE acquisitions can be achieved within a single sequence. This new sequence may be useful for acquiring improved UTE images and the development of UTE imaging protocols.