High-quality FLORET UTE imaging for clinical translation.

Area of Science:

• Magnetic Resonance Imaging
• Medical Imaging Technology
• Biomedical Engineering

Background:

• Developing robust 3D ultrashort-TE (UTE) protocols is crucial for high-quality clinical imaging.
• Previous Fermat looped orthogonally encoded trajectories (FLORET) offered promise but required further optimization.
• Clinical translation of UTE sequences necessitates reproducible, fast, and diagnostically accurate imaging.

Purpose of the Study:

• To develop and validate a robust 3D UTE protocol suitable for clinical translation.
• To achieve reproducible, high-quality imaging with clinically acceptable scan times.
• To assess the diagnostic quality of the developed UTE protocol across various applications and scanners.

Main Methods:

• Optimized a UTE sequence using Fermat looped orthogonally encoded trajectories (FLORET).
• Implemented modifications including gradient waveform frequency limitations, trajectory ordering, balanced SSFP, fast gradient spoiling, and inline reconstruction.
• Acquired images in phantoms and human subjects on multiple MRI scanners at different sites.

Main Results:

• The enhanced FLORET protocol yielded high-quality images in phantom, musculoskeletal, and pulmonary applications.
• Artifacts were significantly reduced through gradient waveform and trajectory ordering modifications.
• Acquisition and reconstruction times were reduced (total < 4 min for MSK/pulmonary), with consistent diagnostic image quality across sites.

Conclusions:

• Recent improvements enable robust, high-quality 3D UTE imaging with short acquisition and reconstruction times.
• The optimized FLORET sequence demonstrates readiness for clinical UTE imaging.
• Successful implementation across multiple scanners and sites validates the protocol's robustness without additional system calibration.