Dual-pathway multi-echo sequence for simultaneous frequency and T2 mapping.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering

Background:

• Traditional MRI techniques require separate pulse sequences for T2 mapping (spin echoes) and field mapping (gradient echoes).
• This limitation complicates the simultaneous acquisition of both T2 and field information, hindering comprehensive tissue analysis.

Purpose of the Study:

• To introduce a novel dual-pathway multi-echo steady state sequence and reconstruction algorithm.
• To enable the simultaneous capture of T2, T2(∗), and field map information from a single dataset.

Main Methods:

• A dual-pathway multi-echo pulse sequence was developed and implemented.
• The sequence was designed to generate both T2 and field maps from the same acquired data.
• Reconstruction algorithms were employed to process the acquired data.

Main Results:

• Quantitative T2, T2(∗), and field maps were successfully generated in phantoms, ex vivo muscle, and human volunteers.
• T2 mapping results demonstrated high agreement with a spin-echo reference standard (R²=0.998).
• In vivo analysis showed minimal bias (0.3%) for R2=1/T2, indicating high accuracy.

Conclusions:

• The dual-pathway multi-echo sequence allows for simultaneous acquisition of T2, T2(∗), and field maps.
• This integrated approach has potential applications in thermometry, susceptibility-weighted imaging, and knee imaging.
• T2-based tissue damage detection may be more motion-robust than temperature-dose measurements.