Magnetization transfer imaging using non-balanced SSFP at ultra-low field.

Area of Science:

• Medical Imaging
• Neuroscience
• Biomarkers

Background:

• Ultra-low field MRI offers improved access and frequent monitoring for diseases.
• White matter disorders benefit from sensitive imaging like magnetization transfer (MT).

Purpose of the Study:

• Develop and validate an on-resonance MT imaging approach for ultra-low field MRI (64 mT).
• Assess the feasibility of using MT imaging for myelin-sensitive assessment in white matter disorders.

Main Methods:

• Implemented an on-resonance MT imaging sequence on a 64 mT scanner.
• Utilized non-balanced steady-state free precession sequence.
• Conducted phantom and in vivo experiments to optimize and validate the sequence.

Main Results:

• T1 and T2 effects were found to have negligible impact on MT weighting.
• Healthy white matter showed MT ratio (MTR) values of 23.1 ± 1.0% with high reproducibility (CV 1.04%).
• A multiple sclerosis participant exhibited lower MTR values in normal-appearing white matter compared to a healthy control.

Conclusions:

• An on-resonance MT imaging method at 64 mT was successfully developed.
• This technique can be performed rapidly (as little as 4 minutes).
• A semi-quantitative, myelin-sensitive imaging biomarker is now available for assessing myelination and demyelination at ultra-low field strengths.