Simultaneous 3D quantitative magnetization transfer imaging and susceptibility mapping.

Area of Science:

• Magnetic Resonance Imaging
• Biophysics
• Medical Physics

Background:

• Magnetization transfer (MT) and susceptibility mapping are crucial for characterizing brain tissue.
• Current methods often require separate acquisitions, increasing scan time and potential for errors.
• Simultaneous quantification of MT, susceptibility (χ), and T2* remains a challenge.

Purpose of the Study:

• To develop and validate a unified MRI acquisition and modeling strategy.
• To simultaneously quantify magnetization transfer (MT), tissue susceptibility (χ), and T2*.
• To overcome limitations of separate measurement techniques and B1+ bias.

Main Methods:

• Developed an RF-spoiled gradient-echo sequence with off-resonance irradiation for MT.
• Incorporated multi-echo acquisition to capture signal magnitude and phase evolution.
• Utilized a binary spin-bath MT model with B1+ inhomogeneity correction and analytical signal modeling.

Main Results:

• Successfully acquired simultaneous 3D T1F, f, kF, χ, and T2* maps of the whole brain in vivo.
• Demonstrated good agreement between regional analysis results and previously reported literature values.
• Validated the method's feasibility and accuracy in five healthy subjects.

Conclusions:

• A novel, unified acquisition and modeling strategy enables simultaneous MT, susceptibility, and T2* quantification.
• The method leverages both signal magnitude and phase for comprehensive tissue characterization.
• The approach provides accurate, B1+-bias-free measurements, advancing neuroimaging capabilities.