Rapid multicomponent relaxometry in steady state with correction of magnetization transfer effects

Area of Science:

• Magnetic Resonance Imaging
• Biophysics
• Tissue Characterization

Background:

• Macromolecule-rich tissues exhibit complex signal behavior in MRI.
• Magnetization transfer (MT) effects can introduce biases in quantitative relaxometry.
• Existing methods like mcDESPOT may be susceptible to MT-induced errors.

Purpose of the Study:

• To investigate the impact of MT on multicomponent T2 parameters.
• To develop and validate a novel method (mcRISE) for correcting MT biases.
• To improve the accuracy of relaxometry in macromolecule-rich tissues.

Main Methods:

• Modified the mcDESPOT model to include an exchanging macromolecule proton pool.
• Developed the mcRISE acquisition scheme for enhanced pool sensitivity.
• Employed incremental fitting to decouple MT and relaxometry parameters.
• Validated mcRISE through simulations and in vivo studies in healthy volunteers.

Main Results:

• MT significantly biased multicomponent T1/T2 values and the fast-relaxing water fraction (fF).
• Ignoring MT led to an overestimation of fF with increasing macromolecule content.
• mcRISE substantially reduced MT biases, providing decoupled relaxometry and MT parameters.

Conclusions:

• mcRISE offers an efficient correction for MT biases in steady-state relaxometry.
• The improved specificity of mcRISE aids in understanding disease-related changes in cartilage and brain tissues.
• This method enhances the diagnostic potential of MRI in various tissues.