Artifacts correction for T1rho imaging with constant amplitude spin-lock

Area of Science:

• Magnetic Resonance Imaging
• Biophysics

Background:

• Constant amplitude spin-lock in T1rho imaging is susceptible to artifacts from B1 radiofrequency (RF) and B0 magnetic field inhomogeneity.
• Existing methods require further improvements for reliable clinical use.

Purpose of the Study:

• To develop methods for simultaneous correction of B1 RF and B0 field inhomogeneity in constant amplitude spin-lock.
• To enhance the robustness and clinical applicability of T1rho imaging.

Main Methods:

• Utilized adiabatic excitation pulses with maximum B1 amplitude matching the spin-lock frequency to align spins with the effective field.
• Introduced a two-acquisition approach to address errors from relaxation during adiabatic half passage in longer pulses.

Main Results:

• Achieved artifact-free T1rho-weighted images despite spatial variations in the effective field.
• Demonstrated superior image quality compared to existing methods through simulations, phantom, and in-vivo scans.
• Validated the effectiveness of the two-acquisition method in resolving adiabatic half passage relaxation effects.

Conclusions:

• The proposed methods significantly improve the robustness of constant amplitude spin-lock for T1rho imaging.
• These advancements pave the way for routine clinical application of artifact-free T1rho MRI.
• The two-acquisition approach effectively mitigates errors in mono-exponential relaxation modeling.