Feedback field control improves the precision of T₂ * quantification at 7 T

Area of Science:

• Magnetic Resonance Imaging
• Biophysics

Background:

• T2* mapping provides crucial tissue parameters and is robust to signal variations.
• However, T2* measurements are sensitive to magnetic field errors, particularly breathing-induced perturbations at high fields.

Purpose of the Study:

• To assess the impact of breathing motion on T2* mapping in the brain at 7 Tesla.
• To evaluate the effectiveness of feedback field control in stabilizing magnetic fields and improving T2* quantification.

Main Methods:

• Phantom and in vivo brain measurements at 7 Tesla.
• Comparison of T2* mapping with and without feedback field control using NMR field sensing and dynamic shim actuation.
• Assessment of precision and reliability through repeated measurements and fitting error analysis.

Main Results:

• Breathing motion introduced significant errors in T2* mapping.
• Feedback field control substantially mitigated these errors in both phantom and in vivo studies.
• In vivo, field control enhanced structural fidelity, reduced fitting residuals, and lowered standard deviation of T2* maps.

Conclusions:

• Feedback field control is an effective method for improving the fidelity of T2* mapping.
• It successfully counters bulk susceptibility effects from breathing, enhancing T2* studies at high magnetic fields.