MaxGIRF: Image reconstruction incorporating concomitant field and gradient impulse response function effects.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Image Reconstruction

Background:

• Non-Cartesian MRI sequences are susceptible to artifacts from concomitant field effects.
• Accurate image reconstruction is crucial for diagnostic quality in MRI.

Purpose of the Study:

• To develop and evaluate MaxGIRF, a novel reconstruction strategy for compensating concomitant field effects in non-Cartesian MRI.
• To simultaneously correct off-resonance, concomitant fields, and trajectory errors without specialized hardware.

Main Methods:

• Introduced MaxGIRF, a higher-order reconstruction method using gradient impulse response functions.
• Estimated spatiotemporally varying concomitant fields using analytic expressions and gradient waveforms.
• Applied MaxGIRF to phantom simulations and in vivo human imaging at 0.55 T.

Main Results:

• MaxGIRF successfully mitigated blurring artifacts in both phantom and in vivo scans.
• The method demonstrated superiority over existing techniques, particularly in challenging regions.
• A low-rank approximation of MaxGIRF achieved <2% error with reduced computational cost.

Conclusions:

• MaxGIRF offers simultaneous correction for off-resonance, trajectory errors, and concomitant field effects in non-Cartesian MRI.
• The method's impact is most significant with longer readouts or lower field strengths.