Accelerated imaging with segmented 2D pulses using parallel imaging and virtual coils.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Pulse Sequence Design
• Image Reconstruction

Background:

• Magnetic field inhomogeneity causes spatial flip-angle variation in MRI, particularly with limited-bandwidth radiofrequency (RF) pulses.
• Multidimensional RF pulses are sensitive to inhomogeneity due to their long duration, reducing bandwidth.

Purpose of the Study:

• To present a method for offsetting increased imaging time caused by breaking 2D RF pulses into undersampled k-space segments.
• To improve excitation bandwidth and mitigate flip-angle variations in MRI.

Main Methods:

• Undersampling acquisition k-space in a phase-encoded dimension aligned with excitation segmentation.
• Reconstructing undersampled data using parallel imaging techniques, treating segments as originating from virtual receive coils.
• In vivo brain imaging at 3T and 4T using a 32-channel head coil and GRAPPA.

Main Results:

• Demonstrated successful application of the method in vivo for brain imaging.
• Validated the use of parallel imaging (GRAPPA) for reconstructing undersampled data from virtual coils.
• Showcased the potential to offset increased imaging time associated with segmented RF pulses.

Conclusions:

• The proposed method effectively compensates for increased scan times in segmented RF pulse sequences.
• This technique enhances the robustness of MRI against magnetic field inhomogeneity.
• Offers potential for faster and more accurate MRI acquisition in clinical settings.