B1+ compensation in 3T cardiac imaging using short 2DRF pulses

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Engineering
• Cardiac Imaging

Background:

• In-plane radiofrequency (RF) field inhomogeneity is a significant challenge in 3T MRI, particularly affecting cardiac imaging.
• Variations in the transmitted RF field can lead to inaccurate flip angles and degraded image quality in the left ventricle.

Purpose of the Study:

• To investigate the efficacy of tailored 2D radiofrequency (RF) pulses in compensating for in-plane RF field variations at 3T.
• To assess the impact of these tailored pulses on flip angle uniformity within the left ventricle during cardiac imaging.

Main Methods:

• Design of excitation pulse profiles approximating the reciprocal of measured RF transmit variations.
• Utilized a simple 2D RF pulse design with three subpulses for adaptability to different regions of interest.
• Evaluated performance using phantom studies and in vivo cardiac imaging at 3T.

Main Results:

• Tailored 2D RF pulses significantly reduced average flip angle variation over the left ventricle (p < 0.001).
• An average reduction of 41% in flip angle variation was observed in cardiac studies compared to conventional slice-selective excitation.
• The pulse design allowed for quick adaptation to specific regions of interest.

Conclusions:

• Tailored 2D RF pulses offer an effective strategy for mitigating in-plane RF field inhomogeneities at 3T.
• This technique improves flip angle uniformity in cardiac MRI, leading to enhanced image quality.
• The proposed pulse design is practical and adaptable for clinical applications in cardiac imaging.