Optimized saturation pulse train for human first-pass myocardial perfusion imaging at 7T

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Cardiovascular Imaging
• Biophysics

Background:

• Clinical myocardial perfusion imaging often utilizes 3T MRI.
• Saturation pulses are crucial for suppressing unwanted signals in perfusion imaging.
• Existing saturation techniques developed for 3T may not translate effectively to 7T due to field variations and power deposition.

Purpose of the Study:

• To evaluate the feasibility of existing 3T saturation methods for 7T myocardial perfusion imaging.
• To develop and propose a novel saturation pulse train design optimized for 7T imaging.
• To assess the performance of the new design compared to existing methods.

Main Methods:

• A new saturation pulse train using four hyperbolic-secant (HS8) pulses was designed.
• Pulse amplitudes were optimized considering 7T field variations and radiofrequency power deposition limits in the myocardium.
• The proposed method was compared against existing techniques through simulations, phantom studies, and in vivo human experiments.

Main Results:

• The proposed method achieved an average saturation efficiency of 97.8% in healthy volunteers.
• This efficiency significantly outperformed previously published methods (86%, 95%, 90.8%).
• Successful acquisition of the first human first-pass myocardial perfusion images at 7T was demonstrated using the new method.

Conclusions:

• Standard 3T saturation methods are suboptimal for 7T myocardial perfusion imaging.
• The novel saturation pulse train design effectively achieves high saturation.
• This advancement makes first-pass myocardial perfusion imaging feasible in humans at 7T.