Parallel excitation with an array of transmit coils.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Engineering
• Medical Physics

Background:

• Standard MRI excitation pulses can be lengthy, requiring prolonged RF and gradient usage.
• Accelerating spatial encoding in MRI often relies on complex, time-consuming pulse sequences.
• Managing radiofrequency (RF) power deposition is crucial for patient safety in MRI.

Purpose of the Study:

• To establish the value of parallel excitation with transmit coil arrays for accelerating MRI scans.
• To demonstrate improved management of RF power deposition using parallel excitation.
• To present a method for designing accelerated multidimensional excitations.

Main Methods:

• Developed a closed-form design for accelerated multidimensional excitations in the small-tip-angle regime.
• Utilized the localization characteristics of parallel transmit coil arrays.
• Designed and experimentally evaluated sample accelerated and specific absorption rate (SAR)-reduced excitation pulses.

Main Results:

• Parallel excitation enables faster excitation profiles using shorter RF pulses without gradient strain.
• A novel design suppresses aliasing lobes, analogous to SENSE (Sensitivity Encoding).
• Parallel excitation offers superior RF power deposition management and faithful profile production.

Conclusions:

• Parallel excitation with transmit coil arrays is valuable for accelerating MRI and managing RF power deposition.
• The technique provides greater control over excitation profiles and SAR.
• This approach enhances MRI efficiency and safety through optimized RF pulse design.