Direct visualisation of B1 inhomogeneity by flip angle dependency

Area of Science:

• Medical Imaging
• Physics
• Engineering

Background:

• Spatial inhomogeneities in the Radio Frequency (RF) field are a primary cause of artifacts and reduced signal-to-noise ratio in Magnetic Resonance Imaging (MRI).
• Existing methods for quantifying RF field distribution can be complex.
• Direct visualization of RF field distribution is crucial for optimizing MRI performance.

Purpose of the Study:

• To present a straightforward MRI procedure for direct visualization of RF field inhomogeneities.
• To evaluate the performance of RF coils by assessing their field distribution.
• To demonstrate the sensitivity of the method to sample properties affecting RF fields.

Main Methods:

• Developed a simple MRI imaging procedure to visualize RF field distribution using image magnitude or phase.
• Submerged the entire RF coil in a non-conducting fluid to examine field distribution in both inner and outer volumes.
• Conducted experiments to assess the impact of sample properties on the effective RF wavelength.

Main Results:

• Successfully visualized RF field inhomogeneities directly using the proposed MRI method.
• The submerged coil technique provided a novel approach to evaluate RF coil performance.
• The method demonstrated sensitivity to sample-induced changes in the effective RF wavelength.

Conclusions:

• The presented MRI technique offers a simple and effective way to visualize RF field inhomogeneities.
• This method aids in identifying and mitigating artifacts, thereby improving MRI quality.
• The approach is valuable for RF coil characterization and understanding sample-RF field interactions.