Development and optimization of hardware for delta relaxation enhanced MRI

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Physics

Background:

• Delta relaxation enhanced magnetic resonance (dreMR) imaging requires an auxiliary B0 electromagnet to shift the main magnetic field in clinical 1.5T MRI systems.
• Interactions between insertable resistive B0 electromagnets and superconducting MR systems can cause image artifacts.

Purpose of the Study:

• To identify and mitigate the primary causes of interaction between an actively shielded, insertable resistive B0 electromagnet and a 1.5T superconducting MR system.
• To enable dreMR imaging within a clinical 1.5T MRI environment.

Main Methods:

• Consideration of nonideal fabrication effects through precise winding measurements and improved active shield design.
• Comparison of shielding performance against a prior system using an ideal primary coil model.
• Implementation of hardware and software solutions to eliminate residual image artifacts.

Main Results:

• The newly constructed dreMR system exhibits a significantly reduced "long-time-constant" component in eddy currents.
• This reduction suggests less energy deposition into the MR system's cryostat.
• Active compensation effectively mitigated residual eddy-current fields.

Conclusions:

• The dreMR imaging system, with active compensation, achieves 0.22T field shifts within a 1.5T MRI.
• No significant residual eddy-current fields were detected, validating the mitigation strategies.
• This work paves the way for advanced dreMR imaging applications in clinical settings.