Coupled transfer function model for the evaluation of implanted cables safety in MRI.

Area of Science:

• Biomedical Engineering
• Medical Imaging Physics

Background:

• Multiple medical device leads are often implanted in close proximity.
• Evaluating the safety of these leads during MRI is critical.

Purpose of the Study:

• To develop and validate a coupled transfer function model for assessing the radiofrequency (RF) field safety of adjacent medical leads during 1.5T MRI.
• To investigate the influence of lead coupling on heating effects.

Main Methods:

• Experimental evaluation of RF field-induced heating in coupled cables with varying termination conditions.
• Determination of coupled and single transfer functions experimentally.
• Simulation and comparison of additive and global coupled models.
• Prediction of relative temperature increases for isolated and coupled leads.

Main Results:

• Lead coupling strongly influences electrode heating.
• An experimentally determined coupled additive transfer function model accurately predicts heating for leads with constant separation.
• The global model showed a significant underestimation of heating (~30%) in one scenario.
• Simulated and measured coupled transfer functions showed good agreement.

Conclusions:

• Accounting for lead coupling is essential for evaluating the safety of implanted medical devices during MRI.
• The validated coupled transfer function model provides a reliable method for estimating heating in closely spaced leads.
• Future research should address the dynamic, in vivo variations in lead distances.