Tracking the position and rotational orientation of a catheter using a transmit array system

Modeling Endovascular MRI Coil Coupling With Transmit RF Excitation

OBJECTIVE

To model inductive coupling of endovascular coils with transmit RF excitation for selecting coils for MRI-guided interventions.

METHODS

Independent and computationally efficient FEM models are developed for the endovascular coil, cable, transmit excitation, and imaging domain. Electromagnetic and circuit solvers are coupled to simulate net B₁ + fields and induced currents and voltages. Our models are validated using the Bloch-Siegert B₁ + mapping sequence for a series-tuned multimode coil, capable of tracking, wireless visualization, and high-resolution endovascular imaging.

RESULTS

Validation shows good agreement at 24-, 28-, and 34-μT background RF excitation within experimental limitations. Quantitative coil performance metrics agree with simulation. A parametric study demonstrates tradeoff in coil performance metrics when varying number of coil turns. Tracking, imaging, and wireless marker multimode coil features and their integration is demonstrated in a pig study.

CONCLUSION

Developed models for the multimode coil were successfully validated. Modeling for geometric optimization and coil selection serves as a precursor to time consuming and expensive experiments. Specific applications demonstrated include parametric optimization, coil selection for a cardiac intervention, and an animal imaging experiment.

SIGNIFICANCE

Our modular, adaptable, and computationally efficient modeling approach enables rapid comparison, selection, and optimization of inductively coupled coils for MRI-guided interventions.