Caterpillar traps: A highly flexible, distributed system of toroidal cable traps

Area of Science:

• Medical Imaging
• Radiofrequency Engineering
• Biomedical Engineering

Background:

• Magnetic Resonance Imaging (MRI) systems utilize shielded coaxial cables that can experience radiofrequency (RF) coupling.
• This coupling can induce high shield currents, leading to potential risks of heating and RF burns for patients.

Purpose of the Study:

• To develop a flexible and effective solution for mitigating RF shield currents in MRI cables.
• To introduce a novel 'caterpillar trap' design as an alternative to traditional stiff RF traps.

Main Methods:

• A distributed system of small, elastic resonant traps ('caterpillar traps') was designed and implemented along the full length of MRI cables.
• Benchtop measurements were conducted to assess the RF blocking capabilities and bending robustness of the caterpillar traps.
• Comparative analysis included B1+ mapping and heating measurements of an anterior array cable equipped with caterpillar traps against a commercial cable.

Main Results:

• Caterpillar traps demonstrated high robustness to bending, with minimal impact on individual trap resonance.
• Experiments showed improved RF blocking and enhanced flexibility of MRI cables using caterpillar traps compared to commercial alternatives.
• The distributed design proved effective in providing high blocking efficiency across various positions and orientations.

Conclusions:

• Caterpillar traps offer a viable solution for attenuating shield currents while maintaining essential cable flexibility in MRI systems.
• This distributed trapping approach enhances safety and system adaptability, overcoming limitations of conventional rigid traps.