Caterpillar Traps

The management of long cables connecting a coil array to the main MRI system remains to be a challenge. Radiofrequency (RF) coupling of these cables to the main MRI transmit coil can cause high shield currents [1,2]. These currents affect coil performance, result in B1 field inhomogeneities, and, most importantly, pose serious safety hazards like heating and RF burns [3]. Traditional traps are designed to be stiff to avoid changes in their resonant frequency, hindering the overall system flexibility [4,5]. Instead of a few high-blocking traps, we propose caterpillar traps, a distributed system of small, elastic traps that cover the full length of cables. We leverage an array of resonant toroids as traps, forming a caterpillar-like structure, where bending only minimally impacts individual traps. Caterpillar traps provide sufficient attenuation to shield currents while allowing cable flexibility. Our distributed design can provide high blocking efficiency at different positions and orientations, even in cases where commercial cable traps cannot.

References

[1] Peterson, D.M., Beck, B.L., & Duensing G.R. (2002). Reduction of cable shield currents generated by high field body coils at 3 Tesla and above. Int Soc Magn Reson Med, Honolulu, HI. p 850. 2.
[2] Beck, B.L., Peterson, D.M., Duensing G.R., & Fitzsimmons J.R. (2000). Implications of Cable Shield Currents at 3.0 and 4.7 Tesla. Int Soc Magn Reson Med, Denver, CO. p 641
[3] Peterson, D. M., Beck, B. L., Duensing, G. R., & Fitzsimmons, J. R. (2003). Common mode signal rejection methods for MRI: Reduction of cable shield currents for high static magnetic field systems. Concepts in Magnetic Resonance, 19B(1), 1–8. https://doi.org/10.1002/cmr.b.10090
[4] Burl, M., Chmielewski, T., & Braum, W.O., Koninklijke Philips Electronics, assignee. (2003). Multi-channel RF cable trap for magnetic resonance imaging. U.S. patent 6593744.
[5] Seeber, D. A., Jevtic, J., & Menon, A. (2004). Floating shield current suppression trap. Concepts in Magnetic Resonance, 21B(1), 26–31. https://doi.org/10.1002/cmr.b.20008