General Considerations Regarding Scattering of the MRI RF Field by Implanted Medical Devices

S. A. Mohsin, N. M. Sheikh, F. Mahmood, W. Abbas

Abstract


The electromagnetic scattering problem posed by the interaction of the magnetic resonance imaging (MRI) RF field with a medical implant in tissue is explored. An exact formulation is computationally expensive since the domain includes all of the body tissue, the implant, the air region, and the surfaces of the RF coil conductors. It is shown that a division of the problem into two parts makes it more amenable to a numerical computation. In the first part, the RF field in the presence of body tissue only is found, and in the second part, the RF field that has already been computed is used as the incident field in the presence of the implant. Taking this incident field approximation into account, a domain simplification approximation is presented. A nonhomogeneous tissue layer surrounding the implant is considered and it is shown that then it is no longer necessary to integrate over all of the body tissue, and that the errors introduced due to this approximation are small enough to be considered as negligible. Numerical results validating the approximations are also presented.

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References


A.R. Rezai, D. Finneli, J. A. Nyenhuis, G. Hrdlicka, J. Tkach, A. Sharan, P. Rugieri, P. H Stypulkowski, and F. G. Shellock, “Neurostimulation Systems for Deep Brain Stimulation: In Vitro Evaluation of Magnetic Resonance Imaging-Related Heating at 1.5 Tesla,” J Magn. Reson. Imaging, Vol. 15, pp. 241-250, 2002.

M. Bock, R. Umathum, S. Zuehlsdorff, S. Volz, C. Fink, P. Hallscheidt, H. Zimmermann, W. Nitz and W. Semmler, “Interventional Magnetic Resonance Imaging: an Alternative to Image Guidance with Ionizing Radiation”, Radiation Protection Dosimetry, Vol. 117, No. 1-3, pp. 74-78, February 2006.

T. M. Peters., “Image-Guidance for Surgical Procedures”, Phys. Med. Biol., Vol. 51, No. 14, pp. R505-R540, July 2006.

W. R. Nitz, A. Oppelt, W. Renz, C. Manke, M. Lenhart, and J. Link, “On the Heating of Linear Conductive Structures as Guide Wires and Catheters in Interventional MRI,” J. Magn. Reson. Imag., Vol. 13, pp. 105-113, 2001.

R. P. King , “Antennas in material media near boundaries with application to communication and geophysical exploration, Part I: The bare metal dipole,” IEEE Transactions on Antennas and Propagation, Volume 34, Issue 4, pp. 483 – 489, April 1986.

R. P. King, “Antennas in material media near boundaries with application to communication and geophysical exploration, Part II: The terminated insulated antenna,” IEEE Transactions on Antennas and Propagation, Volume 34, Issue 4, pp. 490 – 496, April 1986.

S.M. Park, R. Kamondetdacha, A. Amjad, and J. A. Nyenhuis, “MRI safety: RF induced heating on straight wires,” IEEE Trans. Magn., Vol. 41, No. 10, pp. 4197- 4199, Oct. 2005.

J. A. Nyenhuis, S.M. Park, R. Kamondetdacha, A. Amjad, F.G. Shellock, and A. Rezai, “MRI and Implanted Medical Devices: Basic Interactions With an Emphasis on Heating,” IEEE Trans. Device and Materials Reliability, Vol. 5, No. 3, Sep. 2005.

Mohsin, S. A., N. M. Sheikh, U. Saeed, “MRI-induced heating of deep brain stimulation leads,” Phys. Med. Biol., 5745-5756, 2008

Mohsin, S. A., N. M. Sheikh, U. Saeed, “MRI induced heating of deep brain stimulation leads: effect of the air-tissue interface,” Progress In Electromagnetics Research, PIER 83, 81–91, 2008.

H. S. Ho, “Safety of Metallic Implants in Magnetic Resonance Imaging,” J. Magn. Reson. Imag., Vol. 14, pp. 472-474, 2001.

A. Amjad, R. Kamondetdacha, A.V. Kildishev, S. M. Park, J. A. Nyenhuis, “Power deposition inside a phantom for testing of MRI heating,” IEEE Trans Magn 2005, 41:4185–4187.

A. Amjad, “Specific Absorption Rate during Magnetic Resonance Imaging,” Ph.D Thesis, Purdue University, 2007.

S. M. Park, “MRI Safety: Radiofrequency Field Induced Heating of Implanted Medical Devices,” Ph. D Thesis, Purdue University, 2006.

Sung-Min Park, Rungkiet Kamondetdacha, and John A. Nyenhuis, “Calculation of MRI-Induced Heating of an Implanted Medical Lead Wire With an Electric Field Transfer Function”, Journal of Magnetic Resonance Imaging 26:1278–1285, 2007.

W. Kainz,. SAR intercomparison protocol for 1.5 T MR systems draft, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, 2006.

John L. Volakis, Arindam Chatterjee, and Leo C. Kempel, “Finite Element Method for Electromagnetics,” The IEEE/OUP Series on Electromagnetic Wave Theory.

Roger F. Harrington, “Field Computation by Moment Methods,” Wiley-Interscience and IEEE Press Series on Electromagnetic Wave Theory, 1993.






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