Ensuring safety of implanted devices under MRI using reversed RF polarization

Patients with long‐wire medical implants are currently prevented from undergoing magnetic resonance imaging (MRI) scans due to the risk of radio frequency (RF) heating. We have developed a simple technique for determining the heating potential for these implants using reversed radio frequency (RF) polarization. This technique could be used on a patient‐to‐patient basis as a part of the standard prescan procedure to ensure that the subject's device does not pose a heating risk. By using reversed quadrature polarization, the MR scan can be sensitized exclusively to the potentially dangerous currents in the device. Here, we derive the physical principles governing the technique and explore the primary sources of inaccuracy. These principles are verified through finite‐difference simulations and through phantom scans of implant leads. These studies demonstrate the potential of the technique for sensitively detecting potentially dangerous coupling conditions before they can do any harm. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.

[1]  Ali R. Rezai,et al.  Gelled versus nongelled phantom material for measurement of MRI-induced temperature increases with bioimplants , 2003 .

[2]  G.,et al.  Electromagnetic Considerations for RF Current Density Imaging , 2004 .

[3]  M. Kales,et al.  Techniques for Handling Elliptically Polarized Waves with Special Reference to Antennas: Part III - Elliptically Polarized Waves and Antennas , 1951, Proceedings of the IRE.

[4]  Steven M. Conolly,et al.  Monitoring Induced Currents on Long Conductive Structures During MRI , 2008 .

[5]  C. Balanis.  Advanced Engineering Electromagnetics , 1989 .

[6]  Jean A. Tkach,et al.  Permanent Neurological Deficit Related to Magnetic Resonance Imaging in a Patient with Implanted Deep Brain Stimulation Electrodes for Parkinson’s Disease: Case Report , 2005, Neurosurgery.

[7]  Michael O Zenge,et al.  Interventional magnetic resonance angiography with no strings attached: Wireless active catheter visualization , 2005, Magnetic resonance in medicine.

[8]  G. Breithardt,et al.  Safe Performance of Magnetic Resonance Imaging on a Patient with an ICD , 2005, Pacing and clinical electrophysiology : PACE.

[9]  Ergin Atalar,et al.  A catheter tracking method using reverse polarization for MR‐guided interventions , 2007, Magnetic resonance in medicine.

[10]  R. F. Harrington,et al.  Reciprocity Relationships for Gyrotropic Media , 1958 .

[11]  F. Shellock,et al.  Magnetic resonance imaging safety: implications for cardiovascular patients. , 2001, Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance.

[12]  Petros Martirosian,et al.  Effects on MRI due to altered rf polarization near conductive implants or instruments. , 2005, Medical physics.

[13]  Harold Litt,et al.  Strategy for Safe Performance of Extrathoracic Magnetic Resonance Imaging at 1.5 Tesla in the Presence of Cardiac Pacemakers in Non–Pacemaker-Dependent Patients: A Prospective Study With 115 Examinations , 2006, Circulation.

[14]  T. Cohen,et al.  Implanted devices and electromagnetic interference: case presentations and review. , 1995, The Journal of invasive cardiology.

[15]  Fritz Schick,et al.  RF artifacts caused by metallic implants or instruments which get more prominent at 3 T: an in vitro study. , 2005, Magnetic resonance imaging.

[16]  H. H. Pennes.  Analysis of tissue and arterial blood temperatures in the resting human forearm. , 1948, Journal of applied physiology.

[17]  R. Fimmers,et al.  Safety of brain 3-T MR imaging with transmit-receive head coil in patients with cardiac pacemakers: pilot prospective study with 51 examinations. , 2008, Radiology.

[18]  Jean A. Tkach,et al.  Is magnetic resonance imaging safe for patients with neurostimulation systems used for deep brain stimulation? , 2005, Neurosurgery.

[19]  C. Goodman,et al.  Food and Drug Administration Center for Devices and Radiological Health , 1988 .

[20]  Volkmar Schulz,et al.  Transmission line for improved RF safety of interventional devices , 2005, Magnetic resonance in medicine.

[21]  T. W. Athey.  Current FDA Guidance for MR Patient Exposure and Considerations for the Future a , 1992, Annals of the New York Academy of Sciences.

[22]  R. Mark Henkelman,et al.  Electromagnetic considerations for RF current density imaging [MRI technique] , 1995, IEEE Trans. Medical Imaging.

[23]  M. Ladd,et al.  Reduction of resonant RF heating in intravascular catheters using coaxial chokes , 2000, Magnetic Resonance in Medicine.

[24]  Ergin Atalar,et al.  of the 23 rd Annual EMBS International Conference , October 25-28 , Istanbul , Turkey RF Safety of Wires in Interventional MRI : Using a Safety Index , 2004 .

[25]  Frank G Shellock,et al.  Simple design changes to wires to substantially reduce MRI-induced heating at 1.5 T: implications for implanted leads. , 2005, Magnetic resonance imaging.

[26]  H. Halperin,et al.  Clinical Utility and Safety of a Protocol for Noncardiac and Cardiac Magnetic Resonance Imaging of Patients With Permanent Pacemakers and Implantable-Cardioverter Defibrillators at 1.5 Tesla , 2006, Circulation.

[27]  Jianming Jin.  Electromagnetic Analysis and Design in Magnetic Resonance Imaging , 1998 .

[28]  J. Schenck,et al.  An efficient, highly homogeneous radiofrequency coil for whole-body NMR imaging at 1.5 T , 1985 .

[29]  A. Lang,et al.  Deep Brain Stimulator Electrodes Used for Lesioning: Proof of Principle , 2001, Neurosurgery.

[30]  W. Nitz,et al.  On the heating of linear conductive structures as guide wires and catheters in interventional MRI , 2001, Journal of magnetic resonance imaging : JMRI.

[31]  Robert Fair,et al.  Magnetic resonance imaging and cardiac pacemaker safety at 1.5-Tesla. , 2004, Journal of the American College of Cardiology.

[32]  V. H. Rumsey,et al.  Reaction Concept in Electromagnetic Theory , 1954 .