Magnetic resonance imaging and cardiac pacemaker safety at 1.5-Tesla

Martin, Edward T.; Coman, James A.; Shellock, Frank G.; Pulling, Christopher C.; Fair, Robert; Jenkins, Kim

doi:10.1016/j.jacc.2003.12.016

Cited by 378 publications

(290 citation statements)

References 35 publications

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“…This suggests that there is no detrimental effect on the MCGR extension mechanism or internal motor by the MRI protocol employed. There was no discernable temperature increases to the outer casing of the implant following the MRI protocol in keeping with reports evaluating cardiac leads and cochlear implants, although the current study utilized a relatively low energy dissipation scanning sequence and tested the rod in isolation [21][22][23]. Furthermore, subjecting the MCGRs to the MRI protocols did not result in any elongation or shortening of the rod.…”

Section: Methodssupporting

confidence: 73%

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

et al. 2015

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Disclosures: Ellipse Technologies donated the 2 magnetically controlled growing rods that were used in this study.OMS has previously received travel grants from Ellipse Technologies to support attendance at academic spinal meetings. OMS has previously received an honorarium from Ellipse Technologies for preparing and delivering a symposium at an academic spinal meeting. None of these disclosures relates to this study.The authors have no other financial or competing interests to disclose in relation to this work. Purpose:Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset paediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare-earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion. Methods:This is an in-vitro experiment using two magnetic growth rods secured in a 1.5 T MRI. A gradient echo sequence MRI was performed to evaluate whether the rods elongated, contracted or rotated during scanning and a phantom model was used to evaluate the amount of artifact induced.Results:The rod was not activated or subsequently impaired by the process of MRI. Image distortion of 28.9 cm was seen with the phantom model measured from the magnet housing. Conclusions:This study has demonstrated that there are no detrimental effects of MRI on the MCGR and imaging of the head and neck phantom can still be interpreted. Further in-vivo study is warranted.

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Section: Methodssupporting

confidence: 73%

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

et al. 2015

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“…The scaling term ␣ was then calculated according to Eq. [3] using the calculated S 1 and E tan . The electric field E 1 at the end of the wire was calculated with the method of moments and the SAR around the end of the wire was calculated with Eq.…”

Section: Experimental Validationmentioning

confidence: 99%

“…IMPLANTED MEDICAL DEVICES such as deep brain stimulators and cardiac pacemakers interact with the magnetic fields in magnetic resonance imaging (MRI) (1)(2)(3)(4)(5). One of the interactions is tissue heating.…”

mentioning

confidence: 99%

Calculation of MRI‐induced heating of an implanted medical lead wire with an electric field transfer function

Park

Kamondetdacha

Nyenhuis

2007

Magnetic Resonance Imaging

195

210

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Purpose:To develop and demonstrate a method to calculate the temperature rise that is induced by the radio frequency (RF) field in MRI at the electrode of an implanted medical lead. Materials and Methods:The electric field near the electrode is calculated by integrating the product of the tangential electric field and a transfer function along the length of the lead. The transfer function is numerically calculated with the method of moments. Transfer functions were calculated at 64 MHz for different lengths of model implants in the form of bare wires and insulated wires with 1 cm of wire exposed at one or both ends.Results: Heating at the electrode depends on the magnitude and the phase distribution of the transfer function and the incident electric field along the length of the lead. For a uniform electric field, the electrode heating is maximized for a lead length of approximately one-half a wavelength when the lead is terminated open. The heating can be greater for a worst-case phase distribution of the incident field. Conclusion:The transfer function is proposed as an efficient method to calculate MRI-induced heating at an electrode of a medical lead. Measured temperature rises of a model implant in a phantom were in good agreement with the rises predicted by the transfer function. The transfer function could be numerically or experimentally determined. IMPLANTED MEDICAL DEVICES such as deep brain stimulators and cardiac pacemakers interact with the magnetic fields in magnetic resonance imaging (MRI) (1-5). One of the interactions is tissue heating. The heating arises from the scattered electric field due to interaction of the MRI radio frequency (RF) magnetic field (B 1 ) and a medical implant. The greatest, and potentially dangerous, temperature rises occur at the ends of elongated implants, such as at the electrode of an implanted lead (6,7).In vitro testing in phantoms has been undertaken to characterize the RF-induced temperature rise (8). Recently, there has been an increased interest in mathematical modeling to assess the in vivo temperature rise. Numerical modeling based on the finite difference time domain (FDTD) method has been used to calculate the RF-induced electric field in human (9,10) and phantom models (11). It is difficult to numerically solve human and lead models simultaneously due to the complex structure of medical lead systems. It may be advantageous to model the lead and the human separately and then combine the results to determine the heating. The focus in this work is on modeling the lead. We describe the transfer function of a lead that relates the incident electric field to the scattered electric field in the vicinity of the electrode. From knowledge of the transfer function, the heating at the electrode and the resonant behavior of leads in phantom and human models can be predicted. Figure 1 shows the concept of the transfer function of a lead wire. An incident electric field with a tangential component E tan couples with the lead. The overall length of the lead is L, is the dis...

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“…It seems that none of these deaths occurred when there was a physician present directly supervising or monitoring the scan [2]. In several published small studies of patients knowingly undergoing MR examinations with pacemakers in situ there were no reported deaths, although these studies have clearly been performed in highly specialised institutions [4].…”

Section: ' 2011 the British Institute Of Radiologymentioning

confidence: 99%

MRI conditional pacemakers: the start of a new era

Harden¹

2011

BJR

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Magnetic resonance imaging and cardiac pacemaker safety at 1.5-Tesla

Abstract: Safety was demonstrated in this series of patients with pacemakers at 1.5-T.

Cited by 378 publications

References 35 publications

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

Calculation of MRI‐induced heating of an implanted medical lead wire with an electric field transfer function

MRI conditional pacemakers: the start of a new era

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