Complexity of MRI induced heating on metallic leads: Experimental measurements of 374 configurations

Mattei, Eugenio; Triventi, Michele; Calcagnini, Giovanni; Censi, Federica; Kainz, Wolfgang; Mendoza, Gonzalo; Bassen, H.; Bartolini, Pietro

doi:10.1186/1475-925x-7-11

Cited by 154 publications

(147 citation statements)

References 16 publications

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“…The system is installed at the Department of Technology and Health of the Italian National Institute of Health and has been specially designed to provide a controlled exposure for MRI safety testing with regards to the RF field. Systems with the same features have been widely used in previous published studies (17,(22)(23)(24). It has also been demonstrated that, given the same implant configuration and the same WB-SAR delivered to the phantom, the induced heating inside the isolated birdcage coil is comparable with the one obtained in an actual MRI system using clinical MRI sequences (23).…”

Section: Exposure Systemmentioning

confidence: 87%

“…The simulator consists of a torso-shaped transparent PVC phantom of the size of a 70 kg male and of an internal volume of about 30 L. The leads were fixed on a PVC grid placed inside the phantom. The use of human-shaped phantoms, even if not prescribed by technical standards, has been already used to complement measurements obtained with standardized phantoms (17,23). It has been demonstrated that the geometry of the phantom can affect the amount of the induced heating at the implant tip (17).…”

Section: Phantomsmentioning

confidence: 99%

“…The use of human-shaped phantoms, even if not prescribed by technical standards, has been already used to complement measurements obtained with standardized phantoms (17,23). It has been demonstrated that the geometry of the phantom can affect the amount of the induced heating at the implant tip (17). For this reason, besides the experiments inside the ASTM phantom, a set of measurement was performed in more realistic conditions, both in terms of implant positioning and phantom shape.…”

Section: Phantomsmentioning

confidence: 99%

“…The lead tip was kept in the same position during all the experiments. Such configuration was chosen to provide easily repetitive and comparable measurements, and to maximize the amount of the RF-induced current along the lead (17). As already mentioned, the temperature rise measured at a lead tip can be affected by a large number of elements, and in particular by the implant geometry and lead path.…”

Section: Implantsmentioning

confidence: 99%

“…Previously published papers demonstrated how the implant geometry and location, as well as the position of the patient inside the RF coil, can significantly affect the amount of induced heating at the implant tip (17,18). Besides the large body of excellent works that have been published in the last year on the MRI-induced heating on metal implants, there are still a number of elements that have not been exhaustively considered yet, and thus need further investigations.…”

mentioning

confidence: 99%

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Role of the lead structure in MRI‐induced heating: In vitro measurements on 30 commercial pacemaker/defibrillator leads

Mattei¹,

Calcagnini²,

Censi³

et al. 2011

Magnetic Resonance in Med

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MRI-induced heating on endocardial leads is a serious concern for the safety of patients with implantable pacemakers or cardioverter-defibrillator. The lead heating depends on many factors and its amount is largely variable. In this study, we investigated the role of those structural properties of the lead that are reported on the accompanying documents of the device: (1) fixation modality (active vs. passive); (2) number of electrodes (unipolar vs. bipolar); (3) length; (4) tip surface; and (5) tip and ring resistance. In vitro temperature and specific absorption rate measurements on 30 leads (27 pacemakers, three implantable cardioverter-defibrillator leads) exposed to the radiofrequency field typical of a 1.5 T MRI scanner are presented. The data show that each lead has its own attitude to radiofrequency-induced heating and that the information that is available in the accompanying documents of the pacemaker is not sufficient to explain such attitude. Even if combined with that of the implant geometry, this information is still not sufficient to estimate the amount of heating due to the exposure to the radiofrequency field during MRI examination. Magn Reson Med 67:925-935,

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Section: Exposure Systemmentioning

confidence: 87%

Section: Phantomsmentioning

confidence: 99%

Section: Phantomsmentioning

confidence: 99%

Section: Implantsmentioning

confidence: 99%

mentioning

confidence: 99%

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Role of the lead structure in MRI‐induced heating: In vitro measurements on 30 commercial pacemaker/defibrillator leads

Mattei¹,

Calcagnini²,

Censi³

et al. 2011

Magnetic Resonance in Med

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Magnetic Resonance Imaging in Patients With Cardiac Implantable Electronic Devices With Abandoned Leads

et al. 2021

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IMPORTANCE Magnetic resonance imaging (MRI) is the modality of choice for many conditions. Conditional devices and novel protocols for imaging patients with legacy cardiac implantable electronic devices (CIEDs) have increased access to MRI in patients with devices. However, the presence of abandoned leads remains an absolute contraindication.OBJECTIVE To assess if the performance of an MRI in the presence of an abandoned CIED lead is safe and whether there are deleterious effects on concomitant active CIED leads. DESIGN, SETTING, AND PARTICIPANTSThis cohort study included consecutive CIED recipients undergoing 1.5-T MRI with at least 1 abandoned lead between January 2013 and June 2020. MRI scans were performed at the Hospital of the University of Pennsylvania. No patients were excluded.EXPOSURES CIEDs were reprogrammed based on patient-specific pacing needs. Electrocardiography telemetry and pulse oximetry were monitored continuously, and live contact with the patient throughout the scan via visual and voice contact was performed if possible. After completion of the MRI, CIED evaluation was repeated and programming returned to baseline or to a clinically appropriate setting.MAIN OUTCOMES AND MEASURES Variation in pre-and post-MRI capture threshold of 50% or more, ventricular sensing 40% or more, and lead impedance 30% or more, as well as clinical sequelae such as pain and sustained tachyarrhythmia were considered significant. Long-term follow-up lead-related data were analyzed if available.RESULTS A total of 139 consecutive patients (110 men [79%]) with a mean (SD) age of 65.6 (13.4) years underwent 200 MRIs of various anatomic regions including the thorax. Repeat examinations were common with a maximum of 16 examinations for 1 patient. There was a total of 243 abandoned leads with a mean (SD) of 1.22 (0.45) per patient. The mean (SD) number of active leads was 2.04 (0.78) and 64 patients (46%) were pacemaker dependent. A transmit-receive radiofrequency coil was used in 41 patients (20.5%), all undergoing MRI of the brain. There were no abnormal vital signs or sustained tachyarrhythmias. No changes in battery voltage, power-on reset events, or changes of pacing rate were noted. CIED parameter changes including decreased right atrial sensing in 4 patients and decreased left ventricular R-wave amplitude in 1 patient were transiently noted. One patient with an abandoned subcutaneous array experienced sternal heating that subsided on premature cessation of the study. CONCLUSIONS AND RELEVANCEThe risk of MRI in patients with abandoned CIED leads was low in this large observational study, including patients who underwent examination of the thorax. The growing aggregate of data questions the absolute contraindication for MRI in patients with abandoned CIED leads.

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Local tissue temperature increase of a generic implant compared to the basic restrictions defined in safety guidelines

Kyriakou

Christ

Neufeld

et al. 2011

Bioelectromagnetics

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The objective of this study was to investigate if persons with implantable medical devices are intrinsically protected by the current electromagnetic safety guidelines. For inter-laboratory comparisons, the U.S. Food and Drug Administration has defined a generic implant as consisting of an insulated wire with noninsulated tips, simulating active implants composed of a metallic case, and insulated wires with electric contacts at the tip. In this study, we determined the amplitude of the uniform electric fields induced in body tissues that cause a local increase in the tissue temperature by 1 °C in the presence of this generic implant for a wide range of frequencies and wire lengths. The field amplitudes were compared to the basic restrictions of the current exposure guidelines for both occupational and uncontrolled exposure. Results showed that a 1 °C temperature increase in the tissues around the tips of the generic implant can be reached for field strengths much smaller than 1% of those in the basic restrictions. The simulated results were validated by experimental evaluations. The impact of perfusion was investigated and was found to lead to a reduction in the local temperature peak by only 1.6-3 times. Additional simulations inside an inhomogeneous anatomical model were performed to ascertain whether similar heating as in the generic model was observed. The significant temperature elevations due to the presence of a generic implant indicate that demonstrating compliance with the basic restrictions might not be sufficient for persons with implants. Special considerations may be required, especially in the case of novel, emerging technologies that feature strong near-fields at frequencies below 10 MHz (e.g., wireless power-transfer systems).

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Complexity of MRI induced heating on metallic leads: Experimental measurements of 374 configurations

Abstract: Background: MRI induced heating on PM leads is a very complex issue. The widely varying results described in literature suggest that there are many factors that influence the degree of heating and that not always are adequately addressed by existing testing methods.

Cited by 154 publications

References 16 publications

Role of the lead structure in MRI‐induced heating: In vitro measurements on 30 commercial pacemaker/defibrillator leads

Role of the lead structure in MRI‐induced heating: In vitro measurements on 30 commercial pacemaker/defibrillator leads

Magnetic Resonance Imaging in Patients With Cardiac Implantable Electronic Devices With Abandoned Leads

Local tissue temperature increase of a generic implant compared to the basic restrictions defined in safety guidelines

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