On the development of equivalent medium for active implantable device radiofrequency safety assessment

Wang, Yu; Wang, Qingyan; Liu, Jingshen; Zeng, Qi; Zheng, Jianfeng; Kainz, Wolfgang; Chen, Ji

doi:10.1002/mrm.27785

Cited by 13 publications

(12 citation statements)

References 20 publications

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“…Unfortunately, however, postoperative application of MRI is limited for these patients due to risks of radio frequency (RF) heating of the tissue surrounding electrode contacts, a phenomenon known as the "antenna effect" (5)(6)(7)(8). Although MR-conditional DBS devices are available, conditions of imaging are restrictive: only 1.5T horizontal scanners are allowed, and only pulse sequences with reduced power (global SAR ≤ 0.1W/kg or B1rms ≤ 2 µT) are recommended (9)(10)(11).…”

Section: Resultsmentioning

confidence: 99%

The effect of device configuration and patient’s body composition on image artifact and RF heating of deep brain stimulation devices during MRI at 1.5T and 3T

Bhusal¹,

Nguyen²,

Vu³

et al. 2020

Preprint

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BACKGROUNDPatients with deep brain stimulation (DBS) implants have limited access to MRI due to safety concerns associated with RF-induced heating. Currently, MRI in these patients is allowed only in 1.5T horizontal scanners and with pulse sequences with reduced power.Nevertheless, off-label use of MRI at 3T is increasingly reported based on limited safety assessments. Here we present results of systematic RF heating measurements for two commercially available DBS systems during MRI at 1.5T and 3T. from 0.10℃ to 7.39℃ at 3T. The presence of subcutaneous fat substantially altered RF heating at electrode tips (-3.06℃ < ∆ < 19.05℃). Introducing concentric loops in the extracranial portion of the lead at the surgical burr hole reduced RF heating by up to 89% at 1.5T and up to 98% at 3T compared to worst case heating scenarios. DATA CONCLUSIONDevice configuration and patient body composition significantly altered the RF heating of DBS leads during MRI at 1.5T and 3T. Interestingly, certain lead trajectories consistently reduced RF heating and image artifact over different imaging landmarks, RF frequencies, and phantom compositions. Such trajectories could be implemented in patients with minimal disruption to the surgical workflow.

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Section: Resultsmentioning

confidence: 99%

The effect of device configuration and patient’s body composition on image artifact and RF heating of deep brain stimulation devices during MRI at 1.5T and 3T

Bhusal¹,

Nguyen²,

Vu³

et al. 2020

Preprint

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“…Unfortunately, postoperative application of MRI is limited for patients with DBS implants due to risks of RF heating of the tissue surrounding electrode contacts, a phenomenon known as the “antenna effect.” 7–10 Although MR‐conditional DBS devices are available, conditions of imaging are restrictive: 1.5T horizontal scanners are allowed, and pulse sequences with reduced power (whole‐head specific absorption rate [SAR] ≤ 0.1 W/kg or B 1 rms ≤ 2 μT) are recommended 11,12 . Complying with the manufacturer's guidelines is difficult in practice, as MRI protocols for optimal visualization of DBS target structures tend to have much higher SAR than current guidelines allow 13 .…”

mentioning

confidence: 99%

Effect of Device Configuration and Patient's Body Composition on the RF Heating and Nonsusceptibility Artifact of Deep Brain Stimulation Implants During MRI at 1.5T and 3T

Bhusal

Nguyen

Sanpitak

et al. 2020

Magnetic Resonance Imaging

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BackgroundPatients with deep brain stimulation (DBS) implants have limited access to MRI due to safety concerns associated with RF‐induced heating. Currently, MRI in these patients is allowed in 1.5T horizontal bore scanners utilizing pulse sequences with reduced power. However, the use of 3T MRI in such patients is increasingly reported based on limited safety assessments. Here we present the results of comprehensive RF heating measurements for two commercially available DBS systems during MRI at 1.5T and 3T.PurposeTo assess the effect of imaging landmark, DBS lead configuration, and patient's body composition on RF heating of DBS leads during MRI at 1.5T and 3T.Study TypePhantom and ex vivo study.Population/Subjects/Phantom/Specimen/Animal ModelGel phantoms and cadaver brain.Field Strength/Sequence1.5T and 3T, T1‐weighted turbo spin echo.AssessmentRF heating was measured at the tips of DBS leads implanted in brain‐mimicking gel. Image artifact was assessed in a cadaver brain implanted with an isolated DBS lead.Statistical TestsDescriptive.ResultsWe observed substantial fluctuation in RF heating, mainly affected by phantom composition and DBS lead configuration, ranging from 0.14°C to 23.73°C at 1.5T, and from 0.10°C to 7.39°C at 3T. The presence of subcutaneous fat substantially altered RF heating at the electrode tips (3.06°C < ∆T < 19.05° C). Introducing concentric loops in the extracranial portion of the lead at the surgical burr hole reduced RF heating by up to 89% at 1.5T and up to 98% at 3T compared to worst‐case heating scenarios.Data ConclusionDevice configuration and patient's body composition substantially altered the RF heating of DBS leads during MRI. Interestingly, certain lead trajectories consistently reduced RF heating and image artifact.Level of Evidence 1Technical Efficacy Stage 1J. MAGN. RESON. IMAGING 2021;53:599–610.

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“…The relative increase of lead‐tip heating of the abandoned leads with metal ends for the SNM and CRM pacemaker systems occur either at very low temperatures or are very small (less than 0.05, which is equivalent to < 1℃); in both cases they are negligible and fall within the combined uncertainty. Although the relative lead‐tip heating increase of the metal‐end abandoned DBS leads occurs at higher heating (ie, up to 0.86), the maximum increase of 10% is negligible and within the combined uncertainty (16% ± 0.05, which is equivalent to 16% ± 1℃) of the TF model prediction and measurement 15 . The increase of the abandoned leads with metal ends over the complete AIMD is even lower for the SNM and the CRM pacemaker systems.…”

Section: Resultsmentioning

confidence: 78%

“…Such interactions can lead to concentrated energy deposition at the lead tip, resulting in RF-induced tissue heating around the lead tip and possible tissue damage. [14][15][16][17] To gain market approval and to ensure patient safety, all AIMDs require MR Conditional labeling reviewed and granted by regulatory bodies. It has been demonstrated also that non-MR Conditional implants can, in some cases, undergo MRI without posing significant risks to the patient.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic resonance conditionality of abandoned leads from active implantable medical devices at 1.5 T

Wang

Guo

et al. 2021

Magnetic Resonance in Med

Self Cite

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During MR scans, abandoned leads from active implantable medical devices (AIMDs) can experience excessive heating at the lead tip, depending on the type of termination applied to the proximal contacts (proximal end treatment). The influence of different proximal end treatments (ie, [1] freely exposed in the tissue, [2] terminated with metal in contact with the tissue, or [3] capped with plastic, and thereby fully insulated, on the RF-induced lead-tip heating) are studied. A technique to ensure that MR Conditional AIMD leads remain MR Conditional even when abandoned is recommended. Methods: Abandoned leads from three MR Conditional AIMDs ([1] a sacral neuromodulation system, [2] a cardiac rhythm management pacemaker system, and [3]a deep brain stimulator system) were investigated in this study. The computational lead models (ie, the transfer functions) for different proximal end treatments were measured and used to assess the in vivo lead-tip heating for four virtual human models (FATS, Duke, Ella, and Billie) and compared with the lead-tip heating of the complete MR Conditional AIMD system. Result: The average and maximum lead-tip heating for abandoned leads proximally capped with metal is always lower than that from the complete AIMD system. Abandoned leads proximally insulated could lead to an average in vivo temperature rise up to 3.5 times higher than that from the complete AIMD system. Conclusion: For the three investigated AIMDs under 1.5T MR scanning, our results indicate that RF-induced lead-tip heating of abandoned leads strongly depends on the proximal lead termination. A metallic cap applied to the proximal termination of the tested leads could significantly reduce the RF-induced lead-tip heating.

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On the development of equivalent medium for active implantable device radiofrequency safety assessment

Cited by 13 publications

References 20 publications

The effect of device configuration and patient’s body composition on image artifact and RF heating of deep brain stimulation devices during MRI at 1.5T and 3T

The effect of device configuration and patient’s body composition on image artifact and RF heating of deep brain stimulation devices during MRI at 1.5T and 3T

Effect of Device Configuration and Patient's Body Composition on the RF Heating and Nonsusceptibility Artifact of Deep Brain Stimulation Implants During MRI at 1.5T and 3T

Magnetic resonance conditionality of abandoned leads from active implantable medical devices at 1.5 T

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