A technique for the reduction of RF‐induced heating of active implantable medical devices during MRI. Issue 1 (10th August 2021)

• Record Type: Journal Article
• Authors: Wang, Yu; Zheng, Jianfeng; Guo, Ran; Wang, Qingyan; Kainz, Wolfgang; Long, Stuart; Chen, Ji
• Is Part Of: Magnetic resonance in medicine. Volume 87:Issue 1(2022)
• Page Start: 349
• Page End: 364
• Publication Date: 2021-08-10
• Subjects: active implantable medical devices -- decoying conductor -- MRI -- RF‐induced heating reduction -- transfer function; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.28953
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: The paper presents a novel method to reduce the RF‐induced heating of active implantable medical devices during MRI. Methods: With the addition of an energy decoying and dissipating structure, RF energy can be redirected toward the dissipating rings through the decoying conductor. Three lead groups (45 cm‐50 cm) and 4 (50 cm‐100 cm) were studied in 1.5 Tesla MR systems by simulation and measurement, respectively. In vivo modeling was performed using human models to estimate the RF‐induced heating of an active implantable medical device for spinal cord treatment. Result: In the simulation study, it was shown that the peak 1g‐averaged specific absorption rate near the lead‐tips can be reduced by 70% to 80% compared to those from the control leads. In the experimental measurements during a 2‐min exposure test in a 1.5 Telsa MR system, the temperature rises dropped from the original 18.3℃, 25.8℃, 8.1℃, and 16.1℃ (control leads 1‐4) to 5.4℃, 6.9℃, 1.6℃, and 3.3℃ (leads 1‐4 with the energy decoying and dissipation structure). The in vivo calculation results show that the maximum induced temperature rise among all cases can be substantially reduced (up to 80%) when the energy decoying and dissipating structures were used. Conclusion: Our studies confirm the effectiveness of the novel technique for a variety of scanning scenarios. The results also indicate that the decoying conductor length, number of rings, and ring area must be carefully chosen and validated.