[CCoE Notice] Dissertation Announcement: Lijian Yang, "Unanticipated Peripheral Nerve Stimulation in MRI: Implications for Patients with Implantable Devices"

[Greenwell, Stephen J]

[Dissertation Defense Announcement at the Cullen College of Engineering]
Unanticipated Peripheral Nerve Stimulation in MRI: Implications for Patients with Implantable Devices
Lijian Yang
April 18, 2025, 12 p.m. to 2 p.m. (CST)
Location: Engineering Building 1 N325, or Microsoft Teams <https://urldefense.com/v3/__https://teams.microsoft.com/l/meetup-join/19*3ameeting_NjVjZTc3NGYtYzA1OC00YTU2LWE4YWUtYmRlM2M0OGUwNjE1*40thread.v2/0?context=*7b*22Tid*22*3a*22170bbabd-a2f0-4c90-ad4b-0e8f0f0c4259*22*2c*22Oid*22*3a*221a5e5d81-8c9a-4801-b362-fe4f2c03439b*22*7d__;JSUlJSUlJSUlJSUlJSUl!!LkSTlj0I!E1BxhLln6Tj2q7NWlJRRG3zRkOjudDPEe0vyyUUMQz2JpwSXp7hZ8MCDJdYXKVAr5TzUVYmmKcVpEkCrGOiOBk7ApIA$ >
Committee Chair:
Dr. Ji Chen, Ph.D.
Committee Members:
Dr. David R. Jackson, Ph.D. | Dr. Hui Ye, Ph.D. | Dr. Norbert Kaula, Ph.D. |
Dr. Jianfeng Zheng, Ph.D.
Abstract
This dissertation presents computational investigations into the effects of metallic implants and implanted electrodes on peripheral nerve stimulation (PNS) during magnetic resonance imaging (MRI). By integrating anatomical electromagnetic simulations with thermal and neurophysiological modeling, the work aims to assess how implant-related modifications to the local electromagnetic environment influence neural activation thresholds under MRI exposure.
The first study examines the impact of orthopedic plates implanted in clinically relevant anatomical regions on gradient-induced PNS thresholds. Results demonstrate that metallic implants can significantly reduce activation thresholds-by up to 80%-bringing some values close to the safety limits defined in IEC 60601-2-33. The second study extends this analysis by evaluating how the length of orthopedic plates affects both gradient-induced electric field distribution and RF-induced tissue heating. It reveals that longer plates enhance electric field gradients near their edges, lowering nerve activation thresholds, while also exhibiting higher local RF heating, which further modulates nerve excitability. The third study focuses on unintended vagus nerve stimulation in the presence of cuff electrodes, where combined gradient and RF fields are shown to reduce activation thresholds, particularly during short-pulse gradient waveforms.
Together, these studies highlight critical interactions between implants, MRI gradient and RF fields, revealing potential safety concerns for patients with orthopedic implants or implantable neurostimulators. The findings show the importance of incorporating neurophysiological modeling into MRI safety assessments for individuals with implants.
[Engineered For What's Next]


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://Bug.EGR.UH.EDU/pipermail/engi-dist/attachments/20250403/eff5b857/attachment-0001.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 28058 bytes
Desc: image001.png
Url : http://Bug.EGR.UH.EDU/pipermail/engi-dist/attachments/20250403/eff5b857/attachment-0002.png 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.png
Type: image/png
Size: 5699 bytes
Desc: image002.png
Url : http://Bug.EGR.UH.EDU/pipermail/engi-dist/attachments/20250403/eff5b857/attachment-0003.png