Electromagnetic Modeling

Contact

Kyoko Fujimoto, Ph.D.

Summary

This group supports the agency's regulatory and guidance role by advancing our knowledge on the complex interactions between electromagnetic (EM) fields and the human body. The research combines anatomically detailed computational models and experimental measurements applied to several areas of clinical significance, including the: 1) analysis of radiofrequency (RF)-induced energy deposition in patients during magnetic resonance imaging (MRI); 2) heating in patients with implanted passive medical devices during MRI scans; 3) analysis of the safety and effectiveness of active implantable devices such as deep brain stimulators and pacemakers; 4) RF safety of human subjects during interventional MRI; and 5) analysis of patient safety with respect to gradient-induced heating and unintended nerve stimulation undergoing MRI, 6) evaluation of effectiveness of wireless technology which can be implanted in patients. These projects are conducted with active collaborations between several researchers, within the FDA and worldwide, at leading academic research institutes and industry organizations.

There is a direct impact on the regulatory mission of the Agency, as the tools developed by our research are extensively used by industry in pre-market evaluation for the safety and effectiveness of their medical devices. The research is funded by both internal (Office of Women's Health) and external (CRADA) support. Additionally, we are currently leading the Medical Device Innovation Consortium (MDIC) working group on Computational Modeling and Simulations – RF heating in MRI.

The Virtual Family: Four highly detailed, anatomically correct whole-body computer models in CAD (Computer Aided Design) format of an adult male, an adult female, and two children.

---

Surface view of the MIDA model, a Multimodal Imaging-based Detailed Anatomical computer model of the human head and neck. The MIDA model offers detailed representation of 153 different structures and can be used for modeling and numerical analysis of medical devices in, on, or near the head.

---

3D specific absorption rate (SAR) maps of the blood vessels for the hip bone imaging landmark during 1.5 T MRI.

Current funding sources

FDA Office of Women's Health
Cooperative Research and Development Agreement (CRADA) – Imricor Inc.

Personnel

FDA Staff:
Kyoko Fujimoto, Ph.D.
Howard Bassen
Joshua Guag
Wolfgang Kainz, Ph.D.
Sunder Rajan, Ph.D.

External collaborators

• ANSYS Inc.
• Imricor Medical Systems
• IT'IS Foundation, Zurich, Switzerland
• Massachusetts General Hospital, Harvard Medical School
• Max Plank Institute, Leipzig, Germany
• Medical Device Innovation Consortium
• Northwestern University
• University of Houston
• Hitachi Medical Systems

Resource facilities

Hardware

• Gradient coil simulator with amplifiers (MRCOMP, Germany)
• MITS1.5 and MITS3.0: RF coils at 64MHz and 128MHz  (ZMT Zurich MedTech AG, Zurich, Switzerland)
• DASY52 AIMD Scanner: robotic measurement system  (SPEAG, Zurich, Switzerland)

Software

• Electromagnetic and thermal solvers:
  • Sim4Life (ZMT Zurich MedTech AG, Zurich, Switzerland),
  • XFDTD (Remcom Inc., State College, PA)
  • HFSS (ANSYS Inc., Canonsburg, PA)

Public domain software

Virtual Family Website
MIDA Website

Relevant standards & guidance

Reporting of Computational Modeling Studies in Medical Device Submissions - Draft Guidance for Industry and Food and Drug Administration Staff

Selected peer reviewed publications

• Fujimoto K et al. Radio-Frequency Safety Assessment of Stents in Blood Vessels During Magnetic Resonance Imaging. Frontier in Physiology. 2018
• Kozlov et al. Lead Electromagnetic Model to Evaluate RF-Induced Heating of a Coax Lead: A Numerical Case Study at 128 MHz. IEEE J Electromagn RF Microw Med Biol. 2018.
• Song et al. Retrospective analysis of RF heating measurements of passive medical implants. Magnetic Resonance in Medicine. 2018
• Lucano E et al. A numerical investigation on the effect of RF coil feed variability on global and local electromagnetic field exposure in human body models at 64 MHz. Magnetic Resonance in Medicine. 2017
• Golestanirad et al. Pushing the boundaries of deep brain stimulation imaging: Promising results of SAR-reduction performance of a reconfigurable MRI coil in a realistic patient population. Neuroimage. 2017
• Murbach et al. Pregnant women models analyzed for RF exposure and temperature increase in 3T RF shimmed birdcages. Magnetic Resonance in Medicine 2017.
• Neufeld E et al. Numerical Modeling of MRI Gradient Coil Switching Induced Nerve Stimulation. Physics in Medicine and Biology 2016
• Lucano et al. Assessing the electromagnetic field generated by a radiofrequency body coil at 64 MHz: defeaturing vs. accuracy. IEEE Trans Biomed Eng. 2016.
• Serano et al., A Novel Brain Stimulation Technology Provides Compatibility with MRI, Sci. Rep. 2015.
• Iacono et al., MIDA: A Multimodal Imaging-Based Detailed Anatomical Model of the Human Head and Neck, PLoS ONE 2015
• Park et al., A novel method to decrease electric field and SAR using an external high dielectric sleeve at 3 T head MRI: numerical and experimental results, IEEE Trans Biomed Eng. 2015.
• Gosselin et al., Development of a new generation of high-resolution anatomical models for medical device evaluation: the Virtual Population 3.0, Physics in Medicine and Biology 2015.