Numerical simulation of electromagnetic fields, SAR and temperature distribution

SAR distribution (EM simulation)

Electromagnetic interactions are important MR safety issues in the field of MR imaging if medical devices (e.g. implants) or other items enter the MR environment. Testing of induced voltages and radio frequency (RF) induced heating are multi parameter dependent issues not only for implants and devices, which have countless different configurations or implantation positions, e.g.

  • orthopedic fixation systems
  • neurostimulators or
  • pacemakers with one or more electrodes
  • other active medical devices with telemetry units, e.g. cochlear implants

but also for

  • less complex devices like single vascular implants (e.g. stents, filters, valves, etc.)
  • different combined implants within the human body

Based on the complex interaction of such devices with the electromagnetic MR environment, simulation of electromagnetic fields assists in determination of worst-cases and supports MR testing of medical devices.

The simulation process consists of several levels:

Input level

  • definition of the MR environment
  • implementation of MR pulse criteria according to a specific sequence protocol

1st project level

  • implementation of a CAD model of the medical device and determination of geometric boundary conditions
  • simulation of E- and B-fields
  • evaluation of induced voltages and currents

2nd project level

  • simulation of RF heating, SAR and temperature distribution

Experimental level

  • verification of simulation results
  • testing of RF heating in a real MR environment (MRI scanner)