Date of Award


Degree Type


Degree Name

Master of Science


Medical Biophysics


Dr. Blaine Chronik

Second Advisor

Dr. Martin Zinke-Allmang


In magnetic resonance imaging (MRI), peripheral nerve stimulation (PNS) resulting from electric fields induced from the rapidly changing magnetic fields of gradient coils is a concern. Nerves exposed to either electric fields or time-varying magnetic fields would be expected to display consistent threshold characteristics, motivating the direct application of electric field exposure criteria from literature to guide the development of gradient coil exposure criteria for MRI. The chronaxie times (an indicator of nerve excitability) for electric and magnetic PNS threshold curves were compared in two consecutive studies. Peripheral nerves were stimulated electrically and magnetically using surface electrodes and a figure-eight coil, respectively. The main finding of these studies is that chronaxie time is significantly different between electric and magnetic stimulation. These results suggests that special care must be taken when using electric field exposure data from literature to set gradient coil PNS safety standards in MRI.



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