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A simple analytical expression for the gradient induced potential on active implants during MRI
Esra A Turk1, Emre Kopanoglu, Sevin Guney
1Department of Electrical and Electronics Engineering and the National Magnetic Resonance Research Center, Bilkent University, Ankara 06800, Turkey. esra@ee.bilkent.edu.tr
IEEE Transactions on Bio-Medical Engineering
|August 16, 2012
Summary
Researchers developed simplified analytical expressions to calculate electric fields and potentials induced by magnetic resonance imaging in active implantable medical devices (AIMDs). This aids in assessing stimulation risks for patients with implants.
Area of Science:
- Biomedical Engineering
- Medical Imaging Physics
- Electromagnetism
Background:
- Active implantable medical devices (AIMDs) interact with time-varying magnetic fields during MRI.
- Understanding this interaction is crucial for patient safety.
Purpose of the Study:
- To derive simplified analytical expressions for electric fields induced by time-varying magnetic fields.
- To approximate the gradient-induced potential on AIMD electrodes.
- To assess the risk of gradient-induced stimulation in patients with AIMDs.
Main Methods:
- Derived simplified analytical expressions for electric fields in a homogeneous cylindrical volume.
- Utilized the linear magnetic field property of gradient coils.
- Computed induced potentials on implant electrodes using simplified expressions on a cylindrical phantom.
- Verified results by comparing with measured potentials and frog leg stimulation experiments.
Main Results:
- Successfully derived closed-form electric field expressions.
- Approximated induced potentials on implant electrodes for various lead positions.
- Validated the method through phantom measurements and physiological experiments.
Conclusions:
- The simplified expressions provide an effective method for assessing gradient-induced potentials.
- This approach can help evaluate the stimulation risk for patients with AIMDs during MRI.
- Further research can refine risk assessment protocols for MRI in patients with implants.
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