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Controlling radiofrequency-induced currents in guidewires using parallel transmit.
Maryam Etezadi-Amoli1, Pascal Stang1, Adam Kerr1
1Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA.
Magnetic Resonance in Medicine
|December 19, 2014
Summary
Parallel transmit technology minimizes dangerous MRI radiofrequency (RF) heating in elongated conductors like pacemaker leads. This method effectively controls induced currents, enhancing patient safety during MRI scans.
Area of Science:
- Medical Physics
- Biomedical Engineering
- Radiology
Background:
- Elongated conductors (pacemaker leads, neurostimulator leads, guidewires) can interact with MRI radiofrequency (RF) fields.
- This interaction may lead to dangerous tissue heating, posing a risk during interventional procedures and MRI scans.
Purpose of the Study:
- To investigate the feasibility of using parallel transmit technology to mitigate RF-induced currents in elongated conductors.
- To reduce the potential for hazardous tissue heating associated with these devices during MRI.
Main Methods:
- Experiments conducted on a 1.5T four-channel parallel transmit MRI system.
- Design of "null mode" excitations to minimize induced currents using B1 (+) maps.
- Evaluation of current reduction using B1 (+) maps, current sensors, and temperature probes.
Main Results:
- Parallel transmit reduced maximum coupling mode currents by factors of 2 to 80.
- A single current null effectively reduced tip heating for straight wires.
- Multiple current nulls improved heating reduction for curved geometries and longer conductors.
Conclusions:
- Parallel transmit is a viable method for reducing RF-induced currents in elongated conductors.
- This technique significantly decreases the risk of RF heating during MRI.
- It allows for safe MRI visualization while managing heating risks.
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