Related Experiment Video
Updated: Dec 30, 2025
Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging
Published on: April 4, 2013
MR safety watchdog for active catheters: Wireless impedance control with real-time feedback
Ali Caglar Özen1,2,3, Berk Silemek4,5, Thomas Lottner1
1Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Freiburg, Germany.
Purpose:
To dynamically minimize radiofrequency (RF)-induced heating of an active catheter through an automatic change of the termination impedance.
Methods:
A prototype wireless module was designed that modifies the input impedance of an active catheter to keep the temperature rise during MRI below a threshold, ΔTmax . The wireless module (MR safety watchdog; MRsWD) measures the local temperature at the catheter tip using either a built-in thermistor or external data from a fiber-optical thermometer. It automatically changes the catheter input impedance until the temperature rise during MRI is minimized. If ΔTmax is exceeded, RF transmission is blocked by a feedback system.
Results:
The thermistor and fiber-optical thermometer provided consistent temperature data in a phantom experiment. During MRI, the MRsWD was able to reduce the maximum temperature rise by 25% when operated in real-time feedback mode.
Conclusion:
This study demonstrates the technical feasibility of an MRsWD as an alternative or complementary approach to reduce RF-induced heating of active interventional devices. The automatic MRsWD can reduce heating using direct temperature measurements at the tip of the catheter. Given that temperature measurements are intrinsically slow, for a clinical implementation, a faster feedback parameter would be required such as the RF currents along the catheter or scattered electric fields at the tip.
