Heating around intravascular guidewires by resonating RF waves

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Physics

Background:

• Interventional magnetic resonance imaging (MRI) utilizes guidewires for minimally invasive procedures.
• Unwanted heating of metallic guidewires during MRI is a known safety concern.
• Understanding the mechanisms behind guidewire heating is crucial for patient safety.

Purpose of the Study:

• To investigate the radiofrequency (RF) heating of an endovascular guidewire during interventional MRI.
• To quantify the temperature rise at the guidewire tip under specific MRI conditions.
• To identify the underlying physical phenomenon responsible for excessive guidewire heating.

Main Methods:

• A Terumo guidewire was partially submerged in a saline bath simulating an endovascular environment.
• Temperature measurements were taken using a Luxtron fluoroscopic fiber during an FFE MRI sequence.
• The average specific absorption rate (SAR) was maintained at 3.9 W/kg.

Main Results:

• The guidewire tip temperature increased from 26°C to up to 74°C within 30 seconds of scanning.
• Contact with the heated guidewire caused a skin burn in one instance.
• Excessive heating was attributed to resonating RF waves acting on the linear conductor.

Conclusions:

• Guidewire heating during interventional MRI is a significant safety risk.
• Resonating RF waves are the primary cause of excessive guidewire heating.
• The unpredictable nature of this resonance necessitates revised safety guidelines for interventional MRI procedures.