On the heating of linear conductive structures as guide wires and catheters in interventional MRI

The Interest in performing vascular interventions under magnetic resonance (MR) guidance has initiated the evaluation of the potential hazard of long conductive wires and catheters. The objective of this work is to present a simple analytical approach to address this concern and to demonstrate the a greement with experimental results. The first hypothesis is that a long con ductive structure couples with the electric field of the radio frequency (R F) transmit coil. The second hypothesis is that this coupling induces high voltages near the wire ends. These voltages can cause tissue heating due to induced currents. The experimental results show an increase In coupling wh en moving a guide wire toward the wall of an RF transmit coil, documented w ith a temperature increase of a saline solution in close proximity to the t ip of the guide wire. The coupling of the wire not only presents a potentia l hazard to the patient, but also interferes with the visualization of the wire. A safe alternative would be the use of nonconducting guide wires. (C) 2001 Wiley-Liss, Inc.