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Influence of mobile magnetic resonance imaging on implanted pacemakers
Ryoji Kishi1, Naoki Matsumoto, Kiyoshi Nakazawa
1St. Marianna University School of Medicine, Division of Cardiology, Japan. rkishi@marianna-u.ac.jp
Purpose:
Mobile magnetic resonance imaging (MRI) systems will be widely used in Japan. When traveling, mobile MRI generate alternating electromagnetic waves which may cause electromagnetic interference (EMI). This study was designed to determine whether this may influence the function of implanted pacemakers (PM).
Methods And Results:
The influence of the static magnetic fields was tested in the first method using a PM-human model (Phantom). Magnetic force was simultaneously measured. The PM was switched to the magnet mode within 90 cm from the vehicle, where the magnetic force was = 2 mT. In the second method, six phantoms were placed on the side of the road, facing in three different directions in X-Y-Z axis orientations, at 1.3 m and 2.0 m above the ground. The mobile MRI passed by at a distance of 1 m from the phantoms at the speed of 20 or 40 km/h. In these experiments, magnet mode switch of the PM was observed for 2 seconds when the vehicle passed close to the phantoms, though no electrical noise was recorded.
Conclusion:
Mobile MRI vehicles can switch a PM to magnet mode when the distance between patient and vehicle is < 90 cm, regardless of whether the vehicle is moving or at a stop. Patients with implanted PM should not approach within < 1 m of a mobile MRI. No other EMI-induced PM dysfunction was detected.