Low-field magnetic resonance imaging: increased safety for pacemaker patients?

Abstract

The number of low-field (<0.5 T) magnetic resonance (MR) scanners installed worldwide is increasing due to a favourable cost and safety profile and improved patient comfort using an open-scanner design. Therefore, the aim of our study was to evaluate a strategy for the safe performance of magnetic resonance imaging (MRI) at a field strength of 0.2 T, in pacemaker (PM) patients without limitations on scan region, PM dependency, or the presence of abandoned leads. One hundred and fourteen PM patients, including PM-dependent patients and patients with abandoned leads, examined at a 0.2 T MR scanner due to an urgent clinical need for an MRI examination, were evaluated. All PMs were reprogrammed before MRI: if heart rate was <60 bpm, the asynchronous mode (with a rate of 80 bpm) was programmed to avoid MR-induced inhibition; if heart rate was >60 bpm, sense-only mode (ODO/OVO/OAO) was used to avoid MR-induced competitive pacing and potential proarrhythmia. Patients were monitored with electrocardiogram (ECG) and pulse oximetry. All PMs were interrogated before and after MRI, including measurement of lead impedance, pacing capture threshold (PCT), and battery voltage. All MRI scans were completed safely. No induction of arrhythmias or inhibition of PM output occurred. There were no statistically significant changes in lead impedance, PCT, or battery voltage (P>0.05). Low-field MRI of PM patients, including high-risk PM patients and MRI scan regions, can be performed with an acceptable risk-benefit ratio under controlled conditions.