Pacemakers in MRI for the Neuroradiologist

Abstract

Cardiac implantable electronic devices are frequently encountered in clinical practice in patients being screened for MR imaging examinations. Traditionally, the presence of these devices has been considered a contraindication to undergoing MR imaging. Growing evidence suggests that most of these patients can safely undergo an MR imaging examination if certain conditions are met. This document will review the relevant cardiac implantable electronic devices encountered in practice today, the background physics/technical factors related to scanning these devices, the multidisciplinary screening protocol used at our institution for scanning patients with implantable cardiac devices, and our experience in safely performing these examinations since 2010.

Fig 1.

Normal versus first-level mode: normal level only for neuroradiology. SAR information panel at the scanner console for a sagittal STIR TSE acquisition of the lumbar spine. Any neurologic imaging study that can be run on a 1.5T magnet, including echo-planar imaging, can be performed in a patient with a CIED, as long as the examination is performed in normal operating mode. Image courtesy of Charles Fasanati.

Fig 2.

Comprehensive safety protocol: collaboration between neuroradiology and cardiology.

Fig 3.

Risk categorization: inappropriate device sensing during MR imaging. Intracardiac electrograms from a patient with a dual-chamber ICD. Electromagnetic interference is seen on both atrial and ventricular channels (solid arrows), resulting in oversensing (dashed arrow) and an inappropriate ICD shock (asterisk).

Fig 4.

Absolute contraindications: chest x-ray examinations with abandoned and epicardial leads. Posteroanterior view of the chest (A) demonstrates an abandoned lead (black arrows) in a patient with a dual-chamber pacemaker device. B, An abandoned right ventricular lead (black arrows) in a patient with a single-lead pacemaker device. The black arrowhead denotes a fracture of the abandoned lead. C, A patient with a biventricular ICD pacing system, which includes transvenous atrial and right ventricular leads and 2 permanent epicardial pacing leads (black arrows). None of these 3 patients would be cleared to undergo MR imaging examination at our institution.