MRI Safety Guidelines for MRI Conditional Devices
MRI conditional devices can be safely scanned when specific manufacturer-defined conditions are strictly followed, requiring verification of device specifications, appropriate MRI mode programming, and multidisciplinary coordination between radiology and cardiology/electrophysiology teams. 1
Pre-Scan Verification Protocol
Obtain and verify the patient's implant pass or device card before scheduling the MRI. 1 The three-tier MRI safety classification system categorizes devices as:
- MRI Safe: No contraindication, can proceed without restrictions 1
- MRI Conditional: Relative contraindication requiring specific conditions to be met 1
- MRI Unsafe: Absolute contraindication, cannot scan 1
For MRI conditional devices, you must verify the following specific parameters from the manufacturer or online resources (such as mrisafety.com): 1
- Maximum magnetic field strength allowed (typically 1.5T or 3T) 1
- Specific absorption rate (SAR) limits 2
- Allowable scanning sequences and exclusions 2
- Required device programming changes 3
- Positioning requirements relative to the MRI bore 2
Mandatory Multidisciplinary Coordination
MRI conditional cardiac devices require collaboration with the electrophysiology team for both pre-scan programming and post-scan device interrogation. 1 This is non-negotiable for cardiac implantable electronic devices (CIEDs) including pacemakers and ICDs. 4, 5
The electrophysiology team must reprogram the device to "MRI mode" before scanning, which typically involves: 3
- Disabling rate-responsive pacing 3
- Setting appropriate pacing rates to prevent competition with intrinsic rhythm 3
- Disabling tachycardia detection and therapy in ICDs 1
- Adjusting sensing thresholds 3
Critical Intraoperative Monitoring Requirements
Continuous electrocardiographic monitoring per ASA standards is mandatory throughout the entire MRI examination. 1 Additionally:
- Monitor peripheral pulse continuously (pulse oximeter plethysmogram, arterial line, or manual palpation) 1
- Have temporary pacing and defibrillation equipment immediately available in the MRI suite 1
- Maintain visual monitoring of the patient throughout the scan 1
Device-Specific Considerations and Artifacts
Be aware that MRI conditional cardiac devices produce significant artifacts that may compromise image quality, particularly in cardiac and thoracic imaging. 1 The artifacts create signal voids and geometric distortions that can limit diagnostic utility. 1
For cardiac pacemakers and ICDs specifically, individual MRI mode programming must be carefully selected based on the patient's underlying rhythm: 3
- Patients with intrinsic heart rates that may increase during scanning require different programming than pacemaker-dependent patients 3
- Patients with atrial fibrillation need special consideration to prevent paced beats competing with intrinsic rhythm 3
Post-Scan Protocol
Immediately after MRI completion, the device must be interrogated and reprogrammed to normal settings by the electrophysiology team. 1, 4
Continue cardiac rate and rhythm monitoring with backup pacing/defibrillation equipment immediately available throughout the immediate postoperative period. 1
Common Pitfalls to Avoid
Do not assume all devices from the same manufacturer have identical MRI conditional specifications - each model has unique requirements that must be verified individually. 1, 2
Never proceed with MRI on a conditional device without confirming the specific field strength limit - a device conditional at 1.5T may not be safe at 3T. 1
Do not skip device reprogramming after the scan - leaving devices in MRI mode can result in inappropriate pacing or failure to deliver necessary therapies. 3
Recognize that "safe protocols" for non-conditional devices exist in some centers, but these carry higher risk and require even more stringent protocols and institutional expertise. 4, 6 When MRI conditional devices are available, they should always be the preferred option.