An Implanted Neurostimulator is a Contraindication to Non-Contrast MRI
The correct answer is B: An implanted neurostimulator represents a contraindication to non-contrast MRI unless the device is specifically labeled as MRI-conditional and manufacturer-specified scanning conditions are strictly followed. 1, 2
Why Neurostimulators Are Contraindicated
Traditional Absolute Contraindication
- The American Academy of Otolaryngology-Head and Neck Surgery explicitly states that the presence of implantable medical devices such as pacemakers and neurostimulators precludes MRI scanning. 1
- Neurostimulators pose multiple safety risks during MRI including heating of leads, magnetic field interactions causing device displacement, induced electrical currents in the leads, and functional disruption of the device. 3
- Failure to follow strict safety protocols has resulted in serious injuries including transient dystonia, paralysis, coma, and even death. 3
Modern MRI-Conditional Devices Require Special Protocols
- Most contemporary neurostimulators are classified as MRI-conditional rather than absolutely unsafe, meaning they can be scanned only when manufacturer-specified conditions are met (specific field strength limits, patient positioning, and scanning protocols). 2
- MRI-conditional neurostimulators require consultation with the electrophysiology team and strict adherence to manufacturer protocols before any scanning can proceed. 2
- Even when deemed MRI-conditional, these devices generate significant image artifacts that can compromise diagnostic quality. 2
Why the Other Options Are NOT Contraindications
A. Cardiac Stent Placed 6 Months Ago
- Coronary artery stents are MRI-safe at field strengths up to 3 Tesla with no waiting period required. 2
- Cardiac stents do not pose any risk of migration or thrombosis during MRI, though they may cause local artifacts (an image quality issue, not a safety concern). 2
C. History of Migraines
- A history of migraine is not listed as an MRI contraindication in any current guideline. 2
- MRI is routinely employed to evaluate patients with headache or other neurological symptoms without restriction based on migraine history. 2
Mandatory Pre-MRI Screening Protocol
Essential Steps Before Any MRI
- Every patient must complete a standardized safety questionnaire screening for implants, ports, catheters, metallic devices, vascular stents, coils, active devices, cardiac pacemakers, and other foreign bodies. 2
- Verification of the patient's implant documentation (manufacturer, model, material composition, and MRI safety classification) is required prior to scanning. 2
- If implant documentation is unavailable, online resources (e.g., https://mrisafety.com/) should be consulted to confirm the device's safety level. 2
Critical Pitfalls to Avoid
Common Errors in MRI Safety Assessment
- Do not confuse vascular stents with cardiac pacemakers or neurostimulators—they have completely different safety profiles. 2
- Do not assume all neurostimulators are absolutely contraindicated—many modern devices are MRI-conditional and can be scanned safely when protocol requirements are met. 2
- Recognize that artifact does not equal danger—coronary stents cause local artifacts but this is an image quality issue, not a safety concern. 2
When Neurostimulators Can Be Scanned
- If the neurostimulator is confirmed to be MRI-conditional through manufacturer documentation, scanning may proceed only after: 2, 4
- Verifying specific field strength limits (typically 1.5T with send/receive head RF coil only)
- Limiting specific absorption rate to manufacturer specifications (often ≤0.4 W/kg)
- Consulting with the device manufacturer and electrophysiology team
- Implementing continuous patient monitoring during the scan
- Deep brain stimulators with tested leads (such as ITREL II and 3 connected to an IPG) have been studied and may be scanned under strict conditions, but this requires device-specific verification. 5