Which of the following is a contraindication to a non‑contrast magnetic resonance imaging: a cardiac stent placed six months ago, an implanted neurostimulator, a history of migraine, or orthopedic hardware from a hip replacement?

MRI Contraindications: Device and Implant Safety

An implanted neurostimulator is the contraindication to non-contrast MRI among the options listed. While modern neurostimulators may be MRI-conditional under specific circumstances, they require careful pre-screening and protocol adherence, whereas cardiac stents placed 6 months ago, orthopedic hardware, and migraine history pose no contraindication 1.

Analysis of Each Option

Cardiac Stent Placed 6 Months Ago: NOT a Contraindication

• Patients with remotely placed coronary stents can safely undergo MRI at any time after placement with no waiting period required 2.
• Current coronary stents are MRI-safe at field strengths up to 3 Tesla and do not pose migration or thrombosis risks 2.
• Carotid and intracranial stents are similarly MRI-safe, though they cause local artifacts that affect image quality rather than safety 2.
• The artifact from stents prevents visualization of the immediate stent lumen but does not represent a safety hazard 2.

Implanted Neurostimulator: CONTRAINDICATION (with important caveats)

• The presence of implantable neurostimulators, including deep brain stimulators and spinal cord stimulators, traditionally precludes MRI scanning 1.
• Non-MR-compatible pacemakers, implantable cardioverter defibrillators, cochlear implants, and other ferromagnetic devices should be ruled out during safety screening prior to every MRI exam 1.
• Cardiac pacemakers and implantable cardioverter-defibrillators are generally contraindicated due to risk of heating of pacemaker leads 3.

Critical nuance: Most implanted devices today are classified as "MRI-conditional" rather than absolutely contraindicated 1. MRI-conditional devices can be scanned when specific conditions are met, including field strength limits and positioning requirements, but require collaboration with the electrophysiology team and may produce significant artifacts 1. Research has shown that under careful monitoring with appropriate protocols, MRI can be performed safely even with some non-MRI conditional neurostimulators 4, 5.

History of Migraines: NOT a Contraindication

• Migraine history is not mentioned as a contraindication in any guideline 1.
• MRI is frequently used to evaluate patients with headaches and neurological symptoms without restriction 1.

Orthopedic Hardware from Hip Replacement: NOT a Contraindication

• Standard orthopedic hardware, including hip replacement components, is generally MRI-safe 3.
• Most orthopedic implants are made from titanium or other non-ferromagnetic materials that are MRI-compatible 3.
• Patients with non-removable metallic prostheses should preferably undergo scanning on 1.5T systems to limit susceptibility artifacts and image distortion, but this is an image quality consideration rather than a safety contraindication 3.

Mandatory Pre-MRI Screening Protocol

All patients must undergo standardized safety screening before any MRI examination 1, 3:

• Use a written questionnaire covering implants, ports, catheters, metallic implants, vascular stents, coils, active devices, cardiac pacemakers, and foreign bodies 3.
• Obtain and verify the patient's implant card to determine device manufacturer, specific model, material composition, and MRI safety classification 2, 3.
• Check online resources (such as mrisafety.com) to confirm implant safety level if documentation is unavailable 3.
• Remove all metallic items including jewelry, clothing with zippers or buttons, and transdermal patches containing metal 6, 3.

MRI Safety Classification System

The three-tier classification system guides decision-making 6, 3:

• MRI Safe: No contraindication to MRI under any conditions
• MRI Conditional: Safe under specific conditions (field strength limits, positioning requirements, specific protocols)
• MRI Unsafe: Absolute contraindication to MRI

Common Pitfalls to Avoid

• Do not confuse vascular stents with cardiac pacemakers—they have completely different safety profiles 2, 3.
• Do not assume all neurostimulators are absolutely contraindicated—many modern devices are MRI-conditional and can be scanned with appropriate protocols 1, 5.
• Recognize that artifact does not equal danger—coronary stents cause local artifacts, but this is an image quality issue, not a safety concern 2, 3.
• Never proceed without verifying the specific device model and its MRI classification—generic assumptions about device types can lead to inappropriate denial of necessary imaging 3.