Can a patient with metal (e.g. implant) in their body get a Magnetic Resonance Imaging (MRI) scan?

MRI Safety in Patients with Metal Implants

Most patients with metal in their body can safely undergo MRI, but this depends entirely on the specific type, location, and ferromagnetic properties of the metal—not all metal is created equal, and proper screening is mandatory before any scan. 1, 2, 3

Safety Classification System

The critical first step is determining the MRI safety classification of any metal implant or foreign body:

• MRI Safe: No contraindication; proceed with scanning 1, 2
• MRI Conditional: Relative contraindication requiring specific conditions (field strength limits, positioning requirements, timing restrictions) to be met 1, 2
• MRI Unsafe: Absolute contraindication; do not scan 1, 2

Absolute Contraindications (Do Not Scan)

The following metal implants remain absolute contraindications for MRI:

• Cardiac pacemakers and implantable cardioverter-defibrillators (ICDs) are generally contraindicated, as heating of pacemaker leads is the major safety concern 2, 3, 4
• Ferromagnetic cerebral aneurysm clips pose significant risk of movement near vital brain structures 2, 3
• Steel fragments near the brain or retina can cause catastrophic injury if displaced 2, 3
• Certain orthopedic implants with substantial ferromagnetic properties (e.g., Perfix interference screws cause extensive artifact and deflection) 5

Safe for MRI (Proceed with Scanning)

The following are not contraindications and patients can safely undergo MRI:

• Coronary artery stents are MRI-safe at field strengths up to 3 Tesla with no waiting period required, regardless of how recently placed 2, 4
• Carotid artery stents are MRI-safe, though they cause local artifacts 2
• Intracranial stents produce minimal artifact 2
• Prosthetic cardiac valves are safe for MRI 4, 6
• Metal sternal sutures and mediastinal vascular clips do not contraindicate MRI 4
• Epicardial pacing wires are safe 4
• Most vascular coils, filters, and stents (66 of 127 tested metallic materials showed no ferromagnetic deflection) 6

Mandatory Pre-MRI Screening Protocol

Every patient must undergo standardized screening before MRI to identify contraindications:

1. Use a standardized written questionnaire covering implants, ports, catheters, metallic implants, vascular stents, coils, active devices, cardiac pacemakers, shrapnel, and claustrophobia 1, 3, 7

2. Obtain and verify the patient's implant pass to determine the device manufacturer, specific model, material composition, and MRI safety classification 1, 2

3. Check online resources (e.g., https://mrisafety.com/) to confirm the implant's safety level if documentation is unavailable 1

4. Remove all metallic items including jewelry, dental prostheses, clothing with zippers or buttons, and transdermal patches containing metal 1, 8

5. Obtain plain radiographs (AP and lateral views of chest, abdomen, pelvis, or orbits as indicated) if there is any suspicion of retained metallic foreign bodies, particularly in patients with history of shrapnel wounds or metal-working occupations 3, 7

Field Strength Considerations

• Standard clinical field strengths (≤2.5 Tesla) are considered safe for most patients without evidence of harmful effects 1
• Patients with non-removable metallic prostheses should preferably undergo scanning on 1.5T systems to limit susceptibility artifacts and image distortion 1
• Above 4 Tesla, harmful effects may occur and should be avoided 1

Special Populations Requiring Caution

• Pregnant women require special consideration, particularly regarding gadolinium contrast administration 1, 3
• Patients with shrapnel wounds from combat or terrorist attacks can generally undergo 1.5T MRI safely if fragments are subcutaneous and not near vital organs, though one case of superficial 10mm fragment migration has been reported 9
• Patients with metal fragments from metal-working occupations require orbital radiographs to exclude intraocular foreign bodies before scanning 3, 7

Common Pitfalls to Avoid

• Do not confuse vascular stents with cardiac pacemakers—they have completely different safety profiles, with stents being safe and pacemakers being contraindicated 2, 4
• Do not assume all metal is ferromagnetic—75% (95/127) of tested metallic implants were either nonferromagnetic or exhibited only minimal deflection insufficient to cause harm 6
• Stop scanning immediately if the patient reports discomfort, as this may indicate heating or movement of metal 1
• Recognize that artifact does not equal danger—coronary stents cause local artifacts preventing visualization of the immediate stent area, but this is an image quality issue, not a safety concern 2
• Do not perform digital examination before imaging when foreign bodies are suspected, as this risks injury to the examiner from sharp metallic objects 8

Documentation Requirements

• Document body weight for standardized uptake value measurements if PET/MRI is performed 1
• Record all screening findings in the patient's medical record 3
• Ensure trained personnel who understand MRI risks perform the screening 3