What precautions should be taken before undergoing a Magnetic Resonance Imaging (MRI) procedure?

MRI Safety Precautions

Before undergoing an MRI procedure, thorough screening for ferromagnetic materials and medical conditions is essential to prevent potentially life-threatening injuries from projectile objects, thermal burns, and adverse reactions to contrast agents.

Screening for Ferromagnetic Objects

• All individuals, including patients and accompanying persons, must be thoroughly screened for ferromagnetic materials before entering the MRI suite 1
• Remove all metallic items including:
  • Personal items: jewelry, watches, credit cards, phones, pagers, pens 1
  • Clothing with metallic components: zippers, buttons, underwire bras 1
  • Dental prostheses and other removable metal items 1
• Patients should be provided with cotton clothing free of metal components 1

Medical Implants and Device Screening

• All implants must be evaluated according to MRI safety classification 2:
  • MR Safe: Contains no metallic materials, safe in all MRI environments
  • MR Conditional: Safe under specific conditions (field strength, scanning parameters)
  • MR Unsafe: Presents unacceptable risks in MRI environment
• Absolute contraindications (MR Unsafe) 1:
  • Most electronic implants (infusion pumps, neurostimulation devices)
  • Certain older cerebrovascular clips
  • Ferromagnetic foreign bodies
• Relative contraindications (MR Conditional) 1:
  • Pacemakers and implantable cardioverter-defibrillators (traditionally contraindicated but some newer models may be MR conditional)
  • Implant documentation must be verified with manufacturer specifications 1

Medication and Transdermal Patch Considerations

• Transdermal medication patches containing metal (like Minitran) must be removed before MRI to prevent thermal burns 2
• Document removal and plan for reapplication after the procedure 2
• For patients requiring continuous medication, alternative delivery methods should be arranged during the MRI 2

Contrast Agent Precautions

• Gadolinium-based contrast agents (GBCAs) require renal function assessment 1
• Contraindicated in patients with:
  • Known allergic reactions to gadolinium 3
  • Severe renal insufficiency (GFR <30 mL/min/1.73 m²) due to risk of nephrogenic systemic fibrosis (NSF) 1, 3
  • Acute renal insufficiency of any severity due to hepato-renal syndrome 1
• Consider prompt hemodialysis after GBCA administration in patients with end-stage renal disease 3

Special Patient Populations

Pediatric Patients

• Special MRI-compatible monitoring equipment is required 1
• MRI-compatible pulse oximeters and capnographs should be used for sedated or restrained children 1
• Avoid coiling of monitoring wires and place oximeter probes far from the magnetic coil to prevent thermal injuries 1
• If sedation is required, use MRI-compatible infusion pumps or place standard pumps outside the scanner room with extended tubing 1

Claustrophobic Patients

• Inform patients about the procedure to reduce anxiety 1
• Patients should be able to lie still for at least 5-20 minutes 1
• Consider sedation for patients with severe claustrophobia 1, 4

Procedural Safety Measures

• Empty bladder before scanning for patient comfort and reduced radiation exposure 1
• For patients receiving gadolinium contrast:
  • Visually inspect solution for discoloration or particulate matter 3
  • Administer as rapid intravenous infusion or bolus according to weight-based dosing 3
  • Flush with at least 5 mL normal saline immediately after injection 3
  • Complete imaging procedures within 1 hour of administration 3
• For patients requiring glucose monitoring, check glycemia before FDG-PET/MRI and postpone if >160 mg/dL 1

Emergency Preparedness

• All MRI facilities must have documented emergency protocols for 4:
  • Cardiac arrest
  • Magnet quench
  • Fire in the MRI suite
• All emergency equipment in the MRI room must be MRI-compatible, including laryngoscope blades, oxygen tanks, and other resuscitation equipment 1

By following these comprehensive safety precautions, the risks associated with MRI procedures can be significantly minimized while maintaining the diagnostic benefits of this powerful imaging modality.