What are the preparation and treatment guidelines for a patient undergoing an MRE?

MRE Preparation and Treatment Guidelines

Patients undergoing MRE (Magnetic Resonance Enterography) require thorough safety screening, specific preparation protocols, and careful monitoring to ensure optimal imaging quality and patient safety. This comprehensive approach is essential for accurate diagnosis and management of small bowel conditions, particularly inflammatory bowel disease.

Patient Screening and Safety Protocols

Pre-MRE Safety Screening

• All patients must undergo thorough screening for contraindications and implanted devices 1
• Complete a standardized MRI safety questionnaire to identify:
  • Implanted medical devices
  • Metallic implants or foreign bodies
  • History of surgeries with potential metallic components
  • Pregnancy status
  • Renal function (especially if contrast will be used)
  • Claustrophobia or anxiety disorders 1

Special Considerations for Implanted Devices

• Cardiac devices: MR Conditional pacemakers/ICDs require cardiology consultation, monitoring during scan, and reprogramming afterward 2, 1
• Programmable shunts: Require neurosurgical assessment before and after scanning to verify settings 2
• Neurostimulators: May cause thermal injury during scanning; many newer models are MR Conditional but require specific scanning parameters 2
• Implantable pumps: Baclofen pumps may need to be emptied before scanning to prevent discharge of medication 2

MRE-Specific Patient Preparation

Oral Contrast Administration

• Adequate bowel distension is essential for optimal MRE image quality
• Patients must drink oral contrast material (typically 1-1.5 liters) over 45-60 minutes before the examination 3
• Pediatric patients require adjusted volumes based on weight and age 2

Hydration Requirements

• Proper hydration is essential before the procedure
• For fasting patients, IV hydration may be necessary 2
• Patients should void immediately before entering the scanner to:
  • Reduce artifacts related to radiotracer excretion
  • Improve patient comfort
  • Lower radiation exposure 2

Fasting Requirements

• Patients should fast for 4-6 hours before the examination to:
  • Reduce bowel motility
  • Minimize food residue in the small bowel
  • Optimize contrast visualization 3

During the MRE Procedure

Patient Positioning and Comfort

• Patients are typically positioned supine with arms above head
• Hearing protection is mandatory for all patients 1
• All metal objects, jewelry, and clothing with metallic components must be removed to prevent burns 1

Antiperistaltic Agents

• Administration of antiperistaltic agents (glucagon or buscopan) is recommended to reduce bowel motion artifacts 3, 4
• These are typically administered intravenously just before image acquisition

Contrast Administration

• Approximately 30% of MRI scans require intravenous gadolinium-based contrast 2
• Safety considerations include:
  • Risk of anaphylactoid reactions (0.01%)
  • Mild side effects like headaches, nausea, and dizziness (1-5%)
  • Nephrogenic systemic fibrosis risk in patients with eGFR <30 ml/min/1.73m² 2
• Newer macrocyclic compounds have better safety profiles 2

Sedation and Anesthesia When Required

• May be necessary for patients with movement disorders, claustrophobia, or reduced consciousness
• Only MR Safe or MR Conditional anesthesia equipment should be used
• Standard infusion pumps are MR Unsafe and must be replaced with MR Conditional alternatives 2, 1

MRE Imaging Protocol

Core Sequences

• T2-weighted sequences: Assess bowel wall edema and inflammation
• T1-weighted sequences: Pre- and post-contrast for enhancement patterns
• Diffusion-weighted imaging: Helps identify active inflammation
• Dynamic contrast-enhanced sequences: Evaluate bowel wall vascularity 4

Imaging Assessment

• Key findings of active inflammation include:
  • Bowel wall thickening
  • Intramural edema
  • Mural hyperenhancement
  • Restricted diffusion 4
• Evaluation for complications such as strictures, fistulae, and abscesses 2

Emergency Preparedness During MRE

• Documented emergency plans must include:
  • Cardiac arrest protocol
  • Magnet quench procedure
  • Fire response
  • Patient evacuation protocol 2, 1
• Staff must know emergency quench procedures
• Oxygen sensors and ventilation controls are required to prevent risks associated with magnet quench 1

Post-MRE Follow-up

• Patients with implanted devices require verification of proper functioning
• Programmable shunts need settings verification 2
• Patients who received sedation require monitoring until fully recovered
• Adequate hydration should be encouraged after the procedure, especially if contrast was administered

By following these comprehensive guidelines, healthcare providers can ensure safe and effective MRE examinations while obtaining optimal diagnostic images for accurate assessment of small bowel conditions.