MRI Under General Anesthesia (Pediatric)
Patient phenotype
Children too young (typically < 6) or unable to cooperate (developmental delay, autism, anxiety) for awake MRI. Some have OSA, syndromes, or cardiac comorbidities.
Procedure
Imaging in MRI scanner (1.5T or 3T magnet — magnet always on). Length 30-90 min. Patient must be still. Anesthesia provider remote during scanning (control room).
Anesthetic plan
Propofol infusion + LMA (or natural airway) most common. Propofol 100-200 mcg/kg/min titrated. Some use sevo + LMA. Dex-only protocols increasingly used (dex 1-2 mcg/kg load + 1-2 mcg/kg/h infusion) — avoids airway instrumentation.
Setup
- ·MRI-COMPATIBLE everything: ventilator, monitor, infusion pumps, IV poles, oxygen tank, stethoscope, laryngoscope. Standard equipment is FERROMAGNETIC and DANGEROUS in scanner.
- ·Remote video monitoring of patient + monitor
- ·Remote ventilation visible from control room
- ·PIV (in MRI-safe location)
- ·Long extension tubing for IV + ventilator
- ·MRI-safe pulse ox (fiberoptic), MRI-safe ECG (carbon-fiber leads)
- ·Earplugs / hearing protection (loud)
Biggest concerns by phase
MRI safety screening
Both anesthesia provider + patient screened: pacemakers, implants, metal, drug pumps. ANY ferromagnetic object near magnet = projectile. Documented allergic to gadolinium contraindication.
Induction in induction room (outside zone IV)
Standard equipment OK in induction room. Induce → secure airway → transport into scanner. Pediatric inhalation induction common.
Remote monitoring + vigilance
Anesthesia provider in control room during scan. Continuous video + monitor display. Common errors: missed disconnection, missed apnea, monitor failure. Re-enter scanner promptly for any concern (always with safety checklist).
Hypothermia
MRI suite often cold (magnet cooling). Forced air warmer (MRI-compatible) on patient. Cover.
Apnea / airway loss
Propofol-induced apnea or LMA dislodgement → must be detected + corrected promptly. Capnography is mandatory. Some institutions require ETT for very young/at-risk.
Recovery in nearby PACU
Transport out of scanner with MRI-safe equipment. Then standard pediatric PACU. Watch for delayed emergence (long propofol infusion).
Mock-defense scenarios
Practice answering these out loud. The probes show what an examiner is listening for.
4-yo with developmental delay (severe autism), 15 kg, has dental caries, scheduled brain MRI. Mom says he can't sit still. Plan?
What an examiner probes for
- ▹MRI safety screening
- ▹Inhalational induction in induction room → LMA → transport to scanner
- ▹Propofol or dex-based maintenance
- ▹Remote monitoring vigilance
- ▹PONV + emergence delirium consideration
Sources
- Miller's Ch 80
- Coté Peds Anesthesia 6e Ch 30
- ACR MR Safety Guidelines
Anatomy reference
Sourced reference images. 4 matches for "brain pediatric imaging".
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