MRI Safety in Preterm Infants
MRI is generally safe in preterm infants, but requires careful attention to sedation risks, acoustic noise protection, thermoregulation, and judicious use of gadolinium-based contrast agents, which should be avoided when possible due to unknown long-term effects of gadolinium deposition in the developing brain.
Key Safety Considerations
Sedation and Anesthesia Risks
Preterm infants are particularly susceptible to respiratory depression from sedative medications, requiring careful monitoring and available resuscitation equipment 1.
Barbiturates (commonly used for sedation) can cause respiratory depression in newborns, with premature infants being especially vulnerable to these depressant effects 1.
Published studies demonstrate that anesthetic and sedation drugs blocking NMDA receptors or potentiating GABA activity for longer than 3 hours may increase neuronal apoptosis in the developing brain, with potential long-term cognitive deficits 1.
The window of vulnerability extends from the third trimester of pregnancy through approximately the first 3 years of life, making preterm infants particularly at risk 1.
Deep sedation or general anesthesia requires MRI-compatible equipment and an experienced multidisciplinary team 2.
Gadolinium-Based Contrast Agent Concerns
Gadolinium should be avoided in preterm infants unless absolutely critical, as the risk-benefit analysis heavily favors non-contrast imaging in this population 3.
Gadolinium accumulates in the brain, and long-term effects of this deposition remain unknown, particularly concerning for the developing pediatric brain 2, 3.
Since 2018, only macrocyclic ionic gadolinium molecules are recommended for cardiovascular MR scans due to safety concerns 2.
Gadolinium-based contrast agents are generally safe with very rare adverse events in children, but the unknown long-term effects of brain deposition warrant cautious use 2, 3.
Risk-benefit analysis must be performed for each patient to avoid administration when not necessary 3.
Renal Function Considerations
Severe kidney disease (glomerular filtration rate <30 mL/min/1.73m²) represents a relative contraindication due to nephrogenic systemic fibrosis risk, though this is rare in neonates 2, 4.
Nephrogenic systemic fibrosis is a serious, potentially fatal multiorgan fibrosing disease causing cutaneous sclerosis, subcutaneous edema, disabling joint contractures, and internal organ injury 4.
Physical Safety Hazards
Electromagnetic energy exposure includes static magnetic fields, gradients, and radiofrequency pulses with intrinsic hazards from ferromagnetic devices, induced electrical currents, heating, and acoustic noise 2.
Safety screening must be performed prior to every exam to rule out contraindications including non-MR-compatible devices 2.
Acoustic noise requires hearing protection to prevent potential auditory damage in preterm infants 2.
Thermoregulation
Preterm infants have immature thermoregulatory systems and require careful temperature monitoring during prolonged MRI examinations 2.
MRI-compatible warming devices should be available for temperature maintenance during scanning 2.
Recommended Approach for Preterm Infants
When MRI is Necessary
Prioritize non-contrast MRI protocols whenever diagnostically adequate to avoid gadolinium exposure 2, 3.
Use the shortest possible scan time to minimize sedation requirements and reduce neuroapoptosis risk 1.
Ensure resuscitation equipment is immediately available given respiratory depression risks 1.
Contrast Administration Decision Algorithm
Only administer gadolinium when:
- The diagnostic information is absolutely critical and cannot be obtained without contrast 3
- Non-contrast sequences (including diffusion-weighted imaging) are insufficient 2
- The clinical benefit clearly outweighs the unknown long-term risks of gadolinium brain deposition 3
If contrast is deemed essential:
- Use the lowest effective dose 2
- Select macrocyclic ionic formulations (Group II or III agents) 2, 4
- Document the date, dose, and specific formulation used 5
Common Pitfalls to Avoid
Never use gadolinium empirically without clear clinical justification in preterm infants given unknown neurodevelopmental effects 3.
Do not underestimate sedation risks—premature infants require lower doses and more intensive monitoring than term infants 1.
Avoid prolonged sedation (>3 hours) when possible due to neurotoxicity concerns 1.
Do not skip safety screening for ferromagnetic materials, even in neonates who may have medical devices 2.