Feature

MRI for Emergency Clinicians

Emergency Medicine. 2018 December;50(12):1-6

References

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Pacemakers and defibrillators are worthy of special mention. Some are now considered MR-conditional in limited circumstances, and this situation will continue to evolve. Consult your radiologist and/or the physician who placed the medical device with any safety concerns.

Intraocular metallic foreign bodies are an MRI contraindication. If any concern exists for an intraocular metallic foreign body, perform an orbital CT before considering an MRI. Headphones and ear plugs are used during MRI examinations to prevent hearing damage due to machine noise or nerve and muscle stimulation.

A 2016 JAMA study of MRI in pregnancy involving more than 1.4 million deliveries concluded “exposure to MRI during the first trimester of pregnancy compared with non¬exposure was not associated with increased risk of harm to the fetus or in early childhood. Gadolinium MRI at any time during pregnancy was associated with an increased risk of a broad set of rheumatological, inflammatory, or infiltrative skin conditions and for stillbirth or neonatal death.”⁶

There is limited data on the use of MRI in pediatric patients, but a 2015 study noted, “to date, no studies have demonstrated any definite risk to the fetus, mother, or neonate when MR scanners are operated within the regulatory guidelines set forth by the FDA and other regulatory agencies.”⁷

A variety of gadolinium-based contrast agents (GBCAs) are currently used. GBCA administrations in renally impaired patients has been linked to nephrogenic systemic fibrosis (NSF), a rare, progressive, potentially fatal, incompletely understood, systemic disorder with a spectrum of manifestations. Its occurrence has prompted alerts, and a recent set of recommendations for at-risk patients (ie, those with acute kidney injury or an eGFR < 30 mL/min/1.73 m² and those who are dialysis dependent) specifies that (1) a low-risk GBCA should be used; (2) GBCA dose should be as low as possible; and (3) dialysis should be performed as indicated immediately after GBCA-enhanced MRI.^8,9 Additionally, the EP may wish to obtain informed consent from at-risk patients prior to the administration of GBCAs.