MRI Contrast Agents and Breast Feeding Mothers*

Administration of a gadolinium-based MRI contrast agent occasionally is indicated for an imaging study in a woman who is breast-feeding. Both the patient and the patient's physician may have concerns regarding potential toxicity to the infant from contrast media that is excreted into the breast milk.

The literature on the excretion into breast milk of gadolinium-based MRI contrast agents and the gastrointestinal absorption of these agents from breast milk is very limited. A review of the literature, however, reveals important facts: (1) less than 1% of the administered maternal dose of contrast agent is excreted into breast milk; and (2) less than 1% of the contrast medium in breast milk ingested by an infant is absorbed from the gastro-intestinal tract. Therefore, the expected dose of contrast medium absorbed by an infant from ingested breast milk is extremely low.

The Committee on Drugs and Contrast Media of the American College of Radiology (ACR) has discussed this issue extensively and has prepared the following summary information and recommendations.

Gadolinium-based MRI Contrast Agents and Breast Feeding Mothers
Background. Gadolinium compounds are safe and useful as magnetic resonance imaging (MRI) contrast agents. Although free gadolinium is neurotoxic when complexed to one of a variety of chelates, it is safe for use in adults and children. These hydrophilic gadolinium chelate agents have pharmacokinetic properties very similar to those of iodinated X-ray contrast media. Like iodinated contrast agents, gadolinium contrast agents have a plasma half-life of approximately 2 hours and are nearly completely cleared from the bloodstream within 24 hours.

Less than 0.04% of the intravascular dose given to the mother is excreted into the breast milk in the first 24 hours. Because less than 1% of the contrast medium ingested by the infant is absorbed from its gastrointestinal tract, the expected dose absorbed by the infant from the breast milk is less than 0.0004% of the intravascular dose given to the mother. Even in the extreme circumstance of a mother weighing 150 kg and receiving a dose of 0.2 mmol/kg, the absolute amount of gadolinium excreted in the breast milk in the first 24-hours after administration would be no more than 0.012 mmol. Thus, the dose of gadolinium absorbed from the gastrointestinal tract of a breast-feeding infant weighing 1,500 grams or more would be no more than 0.00008 mmol/kg, or 0.04% (four ten-thousandths) of the permitted adult or pediatric (2 years of age or older) intravenous dose of 0.2 mmol/kg. The potential risks to the infant include direct toxicity (including toxicity from free gadolinium, because it is unknown how much, if any, of the gadolinium in breast milk is in the unchelated form) and allergic sensitization or reaction, which are theoretical concerns but have not been reported.

Recommendation
Review of the literature shows no evidence to suggest that oral ingestion by an infant of the tiny amount of gadolinium contrast agent excreted into breast milk would cause toxic effects. Therefore, the available data suggest that it is safe for the mother and infant to continue breast-feeding after receiving such an agent.

If the mother remains concerned about any potential ill effects, she should be given the opportunity to make an informed decision as to whether to continue or temporarily abstain from breast-feeding after receiving a gadolinium contrast agent. If the mother so desires, she may abstain from breast-feeding for 24 hours with active expression and discarding of breast milk from both breasts during that period. In anticipation of this, she may wish to use a breast pump to obtain milk before the contrast study to feed the infant during the 24-hour period following the examination.

[*Excerpted with permission from the American College of Radiology, Manual on Contrast Media, 5th Edition, 2004; Reprinted with permission of the American College of Radiology. No other representation of this article is authorized without express, written permission from the American College of Radiology.

Also, please see the new version of this document Manual on Contrast Media, Version 6, 2008 - full version available at www.acr.org]

REFERENCES
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Johansen JG. Assessment of a non-ionic contrast medium (Amipaque) in the gastrointestinal tract. Invest Radiol 1978;13:523-527.

Kubik-Huch RA, Gottstein-Aalame NM, Frenzel T, et al. Gadopentetate dimeglumine excretion into human breast milk during lactation. Radiology 2000;216:555-558.

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Shellock FG, Kanal E. Safety of magnetic resonance imaging contrast agents. Journal of Magnetic Resonance Imaging 1999;10:477-484.

Weinmann HJ, Brasch RC, Press WR, et al. Characteristics of gadolinium-DTPA complex: a potential NMR contrast agent. American Journal of Roentgenology 1984;142: 619-624.