A global imaging group is urging providers to continue using ultrasound contrast following recent rare fatalities reported by the U.S. Food and Drug Administration.

The FDA first issued its warning on Thursday, April 22, citing 11 cases of anaphylaxis and two deaths stemming from the administration of Definity or Lumason. These drugs contain the inactive ingredient polyethylene glycol, derived from petroleum, which may cause allergic reactions.

In a statement published the following day, the International Contrast Ultrasound Society estimated that these allergic reactions only occur in 1 of every 10,000 doses.

“This does not seem to represent a new risk, but rather a specific type of hypersensitivity that the labels already warned against,” Kassa Darge, MD, PhD, a member of the society’s board of directors and chair of the Department of Radiology at Children's Hospital of Philadelphia, said April 23.

The society further noted that with the two deaths, the FDA did not detail each patients’ medical history, comorbidities, or other exposures—which may have also played a factor. Millions of ultrasound contrast agents have been administered for decades, they added, without any complications. They urged physicians to continue to follow standard safety protocols to avoid adverse reactions.

“ICUS supports the continued use of [ultrasound contrast agents] where medically appropriate as well as the FDA’s efforts to draw attention to the potential for a rare PEG reaction,” added Steven Feinstein, MD, co-president of International Contrast Ultrasound Society and a cardiologist at Rush University Medical Center.

Lantheus and Bracco, the makers of Definity and Lumason, respectively, did not immediately respond to a Radiology Business request for comment Monday. You can read the full statement from the ultrasound society here.