AJR: Adverse effects rare from iodinated-, gadolinium-based agents

The use of iodinated- and gadolinium-based contrast agents, which are frequently used during CT and MRI scans, has a low rate of adverse effects on patients, according to a study in the October issue of the American Journal of Roentgenology.

The study, performed at the Mayo Clinic in Rochester, Minn., involved the review of 456,930 contrast doses between 2002 and 2006, according to Christopher H. Hunt, MD, from the department of radiology at the facility, and colleagues. Among these doses, 298,491 were of low-osmolar iodinated contrast material and 158,439 were of gadolinium contrast material. A total of 522 adverse effects were identified (0.114 percent of all doses). The found that 458 of these adverse effects were associated with low-osmolar iodinated contrast material, for an adverse effect rate of 0.153 percent for these doses. Gadolinium had an even lower adverse reaction rate, with 64 adverse effects reported (0.0404 percent of doses of these agents).

According to the authors, the overwhelming majority of adverse effects were mild, represented by nausea, vomiting, and a mild rash. Most of the adverse effects, 91.9 percent associated with low-osmolar iodinated and 87.5 percent with gadolinium contrast material, were managed with observation or diphenhydramine.

More aggressive treatment (such as transfer to an emergency department or administration of epinephrine) was rarely needed. Seven patients with a severe reaction after administration of low-osmolar iodinated contrast material needed epinephrine, while two patients with adverse reactions after receiving gadolinium contrast material needed epinephrine. Ten patients with adverse reactions to either low-osmolar iodinated contrast or gadolinium contrast material had to be transported to the emergency department.

One death “presumed” to be caused by low-osmolar iodinated contrast material was reported during the study period. The patient, a 79-year old man, experienced sudden cardiovascular collapse and—after initially displaying no symptoms—died less than 20 minutes after receiving the contrast material.

The authors concluded that the use of low-osmolar iodinated contrast material and pretreatment regimens have decreased the number of instances of contrast-related adverse effects. However, these effects can still occur, and the authors suggested that while these “adverse effects can be successfully managed in the radiology suite, many with observation alone, severe adverse effects can necessitate aggressive treatment and transfer for emergency care. Careful review of reporting and treatment protocols is necessary to prevent morbidity and mortality.”