It's better for patients who have experienced allergic reactions to iodinated contrast material to use an iodinated substitute on additional imaging rather than administering steroids, according to a study published August 3 in Radiology.
A group led by Dr. Jennifer McDonald of the Mayo Clinic in Rochester, MN, compared the efficacy of substituting contrast in patients who had reacted to iodinated agents -- specifically using iohexol instead of iopromide -- to premedicating with steroids at 12 and two hours before imaging. Their study included 1,973 patients who underwent 4,360 iodine-based-contrast CT exams between June 2009 and May 2017; of these patients, 224 had 280 allergic reactions.
The group found a lower rate of repeat reactions in patients who were administered an iodinated contrast material substitute -- with or without contrast -- compared with patients who received steroid premedication and the same iodine-based contrast. The results included the following data points:
- Same iodinated contrast material and steroid premedication: 80 of 423 examinations (19%)
- Different iodinated contrast material and steroid premedication: five of 166 patients (3%)
- Different iodinated contrast material and no steroid premedication: 10 of 322 examinations (3%)
"In this cohort, using an iodinated contrast material (ICM) substitution was more effective for preventing repeat allergic-like reactions than using steroid premedication and the same ICM that caused the previous reaction," the group wrote.
![Images show the pectoralis muscles of a healthy male individual who never smoked (age, 66 years; height, 178 cm; body mass index [BMI, calculated as weight in kilograms divided by height in meters squared], 28.4; number of cigarette pack-years, 0; forced expiratory volume in 1 second [FEV1], 97.6% predicted; FEV1: forced vital capacity [FVC] ratio, 0.71; pectoralis muscle area [PMA], 59.4 cm2; pectoralis muscle volume [PMV], 764 cm3) and a male individual with a smoking history and chronic obstructive pulmonary disorder (COPD) (age, 66 years; height, 178 cm; BMI, 27.5; number of cigarette pack-years, 43.2, FEV1, 48% predicted; FEV1:FVC, 0.56; PMA, 35 cm2; PMV, 480.8 cm3) from the Canadian Cohort Obstructive Lung Disease (i.e., CanCOLD) study. The CT image is shown in the axial plane. The PMV is automatically extracted using the developed deep learning model and overlayed onto the lungs for visual clarity.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/03/genkin.25LqljVF0y.jpg?auto=format%2Ccompress&crop=focalpoint&dpr=2&fit=crop&h=167&q=70&w=250)
