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.
![Axial images from unenhanced calcium score cardiac CT (left) and curved planar reformation images from CT angiography (right) show that higher long-term exposure to air pollution is associated with greater coronary artery calcium and more obstructive coronary artery disease (CAD). Top row: Images in a 68-year-old male patient with higher 10-year mean ambient air pollution exposure (7.9 μg/m3 for particulate matter measuring ≤2.5 μm in diameter [PM2.5] and 17.4 parts per billion [ppb] for NO2) with extensive CAD (coronary artery calcium score [CACS] >1,000 and obstructive CAD [≥70% diameter stenosis]). Bottom row: Images in a 57-year-old female patient with lower 10-year mean ambient air pollution exposure (6.3 μg/m3 for PM2.5 and 4.6 ppb for NO2) with no CAD (CACS = 0 and no obstructive stenosis).](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/06/hanneman.r6SMLzkezo.png?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
