DOI: 10.1148/radiol.2453070428
(Radiology 2007;245:919-921.)
© RSNA, 2007
Management of Patients with History of Adverse Effects to Contrast Media When Pulmonary Artery CT Angiography Is Required
Guillaume Bierry, MD *,
Frauke Kellner, MD 
and
Cindy Barnig, MD 
* Department of Radiology, University Hospital of Strasbourg, 1 Place de l'Hôpital, 67091 Strasbourg Cedex, France
e-mail: guillaume.bierry{at}chru-strasbourg.fr
Department of Chest Diseases and Allergology, University Hospital of Strasbourg, 1 Place de l'Hôpital, 67091 Strasbourg Cedex, France
Department of Radiology, Inselspital, Bern, Switzerland
Editor:
We read with great interest the article by Dr Stein and colleagues entitled "Diagnostic Pathways in Acute Pulmonary Embolism: Recommendations of the PIOPED II Investigators" in the January 2007 issue of Radiology (1).
The authors pointed out the problem presented by patients with allergy to contrast media when a diagnosis of pulmonary embolism at pulmonary artery computed tomographic (CT) angiography is required. Dr Stein and colleagues recommended that patients with "mild to moderate iodine allergies" receive prophylactic corticosteroid therapy, whereas patients with "severe iodine allergy" might rather benefit from pulmonary scintigraphy.
We would like to comment on the authors' distinction between patients with mild allergy and those with severe allergy and the prophylactic treatments recommended.
The severity of immunoglobulin E (IgE)-mediated anaphylactic reactions to contrast media is not dose-dependent, and clinical consequences are unpredictable, ranging from cutaneous rashes to vital symptoms (2–7). The distinction made between patients with "mild to moderate iodine allergies" and patients with "severe iodine allergy" is therefore not entirely correct. Instead, physicians have to distinguish patients with anaphylaxis from patients without anaphylaxis. It should not be overlooked that patients who previously manifested only moderate anaphylactic symptoms (ie, cutaneous rashes) can none the less exhibit severe or life-threatening symptoms at subsequent application of contrast medium.
Dr Stein and colleagues recommended that patients with "mild to moderate iodine allergies" receive prophylactic corticosteroid treatment before contrast medium administration. To date, no randomized trial has demonstrated the effectiveness of this practice (4,5,8–10). Such prophylactic treatment has been criticized and appears obsolete (5,7). Moreover, this kind of treatment is beyond the scope of emergency room procedures such as pulmonary artery CT angiography.
In conclusion, any patient with a history of anaphylactic reaction following administration of contrast medium, independent of its clinical severity, should be considered a "high risk" patient. Thus, if application of contrast medium is absolutely necessary, the use of corticosteroid prophylactic treatment should not falsely reassure radiologists about the likelihood of life-threatening symptoms occurring.
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References
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- Stein PD, Woodard PK, Weg JG, et al. Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II Investigators. Radiology 2007;242:15–21.[Free Full Text]
- Katayama H, Yamaguchi K, Kozuka T, Takashima T, Seez P, Matsuura K. Adverse reactions to ionic and nonionic contrast media: a report from the Japanese Committee on the Safety of Contrast Media. Radiology 1990;175:621–628.[Abstract/Free Full Text]
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- Brockow K. Contrast media hypersensitivity: scope of the problem. Toxicology 2005;209:189–192.[CrossRef][Medline]
- Morcos SK. Acute serious and fatal reactions to contrast media: our current understanding. Br J Radiol 2005;78:686–693.[Abstract/Free Full Text]
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Response
Pamela K. Woodard, MD *,
Lawrence R. Goodman, MD 
,
John G. Weg, MD , and
Paul D. Stein, MD 
* Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Mo
Department of Radiology, Medical College of Wisconsin, Milwaukee, Wis,
Department of Medicine, University of Michigan, Ann Arbor, Mich
Department of Research, St. Joseph Mercy Oakland Hospital, 44405 Woodward Ave, Pontiac, MI 48341-5023
e-mail: steinp{at}trinity-health.org
Dr Bierry and colleagues are correct in noting that the severity of IgE-mediated anaphylactic reactions is not dependent on the dose of the iodinated contrast agent. They are also correct in stating that patients who previously had only mild to moderate anaphylactic reactions (ie, cutaneous rashes) may develop severe or life-threatening reactions at subsequent administration of contrast medium (1). The radiologist should always be prepared to treat an anaphylactic reaction to contrast medium, despite corticosteroid administration (2). Nevertheless, corticosteroid administration is currently used. While it is true that corticosteroid administration has not been shown to eliminate the possibility of a repeat reaction to contrast medium, corticosteroid administration at least 6 hours in advance of iodinated contrast medium administration has been shown to decrease both the likelihood and severity of the reaction (1,3,4). Therefore, corticosteroids are of use in patients who have had mild to moderate allergies to contrast medium in the past and for whom the results of contrast material–enhanced CT would provide benefit. In patients with a high clinical suspicion of pulmonary embolism, short-term anticoagulation can be used while waiting for the corticosteroids to become effective (5).
Our recommendations are in keeping with the American College of Radiology manual on contrast media (1). Indeed, no randomized controlled trial has been performed to demonstrate benefit in a patient population with mild reactions, perhaps because withholding corticosteroids in this patient group prior to contrast material administration may be unethical. We continue to believe that alternative pathways of diagnosis should be used, when possible, instead of using iodinated contrast material in a patient with a history of iodine allergy.
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References
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- American College of Radiology. Patient selection and preparation strategies, manual on contrast media, version 5.0. Reston, Va: American College of Radiology, 2004;15–19.
- Morcos SK. Acute serious and fatal reactions to contrast media: our current understanding. Br J Radiol 2005;78:686–693.[Abstract/Free Full Text]
- Greenberger PA, Patterson R. The prevention of immediate generalized reactions to radiocontrast media in high-risk patients. J Allergy Clin Immunol 1991;87:867–872.[CrossRef][Medline]
- Greenberger PA, Patterson R, Tapio CM. Prophylaxis against repeated radiocontrast media reactions in 857 cases: adverse experience with cimetidine and safety of beta-adrenergic antagonists. Arch Intern Med 1985;145:2197–2200.[Abstract]
- Buller HR, Agnelli G, Hull RD, Hyers TM, Prins MH, Raskob GE. Antithrombotic therapy for venous thromboembolic disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004;126(3 suppl):401S–428S.[CrossRef][Medline]
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