From the Guidelines
For patients with an iodine allergy requiring a CT adrenal protocol, the recommended approach is premedication with corticosteroids and antihistamines before administering low-osmolality or iso-osmolality contrast media, as supported by the most recent and highest quality study available 1.
Key Considerations
- The incidence of anaphylactoid reactions to contrast media is low, but premedication can reduce the risk of recurrence in patients with a history of prior anaphylactoid reactions 1.
- A typical premedication regimen includes prednisone 50 mg orally at 13 hours, 7 hours, and 1 hour before the procedure, along with diphenhydramine 50 mg orally or intravenously 1 hour before the procedure.
- Non-contrast CT is an alternative option, though it provides less detailed information about adrenal lesions, and MRI with gadolinium-based contrast agents can also be considered as they rarely cause allergic reactions in iodine-allergic patients.
Recommended Approach
- Premedication with corticosteroids and antihistamines before administering low-osmolality or iso-osmolality contrast media.
- Use of non-contrast CT or MRI with gadolinium-based contrast agents as alternative options.
- Consideration of the patient's individual risk factors and medical history when determining the best approach.
Supporting Evidence
- The 2022 study published in Radiologia Medica 1 provides guidance on the use of cardiovascular computed tomography and magnetic resonance in congenital heart disease, including the use of contrast media and premedication regimens.
- The 2011 study published in Circulation 1 discusses the incidence of anaphylactoid reactions to contrast media and the effectiveness of premedication regimens in reducing the risk of recurrence.
From the Research
Recommended Approach for Patients with Iodine Allergy Undergoing CT Adrenal Protocol
- For patients with an iodine allergy undergoing a computed tomography (CT) adrenal protocol, it is essential to assess the risk of an allergic reaction to iodinated contrast media 2.
- Premedication with corticosteroids and antihistamines may be considered to reduce the risk of an allergic reaction, as studies have shown that premedication can be effective in preventing recurrence of acute allergic-like reactions to low osmolar contrast media (LOCM) 3, 4.
- However, it is crucial to note that the term "iodine allergy" is imprecise and can lead to uncertainty in clinical management, and a more specific diagnosis of contrast media allergy or identification of the exact culprit contrast media is recommended 5.
- In some cases, avoiding contrast media altogether may be appropriate, but in situations where contrast media is necessary, the radiologist plays a vital role in preventing or mitigating an allergic reaction 2.
- The use of premedication protocols, such as those involving corticosteroids, can help reduce the risk of adverse reactions, but it is essential to carefully evaluate the risk-benefit ratio and consider alternative imaging modalities if possible 6.
Key Considerations
- Patients with a history of severe index reactions are still at risk of developing severe reactions despite corticosteroid premedication 3.
- The incidence of adverse reactions to iodinated contrast media can be higher in patients with a history of hypersensitivity against iodinated contrast media 6.
- A systematic approach to preventing hypersensitivity reactions, including premedication and careful patient evaluation, is essential to ensuring patient safety during CT imaging procedures 4.