Allergological evaluation of hypersensitivity reactions after administration of contrast agents: What the radiologist...

To familiarize radiologists with the methodology used in the assessment and management of hypersensitivity reactions to contrast agents.

This review provides diagnostic tools for the appropriate identification this type of reactions, including a checklist of key clinical items and a proposed algorithm to differentiate hypersensitivity reactions from nonspecific reactions and to assess their severity. It also outlines the main in vitro techniques (specific IgE, basophil activation test, mast cell activation test, lymphoblastic transformation test, and ELISpot) and in vivo procedures (skin tests and drug provocation tests) used to identify the culprit contrast agent and guide the selection of a safe alternative.

Although premedication is commonly used, its effectiveness is limited. Administering an alternative contras agent is a more effective strategy, but empirical selection carries a risk of recurrence. Allergy testing enables safer selection of an alternative agent. Integrating allergy evaluation into radiological practice can improve patient safety and outcomes in patients with a history of previous reactions.

Allergological techniques are valuable tools that support radiologists in the safe management of patients with hypersensitivity reaction to contrast agent, particularly in cases requiring re-exposure. The article concludes by presenting a diagnostic algorithm for both immediate and delayed reactions.

Switching to an alternative contrast agent is the most effective way to prevent a new hypersensitivity reaction. Radiologists should be familiar with the in vivo and in vitro techniques used in the allergy work-up to select a safe alternative agent.