Requests for Imaging Using Contrast Agents: What Information Must be Provided

There are potential risks associated with the administration of contrast agents and adverse reactions may occur. In addition, contrast agents may interact with some of the drugs and clinical tests used in the management of patients ( Thomsen 2006; Morcos 2005a,b Morcos and Thomsen 2001 Morcos et al. 2001, 2005). Although most serious reactions are observed after intravascular injection, adverse effects may also develop after oral or intra-cavitary administration because some of the contrast molecules may be absorbed into the circulation ( Morcos 2005). Reactions to contrast agents can be divided into non-renal and renal adverse reactions. Non-renal reactions may be acute (developing within 1 h of contrast agent administration) or delayed (developing after 1 h but less than a week) ( Morcos and Thomsen 2001). Some reactions, such as thyrotoxicosis and nephrogenic systemic fibrosis, may occur after 1 week and are termed very late reactions. Patients at high risk of these reactions should be identified before contrast administration to ensure that all necessary measures to reduce the risk are taken.