Exanthema after a stress Tc-99m sestamibi study: continue with a rest sestamibi study?

A mild allergic reaction assumed to be caused by injection of Tc-99m sestamibi for a stress myocardial perfusion imaging (MPI) is presented. We want to discuss the risk involved in completing the MPI with another sestamibi injection, and the precautions and possible treatment in case of a further reaction.

A patient experienced a maculo-papular exanthema, i.e. a mild, probably allergic, adverse event (AE) after a stress MPI including administration of a dose of Tc-99m sestamibi. A rest MPI was needed to decide whether coronary bypass surgery should be performed. After prophylactic treatment with antihistamine and corticosteroid, an uneventful rest MPI was performed.

International recommendations or guidelines related to treatment of AEs after nuclear medicine studies do not exist. Serious AEs in nuclear medicine are very rare, but anaphylactic reactions have been reported and may be life threatening. If repeated administration of the radio-pharmaceutical must be given, the prophylactic and therapeutic interventions should follow general international guidelines for allergic reactions.