Chocolate intake associated with failed labeling of (99m)Tc red blood cells.

Unlabelled: Red blood cells (RBC) labeled in vivo with (99m)Tc-pertechnetate are used worldwide in nuclear medicine departments.

Methods: Here, we present a case of (99m)Tc-RBC labeling failure associated with chocolate intake in a 25-y-old woman, resulting in uninterpretable images. Because of this clinical observation, we performed in vitro RBC labeling on blood samples from volunteers after they consumed chocolate.