68 Ga-Oxine-Labeled Erythrocytes as a New PET Tracer for the Localization of Gastrointestinal Bleeding.

A 69-year-old man presented with recurring drops in hemoglobin levels and suspected gastrointestinal bleeding. Endoscopy did not show a site of bleeding so further examinations became necessary. Scintigraphy and SPECT/CT with 99m TcO 4- -labeled red blood cells were performed without evidence of a hemorrhage. Based on an established protocol for splenic PET/CT, autologous erythrocytes can be labeled with 68 Ga-oxine and used as a tracer for the localization of active bleeding sites. In the patient, PET/CT with 68 Ga-oxine-labeled undamaged erythrocytes was performed successfully and revealed a hemorrhage of the gastric corpus that was confirmed and treated by endoscopy.