Experiences with Citrate Rather Than Heparin as an Anticoagulant for 18F-FDG Labeling of Leukocytes

In all reported clinical studies with 18 F-FDG–labeled leukocytes, heparin was used as an anticoagulant during labeling. Theoretically, the substitution of heparin with citrate should be advantageous. Methods: Blood from healthy controls was sampled in duplicate, anticoagulated with citrate or heparin, and labeled with 18F-FDG, and the labeling yield was measured. Viability was checked with the trypan blue exclusion technique. Moreover, 4 in vivo PET/CT studies were performed after the reinjection of leukocytes labeled after citrate anticoagulation. Results: The labeling yields obtained with citrate and heparin were not significantly different (P 5 0.447). Viability was greater than or equal to 99%. The quality of the PET/CT studies was excellent. In the in vivo studies, the mean labeling yield was 78%—better than or equal to that reported with heparin as an anticoagulant. Conclusion: Citrate is at least as effective as heparin as an anticoagulant, does not (unlike heparin) increase granulocyte activation, and should be the preferred anticoagulant for 18 F-FDG labeling of leukocytes.