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 (18)F-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 = 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.