Post Mortem Leukocyte Scintigraphy in Juvenile Pigs with Experimentally Induced Osteomyelitis

Abstract

We have previously demonstrated that 111In-labeled autologous leukocyte scintigraphy is able to detect osteomyelitis in living juvenile pigs. In animal research studies, it may well be an advantage if the animals could be scanned after euthanasia. Applying traditional scanning of living animals to euthanized animals will render anaesthesia unnecessary and be ideal for obtaining good and reliable scans for the correct interpretation of imaging afterwards, since the animals do not move. The autologous leukocytes of the pigs were collected, marked with 111In, and reinjected into the pigs and allowed for homing to the site of infections as usual while the pigs were alive. In this study, we demonstrate that it is possible to perform SPECT/CT with 111In-labelled autologous leukocytes almost 24 hrs after euthanasia with the same detectability of osteomyelitic lesions as in living pigs (78% versus 79%). The pigs in this study had exactly the same experimental conditions as the living pigs and were examined in parallel with the living pigs except for euthanasia prior to the leukocyte scan and that no PET/CT scans were performed.

Nuclear Medicine for the Orthopedic Foot and Ankle Surgeon

“…13 Early after injection, the radiotracer displays a predictable distribution pattern throughout the blood, lungs, reticuloendothelial system, bowel, and bladder. 1 Therefore, delayed imaging 18 to 24 hours after injection is optimal to identify pathologic activity. The majority of labeled leukocytes are neutrophils, and so the imaging modality is most useful in neutrophil-mediated inflammation (eg, in bacterial infections) and has lower utility in lymphocyte-predominant processes such as opportunistic infections.…”

“…Ga-67 accumulates in areas of infection and inflammation through multiple proposed mechanisms: (1) it binds to transferrin and leaks through the vascular epithelium at sites of inflammation; (2) it binds to lactoferrin found within leukocytes and macrophages; (3) it is directly absorbed by microorganisms; and (4) it is weakly taken up by osteoblasts. 13,63 Unlike leukocyte scanning, gallium scans have a widely variable distribution, which can confound image interpretation.…”