Introduction In the present study, Tc-99m-radiolabelled E-selectin binding
peptide (Tc-99m-IMP-178) was investigated for its potential to image acutem
pyogenic osteomyelitis in a new animal model. Intraindividual comparisons
were performed using an irrelevant peptide (Tc-99m-IMP-100) to demonstrate
specificity.
Methods An acute pyogenic osteomyelitis was induced by injecting 0.05 ml of
5% sodium morrhuate and 5 x 10(8) CFU of Staphylococcus aureus into the me
dullary cavity of the right tibia in 16 rats. Sixteen additional rats serve
d as untreated controls. Whole-body imaging of pyogenic (n = 4) and untreat
ed (n = 4) animals was performed continously during the first 8 h (12 MBq i
.v. of 99mTc-IMP-178 and Tc-99m-IMP-100 for control), and one further singl
e image was acquired after 16 h p.i. Tissue biodistribution studies were pe
rformed in 12 rats with an acute pyogenic osteomyelitis and in 12 untreated
rats 1, 4 and 24 h after injection. Data of the histological/radiological
and haematological investigations were obtained in all animals.
Results Histopathologically, 15 of 16 treated rats (93%) developed an acute
pyogenic osteomyelitis showing a major infiltration of the bone marrow by
polymorphonuclear leukocytes as well as the formation of sequestra. Haemato
logically, the number of leukocytes increased by 100%, the lymphocytes by 1
1% and the granulocytes decreased by 39%. After i.v. injection, Tc-99m-IMP-
178 rapidly cleared from the body resulting in good scintigraphic target-to
-background (T/B) ratios. The highest uptake of the tracer in the pyogenic
bone was observed at 60 min p.i. (0.43 +/-0.02% ID.g(-1) for Tc-99m-IMP-178
and 0.30 +/-0.02% ID.g(-1) for Tc-99m-IMP-100), resulting in a higher oste
omyelitis-to-healthy collateral ratio with T/B of 2.40 +/-0.65 (Tc-99m-IMP-
178) compared with 1.85 +/-0.48 (Tc-99m-IMP-100). No adverse reactions were
seen after injection of 99mTc-IMP-178.
Conclusions Tc-99m-IMP-178 allows imaging of an acute osteomyelitic lesions
, presumably by interaction of Tc-99m-IMP-178 with activated upregulated va
scular endothelium. ((C) 2001 Lippincott Williams & Wilkins).