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Radiopharmaceutical Chemistry: New Chemistry-OtherNew Chemistry-Other Posters |
1 Radiology; 2 Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
1271
Objectives: The purpose of this study was to assess the feasibility of PET infection imaging using a Cu-64 labeled chemotactic peptide N-formyl-leucyl-phenylalanine (fMLP) (TP1096).
Methods: TP1096 was synthesized to harbor a carboxy terminus Lys-DOTA separated from fMLP by 2[(2-aminoethoxy)ethoxy]acetic acid as a spacer. TP1096 was then labeled with 64Cu. The fMLP analogue (TP765) was synthesized by the addition of 4-aminobutyric acid as a spacer and a Gly-Gly-d-Ala-Gly to the carboxy terminus as a chelating moiety with 99mTc. The synthetic procedure rendered the analogues ready for instant chelating with 64Cu or 99mTc respectively. The stability of TP765 and its blood clearance were evaluated. Bacterial infection was induced in Balb/c mice using 100 µL of 1.0x108/mL mixture of Escherichia Coli, Enterococcus, and Staph lugdunensis. Planar or PET imaging and biodistribution studies were performed 4h and 24h post injection.
Results: Labeling yields of 64Cu-TP1096 and 99mTc-TP765 were >90%. 99mTc-TP765 had rapid but biphasic blood clearance (
t1/2 = 7 min, βt1/2 = 45 min). With 64Cu-TP1096, the 4h post injection abscess uptake was 0.95 ± 0.31 %ID/g versus 0.46 ± 0.5 %ID/g (p < 0.05) for 99mTc-TP765. The two-fold higher uptake of 64Cu-TP1096 could be attributed to the yet to be systematically examined, in vivo stability of Cu-64 as compared to that of Tc-99m.
Conclusions: The significantly higher abscess uptake of 64Cu-TP1096 combined with the higher sensitivity and enhanced resolution of PET imaging make 64Cu-TP1096 a desirable agent for further studies in PET imaging of infection.
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