PET imaging of infection with a HYNIC-conjugated LTB4 antagonist labeled with F-18 via hydrazone formation

H. Rennen, P. Laverman, J. van Eerd, W. Oyen, F. Corstens and O. Boerman

Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Aug, 2007



It was previously shown that the (99m)Tc-labeled hydrazinonicotinamide (HYNIC)-conjugated LTB4 antagonist MB81 visualized infectious foci in rabbits adequately and within a few hours after injection. Here, the bivalent HYNIC-conjugated LTB4 antagonist MB67 (analog of MB81) was fluorinated with (18)F via hydrazone formation and tested in vivo.MB67 was [(18)F]-fluorinated via reaction of the [(18)F]-fluorinated intermediate p-[(18)F]-fluorobenzaldehyde ([(18)F]FB) and the HYNIC moiety of MB67 via hydrazone formation. For comparison, MB67 was also labeled with (99m)Tc. The biodistribution of (18)F- and (99m)Tc-labeled MB67 was investigated in rabbits with intramuscular infection.[(18)F]-MB67 was obtained at a maximum specific activity of 1200 GBq/mmol and proved to be stable in phosphate buffered saline (PBS) at 37 degrees C for at least 4 h. PET images obtained with [(18)F]-MB67 clearly delineated the abscess at 2 and 4 h pi. Counting of dissected tissues at 4 h pi revealed an abscess uptake of 0.073+/-0.005 \%ID/g, as compared to 0.160+/-0.010 \%ID/g for the (99m)Tc-labeled analog. Abscess-to-muscle ratios were 23+/-4 for [(18)F]-MB67 and 35+/-9 for [(99m)Tc]-MB67.The present study showed the feasibility of a new [(18)F]-labeling methodology and its application in the production of a new PET tracer for imaging of infection, [(18)F]-MB67.