Elastin is considered as a key player in human
vascular diseases and it might contribute to the development of
atherosclerosis. The
elastin binding radiotracer, [(18)F]AlF-
NOTA-EBM ([(18)F]2), was evaluated in a wild type mouse to determine its in vivo distribution and on human carotid
atherosclerotic plaque tissues to assess its utility as a PET imaging agent for visualizing human
atherosclerotic plaque lesions. The free
ligand NOTA-EBM, which served as the precursor, was obtained in 25% chemical yield. The radiosynthesis of [(18)F]2 was accomplished by coordination of Al(18)F to
NOTA-EBM in 8-13% decay corrected radiochemical yield (n = 7) and specific radioactivity of 59 ± 12 GBq/μmol. A dynamic in vivo PET scan in a healthy wild type mouse (C57BL/6) showed high accumulation of radioactivity in heart and lungs, organs reported to have high
elastin content. Excretion of [(18)F]2 proceeded via the renal pathway and through the hepatobiliary system as indicated by a high uptake of radioactivity in the liver, intestines and gall bladder. In vitro autoradiography on human
atherosclerotic plaque sections showed a heterogeneous distribution of [(18)F]2 with an elevated accumulation in stable and vulnerable
atherosclerotic plaques compared to control samples of normal arteries. However, there was no statistical significance between the different plaque phenotypes and control samples. Competition experiments with 10.000-fold excess of free
ligand NOTA-EBM resulted in a marked decrease of radioactivity accumulation, consistent with a target-specific
ligand.