Orbital tumor diagnosis by positron emission tomography using 18F-fluorodeoxyuridine.

The distribution of 18F-labeled 5-fluoro-2'-deoxyuridine (18F-FdUrd) in orbital tissue, tumor and aseptic inflammation was examined in rats. The distribution in paraorbital structures, other than bone, was low. The tumor-to-organ ratios were sufficient for tumor imaging by positron emission tomography (PET). Positron emission tomography with 18F-FdUrd clearly showed the experimental orbital VX-2 tumor in rabbits. The difference between the experimental orbital tumor and croton oil-induced aseptic inflammation or a normal orbit was apparently established in the PET image with slow and fast clearance of radioactivity, respectively.