4-Borono-2-[18F]fluoro-D,L-phenylalanine as a target compound for boron neutron capture therapy: tumor imaging potential with positron emission tomography.

We studied the tumor uptake and metabolism of 4-borono-2-[18F]fluoro-D,L-phenylalanine ([18F]FBPA), an 18F-labeled target compound for boron neutron capture therapy. In mice bearing FM3A mammary carcinoma, the accumulation of [18F]FBPA in the FM3A for the first 2 h, and its decrease in all other tissues, resulted in high FM3A-to-tissue uptake ratios. In the FM3A, the tracer was stable for metabolic alteration, which was in contrast to the gradual increase of protein-bound radioactivity in plasma. Imaging of FM3A was demonstrated by whole body autoradiography. [18F]FBPA has potential for use as a PET tracer for tumor imaging with high contrast, even in the pancreas.