Relationship between the uptake of 18F-borono-L-phenylalanine and L-[methyl-11C] methionine in head and neck tumors and normal organs

Abstract

Background and purpose: The purpose of this study was to determine the distribution of 4-borono-2-18F-fluoro-phenylalanine (18F-BPA) and L-[methyl-11C] methionine (11C-Met) in normal organs and tumors and to evaluate the usefulness of 11C-Met/PET in screening potential candidates for boron neutron capture therapy (BNCT). Material methods: Seven patients who had at least one histologically confirmed head and neck tumor were included in this study. They underwent both whole-body 18F-BPA-PET/CT and 11C-Met-PET/CT within a span of 6months. Uptake was evaluated using the maximum standardized uptake value (SUVmax). Regions of interest (ROIs) were placed within the tumors and target organs of brain, thyroid, submandibular gland, lung, liver, esophagus, stomach pancreas, spleen, muscle, and bone marrow. Results: The tumor SUVmax of FBPA and 11C-Met showed strong correlation (r 2=0.72, P=0.015). Although 18F-BPA and 11C-Met showed markedly different uptake in some organs (submandibular gland, liver, heart, stomach pancreas, spleen, and bone marrow), the uptake of 11C-Met was consistently higher than that of 18F-BPA in these cases. Conclusion:11C-Met PET/CT might be used instead of 18F-BPA PET/CT to predict the accumulation of 10B in tumors and to select candidates for BNCT. However, it would not be suitable for evaluating accumulation in some normal organs. Therefore, the 18F-BPA-PET study remains a prerequisite for BNCT. This is the first report of the correlation between 18F-BPA and 11C-Met accumulation.