Larger (18)F-fluoroboronotyrosine (FBY) active volume beyond MRI contrast enhancement in diffuse gliomas than in circumscribed brain tumors

BACKGROUND: To investigate the relationship between (18)F-fluoroboronotyrosine (FBY) positron emission tomography (PET)- and magnetic resonance imaging (MRI)-defined tumor volumes in contrast-enhanced diffuse gliomas and circumscribed brain tumors. METHODS: A total of 16 diffuse gliomas and 7 circumscribed brain tumors were included, and two types of three-dimensional regions of interest (ROIs), namely, MRI-based ROI (ROI(MRI)) and FBY-based ROI (ROI(FBY)), were semiautomatically defined. The overlap volume and DICE score were calculated to reveal the spatial relationship between the ROI(MRI) and ROI(FBY). RESULTS: The ROI(MRI) was smaller than the ROI(FBY) and was mostly contained by the ROI(FBY) with an overlap volume of 0.995 ± 0.006 in the whole population. A significant difference in the DICE score was observed between circumscribed tumors and diffuse tumors (0.886 ± 0.026 vs. 0.684 ± 0.165, p = 0.004), and for the regions that have increased FBY metabolism but not MRI contrast enhancement, diffuse tumors and circumscribed tumors showed similar SUVmean values (0.630 ± 0.19 vs. 0.671 ± 0.18, p = 0.625). CONCLUSION: FBY uptake beyond contrast enhancement is more significant in diffuse tumors than in circumscribed tumors, which may aid the delineation of active tumor areas and facilitate boron neutron capture therapy.