1-(2-Deoxy-2-[18F]fluoro-β-D-arabinofuranosyl)-
5-bromouracil ([18F]FBAU), a substitute for
thymine, has been reported as an effective reporter probe by which to trace cellular metabolism with its positron emission. In the present study, a rat xenograft model bearing F98
glioma transfected with dual reporter genes, herpes simplex virus type 1
thymidine kinase (HSV1-tk) and
firefly luciferase (luc) was used for monitoring
tumor progression by multimodalities of molecular imaging using [18F]FBAU and D-
luciferase as probes. Rat F98
glioma cells were transfected with the pC1-tk-IRES-luc vectors. The selected stable clone was renamed as the F98/tk-luc cell line. Fischer 344 male rats bearing orthotropic F98/tk-luc
gliomas in the left brain were used. On day 13 post
tumor inoculation, biodistribution, positron emission tomography (PET), magnetic resonance imaging (MRI) and ex vivo autoradiography were performed. The surviving fraction of F98/tk-luc cells treated with 15 µM
ganciclovir (GCV) was 15.9%, and the uptake of [131I]
FIAU in these cells was significantly enhanced when compared with F98 cells. The correlation coefficient of
tumor volume vs. the bioluminescence in the F98/tk-luc
glioma-bearing rats was 0.90. The biodistribution showed that the accumulation ratios of [18F]FBAU for
glioma-to-normal brain were 9.16, 14.24, 5.7 and 13.7 at 30, 60, 90 and 120 min post i.v. injection, respectively. Consistent
tumor enhancement of [18F]FBAU/PET imaging was also noted from 30-90 min post injection. Ex vivo autoradiography also confirmed significant [18F]FBAU uptake in
tumors. In conclusion, [18F]FBAU may be used as a PET probe for monitoring
glioma progression in animal models and may have potential for clinical use as well.