Abstract
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Objectives Both 18F-FLT and 123I-ICdR were regarded as tumor proliferation probes. This study aims to demonstrate 18F-FLT-PET and 123I-ICdR-SPECT are promising modalities for noninvasively monitoring the therapeutic efficacy of liposomal doxorubicin (lipo-dox) in a subcutaneous hepatoma mouse model.
Methods Both 18F-FLT and 123I-ICdR were synthesized with high radiochemical purity (≧95%) and acceptable yield (15-20% d.c. for 18F-FLT and 85% for 123I-ICdR). Nude mice were inoculated with HepG2 hepatoma cells in the right flank. Lipo-dox (100 μg/kg bw) was administrated intravenously for treatment on day 26 (tumor size 100~150 mm3), 28, and 31 post hepatoma implantation. 18F-FLT-μPET, 123I-ICdR-μSPECT/CT and biodistribution studies were performed to evaluate the therapeutic efficacy.
Results The tumor-to-muscle (T/M) ratio derived from 18F-FLT-μPET images (acquired at 1 h post-injection) of lipo-dox-treated mice dropped from 12.36±0.56 to 3.85±0.12 after three-dose treatment, while that of control group remained steady (13.89±0.65 to 13.99±0.59). For 123I-ICdR-μSPECT (acquired at 4 h post-injection), the T/M ratio of lipo-dox-treated group also decreased from 2.57±0.05 to 1.67±0.02 during the same period. The results of biodistribution studies confirmed the finding in scintillation imaging.
Conclusions This study clearly demonstrated that both 18F-FLT and 123I-ICdR are promising scintigraphic probes for noninvasively monitoring hepatoma response at early stage of lipo-dox treatment (within one week