[en] Objective: To quantitatively compare the diagnostic capability of ⁶⁸Ga-NGR and ¹⁸F-FDG in well-differentiated hepatocellular carcinoma (HCC) bearing mice by microPET/CT imaging. Methods: The in vitro cellular uptake, in vivo microPET/CT imaging and biodistribution studies of ⁶⁸Ga-NGR and ¹⁸F-FDG were quantitatively compared in SMMC-7721-based well-differentiated HCC. The human fibrosarcoma (HT-1080) and human colorectal adenocarcinoma (HT-29) cells/xenografts were respectively used as positive and negative reference groups for CD13. The expression of CD13 was qualitatively verified by immunohistostaining. The levels of CD13 and glucose-6-phosphatase (G6Pase) were semi-quantitatively analyzed by Western blot test for all 3 types of tumors. Two-sample t test was used for data analysis. Results: The in vitro cellular uptake showed that the ⁶⁸Ga-NGR uptake in SMMC-7721 and HT-1080 cells was higher than that in HT-29 cells, and the ⁶⁸Ga-NGR uptake was higher than ¹⁸F-FDG uptake in SMMC-7721 cells. The in vivo microPET/CT imaging results revealed that the uptake of ⁶⁸Ga-NGR in SMMC-7721 tumor was (2.17 ± 0.21) %ID/g, remarkably higher compared to (0.73 ± 0.26) %ID/g of ¹⁸F-FDG uptake (Z = 8.826, P < 0.01). The tumor/liver ratio of ⁶⁸Ga-NGR was 2.05 ± 0.16, which was 2.03-fold higher than that of ¹⁸F-FDG. In the HT-1080 tumors, the uptakes of ⁶⁸Ga-NGR and ¹⁸F-FDG were both high, and the values were (2.46 ± 0.23) %ID/g, (3.47 ± 0.31) %ID/g. The uptake of ⁶⁸Ga-NGR was significantly lower than that of ¹⁸F-FDG in HT-29 tumors: (0.67 ± 0.20) %ID/g vs (3.17 ± 0.29)%ID/g; Z = 4.221, P < 0.01. Western blot and immunohis-tostaining results were as follows: HT-1080(CD13⁺, G6Pase^-), SMMC-7721(CD13⁺, G6Pase⁺), HT-29 (CD13^-, G6Pase^-). Conclusions: The uptake of ⁶⁸Ga-NGR is higher than ¹⁸F-FDG uptake in SMMC-7721 tumor bearing mice, therefore it is worthwhile to consider the feasibility of clinical translation for PET/CT in diagnosis of HCC. Furthermore, because of the difference in ⁶⁸Ga-NGR and ¹⁸F-FDG avidities in tumors with different molecular phenotypes of CD13 and G6Pase, there is an underlying potential for molecular imaging in the determination of molecular phenotypes. (authors)