The correlation between PET-CT imaging and microvessed density in rabbit lung VX2 tumor model

Objective: To evaluate and compare the suitability of 11C-choline and 18F-FDG PET-CT for reflecting tumors angiogenesis. Methods: Fifty-four New Zealand white rabbits which weighted 2.5∼3.0 kg were used in the experiment. Under general anesthesia, a needle was transthoracically inserted into the right lung, 0.5 ml viable VX2 tumor cell suspension was slowly injected through the needle to establish the model. 11C-choline and 18F-FDG PET-CT were performed after 10∼11 d. The tumors SUVmax were calculated. The sections were stained with hematoxylin and eosin, and immunostained for CD34. Assessment of micro vessel density (MVD) was performed by computer-assisted image analysis. The relationship 11C-choline SUVmax and 18F-FDG SUVmax with tumor size and MVD were statistically analyzed. Results: Thirty-three rabbits successfully completed all imaging examinations. 11C-choline and 18F-FDG differently accumulated in all lung VX2 tumors. The mean of 11C-choline SUVmax was 4.02±3.07 (1.4∼12.2), and the mean of 18F-FDG SUVmax was 5.70±3.45 (1.0∼13.0). The mean size of tumor was (1.68±1.61)cm3 (0.13∼8.00 cm3). Under high power microscope field of vision (200 x 0.739 mm2), the mean of MVD was 35.8±13.6 (13∼64), 11C-choline SUVmax did not correlate with tumor size and MVD. 18F-FDG SUVmax significantly and positively related to MVD (r=0.525, P=0.002). There was a critical positive correlation between 18F-FDG SUVmax and tumor size (r=0.335, P=0.057). Conclusion: In the rabbit VX2 lung tumor model, 18F-FDG SUVmax correlated with MVD, so 18F-FDG PET-CT could reflect tumor angiogenesis. 11C-choline SUVmax did not statistically correlate with MVD, and 11C-choline PET-CT could not reflect tumor angiogenesis. (authors)