Dependence of FDG uptake on tumor microenvironment.

Abstract

To investigate the factors affecting the (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in tumors at a microscopic level, by correlating it with tumor hypoxia, cellular proliferation, and blood perfusion. Nude mice bearing Dunning prostate tumors (R3327-AT) were injected with (18)F-FDG and pimonidazole, bromodeoxyuridine, and, 1 min before sacrifice, with Hoechst 33342. Selected tumor sections were imaged by phosphor plate autoradiography, while adjacent sections were used to obtain the images of the spatial distribution of Hoechst 33342, pimonidazole, and bromodeoxyuridine. The images were co-registered and analyzed on a pixel-by-pixel basis. Statistical analysis of the data obtained from these tumors demonstrated that (18)F-FDG uptake was positively correlated with pimonidazole staining intensity in each data set studied. Correlation of FDG uptake with bromodeoxyuridine staining intensity was always negative. In addition, FDG uptake was always negatively correlated with the staining intensity of Hoechst 33342. For the Dunning prostate tumors studied, FDG uptake was always positively correlated with hypoxia and negatively correlated with both cellular proliferation and blood flow. Therefore, for the tumor model studied, higher FDG uptake is indicative of tumor hypoxia, but neither blood flow nor cellular proliferation.