TY - JOUR T1 - Glucose metabolism in micrometastases by 18F-FDG autoradiography (DAR) JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 274 LP - 274 VL - 50 IS - supplement 2 AU - Xiao-Feng Li AU - Yuanyuan Ma AU - Xiaorong Sun AU - John Humm AU - Clifton Ling AU - Joseph O'Donoghue Y1 - 2009/05/01 UR - http://jnm.snmjournals.org/content/50/supplement_2/274.abstract N2 - 274 Objectives We have shown previously that tumors of less than 1 mm diameter were extremely hypoxic while those of greater size (1-4mm) were not significantly hypoxic (Cancer Res 2007). The objective was to examine glucose metabolism in micrometastases using FDG DAR and to relate to hypoxia, GLUT-1expression, perfusion and proliferation. Methods Human colon cancer HT29 or HCT8 cells were injected i.p. into nude mice to generate peritoneal tumors of varying sizes. Following overnight fasting, animals, either breathing air or carbogen (95% O2+5% CO2), were i.v. administered FDG together with hypoxia marker pimonidazole and proliferation marker bromodeoxyuridine 1h before sacrifice. Hoechst 33342 was administered 1 min before sacrifice. Intratumoral distribution of FDG was assessed by DAR. This was compared with GLUT-1 expression, tumor hypoxia, proliferation and blood perfusion. Results Intensely hypoxic micrometastases were poorly perfused with low level of cellular proliferation but had high FDG accumulation and GLUT-1 expression. Larger tumors (1-4mm) were well-perfused with higher cell proliferation but were not significantly hypoxic and had low 18F-FDG accumulation and GLUT1 expression. Carbogen breathing significantly decreased FDG accumulation and Pimonidzole binding in micrometastases but had little effect on GLUT1 expression. Conclusions Glucose metabolism measured by FDG uptake significantly increased in hypoxic microscopic tumors. Physiological hypoxia rather than proliferation or perfusion or amount of GLUT1 expression may be the underlying mechanism for increased FDG uptake of micrometastases. Our findings may be of importance for better understanding intratumoral FDG distribution in clinical setting. ER -