2-Deoxy-2-[18F] fluoro-D-glucose uptake and correlation to intratumoral heterogeneity

The aim of this study was to investigate the pattern of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) uptake in relation to the intratumoral histopathological appearance.

Intratumoral distribution of FDG in nude mice with xenografted tumours originating from an established head and neck squamous cell carcinoma was studied. FDG uptake and the correlation to histopathological appearance was evaluated in four separate quarters of each tumour.

Variations in FDG uptake correlating to the presence of tumour cells was demonstrated. Quarters containing more than 50% tumour cells showed a significantly higher FDG uptake (p = 0.028) than quarters with more stromal tissue and necrosis.

This study shows that the heterogenic FDG uptake within a tumour correlates to histopathological findings and that the variable appearance of tracer uptake on the PET scan depends on distribution of different tissue components in the tumour. This intratumoral heterogeneity calls for caution when evaluating a PET scan where median values of larger areas will be misguiding and thus small areas with high uptake should be regarded as the regions of interest.