  The radioactive glucose analogue 2-deoxy-2-[18F]fluoro-D-glucose (FDG) is
widely used to reconstruct glucose metabolism and other biological functions in
cells and tissues. The analysis of data on the time course of FDG tracer
distribution is performed by the use of appropriate compartmental models.
Motivated by recent results in cell biochemistry, we describe a new
compartmental model aiming at the reconstruction of tracer kinetics in cells
and tissues, which emphasizes the different roles of the cytosol and of the
endoplasmic reticulum. Two applications of the new model are examined, that are
concerned with real data from cancer cell cultures in vitro, and cancer tissues
in vivo. The results are compared with those obtained through application of
more standard compartmental models against the same datasets and appear to be
in a better agreement with respect to recent biochemical experimental evidence.
In particular, it is shown that tracer tends to accumulate in the endoplasmic
reticulum, rather than cytosol, and that the rate of phosphorylation is higher
than predicted by current models.
