A model to investigate the feasibility of FDG as a surrogate marker of hypoxia
Kelly CJ., Smallbone K., Roose T., Brady M.
Fmiso-PET is a non-invasive modality used for the assessment of tumour hypoxia, and increasingly for planning radiotherapy. However, the availability and contrast properties of Fmiso are not ideal. Recent efforts to compare FDG binding with that of Fmiso, in order to ascertain FDG's potential as a marker of hypoxia, have met with mixed results. The potential reasons for correlated and disparate binding patterns between the two tracers have been postulated, but not formally outlined as yet. We present a model of a key component of the image formation process - tracer pharmacokinetics. This involves a series of coupled PDEs, describing the interplay between concentrations of oxygen, glucose, HIF, Fmiso and FDG. We use this model to assess the general feasibility of FDG as a surrogate marker of hypoxia and find that its utility is dependent on activity of oncogenic pathways.