Quantification of tumour (18) F-FDG uptake: Normalise to blood glucose or scale to liver uptake?

Eur Radiol. 2015 Sep;25(9):2701-8. doi: 10.1007/s00330-015-3659-6. Epub 2015 Apr 22.


Purpose: To compare normalisation to blood glucose (BG) with scaling to hepatic uptake for quantification of tumour (18) F-FDG uptake using the brain as a surrogate for tumours.

Methods: Standardised uptake value (SUV) was measured over the liver, cerebellum, basal ganglia, and frontal cortex in 304 patients undergoing (18) F-FDG PET/CT. The relationship between brain FDG clearance and SUV was theoretically defined.

Results: Brain SUV decreased exponentially with BG, with similar constants between cerebellum, basal ganglia, and frontal cortex (0.099-0.119 mmol/l(-1)) and similar to values for tumours estimated from the literature. Liver SUV, however, correlated positively with BG. Brain-to-liver SUV ratio therefore showed an inverse correlation with BG, well-fitted with a hyperbolic function (R = 0.83), as theoretically predicted. Brain SUV normalised to BG (nSUV) displayed a nonlinear correlation with BG (R = 0.55); however, as theoretically predicted, brain nSUV/liver SUV showed almost no correlation with BG. Correction of brain SUV using BG raised to an exponential power of 0.099 mmol/l(-1) also eliminated the correlation between brain SUV and BG.

Conclusion: Brain SUV continues to correlate with BG after normalisation to BG. Likewise, liver SUV is unsuitable as a reference for tumour FDG uptake. Brain SUV divided by liver SUV, however, shows minimal dependence on BG.

Key points: • FDG standard uptake value in tumours helps clinicians assess response to treatment. • SUV is influenced by blood glucose; normalisation to blood glucose is recommended. • An alternative approach is to scale tumour SUV to liver SUV. • The brain used as a tumour surrogate shows that neither approach is valid. • Applying both approaches, however, appropriately corrects for blood glucose.

MeSH terms

  • Blood Glucose*
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Fluorodeoxyglucose F18 / pharmacokinetics*
  • Humans
  • Liver / diagnostic imaging
  • Liver / metabolism*
  • Liver Neoplasms / diagnostic imaging
  • Liver Neoplasms / metabolism*
  • Multimodal Imaging
  • Positron-Emission Tomography
  • Radiopharmaceuticals / pharmacokinetics*
  • Retrospective Studies
  • Tomography, X-Ray Computed


  • Blood Glucose
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18