title: Quantification of tumour (18) F-FDG uptake: Normalise to blood glucose or scale to liver uptake?
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  • 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.
authors.affiliation: Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, UK, G.Keramida@bsms.ac.uk.
authors.forename: Georgia
authors.initials: G
authors.lastname: Keramida
authors.forename: Sabina
authors.initials: S
authors.lastname: Dizdarevic
authors.forename: Janice
authors.initials: J
authors.lastname: Bush
authors.forename: A Michael
authors.initials: AM
authors.lastname: Peters
mesh_terms: D001786:Blood Glucose; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000378:metabolism*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D001786:Blood Glucose; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18