Erschienen in:
01.09.2015 | Nuclear Medicine
Quantification of tumour 18 F-FDG uptake: Normalise to blood glucose or scale to liver uptake?
verfasst von:
Georgia Keramida, Sabina Dizdarevic, Janice Bush, A. Michael Peters
Erschienen in:
European Radiology
|
Ausgabe 9/2015
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Abstract
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.