Relationships between oxygen and glucose metabolism in human liver tumours: positron emission tomography using 15O and 18F-deoxyglucose

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Abstract
Recently, investigators have measured glucose utilization in liver tumours using 18F-deoxyglucose positron emission tomography (18FDG PET) in order to characterize tumours and predict therapeutic effects. However, the detectability of liver tumours by this method remains unclear. In addition, no study has examined the association between oxygen and glucose metabolism in liver tumours using PET. To evaluate these associations in human liver tumours in vivo using 15O and 18FDG . Thirteen patients with liver tumours were studied: six with hepatocellular carcinoma (HCC), one with cholangiocarcinoma (CCC) and six with metastatic colon cancer (MET). We measured regional tumour blood flow (Ft), regional oxygen extraction fraction (OEF) and regional metabolic rate of oxygen (MRO2) using 15O PET. Using 18FDG PET, we determined a standardized uptake value (SUV) for liver tumours as an index of glucose metabolism. The mean values (mean±SE) for Ft, OEF, MRO2 and SUV were 42.5±7.0 ml·(100 g)−1·min−1, 43.4±4.9%, 2.57±0.39 ml·(100 g)−1·min−1 and 4.01±0.36, respectively. SUV for MET (4.44±0.48) was higher than that for HCC (3.52±0.59), and the blood flow in MET [31.4±4.1 ml·(100 g)−1·min−1] was lower than that in HCC [57.1±12.4 ml·(100 g)−1·min−1]. Significant negative correlations were noted between MRO2 and SUV (r=−0.741, P=0.004), and between Ft and SUV (r=−0.713, P=0.006). No correlation was apparent between Ft and OEF (r=−0.348, P=0.24), or between OEF and SUV (r=−0.023, P=0.94). 15O and 18FDG PET showed a significant negative correlation between MRO2 and SUV in human liver tumours. In addition, MRO2 depends on Ft rather than on OEF.