Influence of blood glucose level for FDG accumulation of various organs in PET study

Objectives The purpose of this study was to clarify the intra- and inter-individual relationship between the blood glucose (BG) level and FDG accumulation of brain, heart, liver and urine in bladder in fasting PET/CT study.

Methods One hundred and sixteen hyperglycemic patients with known or suspected malignancy, and 31 healthy cancer screening subjects with normal BG level as control group were retrospectively evaluated. Hyperglycemic patients were divided into 2 groups by BG level (group 1: 110 to 149 mg/dl, group 2: ≧150mg/dl). More than two FDG-PET/CT studies were performed for each subject. BG level was determined just before FDG administration. Organs quantitatively evaluated by SUV on CT guided region of interest analysis in three contiguous slices. Mean SUVs were analyzed using one-way analysis of variance.

Results The brain SUV correlated negatively in all, especially in group2 (all: r=-0.547, group2: r=-0.66, p<0.001, respectively). The heart SUV correlated slight negatively in all subjects and group2 (all: r=-0.304, group2: r=-0.224, p<0.001, respectively). Heart SUVs in group 1 and in control had been variability and no statically significance was observed. There was no correlation between liver nor urine in bladder SUV and BG level. Mean rates of change in SUVs on the high versus low BG images in individual subjects were significantly lower for brain 14% (p<0.0001), and higher for urine 27% (p=0.0110), and various showing no tendency to increase for heart -4% (p=0.0027) and for liver 1% (p=0.8821).

Conclusions FDG-PET imaging at high BG level demonstrated significantly lower brain and weakly lower heart, and significantly higher urine accumulation. On intra-individual FDG-PET imaging at high compared with low BG level, significant changes of FDG accumulation in organs except for liver were apparent. On FDG-PET imaging at hyperglycemia, it may be useful to refer to brain SUV for appropriate assessment of the pathological accumulation in follow up study