Reproducibility of common semi-quantitative parameters for evaluating lung cancer glucose metabolism with positron...

Positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) has been used for various cancers, but reproducibility of common utilized semi-quantitative parameters, such as the maximal single pixel standardized uptake value (SUV) and effective glycolytic volume (EGV), remains unknown. Knowledge of precision is essential for applying these parameters to treatment monitoring. The purpose of this investigation was to assess the precision of PET results obtained by repeated examinations of patients with untreated lung cancer.

Ten patients with lung cancer underwent two PET examinations within a week with no intervening treatment. The reproducibility of three parameters:((1) maximal SUV of 1 x 1 pixel anywhere in the tumor, calculated on the basis of predicted lean body mass [SULmax]; (2) highest average SUV at 4 x 4 pixels in the tumor adjusted by predicted lean body mass [SULmean]; and (3) EGV calculated by multiplying SUL by tumor volume), using PET images obtained at 50-60 min post-injection, were examined. Plasma glucose, insulin and free fatty acid levels were also monitored.

The SULmax, SULmean, and EGV were measured with a mean +/- S.D. difference of 11.3% +/- 8.0, 10.1% +/- 8.2, and 10.1% +/- 8.0%, respectively. By multiplying SUL by plasma glucose concentration, the mean differences were slightly reduced to 7.2% +/- 5.8, 6.7% +/- 6.2, and 9.5% +/- 8.2, respectively.

These data indicate that commonly used semi-quantitative indices of glucose metabolism on PET show high reproducibly. This supports their use in sequential quantitative analysis in PET, such as in treatment response monitoring.