18F-FDG PET/CT imaging of 100 normal adrenal gland cases

Objective: The purpose of this study was to obtain the 18F-fluorodeoxyglucose (FDG) uptake characteristics in normal adrenal gland as the criteria to diagnose abnormal glucose metabolism in ad- renal gland by 18F-FDG PET or PET/CT imaging. Methods: One hundred healthy persons underwent 18F- FDG PET/CT imaging in this study. The images were reviewed by visual judgement and measured by stand-ardized uptake value (SUV). With reference to normal liver, the uptake of adrenal gland was scored from 0 to 3, namely, 0=no uptake, 1=less than the uptake of normal liver, 2=equal to the uptake of normal liver, 3=more than the uptake of normal liver. SUV was measured on the trans-axial images. The regions of interest (ROIs) of adrenal glands and livers were manually drawn based on the CT images. Both average SUV (SUVavg) and maximum SUV(SUVmax) were calculated. Results: (1) By visual judgment, 94% and 91% of left and right normal adrenal glands had uptake intensity less than that of livers. (2) The SUVavg of left and right adrenal glands were 1.39 and 1.65, and the SUVmax 1.98 and 2.19, respectively with the up- per limit of 95% confidence interval (Cf). (3)The ratios of left and right adrenal glands SUVavg to livers SUVavg were 0.65 and 0.75 and left and right adrenal glands SUVmax to livers SUVmax were 0.76 and 0.83 respectively with the upper limit of 95% CI. (4)The uptake of right adrenal gland was higher than that of the left. (5)There was no significant difference of the SUVs between men and women, except that right ad- renal gland SUVmax of men was higher than that of women. (6) There was no significant difference in 18F- FDG uptake between persons younger and elder than 60 years old. Conclusion: The physiological FDG uptake of the adrenal gland in normal healthy individuals is generally lower than that of liver. (authors)