Head-to-head comparison of 18F-FDG and 18F-FES PET/CT for initial staging of ER-positive breast cancer patients

Purpose To compare the diagnostic performance of 18 F-fluorodeoxyglucose ( 18 F-FDG) and 18 F-fluoroestradiol ( 18 F-FES) positron emission tomography/computed tomography (PET/CT) for initial staging of estrogen receptor (ER) positive breast cancer. Methods Twenty-eight patients with ER-positive breast cancer underwent 18 F-FDG and 18 F-FES PET/CT for initial staging. Diagnostic performance and concordance rates were analyzed for both radiotracers. Semiquantitative parameters of maximum standardized uptake value (SUVmax) and tumor-to-normal ratio (T/N ratio) were compared using Wilcoxon signed-rank test. Factors potentially affecting the degree of radiotracer uptake were analyzed by multi-level linear regression analysis. Results The overall diagnostic performance of 18 F-FES was comparable to 18 F-FDG, except for higher specificity and NPV, with sensitivity, specificity, PPV, NPV, and accuracy of 87.56%, 100%, 100%, 35.14%, and 88.35%, respectively, for 18 F-FES and 83.94%, 30.77%, 94.74%, 11.43%, and 95.37%, respectively, for 18 F-FDG. Diagnostic performance of strong ER expression was better in 18 F-FES but worse for 18 F-FDG. There was a correlation of mucinous cell type and Allred score 7–8 with 18 F-FES uptake, with correlation coefficients of 26.65 (19.28, 34.02), 5.90 (− 0.005, 11.81), and p -value of