Fig. 6

ROC analyses of the SBRs with and without the CSF-mask algorithm in the low, middle, and high EI groups. a The AUCs for the SBRs with and without the CSF-mask algorithm were 0.942 (95% CI 0.898–0.986) and 0.927 (95% CI 0.877–0.978), respectively, in the low EI group (NC). b The AUCs for the SBRs with and without the CSF-mask algorithm were 0.894 (95% CI 0.825–0.963) and 0.872 (95% CI 0.798–0.947), respectively, in the middle EI group (NC). c The AUCs for the SBRs with and without the CSF-mask algorithm were 0.931 (95% CI 0.883–0.978) and 0.900 (95% CI 0.840–0.961), respectively, in the high EI group (NC). d The AUCs for the SBRs with and without the CSF-mask algorithm were 0.961 (95% CI 0.924–0.998) and 0.942 (95% CI 0.895–0.988), respectively, in the low EI group (AC). e The AUCs for the SBRs with and without the CSF-mask algorithm were 0.905 (95% CI 0.843–0.968) and 0.872 (95% CI 0.800–0.944), respectively, in the middle EI group (AC). f The AUCs for the SBRs with and without the CSF-mask algorithm were 0.954 (95% CI 0.917–0.991) and 0.917 (95% CI 0.862–0.973), respectively, in the high EI group (AC). AC attenuation correction, EI Evans index, NC no correction, ROC receiver-operating characteristics, SBR specific binding ratio, CSF cerebrospinal fluid, AUC area under the curve, CI confidence interval