string: …activity concentration, we found in all patients a consistent underestimation for 18F-FDG PET/MR in comparison to 18F-FDGPET/CT inmost of the cortical areas [results not shown], in agreementwith several previous brain studies involving 18F-FDG PET/MR (Dickson et al., 2014; Al-Nabhani et al., 2014).