Ladefoged et al. have recently published a comprehensive comparison of different attenuation correction methods in brain PET/MR (Ladefoged 2017). A total of 11 different algorithms, including two used clinically, were compared to a CT-based attenuation correction. The conclusion of this paper is that some methods clearly outperform the two used clinically and are close to the CT-based attenuation correction performance. For example, the best three methods correct PET scans with variations of +/- 5% around the PET corrected with CT-based attenuation in about 80% of the brain volume.