Wampl S, et al. – In this study, the authors assess and compare the impact of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging. For hybrid aminoacid brain imaging, it was noted that frame duration can potentially be reduced by 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images whether adequate reconstruction settings and quantitative measures are applied. Remarkably, frame times below 4 min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.