Introduction: In PET quantification of physiological parameters at the pixel level may result in unreliable estimates due to the high noise of pixel time activity curves. Global-Two-Stage (GTS) is an estimation technique belonging to the group of “population approaches” that was previously tested on simulated data and provided less noisy maps than those obtained with standard techniques like the Basis Function Method (BFM). In this work GTS performance is analyzed in a clinical context using a [C](R)-PK11195 dataset.