A, Where calcifications merge with the skull base, it is hard to define the delineation line. A, Where calcifications merge with the skull base, it is hard to define the delineation line. B, Changing the window-level setting can then be of help, but observers might still disagree about the exact position of the delineation line. However, the low observer variability assessed in the present study shows that such disagreement only minimally influences total quantification results. Furthermore, the merging of calcifications and skull base prohibits, up to now, fully automated quantification. T.T. de Weert et al. AJNR Am J Neuroradiol 2009;30:177-184 ©2009 by American Society of Neuroradiology