Becker AS, Chaitanya K, Schawkat K, et al. - Six readers segmented the peripheral zone (PZ), transitional zone (TZ) and SV slice-wise on axial T2w prostate MRI examinations of 80 persons in order to assess the interreader variability in prostate and seminal vesicle (SV) segmentation on T2w MRI. A significantly lower dice score (DS) of the segmentations in the apex in comparison with the base and the midgland was seen. With a mean DS of 0.859, Hausdorff distance (HD) of 36.6 and volumetric similarity coefficient (VS) of 0.926, overall segmentation variability was good. The WG exhibited a DS, HD and VS of 0.738, 36.2 and 0.853, respectively. The TZ exhibited usually lower variability with a DS of 0.738, HD of 24.8 and VS of 0.908. The lowest variability was seen for the SV with DS of 0.884, HD of 17 and VS of 0.936. Thus, baseline values for interreader variability of prostate and SV segmentation on T2w MRI were reported. Furthermore, variability was greatest in the apex, lower in the base, and lowest in the midgland.