Across session (A) absolute volume reproducibility error and (B) spatial reproducibility (DICE coefficient) of whole and subfield hippocampus segmentations derived from a single T1 (gray) versus two within‐session coregistered and averaged T1 volumes (black). Results are averaged across sites. Error bars indicate the standard deviation on the mean. Abbreviations: CA2‐3, cornu ammonis 2‐3; Sub, subiculum; CA4‐DG, cornu ammonis 4‐ dentate gyrus; Presub, presubiculum; CA1, cornu ammonis 1; Hp_fiss, hippocampal fissure; Whole HP, whole hippocampus. t, trend forward significance; *P < 0.05, **P < 0.01, ***P < 0.001 at Wilcoxon test between single and averaged T1 mean; &
P < 0.05, &&
P < 0.01 at Levene test between single and averaged T1 variance.