Table 1.
Demographics of the 34 subjects.
Fig 1.
The violin plot of label-wise agreement (ICC) for each MRI scan.
The bootstrapped ICCs of each label from each measurement produced by FreeSurfer are summarized in Fig 1. In addition to the information in the box plot, the shape of the distribution visualized in the violin plot helps to detect clusters or bumps within a distribution. This plot reflects the density of label-wise ICC among different scanners grouped by measurement and parcellation/segmentation types. The distribution of the density plot reveals the portion from different levels that are in agreement within each group. Abbreviations: a2009s, Destrieux Atlas; aparc, Desikan-Killiany Atlas; wm, subcortical white matter; aseg, miscellaneous structures.
Fig 2.
The violin plot of the p value of label-wise Wilcoxon signed rank test for each MRI scan.
The p value is presented as log10(p). This plot reflects the distribution of label-wise p values between different machines by different measurement type and parcellation/segmentation type. The number and percentage of the regions of statistical significance (p < 0.01 or log10(p) < -2) were also labeled below the violin distribution. Abbreviations: a2009s, Destrieux Atlas; aparc, Desikan-Killiany Atlas; wm, subcortical white matter; aseg, miscellaneous structures.
Fig 3.
The regions of significant difference using Wilcoxon signed rank test are labeled and colored on the cortical surface for visualization.
Table 2.
Regions showing significant differences.
Fig 4.
Results of the Bland-Altman analysis comparing results obtained from repeat MRI scans using different MRI models and selected global measures of brain volume.
These plots represent the difference between repeat MRI scans against the average value for each pair of measurements. A continuous line and two dotted lines represent the mean difference between each pair of measurements and the limits of agreement, respectively, for each BA plot.
Table 3.
Bland-Altman analysis of global measures of volume obtained from repeat MRI scans.
Table 4.
Volumetric reproducibility error for the various MRI models from FreeSurfer segmentation.
Each cell represents the mean reproducibility errors (percent absolute difference relative to the mean) across subjects within each MRI scanner. Among these three selected global volumetric measures, there was no significant MRI model effect observed (Kruskal-Wallis test). Although not significant, large percent absolute differences were seen within the TrioTim model (cortex and white matter volume), suggesting the existence of outliers.