Figure 1

Overview of the study protocol. Overview of the study protocol is presented. The study has two phases with phase I implemented two months leading to phase II. Input to both phases of the study is the MRI T1-weighted image volume of the subject. In phase I, Reference manual segmentation of ICV is measured by Operator 1 and the corresponding error of the ICV estimated through automatic software is determined, ${\text{Δ}}_{FS}^1$ for Freesurfer, ${\text{Δ}}_{FSL}^1$ for FSL and ${\text{Δ}}_{SPM}^1$for SPM. Inter-operator variability, ${\text{Δ}}_{Op1}^2$, is also calculated in this phase as the error between estimated ICV by Operator 1 and estimated ICV by Operator 2. For the phase II of the study, Intra-operator variability, ${\text{Δ}}_{OP1}^1$, is calculated as the error between estimated ICV by Operator 1 in phase I and estimated ICV by the same operator in phase II. The automatic measurements of ICV using Freesurfer, FSL and SPM are repeated and the corresponding errors are calculated as ${\text{Δ}}_{FS}^2$ for Freesurfer, ${\text{Δ}}_{FSL}^2$ for FSL and ${\text{Δ}}_{SPM}^2$ for SPM.