Longitudinal multicenter MRI studies require stable and comparable measurements. We scanned two subjects in six different scanners (two vendors) at different time points and assessed hippocampal volumes manually and automatically.
Intrascanner CV was <2.62% for both techniques; Freesurfer is a good alternative for manual delineation for longitudinal studies.
Intervendor variability was sometimes lower than intrascanner variability for the manual technique, which suggests only a modest effect of hardware differences across vendors. Freesurfer results were systematically higher for vendor B compared to A; it is not recommended to compare cross-sectional Freesurfer results between vendors in this multicenter study.