Longitudinal MRI evaluations of human global cortical thickness over minutes to weeks

Magnetic resonance imaging (MRI) was used to evaluate within-subject variability in global mean cortical thickness over test–retest intervals of minutes–weeks in five healthy adults. Within-subject measures of global mean thickness were consistent over these intervals. Test–retest assessments of absolute thickness differences and percent thickness differences indicated variations of, respectively, ≤0.05–0.06 mm and ≤±1.9–2.3%. There have been few evaluations of normal within-subject variations in cortical thickness. The present results suggest that within-subject variability in global mean cortical thickness can be low over test–retest intervals of minutes–weeks, and that longitudinal scans can establish useful baseline estimates of variability from which to assess changes due to injury, disease, or other experiences.