The reliability of a T2 relaxation quantification technique was assessed by repeatedly scanning four subjects (total of 12 scans at 4 time points over 4 years). Both total, biological and scanner variability were assessed across the whole brain and in the frontal, occipital, parietal temporal lobes. Total variability (coefficient-of-variation CoV < 10.3%) was dominated by biological variation (CoV < 10.3%). Scanner variability was low (CoV < 1.6%) despite scanner software and hardware upgrades during this interval. These results suggest that quantitative T2 estimates are reproducible over 4 years and robust to scanner upgrades.