T2 mapping was applied retrospectively to healthy subjects, mild cognitive impairment (MCI) and Alzheimer’s disease (AD) by deriving the T2 from modelling standard dual-echo proton density and T2-weighted fast spin echo sequence, as used in the Alzheimer’s disease and Neuroimaging Initiative (ADNI-1). T2 differences were compared to volume changes in hippocampus and thalamus. In both regions, T2 mapping showed significant differences between MCI and healthy subjects while volume measures did not. Volume was more effective for distinguishing MCI from AD, due to profound hippocampal atrophy. By modelling actual refocusing angles, T2 mapping revealed differences between healthy, MCI and Alzheimer’s subjects.