Prolongation of magnetic resonance T2 time in hippocampus of human patients marks the presence and severity of Alzheimer's disease.

Spin-spin relaxation time (T2) was measured in the hippocampal formation, thalamus, and cortical white matter in 13 patients with probable Alzheimer's disease (AD), 11 elderly normal individuals, 23 healthy young persons, and 9 subjects diagnosed with multi-infarct dementia. A 0.04 tesla magnetic resonance scanner was used. Hippocampal T2 values for all AD patients exceeded those of any non-AD individual, regardless of age or dementia due to infarction. Further, these T2 values were highly correlated (+ 0.96) with the severity of functional and cognitive impairment of the AD patients. This T2 prolongation was not observed at the other sites examined. These results suggest that hippocampal T2 prolongation may provide a specific marker by which AD pathology can be detected, characterized, and followed in vivo.