MR T 2 relaxometry in Alzheimer's disease and age-associated memory impairment

Abstract

A prolonged MR T 2 relaxation time was proposed to mark the presence and severity of Alzheimer's disease (AD). We studied the value of T 2 relaxometry in diagnosing early AD. T 2 was measured from 54 patients with AD, 25 subjects with age-associated memory impairment (AAMI), 18 elderly and 16 young controls. The AD patients had longer T 2 in the right hippocampal head (104 ± 11 ms) and tail (98 ± 10 ms) than age-matched controls (95 ± 5 and 92 ± 9 ms, respectively). This prolongation was not related to age. In the AD group, the T 2 of the left hippocampal head also correlated with the clinical severity. The T 2 of the amygdala did not differ across the groups. Increased T 2 in the temporal and parietal white matter and the thalamus related to increasing age rather than to the diagnostic category. The AAMI subjects had T 2 comparable with those of age-matched controls. Despite the prolongation of T 2 in the AD group the possible diagnostic value was compromized by a substantial overlap between the study groups. We, thus, conclude that the T 2 relaxometry is not a reliable method for diagnosing early AD.