MR T-2 RELAXOMETRY IN ALZHEIMERS-DISEASE AND AGE-ASSOCIATED MEMORY IMPAIRMENT

A prolonged MR T-2 relaxation time was proposed to mark the presence a nd severity of Alzheimer's disease (AD). We studied the value of T-2 r elaxometry in diagnosing early AD. T-2 was measured from 54 patients w ith AD, 25 subjects with age-associated memory impairment (AAMI), 18 e lderly and 16 young controls. The AD patients had longer T-2 in the ri ght hippocampal head (104 +/- 11 ms) and tail (98 +/- 10 ms) than age- matched controls (95 +/- 5 and 92 +/- 9 ms, respectively). This prolon gation was not related to age. In the AD group, the T-2 of the left hi ppocampal head also correlated with the clinical severity. The T-2 of the amygdala did nor differ across the groups. Increased T-2 in the te mporal and parietal white matter and the thalamus related to increasin g age rather than to the diagnostic category. The AAMI subjects had T- 2 comparable with those of age-matched controls. Despite the prolongat ion of T-2 in the AD group the possible diagnostic value was compromiz ed by a substantial overlap between the study groups. We, thus, conclu de that the T-2 relaxometry is not a reliable method for diagnosing ea rly AD.