MRI OF THE HIPPOCAMPUS IN ALZHEIMERS-DISEASE - SENSITIVITY, SPECIFICITY, AND ANALYSIS OF THE INCORRECTLY CLASSIFIED SUBJECTS

In this study, magnetic resonance imaging (MRI) of the hippocampus for the diagnosis of early Alzheimer's disease (AD) is evaluated. We meas ured hippocampal volumes and the area of the medial hippocampus with a 1.5 T MR imager in 160 subjects: 55 patients with probable AD accordi ng to the NINCDS-ADRDA criteria, 43 subjects fulfilling the NIMH crite ria of age-associated memory impairment (AAMI), 42 cognitively normal elderly controls, and 20 controls younger than 50 years. Three methods for normalization were compared. The hippocampi were atrophied in the AD patients, but not in the AAMI subjects or the elderly controls. Th ere was no significant correlation between hippocampal volumes and age in the nondemented subjects. The discrimination based on volumetry re sulted in an overall correct classification of 92% of AD patients vs. nondemented elderly subjects, whereas discrimination based on hippocam pal area was less accurate, producing a correct classification in 80% of the subjects. We conclude that the hippocampal as assessed by MRI v olumetry is atrophied early in AD, and spared by aging or AAMI. A brie f critical review of previous studies is in concordance with the prese nted data: all the previous studies that have used volumetry, have sim ilarly ended up with a good classification, whereas simpler or subject ive measurements, subject to various sources of bias, have produced mo st variable results. (C) 1998 Elsevier Science Inc.