Magnetic resonance imaging of the entorhinal cortex and hippocampus in mild cognitive impairment and Alzheimer's disease

Objectives-To explore volume changes of the entorhinal cortex (ERC) and hip pocampus in mild cognitive impairment (MCI) and Alzheimer's disease (AD) co mpared with normal cognition (NC); to determine the powers of the ERC and t he hippocampus for discrimination between these groups. Methods-This study included 40 subjects with NC, 36 patients with MCI, and 29 patients with AD. Volumes of the ERC and hippocampus were manually measu red based on coronal TI weighted MR images. Global cerebral changes were as sessed using semiautomatic image segmentation. Results-Both ERC and hippocampal volumes were reduced in MCI (ERC 13%, hipp ocampus 11%, p<0.05) and AD (ERC 39%, hippocampus 27%, p<0.01) compared wit h NC. Furthermore, AD showed greater volume losses in the ERC than in the h ippocampus (p<0.01). In addition, AD and MCI also had cortical grey matter loss (p< 0.01) and ventricular enlargement (p<0.01) when compared with NC. There was a significant correlation between ERC and hippocampal volumes in MCI and AD (both p<0.001), but not in NC. Using ERC and hippocampus togethe r improved discrimination between AD and CN but did not improve discriminat ion between MCI and NC. The ERC was better than the hippocampus for disting uishing MCI from AD. In addition, loss of cortical grey matter significantl y contributed to the hippocampus for discriminating MCI and AD from NC. Conclusions-Volume reductions in the ERC and hippocampus may be early signs of AD pathology that can be measured using MRI.