Automated Volumetry of Medial Temporal Lobe Subregions in Mild Cognitive Impairment and Alzheimer Disease

Abstract

Hippocampal subfield volumetry should be more useful than whole hippocampal (WH) volumetry for diagnosing Alzheimer disease (AD). This study sought to confirm this. We investigated cognitively normal (CN) participants and patients with mild cognitive impairment (MCI) or AD using high-resolution T2-weighted and 3-dimensional T1-weighted magnetic resonance imaging. Using medial temporal subregion volumetry, we investigated discriminative power for MCI and AD versus CN. We recruited 30 CN participants, 30 amnestic MCI patients, and 49 AD patients between April 2015 and October 2016. For AD, discriminative power of the combined volumes of the subiculum, entorhinal cortex, and cornu ammonis 1 was highest [area under the curve (AUC)=0.915; 85.7% sensitivity, 86.7% specificity, 86.1% accuracy], and was significantly higher than that of the WH volume (AUC=0.887; 90.0% sensitivity, 75.5% specificity, 84.5% accuracy) (P=0.019). For MCI, discriminative power of the subiculum volume was highest (AUC=0.747; 80.0% sensitivity, 73.3% specificity, 76.7% accuracy), but was only slightly higher than that of the WH volume (AUC=0.730; 56.7% sensitivity, 90.0% specificity, 73.3% accuracy). Using the combined volumes of the subiculum, entorhinal cortex, and cornu ammonis 1 may enable greater diagnostic accuracy compared with the WH volume or any single subfield in AD patients.