MR‐based hippocampal volumetry in the diagnosis of Alzheimer's disease

TLDR

The study evaluated a new MR‑based volumetric technique aimed at aiding the clinical diagnosis of Alzheimer’s disease dementia. The method measured volumes of the anterior temporal lobe and hippocampal formation, normalized them to total intracranial volume, and used a regression model to account for age effects. Normalized hippocampal volumes were markedly smaller in Alzheimer’s patients, with 85 % falling below the control range, and the technique reliably distinguished patients from controls across all ages, supporting its diagnostic utility.

Abstract

We evaluated a new magnetic resonance (MR)-based technique for performing volumetric measurements of temporal lobe structures. The technique was designed to assist in making the clinical diagnosis of dementia of the Alzheimer type (DAT). We chose specific anatomic regions of interest because of their known involvement in memory function and in the neuropathology of DAT and used a regression model to assess the effects of age on the volumes of the anterior temporal lobe (ATL) and the hippocampal formation (HF). These measurements were normalized by total intracranial volume (TIV). The volumetric measurements of both the normalized ATL and HF were significantly smaller (p < 0.001) in DAT patients (N = 20) than in controls (N = 22), but the HF volumes provided much better separation between the two groups. Eighty-five percent of the DAT patients fell below the range of the HF/TIV measurement for the control subjects. This separation held up over the entire age range studied. Normalized volumes of both the HF and ATL decreased with age significantly for both the DAT patients and the controls. These results support the contention that MR-based HF volumetric measurements are accurate in differentiating DAT patients from cognitively normal elderly individuals. This technique may be a useful adjunct in making the clinical diagnosis of DAT.