Measurement of hippocampal subfields and age-related changes with high resolution MRI at 4T

Abstract

Histological studies suggest that hippocampal subfields are differently affected by aging and Alzheimer's disease (AD). The aims of this study were: (1) To test if hippocampal subfields can be identified and marked using anatomical landmarks on high resolution MR images obtained on a 4T magnet. (2) To test if age-specific volume changes of subfields can be detected. Forty-two healthy controls (21-85 years) and three AD subjects (76-86 years) were studied with a high resolution T2 weighted fast spin echo sequence. The entorhinal cortex (ERC), subiculum, CA1, CA2 and CA3/4 and dentate were marked. A significant correlation between age and CA1 (r=-0.51, p=0.0002) which was most pronounced in the seventh decade of life was found in healthy controls. In AD subjects, CA1 and subiculum were smaller than in age-matched controls. These preliminary findings suggest that measurement of hippocampal subfields may be helpful to distinguish between normal aging and AD.

Hippocampal Subregions are Differentially Affected in the Progression to Alzheimer's Disease

“…Imaging studies have used methods for identifying these hippocampal subfields through unfolding methods in high resolution functional MRI (Zeineh et al, 2000(Zeineh et al, , 2001Ekstrom et al, 2009) and high resolution in vivo (Mueller et al, 2007;Theysohn et al, 2009;Van Leemput et al, 2009) and ex vivo (Yushkevich et al, 2009) structural MRI mapping. These subfields are independent of subregional definitions of the hippocampus along its longitudinal axis (head, body, and tail) that are more readily evaluated in lower resolution imaging studies.…”

P2‐231: Systematic Comparison of Different Techniques to Measure Hippocampal Subfield Volumes in ADNI2

“…Brief method summary: The labeling method including assessment of measurement reliability has been described in detail previously (Mueller et al, 2007. In brief, the marking scheme depends on anatomical landmarks, particularly on a hypointense line representing myelinated fibers in the stratum moleculare/lacunosum which can be reliably visualized on these high resolution images.…”

“…Of the currently available approaches ASHS (Yushkevich et al, 2015b) and the latest version of Bayesian inference labeling implemented in Freesurfer 6.0 (Iglesias et al, 2015) were chosen for this project because both algorithms are publicly available and are used by the larger research community. The manual labeling protocol developed by Mueller et al (2007) was chosen as manual reference because its limited labeling scheme made it possible to label the over 100 images required for this project within a reasonable amount of time. The selected approaches use different labeling protocols which prevents a direct comparison of the subfield volumes.…”

Brain Mapping as a Tool to Study Neurodegeneration

“…62 Another research group delineated the hippocampal subfields on T2-weighted MRI data obtained at 4 T on three hippocampal slices and studied the effects of aging on the derived partial subfield volumes. 63 Ultimately, the best approach to delineate hippocampal subfields in vivo may require higher-field MRI-at field strengths as high as 7 T-in which the layers of the entorhinal cortex can be visualized. 64 Neuropathological studies describe hippocampal NFT pathology as a stage-like process affecting the subiculum and CA1 subfields first, followed by the CA2/3 and finally the CA4 subfields.…”