Hippocampal grading provides higher classification accuracy for those in the AD trajectory than hippocampal volume

Abstract

Much research has focused on neurodegeneration in aging and Alzheimer's disease (AD). We developed Scoring by Nonlocal Image Patch Estimator (SNIPE), a non‐local patch‐based measure of anatomical similarity and hippocampal segmentation to measure hippocampal change. While SNIPE shows enhanced predictive power over hippocampal volume, it is unknown whether SNIPE is more strongly associated with group differences between normal controls (NC), early MCI (eMCI), late (lMCI), and AD than hippocampal volume. Alzheimer's Disease Neuroimaging Initiative older adults were included in the first analyses (N = 1666, 513 NCs, 269 eMCI, 556 lMCI, and 328 AD). Sub‐analyses investigated amyloid positive individuals (N = 834; 179 NC, 148 eMCI, 298 lMCI, and 209 AD) to determine accuracy in those on the AD trajectory. We compared SNIPE grading, SNIPE volume, and Freesurfer volume as features in seven different machine learning techniques classifying participants into their correct cohort using 10‐fold cross‐validation. The best model was then validated in the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL). SNIPE grading provided the highest classification accuracy for all classifications in both the full and amyloid positive sample. When classifying NC:AD, SNIPE grading provided an 89% accuracy (full sample) and 87% (amyloid positive sample). Freesurfer volume provided much lower accuracies of 65% (full sample) and 46% (amyloid positive sample). In the AIBL validation cohort, SNIPE grading provided a 90% classification accuracy for NC:AD. These findings suggest SNIPE grading provides increased classification accuracy over both SNIPE and Freesurfer volume. SNIPE grading offers promise to accurately identify people with and without AD.

Automatization and validation of the hippocampal-to-ventricle ratio in a clinical sample

“…For cognitively normal and MCI subjects, the associations with global cognition of both HVR and HCvol were comparable. Contrary to the abundant evidence of the relationship between hippocampus and general cognition in AD (Morrison, Dadar, Shafiee, and Collins 2023;Morrison, Dadar, Shafiee, Collins, et al 2023;Peng et al 2015;Vipin et al 2018), the correlations in our AD cohort were lower compared to the other subgroups, with only HVR's reaching statistical significance across all segmentation methods. This advantage of HVR over HCvol was statistically significant for the MALF segmentations of the MCI and AD cohorts, further suggesting that HVR might be particularly superior when only lower quality segmentations are available.…”