Inter-hemispheric atrophy better correlates with expert ratings than hemispheric cortical atrophy

Brain atrophy is one of the parameters considered by experts for rating dementia from neuro-imaging findings. Research efforts have focused on measuring brain atrophy from images through experts´ visual assessment or computer-based approaches. However, agreement between the visual assessment and computer-based measurement of atrophy is not yet investigated. Accordingly, this paper presents an automated method for cerebral atrophy assessment from cross-sectional MRI through hemispheric volume loss. For this purpose, the proposed method quantifies inter-hemispheric distance, and the distance between the cranium and the brain parenchyma, separately. Discriminative power of the proposed method is evaluated on two datasets with experts´ visual gradings: Yue et al.´s data and a newly created reference dataset. Results show that inter-hemispheric atrophy better correlates with visual grades, and inconsistencies at the skull-stripping or brain tissue extraction steps can degrade the agreement between computer-based measurements and expert gradings.