The visual rating system for hippocampal atrophy: What does it assess?

Abstract

A promising visual rating system for hippocampal atrophy (rated 0-4) has been developed by Scheltens and shown to distinguish between normal aging and AD in numerous studies. The question of it's relation to volumetric measures has not been formally addressed. 5 individuals of varied levels of radiologic expertise (1 radiologist, 1 geriatrician, 1 Ph. D. student & 2 Research assistants) were trained in the use of the visual rating system and then individually assessed a sample of 122 scans selected from a larger cohort enrolled in a study of mild memory loss in the elderly (32 healthy elderly controls, 61 with a diagnosis of Mild Cognitive Impairment, and 29 with a diagnosis of Alzheimer's disease). These ratings were compared to measures of hippocampal volume, lateral ventricular volume, and atrophy ratio (the ratio of lateral ventricular volume to hippocampal volume). Ratings averaged across the group distinguished between the groups (Controls = 0.9, MCI = 1.63, AD = 2.35, p < 0.05). When correlated against volumetric measures, averaged ratings correlated better with the atrophy ratio measure (r = 0.76) than with the hippocampal volume (r = -0.50). All raters scored over r = .6 in their correlations, even those with limited previous expertise. These results suggest that the visual rating system can distinguish between diagnostic groups in a meaningful manner, and that the ratings reflect atrophy ratio more than hippocampal volume alone.