T1-weighted axial visual rating scale for an assessment of medial temporal atrophy in Alzheimer's disease

Background: The most-widely used visual rating scale (VRS) for medial temporal atrophy is the T1-weighted (T1W) coronal VRS developed by Scheltens et al. However, it is often difficult to use the T1W-coronal VRS in cases with limitations in obtaining T1W-coronal images. To overcome this issue, we modified the T1W-coronal VRS onto the axial plane. Objective: The purposes of this study were to validate our T1W-axial VRS by examining its compatibility with the original T1W-coronal VRS and by investigating the correlation with the cognitive functions and hippocampal volumes. Methods: Participants were 50 patients with Alzheimer's disease dementia and 30 elderly with normal cognition. We transposed each component of the T1W-coronal VRS onto T1W-axial images (i.e., the largest height of the hippocampal formation into the width of the medial temporal lobe). The compatibility of T1W-axial VRS with T1W-coronal one was determined using the kappa value. The correlations of T1W-axial VRS with cognitive performance or the hippocampal volumes were analyzed with age, gender, and education as covariates. Results: The kappa value between the T1W-axial and T1W-coronal VRS was 0.772 (p < 0.045). The T1W-axial VRS showed a significant correlation with the scores of cognitive functions, including verbal memory tests (-0.601, p < 0.001 for the left). Furthermore, the T1W-axial VRS also correlated well with hippocampal volumes (-0.576, p < 0.001). Conclusions: The T1W-axial VRS showed good agreement with T1W-coronal VRS and correlated well with cognitive functions as well as hippocampal volumes, which suggests that the T1-axial VRS may replace the original T1W-coronal one.