The utility of medial temporal lobe atrophy (MTA) grading as a practical method for assessing tau pathology and neurodegeneration in early-stage Alzheimer’s disease

Purpose Medial temporal lobe atrophy (MTA) is frequently seen in Alzheimer’s disease (AzD). We aimed to assess the utility of MTA grading as a practical method in evaluating early-stage AzD. Methods All subjects underwent multi-shell diffusion imaging and three-dimensional T1-weighted imaging at 3T and cerebrospinal flow (CSF) measurement. Based on the CSF values, 86 patients with AzD pathology (AzD group) were discriminated from 74 patients with non-AzD pathology (non-AzD group). The 5-point MTA scale was assessed by two neuroradiologists. Interobserver agreement (IOA) for the MTA score was calculated using the kappa statistic. The neurite orientation dispersion and density imaging (NODDI) and diffusion tensor imaging (DTI) parametric maps were generated. Two neuroradiologists created the hippocampal region of interest (ROI) for calculating the diffusion values. Inter-ROI value correlation was calculated for the intraclass correlation coefficients (ICCs). Additionally, the hippocampal volume was calculated. Correlations between MTA scores and each hippocampal value and CSF biomarker value were assessed using Pearson’s correlation analysis. Results IOA for the MTA score and ICCs for ROI values were substantial. In the AzD group, both-side MTA scores were significantly correlated with NODDI-derived neurite density index (NDI), DTI-derived diffusivities and the volume (P < 0.05). Both-side MTA scores were significantly correlated with the CSF total tau and phosphorylated tau values (P < 0.05). In the non-AzD group, both-side MTA scores were significantly correlated with NDI and the volume (P < 0.05). Conclusion MTA grading might be a useful method for assessing tau pathology and neurodegeneration in early-stage AzD.