Fig. 4.

Comparison of annual atrophy rates derived using DBM in T1- and HF-MRI in patients and controls. Atrophy rate is computed from the whole hippocampus ROI and averaged over left and right sides. A value of 0.01 indicates 1% annualized loss in hippocampal volume. Error bars represent standard deviation. In the bar graphs on the left,“*”s on top of an error bar indicate significant non-zero atrophy rate measurement for the corresponding subject group, and those over the line connecting the bar graphs for two groups indicate significant cross-sectional difference in atrophy rates between the groups (patients>controls). In each case, effect size Δ and sample size estimate N (Eqs. (5) and (6)) are also shown. In the scatterplot on the right, each data point shows T1- and HF-MRI based atrophy rate estimates plotted against each other for one subject. Correlations between measurements from the two modalities are shown as well.