Fig. 4.

Binary classification tree to predict Aβ status based on atrophy levels (mild, moderate or severe) in four regions. If the left superior temporal gyrus shows no atrophy or only mild atrophy then the case would be classified as Aβ (−). However, if the left superior temporal gyrus shows moderate or severe atrophy, one should consider the left hippocampus, right SMA and right superior parietal lobe. If the left hippocampus and right superior parietal lobe are both severely atrophic then the case would be classified as Aβ (+). If the left hippocampus is not severely atrophic then the case can only be classified as Aβ (+) if the right SMA is relatively spared. SMA = supplementary motor area.