Figure 5.

Exploratory ultra-high resolution ex vivo MRI. Ultra-high resolution ex vivo magnetic resonance images of a sampled brain area from Case 2 reveal striking detail of CAA-related pathology. Top row: Here we show three representative microbleeds that were identified on the ultra-high resolution T₂*-weighted ex vivo magnetic resonance image (voxel size 75 µm³), of which the larger one (broken arrow) was also visible at the corresponding high resolution T₂*-weighted ex vivo magnetic resonance image (voxel size 200 µm³) (A). This microbleed corresponded to a recent microhaemorrhage on haematoxylin and eosin, characterized by a focal accumulation of intact erythrocytes (broken arrow; B). The hypointense lesions (arrows) that were not rated as microbleeds at high-resolution T₂*-weighted ex vivo MRI, proved to be vasculopathies on haematoxylin and eosin, without parenchymal tissue injury (arrows; B, enlarged in C and D). The vasculopathy in C resembles an occluded vessel containing fibrin deposits. The vasculopathy in D resembles a microaneurysm. Bottom row: Here we show a microinfarct that was identified on microscopic examination of the serial histological sections taken from this sample (F), and retrospectively could be identified as a hyperintense lesion on the corresponding ultra-high resolution T₂-weighted ex vivo magnetic resonance image (voxel size 100 µm³) (E), whereas it escaped detection at high-resolution T₂-weighted ex vivo MRI (voxel size 300 µm³). Note the vessel at the centre of this microinfarct (broken arrow in F), which can be distinguished on the scan (hypointense structure within the hyperintense lesion in E).