Fig. 1

Magnetic resonance imaging vessel wall enhancement in the aneurysm wall in a 49-year-old man, former smoker, non-hypertensive, without previous history of subarachnoid hemorrhage, currently presenting for headache. a–c A red arrow shows the region with vessel wall enhancement (c). In comparison, normal cerebral arteries do not show vessel wall enhancement (b). The image was acquired at 3-T after gadolinium-chelate injection with a BB T1 sequence (field of view 210 mm, matrix 256, in-plane resolution 0.4 × 0.4 mm², slice thickness 0.8 mm, 56 slices, TE/TR 20/600 ms, 3.4 averages, parallel imaging (GRAPPA) acceleration factor 2, acquisition time 6 min 23 s). Observation of AWE can be due to (1) the presence of phagocytes (d, representative example of CD68+ cells stained in brown) that can take up contrast agent (e, schematic illustration, phagocytes containing gadolinium chelate (blue asterisk); (2) compromised endothelial barrier integrity (f, CD31+ cells stained in brown, absence of endothelial cells indicated by the yellow arrow) leading to the passage of contrast agent from the arterial lumen into the aneurysm wall (g, schematic illustration); and/or (3) detection of contrast agent circulating in adventitial vasa vasorum (h, some vasa vasorum are indicated by purple arrows in the representative example; i, schematic illustration). The three representative staining examples (d, f, h) are from IA domes of two different patients and do not refer to the subject imaged in panels a–c. All patients consented to the @neurIST study and to the use of their images in the field of cerebrovascular research. Scale bars represent 100 μm