Communication of subarachnoid spaces with Virchow–Robin spaces (VRS) in the basal ganglia of a control subject. a Fusion image of coronal plane volume rendering constructive interference in the steady state (CISS) image and magnetic resonance angiography (MRA) image of the basal ganglia. Perivascular CSF spaces were observed around perforating arteries from the M1 portion of the middle cerebral artery (red) in the basal ganglia. They passed upward and then medially to the floor of the lateral ventricle (white arrows). Magnified view of the dotted square (b, c) showed clear continuity of CSF between the subarachnoid space in the basal cistern and VRS in the basal ganglia on CISS (b) and fusion images (c). Observation in a normal 69-year-old man, BG basal ganglia; M1, M2 M1 and M2 portions of the middle cerebral artery; LV lateral ventricle; SF Sylvian fissure, scale bar 5 mm.