In panel A, the right anterior and middle cerebral arteries seem dilated, possibly in relationship to compensatory changes given the absence of a contralateral first segment of the anterior cerebral artery. The brain MRI shows evidence of dilated perivascular spaces in the basal ganglia, more demarcated in the right caudate and anterior putamen regions, both which are perfused through penetrating arteries arising from the ipsilateral first segments of the anterior and middle cerebral arteries. On the contralateral basal ganglia, there are dilated perivascular spaces which appear smaller and less well demarcated.