FIG 3. West Nile vasculitis in a 9-year-old girl. MCA indicates middle cerebral artery; ICA, internal carotid artery, ACA, anterior cerebral artery. (A) Graph of transcranial Doppler sonography results plotted for 8 months reveal persistence of elevated peak systolic velocity in the left MCA, ACA, and ICA. (B) MR angiogram reveals decreased caliber and irregularity of the left MCA with slight narrowing of the supraclinoid ICA and A1 segment of the ACA (arrows).