(a) Ultrasound rendering in the coronal plane and (b) representative magnetic resonance angiogram (MRA) (not the same subject) showing the area under ultrasound examination. (c) Paired ultrasound rendering in the transverse plane and (d) dissection image indicating anatomy in vessels of the Circle of Willis. ICA = internal carotid artery, MCA = middle cerebral artery, PCA = posterior cerebral artery. Original MRA image (b) produced by Ofir Glazer, Biomedical Engineering Department, Tel Aviv University, Israel. Reproduced with permission of the author. Original photograph (d) produced by Prof. John a. Beal, Department of Cellular Biology and Anatomy, Louisiana State Health Sciences Center, Shreveport, LA. Reproduced with permission of the author.