Result: mean diameter of cerebral artery segments: left and right A1 segments: 2.28 ± 0.47 and 2.19 ± 0.53 mm; AcomA: 1.71 ± 0.68 mm; left and right M1 segments: 2.82 ± 0.46 mm and 2.8 ± 0.49 mm; left and right PcomA: 1.62 ± 0.5 mm and 1.67 ± 0.48 mm; left and right P1 segments: 2.22 ± 0.49 mm and 2.22 ± 0.56 mm; left and right P2 segments: 2.32 ± 0.38 mm and 2.35 ± 0.36 mm; BA: 3.41 ± 0.69 mm.