Flow velocities of the intracranial ICA segments in subjects without cerebrovascular disease using the transtemporal approach

ICA Segment	Psyst (cm/s)	E-D (cm/s)	Mean (cm/s)	PI*	RI*	Length (mm)	Identified No. (%)
C6
No AC	53 ± 14 (27–106)	25 ± 7 (13–48)	34.3 ± 8.8 (17.7–68.0)	0.83 ± 0.16 (0.49–1.32)	0.53 ± 0.07 (0.37–0.70)	15 ± 4 (5–26)	115 (96.7)
AC (33 ± 10°)	66 ± 15 (34–113)	31 ± 8 (17–52)	42.5 ± 10.0 (26.0–72.3)	0.83 ± 0.17 (0.46–1.32)	0.53 ± 0.07 (0.35–0.70)	18 ± 2 (15–26)	58 (48.3)
C3–4
No AC	57 ± 17 (31–105)	25 ± 8 (12–53)	36.1 ± 10.5 18.3–68.7)	0.89 ± 0.17 (0.56–1.44)	0.55 ± 0.06 (0.41–0.70)	n.d.	120 (100)
C1–2
No AC	77 ± 21 (33–140)	34 ± 10 (12–65)	48.7 ± 13.4 (19.0–90.0)	0.89 ± 0.16 (0.59–1.40)	0.55 ± 0.06 (0.42–0.72)	11 ± 2 (5–21)	120 (100)
AC (37 ± 10°)	93 ± 18 (64–118)	43 ± 6 (34–49)	59.9 ± 9.8 (44.0–71.3)	0.82 ± 0.13 (0.62–1.0)	0.53 ± 0.05 (0.44–0.61)	16 ± 2 (15–21)	9 (7.5)

Note:—Psyst indicates peak-systolic flow velocity; E-D, end-diastolic flow velocity; Mean, mean-flow velocity; ICA, internal carotid artery; PI, pulsatility index; RI, resistance index with standard deviation and range (in parentheses); ICA C6, distal petrosal part of the ICA; ICA C3–4, carotid siphon; ICA C1–2, distal part of the siphon and terminal segment of the ICA. AC, angle-corrected measurement, with the mean angle in parentheses; No AC, no angle correction; angle-corrected flow-velocity measurements were obtained if the vessel segment was visible for at least 15 mm; n.d., not done.

^*With standard deviation and range (in parentheses).