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).