Transcranial Color-Coded Duplex Sonography for Detection of Distal Internal Carotid Artery Stenosis

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Fig 1.
Normal anatomy of the carotid siphon, lateral view DSA (A) and anterior coronal imaging plane TCCS (B) A, C5 (precavernous/ganglionic segment), C4 (inferior carotid siphon), C3 (carotid knee), C2 (upper carotid siphon), and C1 (terminal ICA segment). B, Color coding showing flow toward (red) and away (blue) from the transducer. M1 indicates the first segment of the MCA; A1, the precommunicating segment of the ACA; A2, the postcommunicating segment of the ACA; cA1, the contralateral A1 segment, ICA segments C3/4 and C4/5.
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Fig 2.
High-grade stenosis extending from the C1 segment into the C2 and C3 segments. A, DSA. Note the torturous and elongated course of the intracranial ICA. B, TCCS with a coronal imaging plane and aliasing phenomenon in the C1 and C2 segments.

Table 1:

Age-dependent hemodynamic parameters of the carotid siphon segments C1 (upper) and C5 (lower)

Factor	Mean	<39 Years (95% CI)	SD	Mean	40–59 Years (95% CI)	SD	Mean	>60 Years (95% CI)	SD	P Value
C1 PSV	69.9	65.1–74.8	23.7	69.2	64.9–73.6	19.7	71.3	66.1–76.4	23.39	.96
C1 EDV	29.0	27.0–31.1	10.0	29.8	27.6–32.1	10.2	27.8	25.5–30.1	10.4	.28
C1 MFV	42.7	39.8–45.6	14.2	43.0	40.1–45.8	13.0	42.4	39.2–45.5	14.38	.72
C1 PI	0.86	0.82–0.91	0.22	0.86	0.81–0.90	0.19	0.96	0.91–1.01	0.21	.003
C1 RI	0.52	0.50–0.54	0.10	0.54	0.52–0.55	0.08	0.58	0.56–0.61	0.10	<.001
C1/ICA	1.24	1.15–1.34	0.45	1.31	1.20–1.42	0.49	1.53	1.41–1.64	0.52	<.001
C1/CCA	0.83	0.72–0.94	0.30	1.06	0.95–1.16	0.38	1.30	1.18–1.42	0.46	<.001
C5 PSV	50.9	47.9–53.9	14.4	49.4	45.9–53.0	15.9	51.6	47.8–55.4	17.0	.81
C5 EDV	19.3	18.0–20.6	6.04	20.7	18.9–22.4	7.8	19.6	17.7–21.6	8.7	.31
C5 MFV	29.8	28.1–31.6	8.4	30.3	28.0–32.5	10.1	30.3	27.8–32.7	10.9	.81
C5 PI	0.95	0.89–1.00	0.27	0.88	0.83–0.94	0.25	0.99	0.94–1.04	0.22	.02
C5 RI	0.55	0.52–0.58	0.12	0.54	0.51–0.56	0.11	0.59	0.57–0.61	0.10	.01
C5/ICA	0.73	0.68–0.78	0.26	0.80	0.73–0.86	0.29	0.89	0.82–0.96	0.31	<.001
C5/CCA	0.70	0.59–0.80	0.28	0.78	0.69–0.88	0.33	0.96	0.88–1.03	0.30	<.001

Note:—All velocities are given in centimeters per second. C1/ICA, C1/CCA, C5/M1, and C5/CCA indicate divisions of mean velocities; C5, the ganglionic segment of the carotid siphon; C1, the distal segment of the carotid siphon; ICA, the distal (submandibular) portion of the extracranial ICA; CI, confidence interval; CCA, common carotid artery; PSV, peak systolic velocity; EDV, end diastolic velocity, MFV, mean blood flow velocity; PI, pulsatility index; RI, resistance index.

Table 2:

Clinical characteristics of 40 patients

* Other clinical indications for performing a vascular diagnostic work-up included syncope (n = 2), migraine headache (n = 1), suspected cerebral and temporal vasculitis (n= 3), and sleep apnea syndrome (n = 1).

Table 3:

Angiographic data on ICA stenosis (DSA, n = 40 patients)

ICA Segment	Extracranial	C5	C4	C3	C2	C1	Total Intracranial (n = 400)
Normal	27	58	48	60	48	59	273
<50%	26	16	21	11	13	5	66
>50%	23	1	6	4	11	8	30
<30%	18	10	17	8	10	4	49
30%–49%	8	6	4	3	3	1	17
50%–69%	10	1	4	2	5	1	13
70%–89%	4	0	1	1	2	4	8
90%–99%	9	0	1	1	4	3	9
Occlusion	1	0	0	0	4	4	8
Not assessable	3	5	5	5	4	4	23
Total	80	80	80	80	80	80	400

Table 4:

Mean velocity data derived from TCCS and grouped according to stenosis assessed by angiography

Factor	≥70% Stenosis in C1 (n = 7)	<70% Stenosis in C1 (n = 59)	P Value	≥50% Stenosis in C1 (n = 8)	<50% Stenosis in C1 (n = 58)	P Value
C1 PSV	256.3 ± 84.5	82.9 ± 37.8	.0001	229.5 ± 109.0	83.7 ± 37.7	.001
C1 EDV	146.4 ± 72.5	29.1 ± 18.2	.0001	129.1 ± 83.0	29.4 ± 18.1	.001
C1 MFV	178.5 ± 69.3	47.0 ± 23.5	.0001	158.6 ± 85.4	47.5 ± 23.3	.001
C1 PI	0.62 ± 0.20	1.13 ± 0.4	.001	0.72 ± 0.34	1.13 ± 0.4	.005
C1 RI	0.42 ± 0.10	0.61 ± 0.13	.001	0.45 ± 0.13	0.61 ± 0.13	.004
C5 PSV	21.8 ± 5.5	48.2 ± 22.1	.0001	21.2 ± 5.3	48.8 ± 21.9	.0001
C5 EDV	12.2 ± 4.4	16.3 ± 8.0	.21	11.4 ± 4.5	16.4 ± 7.9	.07
C5 MFV	15.4 ± 4.6	26.9 ± 11.8	.005	14.7 ± 4.6	27.2 ± 11.7	.001
C5 PI	0.66 ± 0.22	1.16 ± 0.39	.001	0.70 ± 0.22	1.17 ± 0.40	.001
C5 RI	0.45 ± 0.11	0.63 ± 0.12	.001	0.46 ± 0.11	0.63 ± 0.12	.001
C1/M1	2.11 ± 1.9	0.82 ± 0.34	.008	1.89 ± 1.9	0.82 ± 0.34	.05
C1/ICA	7.06 ± 6.1	1.27 ± 1.2	.0001	6.28 ± 6.1	1.27 ± 1.2	.001
C1/CCA	5.48 ± 2.1	1.68 ± 0.9	.0001	4.87 ± 2.6	1.70 ± 0.9	.001
C5/M1	0.17 ± 0.10	0.48 ± 0.20	.0001	0.17 ± 0.09	0.49 ± 0.20	.0001
C5/ICA	0.60 ± 0.43	0.66 ± 0.47	.77	0.57 ± 0.40	0.67 ± 0.47	.66
C5/CCA	0.45 ± 0.11	0.94 ± 0.39	.0001	0.43 ± 0.11	0.94 ± 0.39	.0001

Note:—All velocities are given in centimeters per second. C1/M1, C1/ICA, C1/CCA, C5/M1, C5/ICA, and C5/CCA indicate divisions of mean velocities; C5, the ganglionic segment of the carotid siphon; C1, the distal segment of the carotid siphon; ICA, the distal (submandibular) portion of the extracranial ICA.