Table 1. Intra-rater, inter-rater and inter-method agreement of 3D ultrasound (3DUS) for quantification of internal carotid artery stenosis (ICAS).
| Intra-rater agreement (ICC) | Inter-rater agreement (ICC) | Inter-method agreement with 2D-CDS for Ex1(ICC) | Inter-method agreement with 2D-CDS for Ex2 (ICC) | |||||
|---|---|---|---|---|---|---|---|---|
| Ex1 (1. & 2. scan) | Ex2 (1. & 2. scan) | 1. scan | 2. scan | 1. scan | 2. scan | 1. scan | 2. scan | |
| B-mode 3DUS: distal CSA reduction percentage | n.a. | n.a. | 0.36* (CI: 0.27–0.44) | n.a. | 0.15 (CI: 0.09–0.20) | n.a. | 0.51* (CI: 0.44–0.60) | n.a. |
| B-mode 3DUS: distal diameter reduction percentage | n.a. | n.a. | 0.51* (CI: 0.43–0.58) | n.a. | 0.40* (CI: 0.31–0.47) | n.a. | 0.52* (CI: 0.46–0.59) | n.a. |
| power-mode 3DUS: distal CSA reduction percentage | 0.88* (CI: 0.79–0.94) | 0.78* (CI: 0.62–0.88) | 0.90* (CI: 0.82–0.95) | 0.8* (CI: 0.70–0.91) | 0.63* (CI: 0.40–0.79) | 0.63* (CI: 0.39–0.78) | 0.57* (CI: 0.33–0.76) | 0.53* (CI: 0.26–0.72) |
| power-mode 3DUS: distal diameter reduction percentage | 0.83* (CI: 0.70–0.91) | 0.76* (CI: 0.58–0.87) | 0.81* (CI: 0.68–0.90) | 0.85* (CI: 0.73–0.92) | 0.85* (CI: 0.75–0.92) | 0.77* (CI: 0.60–0.87) | 0.78* (CI: 0.61–0.88) | 0.67* (CI: 0.45–0.81) |
Reference standard for grading carotid stenosis was 2D colour-coded duplexsonography. Stenotic value in 3D reconstructed ICAS was calculated as distal diameter respectively distal cross-sectional area (CSA) reduction percentage. ICC intraclass correlation coefficient, Ex1 examiner 1, Ex2 examiner 2, CI 95% confidence interval of the intraclass correlation coefficient, n.a. non available,
* indicates statistical significance i.e. p < 0.05.