Table 2.
Statistical comparison between the UD and the PC-VIPR MRA methods for 5 velocity parameters (PSV, MV, EDV, PI and RI). Note that, in linear regression analysis, ultrasound Doppler velocity parameters are in the X-axis, while MRA velocity parameters are in the Y-axis. As compared to a quantity estimated by the PC-VIPR technique, positive and negative mean differences calculated by the Bland-Altman method indicate underestimation and overestimation of the quantity by the UD technique, respectively.
| (a) Post-correction UD vs. PC-VIPR MRA | ||||||
|---|---|---|---|---|---|---|
| PSV | MV | EDV | PI (unitless) | RI (unitless) | ||
| Absolute Diff (cm/s) mean ± standard deviation |
16.4 ± 14.1 | 12.7 ± 10.4 | 8.1 ± 7.3 | 0.49 ± 0.34 | 0.09 ± 0.08 | |
| Bland-Altman | Mean Diff (cm/s) |
−2.6 | 6.9 | 4.4 | −0.47 | −0.08 |
| l.lim ~ u.lim (cm/s) |
−56.5 ~ 25.0 | −38.4 ~ 23.0 | −16.0 ~ 25.6 | −1.18 ~ 0.08 | −0.31 ~ 0.07 | |
| Spearman’s Correlation |
r | 0.83 | 0.76 | 0.81 | 0.25 | 0.14 |
| P-value | <0.001 | 0.002 | <0.001 | 0.39 | 0.64 | |
| Linear Regression |
Slope | 0.78 | 0.67 | 0.65 | 0.24 | 0.12 |
| Y-Intercept (cm/s) |
17.8 | 21.5 | 13.8 | 0.75 | 0.56 | |
| (b)Pre-correction UD vs. PC-VIPR MRA | ||||||
|---|---|---|---|---|---|---|
| PSV | MV | EDV | PI (unitless) | RI (unitless) | ||
| Absolute Diff (cm/s) (mean ± standard deviation) |
30.7 ± 26.4 | 13.4 ± 14.4 | 8.3 ± 9.8 | 0.49 ± 0.33 | 0.10 ± 0.09 | |
| Bland- Altman |
Mean Diff (cm/s) |
−29.2 | −6.5 | −2.7 | −0.47 | −0.08 |
| l.lim ~ u.lim (cm/s) |
−89.5 ~ 5.1 | −59.4 ~ 9.9 | −39.6 ~ 13.7 | −1.13 ~ 0.07 | −0.31 ~ 0.07 | |
| Spearman’s Correlation |
r | 0.81 | 0.85 | 0.78 | 0.35 | 0.23 |
| P-value | <0.001 | <0.001 | <0.001 | 0.21 | 0.43 | |
| Linear Regression |
Slope | 0.57 | 0.53 | 0.52 | 0.29 | 0.17 |
| Y-Intercept (cm/s) | 21.2 | 20.5 | 13.6 | 0.68 | 0.52 | |