Comparison between conventional duplex ultrasonography and the dual-gate Doppler mode for hemodynamic measurements of the carotid arteries

Figures

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  Fig. 1.. Color-Duplex ultrasonography (DUS) versus dual-gate Doppler (DGD) measurements of carotid artery hemodynamic parameters. A. In the color-DUS gold-standard mode, two separate measurements of flow velocities, at the common carotid artery (CCA) and internal carotid artery (ICA), have to be performed. The ideal positioning of the ultrasound beam is shown by a dotted line. Typical Doppler pictures obtained in the presence of significant stenosis are given, using the CCA (left) and ICA (right) as examples. B. In DGD mode, only one recording is necessary to measure flow velocities in both the CCA and ICA since two Doppler angles can be independently adjusted to ensure a correct alignment with each blood flow. Thus, two Doppler spectra are visualized in real time. ECA, external carotid artery.

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  Fig. 2.. Correlation analyses of hemodynamic measurements between dual-gate Doppler (DGD) and standard Duplex ultrasonography (DUS) modes. A. The peak systolic velocity (cm/s) of the internal carotid artery measured in the DGD mode (x-axis) was highly correlated (r2=0.642) with that measured using the standard DUS mode (y-axis). B. Likewise, the carotid ratio measurements in the DGD mode (x-axis) were closely correlated (r2=0.544) with the values measured using the standard DUS mode (y-axis).

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  Fig. 3.. Bland-Altman graphical representation of hemodynamic measurements. For peak systolic velocity (cm/s) of the internal carotid artery (A) and carotid ratio (B), the difference obtained between standard Duplex ultrasonography (DUS) mode and the dual-gate Doppler mode was plotted against the mean of the two DUS modes. On each plot, the mean of the differences, its bias (i.e., the difference between the mean and 0) and its 95% confidence interval limits are indicated. Although most examinations remained between the confidence intervals for values close to physiological conditions, pathological values were highly dispersed, suggesting discrepancies between the methods regarding the diagnosis of carotid artery stenosis.

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  Fig. 4.. Representative three-dimensional reconstruction of the results of computed tomography angiography of supra-aortic arterial trunks (corresponding to carotid artery stenosis case No. 3 of Table 1). The Duplex ultrasonography examination shows suspicion for hemodynamically significant stenosis of the right internal carotid artery (peak systolic velocity of 160 and 147 cm/s in standard and dual-gate Doppler mode, respectively; carotid ratio of 2.67 and 3.06 in standard and dual-gate Doppler mode, respectively). The three-dimensional reconstruction shows 60% stenosis of the right internal carotid artery in its proximal portion (red ellipse).