Whereas duplex ultrasound parameters for predicting internal carotid artery (ICA) stenosis are well defined, the use of common carotid artery (CCA) Doppler characteristics to predict ICA stenosis when the ICA cannot be insonated directly or accurately because of anatomy, calcification, or tortuosity has not been studied. The objective of this study was to identify CCA Doppler parameters that may predict ICA stenosis.Methods:
We reviewed all patients at our institution who underwent carotid duplex ultrasound (CDU) from 2008 to 2015 and also had a comparison computed tomography, magnetic resonance, or catheter angiogram. We excluded patients whose CDU examination did not correlate with the comparison study, those whose arteries were not visualized on the comparison study, and those with complete occlusion of the CCA. We collected CCA peak systolic velocity (PSV), end-diastolic velocity (EDV), and acceleration time (AT) in addition to CDU and comparison imaging interpretation of degree of stenosis. A multivariate model was used to identify predictors of ICA stenosis.Results:
There were 99 CDU examinations with corresponding comparison imaging included. For every increase of 10 cm/s in EDV in the CCA, the odds of a >50% ICA stenosis being present vs a ≤50% ICA stenosis decreased by 37% (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.41-0.97; P = .03). For every increase of 10 cm/s in EDV in the CCA, the odds of a 70% to 99% ICA stenosis being present vs a ≤50% ICA stenosis decreased by 48% (OR, 0.52; 95% CI, 0.28-0.94; P = .03). A CCA EDV of 19 cm/s or below was associated with a 64% probability of a 70% to 99% ICA stenosis. For every 50-millisecond increase in AT in the CCA, the odds of a >50% stenosis being present vs a ≤50% ICA stenosis increased by 56% (OR, 1.56; 95% CI, 1.03-2.35; P = .04). A CCA AT of 80 milliseconds or above was associated with a 69% probability of a >50% ICA stenosis. There was no correlation between CCA PSV and ICA stenosis.Conclusions:
CCA EDV and AT are independent predictors of ICA stenosis and may be used in the setting of patients whose ICA cannot be directly insonated or when standard duplex ultrasound parameters of ICA PSV, EDV, or ICA/CCA ratio conflict.