To evaluate the diagnostic value of carotid Doppler ultrasound (CDU) in evaluating the hemodynamic changes of severe intracranial stenosis of the internal carotid artery (ICA).

We retrospectively reviewed 171 patients who underwent CDU at Stroke Center, the First Affiliated Hospital of Soochow University with severe intracranial stenosis or occlusion of unilateral ICA confirmed by CTA and/or DSA from January 2018 to December 2019 as a study group. Meanwhile, 99 patients who underwent CDU in the same period with dizziness as the main complaint and without obvious stenosis of intracranial and external large blood vessels (confirmed by CTA and/or DSA) were used as a control group. The diameter (D), peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) of the affected side, healthy side, and control sides of the study group at a distance of 20 mm from the beginning of ICA were recorded. Differences of D, PSV, EDV, and RI of bilateral ICA between the study group and control group were calculated. Using CTA and/or DSA as the gold standard, Logistic regression and ROC curve analysis were used to analyze the parameters of extracranial hemodynamics and combined parameters to evaluate the diagnostic value of ICA for severe intracranial stenosis.

In the study group, 109 of 171 patients showed high resistance flow spectrum with increased systolic peak and decreased diastolic peak. CTA and/or DSA confirmed ICA severe intracranial stenosis or occlusion after occlusion of the ophthalmic artery. The 62 CDU patients showed a diastolic or reversed unimodal or oscillating flow spectrum, and CTA and/or DSA confirmed ICA occlusion before occlusion of the ophthalmic artery. Compared with the healthy side of the study group and the left side of the control group, D, PSV, and EDV in the affected side of study group were significantly decreased, with EDV being most obvious [EDV: (11.89±6.95) cm/s vs (36.14±11.93) cm/s, (29.27±9.69) cm/s], while RI was significantly increased [(0.81±0.06) vs (0.59±0.07), (0.64±0.07)], and the differences were statistically significant (P＜0.001). Compared with the left side of the control group, D, PSV, and EDV in the healthy side of study group were all increased, with EDV being most obvious, while RI was significantly decreased (D: P=0.029; PSV: P=0.011; EDV and RI: P＜0.001).When combining RI ≥0.74 in the ICA on one side, D difference ≥1.1 mm, EDV difference ≥ 15.7cm/s, and RI difference ≥0.13 in the ICA on both sides, the area under the ROC curve was 0.990, and the sensitivity (92.7%) and specificity (98.0%) for diagnosing severe intracranial stenosis in the ICA were the best.

After severe stenosis or occlusion of major branches of the ICA (e.g, the middle cerebral artery and anterior cerebral artery) was excluded, CDU, in combination with TCD and/or TCCD, can effectively evaluate the severe intracranial stenosis of the ICA through the bilateral waveform and hemodynamic parameters of ICA extracranial segment, i.e, RI and differences of D, EDV, and RI, and provide a hemodynamic basis for clinical diagnosis.