Vertebral artery foraminal segment doppler sonography to detect vertebral and basilar artery stenosis or occlusion.

BACKGROUND AND PURPOSE

The diagnostic value of vertebral artery foraminal segment (V2) ultrasonography remains unclear. This study aimed to estimate the predictive value of V2 Doppler imaging for the detection of vertebrobasilar stenosis or occlusion.

METHODS

Three hundred sixty-four vertebral arteries from 182 patients were investigated. Abnormal Doppler spectra were categorized as high-resistance flow (resistive index ≥0.9), low-resistance flow (resistive index ≤0.5), increased flow velocity (peak systolic velocity ≥137.5 cm/second), or no flow signal. On MR angiography, stenosis and occlusion were defined as >50% narrowing and absent flow signals, respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

RESULTS

Sixty of 364 vertebral arteries (16.5%) had V2 Doppler abnormalities, while 89 vertebrobasilar arteries (24.5%) had a stenosis or occlusion. The Doppler abnormalities predicted any stenosis or occlusion in the vertebrobasilar artery with a sensitivity of 56.2% and specificity of 96.4% (PPV, 83.3%; NPV, 87.2%). The hypoplastic vertebral artery (lumen diameter ≤2.7 mm) was more frequently associated with vertebrobasilar stenosis or occlusion, and with abnormal Doppler spectra (mostly high-resistance flow), even when it was nonstenotic, than the normal-diameter vertebral artery (p < .001, chi-square test).

CONCLUSIONS

The low sensitivity seems to be due to the high prevalence of non-V2 lesions not detected on V2 Doppler imaging, suggesting the necessity for a more extensive sonographic examination beyond V2. However, PPV and NPV ≥80% may suggest its usefulness in clinical practice.