Angiographic features in Chinese patients with occlusive cerebrovascular disease

Carotid Ultrasound Criteria for Detecting Intracranial Carotid Stenosis

BACKGROUND/AIMS

This study attempted to establish carotid ultrasound criteria for identifying stenosis of the intracranial internal carotid artery (ICA) and middle cerebral artery (MCA).

METHODS

Two hundred and fifty-five patients were enrolled. Ultrasound measurements for common carotid artery (CCA) and ICA were as follows: flow volume (FV), peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI) and resistance index (RI). The sensitivity and specificity of the ultrasound criteria for determining intracranial ICA or MCA>or=50% stenosis were calculated.

RESULTS

The criteria identified for detecting intracranial ICA>or=50% stenosis were ICA FV<159 ml/min, ICA PSV<33 cm/s and CCA PSV<42 cm/s. When ICA PSV<33 cm/s was combined with CCA PSV<42 cm/s, sensitivity increased to 82%, with 91% specificity. The criteria identified for detecting MCA>or=50% stenosis were CCA FV<285 ml/min, ICA FV<179 ml/min, ICA PSV<33 cm/s, >35% reduction in FV in the CCA, >40% reduction in FV in ICA, and >35% reduction in PSV in ICA. When these criteria were combined, sensitivity increased to 69%, with 85% specificity.

CONCLUSION

This study demonstrated that ultrasound criteria are sensitive and specific for detecting intracranial ICA and MCA significant obstruction.

Carotid ultrasonographic findings in intracranial internal carotid artery occlusion

Five cases of unilateral intracranial internal carotid artery (ICA) occlusion received both carotid angiographic and ultrasonographic studies. The Doppler examination showed that the resistive index (RI) of the common carotid artery (CCA) and ICA was higher but the peak systolic velocity was lower on the diseased side as compared with the normal side. Absence of the diastolic phase was found in the CCA flow in 2 cases and in the ICA flow in 3 cases on the diseased side. The mean CCA flow volume on the diseased side (271 +/- 82 mL/min) was half or less than that on the normal side (680 +/- 86 mL/min) (P < 0.01). The flow volume of the diseased ICA (49 +/- 20 mL/min) was markedly lower than that of the normal side (344 +/- 49 mL/min) (P < 0.01) and was also less than that of the ipsilateral external carotid artery (ECA) (129 +/- 43 mL/min). The Doppler ophthalmic artery flow all showed a forward direction. The authors propose that the following extracranial carotid ultrasonographic findings may be helpful in the prediction of intracranial carotid artery occlusion: (1) diminished frequencies, increased RI, and a more than 50% reduction of flow volume in the CCA as compared with the opposite side; (2) diminished frequencies to loss of the diastolic phase, a more than 50% reduction of the flow volume, and reversed ICA/ECA flow volume in the ICA as compared with the opposite side; and (3) a forward Doppler ophthalmic artery flow.