Deciphering the results of ultrasound Doppler vascular ultrasonography

Signs of subtotal stenosis and occlusion (narrowing more than 85% or blockage) of the internal carotid artery on the affected side are as follows.

• Pathological sound phenomena. They differ depending on the degree of narrowing and the location of sounding - before the stenosis, exactly above the narrowing site or at the exit from it:
  • a sharp whistling sound;
  • a signal resembling a "seagull cry" or a "purr-purr" vibration phenomenon;
  • low-frequency weak damping signal down to a barely perceptible "rustle".
• Pronounced changes in the Doppler sonogram pattern from low-amplitude, non-diastolic to widened at the base with a rounded or split apex.
• A sharp asymmetry in the linear velocity of blood flow due to a decrease of up to 70-80% on the affected side.
• A sharp drop in linear blood flow velocity up to the disappearance of the signal from the ophthalmic artery on the side of the occluded carotid artery and/or retrograde flow that decreases or disappears with compression of the homolateral external carotid artery.
• Presence of turbulence above or behind the suspected area of stenosis of the internal carotid artery.
• Disappearance of the frequency-free window.
• Increase in peripheral resistance index by more than 0.8.
• Combination of stenotic lesions of several main arteries of the head.
• Poor tolerance of common carotid artery compression may occur.

The accuracy of ultrasound Dopplerography in diagnosing subtotal stenosis-occlusion of the internal carotid artery is 90-96%.

Signs of possible stenosis of the internal carotid artery from 70 to 85% on the affected side are as follows.

• Asymmetry of linear blood flow velocity up to 40% with bilateral insonification of similar zones of the carotid artery.
• An increase in the linear velocity of blood flow with the emergence of elements of turbulence above the zone of suspected stenosis of the internal carotid artery, below in the bifurcation area and, if possible, above it.
• An increase in the circulatory resistance index of more than 0.75 is possible.
• It is possible to increase the spectral expansion index by more than 55%.
• Asymmetry of the linear blood flow velocity in the ophthalmic artery up to 30-40%.
• Bidirectional flow is possible in the ophthalmic artery on the side of the stenosis.
• It is also possible that compression of the temporal branch of the homolateral external carotid artery may influence the linear velocity of blood flow in the ophthalmic artery on the side of the carotid artery stenosis.

Naturally, the accuracy of recognizing a narrowing from 70 to 85% is lower than with subtotal stenosis-occlusion, and ranges from 70 to 83%.

Even more modest are the results of using ultrasound Dopplerography when trying to diagnose vertebral artery stenosis. Nevertheless, the following signs are revealed.

• A sharp asymmetry of the linear blood flow velocity of more than 70% is characteristic of vertebral artery stenosis on the side of decreased linear blood flow velocity.
• Whistling character of the signal with a significant change in the spectrogram on the side of the vertebral artery stenosis.
• Frequently associated with carotid artery disease.

The accuracy of diagnostics of stenotic/occlusive lesions of the vertebral artery, according to different authors, ranges from 50 to 75%. A significantly higher percentage of correct results (up to 90%) is recorded with ultrasound Dopplerography diagnostics of subclavian steal syndrome.

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