Significance of transcranial Doppler ultrasound (TCD) in cerebrovascular diseases

1. Big picture

Transcranial Doppler ultrasound, TCD, is a non-invasive ultrasound method used to measure blood flow velocity in the main intracranial arteries. It is especially important in cerebrovascular diseases because it can monitor flow in the middle cerebral artery, anterior cerebral artery, posterior cerebral artery, vertebral arteries, and basilar artery.

The exam wants you to know that TCD is not mainly an anatomical imaging test like CT or MRI. It is a functional vascular test: it tells us how fast blood is flowing, whether there is stenosis/occlusion, whether vasospasm is developing, whether microemboli are passing, and whether cerebral vascular reserve is impaired.

The most important exam indication is:

Monitoring vasospasm after subarachnoid hemorrhage.

Other very important uses:

• Intracranial stenosis or occlusion in ischemic stroke

• Emboli detection

• Cerebrovascular reserve testing

• Patent foramen ovale / paradoxical embolism screening with bubble test

• Vertebrobasilar insufficiency

• Monitoring raised intracranial pressure and cerebral circulatory arrest

• Intraoperative monitoring during carotid or cardiac surgery

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