<< Back

Next Section >>

Transcranial Doppler (TCD)

TCD is an ultrasound technique used to assess blood flow in the basal cerebral arteries. A small ultrasound transducer is placed over the temporal bones, the orbit of the eye and the foramen magnum. Blood flow velocities are obtained from the middle, anterior and posterior cerebral arteries, the cavernous carotid and ophthalmic arteries, and the intracranial vertebral and basiliar arteries. This test is useful in:

• detecting intracranial stenosis/thrombosis/occlusion/dissection
• detecting collateral flow secondary to obstruction proximal to the circle of Willis
• detecting vasospasm in patients with subarachnoid hemorrhage
• determining hyperemia in head trauma
• evaluating feeding vessels to arteriovenous malformations circle of Willis
• detecting vasospasm in patients with subarachnoid hemorrhage
• determining hyperemia in head trauma
• evaluating feeding vessels to arteriovenous malformations
  

  Transcranial ultrasound examination of the basal cerebral arteries.     "Click" on images to view larger.	Vessels of the circle of Willis demonstrated in color with ultrasound power-energy mode.
  	Doppler spectral waveform showing normal middle cerebral artery flow velocities.