Transcranial Ultrasound to Monitor Interoperative/Endovascular Blood Flow

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Swedish Vascular Ultrasound

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Transcranial Doppler can be used to monitor blood flow in the brain during surgery - called interoperative monitoring. It can also be used to monitor blood flow during endovascular procedures in the brain, such as placing a stent. The purpose of this monitoring is to detect significant decreases or increases in blood flow, and/or any possible microemboli (clots) that could result in neurological complications. Information about blood flow is gathered in real time, which allows for corrective action to be taken during a procedure.

What to Expect

An ultrasound technologist will explain their role during the procedure. When monitoring is required for a surgical or endovascular procedure, a headband is used that encircles the patient’s head and holds the ultrasound transducers in place. Information about blood flow is obtained and evaluated in real time throughout the procedure.

Procedures Monitored

Carotid endarterectomy
Endovascular carotid stent placement
Closure of patent foramen ovale
Cardiac surgery

Carotid endarterectomy

The middle cerebral arteries are monitored during this surgical procedure. A headband holds ultrasound transducers in place. A technologist with special training will monitor the patient throughout the procedure, and accompany the patient to the post-operative recovery room for additional monitoring.

Endovascular carotid stent placement

Using transcranial Doppler, the middle cerebral artery on the side of the stent placement is monitored. Waveform analysis provides real-time information regarding changes in blood flow, reports of any microemboli, and provides neuroprotective information to the physician performing the procedure.

Closure of patent foramen ovale (PFO)

The circulation in the middle and anterior cerebral arteries is evaluated using transcranial Doppler ultrasound throughout the procedure to determine PFO status before, during and after PFO closure.

Balloon test occlusion of the internal carotid artery (ICA)

The location of some tumors and giant aneurysms may be near or may directly involve the internal carotid artery (ICA), and treatment may require the removal of the ICA. In this test, a catheter is placed in the ICA and a small balloon is temporarily inflated, eliminating flow in that artery while the patient is examined for symptoms. TCD monitoring plays an important role by identifying changes in flow in the middle cerebral artery during temporary ICA occlusion. This data facilitates the identification of patients who are at risk of low flow or hemodynamic stroke following ICA occlusion.


A specialized physician will analyze the images and put a report in your medical record. Your doctor will talk to you about the results and any further tests or treatments.