An ultrasound is a type of scan that uses sound waves to produce a picture of the inside of your body.

Conventional ultrasound involves transmitting sound waves into the body from an ultrasound probe which are then reflected off the structures we are examining in your body. The ultrasound machine then reconstructs this information into the pictures you see on the monitor, allowing us to visualise all your arteries (Brightness-Mode). Then, to assess your arteries, we use Doppler ultrasound which enables us to measure the speed and direction of your blood flow (Pulse-Mode), using sound waves that track moving objects. Colour Doppler enables us to “see” the movement of the blood flow in your vessels, with additional dedicated imaging set-ups such as Power Mode/SMI. Ultrasound has been in use since the 1950s and is completely safe and non-invasive.

There are no needles or dyes used, nor exposure to radiation or magnetic fields, so there is no need to be worried about this examination. It’s safe, totally painless, and can be done on children and pregnant women as well.

Why am I having this scan?

Your doctor wants you to have a colour flow duplex ultrasound scan of the arteries in your neck or in your head. Your doctor wants to rule out any narrowing or blockages in the arteries supplying blood and oxygen to your brain, which may be causing the symptoms you have been experiencing. Narrowing could be caused by fatty deposits (plaques) on the artery walls which can lead to obstructions or release debris travelling to the brain and causing a stroke. Also clots coming from the heart or developing in the arteries can be investigated. Rarely a haematoma or a spasm of an artery could be the reason for neurological symptoms, and ultrasounds can detect these conditions too.

What causes narrowing of the arteries?

Atherosclerosis, cholesterol plaque formation in the arteries, is the most common reason for arterial narrowing or blockages. It is a condition which causes the fatty deposits to build up on the artery walls causing narrowing or total blockage, with increased risk of clots formation. Risk factors for carotid plaque formations are smoking, high cholesterol, diabetes (high blood sugar), high blood pressure, obesity, lack of physical exercise and a family history of these conditions.

In the Eastern population there could also be a higher rate of narrowing of the arteries inside the brain, so called intra-cranial arterial stenosis, that can lead to juvenile brain attacks/stroke.

Rarely, post-infective conditions and inflammation of the arteries could lead to narrowing of the cerebral blood vessels too.

What is the difference between carotid Doppler and transcranial colour Doppler ultrasound?

With carotid Doppler ultrasound investigation (CDUS), with the use of a Linear 11 Mhz probe and/or a high frequency Linear 18 Mhz probe and dedicated settings, the neuro-sonologist can assess the anatomy and functionality of the carotid arteries (common, external, internal carotid arteries), vertebral arteries (from origin in the chest to atlas loop just under the skull),

subclavian arteries, ophthalmic arteries and temporal arteries.

With the transcranial colour Doppler study (TCCD), using a Phased Array 2Mhz probe, the neuro-sonologist will investigate the cerebral circulation in the main vessels of the brain (carotid syphone, middle cerebral artery, anterior cerebral artery, posterior cerebral artery, communicating arteries, basilar artery, vertebral arteries, right and left sides).

What will happen during the examination?

An experienced neurosonologist will perform a colour flow duplex ultra-sound scan of the arteries of your neck and/or of your head. You will be asked to lie flat on an examination couch and gel will be put on the probe, to have better scans, to make a thin layer in between your skin and the probe itself. An ultrasound probe is moved over your skin surface (over the neck left and right, temporal areas just in front of your ears, on your eyes, on the back of the head) and you will, from time to time, hear noises coming from the ultrasound machine. This is normal and is the Doppler ultrasound measuring the speed and direction of the blood flow in these arteries. The test will take approximately 30-60 minutes.

Do I need any specific preparation before carotid or transcranial Doppler?

There is no preparation necessary for Doppler ultrasound. However, it is important to stay quiet and still during the test. Wear comfortable clothing with an open neck. Avoid turtlenecks or silk clothing, which could be stained by the ultrasound gel. Remove any jewellery.

Since the test could include sampling over the closed eyelid, patients should leave or remove hard contacts during the test. CDUS/TCCD will not be performed on the eyes of patients who have had invasive eye surgery within the previous month, including laser sight correction, implants or cataract removal.

What is transcranial colour Doppler used for?

  • TCCD ultrasound is often the test of choice for:
  • Ischemic stroke/TIA
  • Intracranial stenosis or blockage of the blood vessels
  • Vasospasm, following a ruptured brain aneurysm
  • Sickle cell anemia in children, to determine a patient’s stroke risk
  • Cerebral microembolic signals detection
  • Heart embolism due to a right to left shunt, due to a Patent Foramen Ovale (PFO): a hole in the heart that doesn’t close properly after birth

What kind of carotid or transcranial colour Doppler test can be provided at Mediclinic City Hospital?

Neck vessels Doppler ultrasound is usually requested to assess patency of carotid and vertebral arteries, but in case of a suspected condition known as Subclavian Steal Syndrome (i.e. fainting when keeping/working with elevated arms), a specific test can be performed:

• Ischemic/hyperemic reactive test

This test can detect if there is a problematic blood circulation in the arm, that indirectly affects the brain, causing fainting/loss of consciousness/vertigo. The vertebral arteries will be investigated, and a hand-cuff will be placed on your arm in order to reduce the blood circulation to the arm for five minutes (cold hand and tingling can happen in that arm, which is normal and expected), then it will be released and circulation in the arm will start again: if abnormal, a modification of the blood flow in the brain circulation will be detected.

TCCD ultrasounds are used to evaluate the major arteries supplying blood flow to the brain, but there are other TCCD studies used to identify specialised problems related to brain blood flow:

• Embolic detection monitoring

This test detects any free-floating particles that may be in the bloodstream. These particles can be a significant source of stroke risk.

• TCCD + microbubble test (agitated saline bubble study

This test is specific for identifying whether there is a defect of the heart, an abnormal passageway or hole between the right and left chambers of the heart, through which blood enters the heart (PFO). This hole usually closes after birth. If it doesn’t close, it can be a source of increased stroke risk in certain patients. A small IV catheter will be placed in your arm, and a 10ml solution of sterile normal saline (normally used for hydration for example) will be injected, to detect the passage of the microbubbles through the hole reaching the brain. Considering the high specificity and sensibility of this test, and the non-invasive, painless procedure, it can be considered the test of choice for PFO assessment in many cases.

•CO2 vasomotor reactivity study

This non-invasive study looks at whether the small vessels that regulate blood flow to the brain are working properly. When a small amount of carbon dioxide (CO2) and oxygen are inhaled, as when holding one›s breath, these small vessels should widen and increase blood flow to the brain. When a person hyperventilates, the vessels should shrink and slow blood flow to the brain.

Where the ultrasound Doppler scan could be performed?

CDUS and TCCD ultrasounds are completely painless, and can be performed in any environment at Mediclinic City Hospital, including the:

  • Emergency department (ED)
  • Inpatient rooms
  • Intensive care unit (ICU)
  • Outpatient department (OPD)

Infection prevention

We are committed to maintaining the highest level of safety for our patients and staff by complying with infection control standards.

Your scan results

Images will be uploaded in the system, and a CD can be collected from the Radiology department in 48 hours. The report of the scan will be ready to be collected on the same day from the Nurse’s station.

For further clarification you may need to see your supervising specialist, and provide him a copy of the ultrasound results.

Are there any precautions or rules to follow after the carotid or transcranial Doppler is finished?

For patients who are not currently admitted to the hospital, there are no restrictions following the exam and they may go home immediately.

For an appointment, a second opinion or more information, please call

+971 4 435 9999 or email us at