In contrast, the ECA is located superficially and is directed toward the face. The ICA has a larger diameter, is located deeper than the ECA, and is directed toward the mastoid process. Then, observe the shape of the carotid artery in the longitudinal view. 5 The flow direction is generally the same as the vessel direction, but it can differ from the vessel direction when eccentric atherosclerotic plaques are present.įirst, in the cross-sectional view, trace the carotid artery from the proximal CCA to the distal internal carotid artery (ICA) and then the external carotid artery (ECA), or vice versa. Angle correction is crucial for measuring the actual flow velocity, which should be performed along the flow direction instead of the vessel wall. The peak velocity is measured to detect significant stenosis. 1 Pulse-wave Doppler is needed to precisely measure flow velocity, and uses a small sample volume from the vessel center to assess the velocity at that segment. ![]() This is called the heel-and-toe technique, and is a method for steering probes. Pushing the head- or foot-side edge creates an angle between the probe surface and the vessel, which can achieve the optimal Doppler angle. 1 In most patients, the probe surface runs parallel to the common carotid artery (CCA) in its usual position, which allows scanning of the carotid artery without applying pressure. However, to accurately record velocity using color Doppler ultrasonography, the angle must be between 30° and 60°. The ultrasound beam should be perpendicular to the skin, with a linear probe generating a grayscale image. Placing a pillow induces a poor evaluation window for the carotid artery and therefore normally should not be used.Īn adequate acoustic angle is important in obtaining an accurate color Doppler image. The neck of the patient should be relaxed and the chin should be slightly raised. Tilting the face too far from the test site can distort the anatomy or compress blood vessels, especially veins. The optimal position for tilting the head of the patient is approximately 45° away from the relevant artery. However, obtaining right-posterior projections is difficult. This position makes it easy to control the ultrasound probe. The examiner generally uses their right hand to evaluate both carotid arteries. A lateral sitting position is used for most ultrasonography examinations. However, the examiner should be familiar with the practice of using both hands. This position provides an expanded sonic window with a clear view of the carotid artery and allows many ultrasound probing positions. 1 In the overhead position, the examiner sits behind the head of the patient beside the end of the bed and uses both hands in the test. ![]() ![]() This examination is a quick, non-invasive way of confirming or excluding blockage of the arteries or build-up of plaque which may pose a future threat to the patient.The examiner can observe the carotid artery from either an overhead or a lateral sitting position. The most common reason for referral for this procedure is when a bruit is heard by the patient’s doctor with a stethescope. You can email us a scanned copy or clear photograph of the referral to Once the email has been sent you can proceed to make your online booking.Īlternatively, if your doctor has already sent us a copy of your referral via Healthlink or Email, we will make contact with you to arrange an appointment.Ī Carotid Doppler ultrasound scan serves to image the arteries in the patient’s neck to assess whether they are at risk for stenosis of these vessels or a stroke. Please send your referral in to us prior to making your appointment. You need to have a referral letter from a doctor with an Irish Medical Council (IMC) or Medical Council Registration (MCRN) number before making a booking. We kindly ask that all bookings and payments are to be done online below by selecting your preferred location.
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