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Duplex ultrasound (duplex) combines standard B-mode ultrasound and Doppler ultrasonography to evaluate both structural details of the carotid arteries and blood flow through the arteries. [2] During carotid duplex evaluation, the 2D B-mode structural image is superimposed with the doppler flow data, which provides a more realistic anatomical ...
Duplex scan of the common carotid artery Colour Doppler shows the direction of the blood flow in red or blue (either towards or away from the transducer). Meanwhile, spectral Doppler not only shows the direction of blood flow, it also shows the phases (pulsatility) and acceleration of the blood flow.
To image the vessels of the neck such as common carotid, internal and external carotid arteries, AP, lateral, and 45 degrees bilateral oblique positions are taken. Contrast injection rate is 3 to 4 ml/sec with total volume of 7 to 9 ml. The frame rate of fluoroscopy is 3 to 4 frames/sec. [8]
The condition and health of the vertebral carotid arteries is usually evaluated using Doppler ultrasound, CT angiography or phase contrast magnetic resonance imaging (PC-MRI). Typically, blood flow velocities in the carotid artery are measured in terms of peak systolic velocity (PSV) and end diastolic velocity (EDV). [15]
The carotid artery is the usual site of measurement of IMT and consensus statements for carotid IMT have been published for adults [12] and children. [13] Often, carotid IMT is measured in three locations: in the common carotid artery (typically at one cm proximal to the flow divider), at the bifurcation, and in the internal carotid artery.
70 percent stenosis of the right internal carotid artery as seen by ultrasound. Arrow marks the lumen of the artery. CT image of a 70 percent stenosis of the right internal carotid artery. Carotid artery stenosis is usually diagnosed by color flow duplex ultrasound scan of the carotid arteries in the neck.
Functional transcranial Doppler sonography (fTCD) is a neuroimaging tool for measuring cerebral blood flow velocity changes due to neural activation during cognitive tasks. [8] Functional TCD uses pulse-wave Doppler technology to record blood flow velocities in the anterior, middle, and posterior cerebral arteries.
Carotid endarterectomy is used to reduce the risk of strokes caused by carotid artery stenosis over time. Carotid stenosis can either have symptoms (i.e., be symptomatic), or be found by a doctor in the absence of symptoms (asymptomatic) - and the risk-reduction from endarterectomy is greater for symptomatic than asymptomatic patients.