Mra

MRA is a non-invasive imaging modality which can assess flow characteristics of the carotid circulation and define the degree of carotid stenosis. MRA resolution approaches a 90% sensitivity in detecting carotid stenosis when compared with angiography [24]. Two-dimensional MRA images are sensitive to low blood-flow states but are limited by their lower resolution. Three-dimensional images offer a better resolution and have a higher sensitivity to flow in any direction. Both of these images should be obtained in every evaluation, since it decreases problems associated with interpretation. MRA has the advantage of providing visualization of the entire carotid circulation, from the origin to the carotid siphon, along with the intracranial vasculature in one examination. The main disadvantage of MRA in this setting is its potential to overestimate the degree of stenosis. This is especially important in the mild to moderate group of patients who may have their degree of stenosis placed in a surgical category. Causes of this overestimation are due to loss of signal from disturbed flow or markedly decreased flow and distortion of the reconstructed images.

Ultrasound

Non-invasive evaluation of carotid stenosis usually begins with ultrasound studies. Doppler ultrasound, the most well established non-

Difference between NASCET and ECST in measurement of internal carotid artery stenosis

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Common carotid artery

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