Several studies have been published on the usefulness of MR angiography of carotid bifurcations and epiaortic vessels. Almost all of them were carried out with the Time-of-Flight technique, most of them using the 2D acquisition modality. These studies claim a good overall sensitivity and specificity by comparison to digital subtraction angiography, Doppler ultrasound or both in the demonstration of carotid clinically relevant stenosis, with a slight overestimation of the degree of stenosis, especially in the moderate and severe groups. Unlike Doppler ultrasound, distal cervical and proximal intracranial arteries can be relatively well evaluated by MR angiography. Nevertheless, MR angiography also has limitations, among the best known, difficult visualization of the origin of neck arteries, inaccurate depiction of vessel morphology in case of complex flow and unreliable quantification of the degree of stenosis have to be mentioned. To get the most of the diagnostic potential of MR angiography, imaging strategies and technical considerations have to be adapted to the morphological and hemodynamic particularities of the different segments of the supraaortic arterial structures.
Comparison of Doppler Ultrasound and Digital Subtraction Angiography in extracranial stenosis
