COLOR DOPPLER AND DUPLEX SONOGRAPHY AND ANGIOGRAPHY OF THE CAROTID-ARTERY BIFURCATIONS - PROSPECTIVE, DOUBLE-BLIND STUDY

We undertook a prospective double-blind study of 128 carotid artery bi furcations using colour Doppler and duplex sonography and angiography. Sixty-four patients with cerebrovascular events were admitted for ang iography. All underwent sonography within 24 h of angiography. Standar d duplex sonography and colour Doppler imaging without spectral analys is were performed, on the same device, by two sonographers, using defi ned morphological and haemodynamic criteria. Digital radiological data on vessel diameter were interpreted independently by two radiologists . The two sonographic methods gave similar grading of stenosis, compar ed to angiography, with an accuracy ranging from 96 % in severe to 83 % in minor stenoses. Colour Doppler studies gave better area measureme nts than standard duplex sonography, except for major stenoses. Discre pancies between ultrasonography and angiography were due mainly, to mi nor stenoses and large plaques of calcification on the vessel walls, w hich masked very segmental 70 % stenoses in 2 cases. Angiography is li mited by its own resolution, does not show uncalcified vessel walls an d does not give cross-sectional data. It would therefore be inappropri ate for showing small plaques, the full extent of ectasia or for defin ing the carotid bulb accurately. The advantages of colour methods were in investigating sinuous or deep vessels and hypoechoic plaques. Anal ysis of the residual lumen of a stenosis and its extent could be deter mined more rapidly. Haemodynamic quantification of stenoses by standar d duplex sonography may be difficult because of limited sample volume and error in estimation of angle, whereas colour Doppler allows semiqu antitative estimation of haemodynamics. Standard duplex sonography per mits good analysis of vessel wall over a limited distance and quantifi cation of velocity; colour Doppler affords overall demonstration of tu rbulence, acceleration and backward flow.