Diagnosis of Internal Carotid Pseudo-occlusion by Use of Color-Coded Duplex Scanning

The differentiation of “pseudo” from complete carotid artery occlusion is still widely considered to be an indication for intraarterial angiography. The authors report a case in which color-coded duplex ultrasound revealed a persisting string-like lumen that was not adequately demonstrated by angiography. The duplex diagnosis of “pseudo” occlusion requires the use of low-pulse repetition frequencies and in future may reduce the need for invasive imaging techniques. If angiography is undertaken, even delayed films may fail to demonstrate the residual lumen adequately.