The accuracy of ultrasonic duplex scanning in carotid artery disease

Ultrasonic duplex scanning of the internal carotid artery is highly accurate in the detection of disease as expressed in its sensitivity of 0.97 and specificity of 0.82 for haemodynamic significant lesions. For the detection of obstructions of 20% or over, these parameters are 0.94 and 0.77 respectively. The most striking problem is the poor classification of normal vessels and those with minor lesions. The duplex scanning overestimates the degree of disease in these cases. For the external carotid artery the method differentiates reasonably well between non-haemodynamic and haemodynamic significant lesions.