CAROTID ULTRASOUND - HOW DO I DO IT?

Stella SY Ho

 

INTRODUCTION
Ever since the results of two large randomised trials: North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST), published in 1991 showing the benefit of carotid endarterectomy for high-grade internal carotid artery stenosis greater than 70% diameter reduction1,2, carotid ultrasonography has become an important tool for stroke management and prevention, and is one of the standard investigations for patients suffering from transient ischaemic attacks (TIA) and recent acute strokes.
Hence, the primary role of carotid ultrasonography for these patients is to look for the presence of carotid stenosis and to document the degree of stenosis in conformity to the criteria in these randomized trials - the NASCET criteria are most widely adopted by vascular sonologists.
It is noteworthy that the diagnostic criteria of the two trials are different. In NASCET, the degree of stenosis was determined by comparing the diameter of the residual lumen to the true diameter of a normal portion of ICA on arteriography, whereas in ECST, comparison was made between the diameter of the residual lumen and an estimate of the true diameter in the same segment.