The limitations of B-mode imaging of the carotid bifurcation

Three hundred and four carotid arteries in 152 patients presenting with cerebral symptoms or asymptomatic carotid bruits were scanned with a real time B-mode scanner. These patients were also submitted to three other non-invasive screening modalities of Oculoplethysmography (OPG), Periorbital Doppler (POD) and Carotid Phonangiography (CPA). Contrast angiography was performed on 57 patients (114 arteries). Lesions greater than 50% luminal reduction were considered haemodynamically significant. B-mode identified these lesions with a sensitivity of 75.5% and a specificity of 80.3%. Combined with OPG the sensitivity reached 96.2% but with a reduction of the specificity to 73.8%. In defining the need for angiography, no individual with a potentially surgically correctable lesion was incorrectly refused angiography. The limitations of real time B-mode scanning of the carotid bifurcation are enumerated.