頚動脈病変の超音波診断 経口腔頚部血管超音波検査

Abstract

We introduced transoral carotid ultrasonography (TOCU) which enabled us to evaluate the distal extracranial internal carotid artery (ICA). Examinations were performed using a color Doppler flow imaging system equipped with a convex array stick-like transducers (9 - 5 MHz). We inserted the probe covered with thin gum transorally, touching the tip to the pharyngeal postero-lateral wall. Then we could obtain image and measure flow velocity of the distal portion of extracranial internal carotid artery.TOCU was successfully performed in healthy five volunteers without any difficulty. The ICA was identified at a depth of 2.2 ± 0.6cm and visualized as a vertical linear vessel about 3.0cm in length and bent slightly backwards. The diameter and mean flow velocity of the distal extracranial ICA was 4.7 ± 0.2mm and 50 ± 7 cm/sec, respectively.In acute stage of embolic ICA occlusion, TOCU frequently demonstrated echo lucent lumen at the distal extracranial ICA, while it seldom does in acute stage of atherothrombotic ICA occlusion or in chronic stage of ICA occlusion. Therefore, TOCU seems useful to distinguish mechanism of ICA occlusion in its acute stage.In internal carotid artery dissection, TOCU showed true and pseudo lumens or narrow lumens in the affected side. TOCU seems a useful technique to make up for conventional carotid ultrasonography.