TRANSORAL CAROTID ULTRASONOGRAPHY

Background and Purpose-We attempted ultrasonographic evaluation of the distal extracranial internal carotid artery (ICA) using the transoral method (transoral carotid ultrasonography [TOCU]), Methods-The subjec ts consisted of five healthy volunteers and seven stroke patients. Exa minations were performed with a color Doppler flow imaging system equi pped with convex array transducers (7 or 9.5 MHz), originally designed for transrectal use. After local anesthesia of the pharynx, we insert ed a probe covered with thin gum transorally, touching the tip to the pharyngeal posterolateral wall. We then attempted to detect the ICA an d measure flow velocity of the distal extracranial ICA using principal images obtained by TOCU. Results-TOCU was successfully performed in a ll subjects without any difficulty. In the healthy volunteers, the ICA was identified at a depth of 2:2+/-0.6 cm and visualized as a vertica l linear vessel 2.9+/-0.3 cm in length and bent slightly backward. The diameter and mean flow velocity of the distal extracranial ICA were 4 ,7+/-0.2 mm and 50+/-7 cm/s, respectively, In the stroke patients, som e remarkable findings were obtained, including a narrow ICA with low f low velocity in a patient with possible ICA dissection, a lucent echo without flow signal in a patient with acute cardioembolic ICA occlusio n, and decreased ICA flow velocity in a patient with ipsilateral MCA s tenosis. Conclusions-These preliminary data demonstrate the potential applicability of TOCU to the evaluation of flow in the far distal extr acranial ICA. TOCU definitely warrants further investigation in patien ts with carotid artery disease.