A case of spontaneous dissection of the left internal carotid artery diagnosed using a microconvex probe with B-flow imaging

Abstract

A 33-year-old man had episodic symptoms of motor aphasia and sensory disturbance of the right side of the face that lasted about one minute while running. He had a second attack two days after the first attack. A brain MRI revealed a cortical infarct in the left middle cerebral artery territory. Difficulty was encountered in using duplex carotid ultrasonography with a linear probe to evaluate the left extracranial cervical internal carotid artery (LECICA) with a high bifurcation. As an alternative evaluation, a microconvex probe (MCP) showed the LECICA lesion with a narrow lumen surrounded by a hypoechoic lesion and with an increased vascular diameter for a length of 2 cm, starting from 2 cm distal to the carotid bulb. In addition, B-flow imaging (BFI) clearly showed echogenic structures of a hyperechoic intravascular lumen; a hypoechoic lesion with a subtle flow signal, which indicated a false lumen; and a mobile membranous septal structure between them. The findings of contrast-enhanced CT angiography were consistent with those of the B-flow imaging. The LECICA lesion was diagnosed as a spontaneous dissection. Carotid ultrasonography using MCP with BFI can improve the diagnosis of extracranial carotid artery dissection, which has been difficult for patients with high bifurcation of the carotid artery.