Carotid artery fibromuscular dysplasia: Ultrasound and CT imaging

Abstract

An asymptomatic 54-year-old Caucasian female was found to have a right carotid bruit located high in the cervical region. Carotid duplex ultrasound revealed carotid intimal disease with increased Doppler flow in the mid-distal right internal carotid artery (RICA) with color Doppler turbulence in the distal RICA. Computed tomography angiography (CTA) revealed a typical "string-of-beads" sign in both distal internal carotid artery (ICAs), diagnostic of fibromuscular dysplasia (FMD). While often not diagnostic, carotid duplex ultrasound may yield clues as to diagnosis of FMD with elevated Doppler velocity in the distal carotid, turbulent distal carotid flow, and possibly a "string-of-beads" sign. An "S-curve" distal ICA is associated with FMD and may warrant further evaluation. Magnetic resonance angiography and CTA appear to be better for diagnosis of carotid FMD. The typical "string-of-beads" may be readily identified. While invasive angiography is considered the "gold standard" for diagnosis of carotid FMD, it is infrequently required. Generally, invasive angiography is performed in symptomatic patients in planning for interventional therapy.

Keywords: CT; FMD; bruit; ultrasound.