A 54-year-old Caucasian female was referred by her primary care physician for evaluation of a right carotid bruit heard on routine physical examination. The patient was asymptomatic with no neurological or cardiovascular-related symptoms. There was no history of hypertension, diabetes mellitus, or tobacco abuse. The patient's only medication was simvastatin 20 mg/day for a diagnosis of hypercholesterolemia. Family history was pertinent for a sister diagnosed as developing hypertension of unknown etiology as a teenager.Physical examination was unremarkable except for a long systolic high pitched right carotid bruit heard best high in the neck. Carotid duplex ultrasound revealed intimal left carotid disease with normal velocities and laminar color Doppler flow within the left internal carotid artery (ICA). Evaluation of the right carotid artery revealed intimal disease with an increase in velocity (140 cm/s peak systolic velocity) in the distal right ICA (Figure 1). Color flow Doppler turbulence was also noted in the distal right ICA (Figure 2). Both vertebral arteries demonstrated normal Doppler velocities.Because of the quality and location of the right carotid bruit, and an increase in Doppler velocity and turbulence in the high right ICA by carotid duplex scanning, computed tomography angiography (CTA) was performed of the great vessels. A "string-of-beads" sign was noted in both distal ICAs, diagnostic of fibromuscular dysplasia (FMD) (Figures 3-4). CTA screening of the abdomen and pelvis revealed no evidence of FMD elsewhere.
| D ISCUSS I ONFibromuscular dysplasia is a noninflammatory, nonatherosclerotic disease of unknown etiology. 1,2 It affects mostly women between 20 to 60 years old and may occur in nearly any artery. 3 Most often it affects the renal arteries with an incidence of about 80% of all 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 notdiagnostic, 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.
K E Y W O R D Sbruit, CT, FMD, ultrasound