B-Flow and B-Mode Ultrasound Imaging in Carotid Fibromuscular Dysplasia

BACKGROUND AND PURPOSE: Previous ultrasound studies in fibromuscular dysplasia (FMD) have largely reported on color flow imaging, power Doppler, and Doppler flow augmentation. We here report on arterial wall imaging findings by B-flow and B-mode in patients with carotid FMD. METHODS: We retrospectively reviewed ultrasonographic findings in subjects with known or suspected FMD. All patients were evaluated with a standardized imaging protocol including Doppler, B-mode, and B-flow. Vessel wall abnormalities were classified as normal, luminal irregularities, or classical beading (fusiform dilatations). RESULTS: We identified 23 patients and 33 carotid arteries were found to be abnormal, of which 10 had classical beading and 23 showed endoluminal irregularities. Bilateral disease was present in 10/23 patients. In the classical beading cases, B-mode revealed isoechoic ridges, which protruded into the lumen, alternating with dilated arterial segments, which were also clearly demonstrated by B-flow imaging. In cases with endoluminal irregularities, B-mode and B-flow showed isoechoic subendothelial irregular thickening, which did not lead to a fusiform dilatory appearance of the artery. The average distal internal carotid artery peak systolic velocity of arteries with classical beading (123 +/- 29 cm/second) was significantly greater than that of arteries with mild irregularities (94 +/- 34 cm/second) (P = .024). CONCLUSION: Morphological arterial wall changes of FMD were well depicted by careful B-flow and B-mode imaging of the distal internal carotid artery. We would like to emphasize the utility of B-flow and B-mode in the noninvasive evaluation of FMD.