Fibromuscular dysplasia of internal carotid arteries: features on high-resolution magnetic resonance imaging

Fibromuscular dysplasia (FMD) is a noninflammatory and nonatherosclerotic disease that predominantly affects the renal and internal carotid arteries. However, the cause of this disease remains unclear. Radiological studies are important diagnostic methods, which generally involve luminal features on computed tomographic angiography, magnetic resonance angiography, and digital subtraction angiography. However, the high-resolution magnetic resonance imaging (HR-MRI) features of FMD have not yet been reported. Herein, we report the HR-MRI features of patients with FMD who showed typical involvement of the internal carotid arteries. Although both patients presented a beading appearance typical of medial fibroplasia, HR-MRI nevertheless showed distinct features. HR-MRI revealed concentric wall thickening and circular enhancement with dystrophic calcification in one and wall thickening, but no enhancement in the others. Further studies are required to determine whether these HR-MRI features are related to the type of FMD or patient prognosis.