Abstract
Fibromuscular dysplasia (FMD) is a rare idiopathic, noninflammatory, nonatherosclerotic arteriopathy that leads to wall abnormalities in medium- and small-caliber arteries, typically resulting in alternating areas of stenosis and dilatation, or "beading" at angiography. Stenosis, dissection, and aneurysm can also be seen, and clinical manifestations depend on the vascular territory affected by FMD, with the renal and carotid arteries being most frequently involved. The diagnosis of FMD is made based on imaging features of FMD classified according to the angiographic appearance as focal FMD or multifocal FMD. Early diagnosis is often challenging, as mimics of FMD must first be excluded. The presence of aneurysm, dissection, or tortuosity alone is inadequate to establish the diagnosis, as these are variant manifestations; however, if a patient has focal or multifocal manifestations such as stenosis or stenosis and dilatation in one vascular bed, establishing the diagnosis of FMD, the presence of aneurysm, dissection, or tortuosity in additional vascular beds is considered multivessel involvement of all affected vascular beds. The cerebrovascular system, coronary arteries, renal and mesenteric arteries, and extremities should be evaluated for FMD involvement. The most serious potential complications of FMD are hypoperfusion secondary to aneurysm, dissection, or arterial occlusion, which can lead to hypertension, stroke, or myocardial infarction, as well as subarachnoid hemorrhage. Prompt intervention, blood pressure management, and revascularization are necessary to avoid devastating complications. Radiologists play an important role in timely identification of diverse FMD-associated morbidities and thus may contribute to early diagnosis and treatment of FMD. (©)RSNA, 2026 Supplemental material is available for this article.