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.
Fibromuscular dysplasia (FMD) is a non-inflammatory and non-atherosclerotic disease of unknown cause which affects the small- and medium-sized arteries. The most commonly involved blood vessels are the renal and cervicocephalic arteries. If the disease involves the cervicocephalic arteries, it can cause abnormalities, including carotid and vertebral artery stenosis, arterial dissection, and aneurysm formation [
FMD is definitively diagnosed by imaging studies such as computed tomographic angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA) [
A 60-year-old previously healthy woman was admitted with short-term vertigo lasting a few seconds. Vertigo was aggravated by positional changes and improved with bed rest. Initial neurological examination results were normal. She was diagnosed with benign paroxysmal positional vertigo as the cause of symptoms. Brain CTA showed multiple stenoses and dilatations with a string-of-beads appearance in the left internal carotid artery (ICA) (
A 42-year-old, previously healthy woman visited our hospital with headache and shoulder pain. Initial neurological examination results were normal. She underwent brain MRI and MRA to rule out secondary headache. MRA of the brain further revealed dilatation and tortuosity of the right ICA (
Written informed consents by the patients were waived due to retrospective nature of our study.
Intracranial arteries are involved in 7% to 20% of cases of cervicoencephalic FMD [
Our patient presented with headaches and vertigo. In the United States registry for FMD, 60% of patients experienced significant headache [
The pathological classification of FMD is based on the dominant vessel wall layer, intima, media, and adventitia. Among the three pathological FMD types, the media type is the most common, accounting for more than 85% of cases [
In this series, HR-MRI of the first case showed concentric wall thickening and saccular enhancement, whereas the other case showed no enhancement. The clinical implications of vascular enhancement in FMD remain unclear. In cases with carotid web, also known as carotid intimal variant FMD, previous studies have shown that HR-MRI reveals protrusion with enhancement along the posterior margin of carotid bulb [
In conclusion. HR-MRI can be used to directly visualize vessel walls. As the natural course of this disease varies among patients with FMD despite similarities in luminal features, further studies with HR-MRI are needed to test the diagnostic and prognostic role of HR-MRI in patients with FMD.
No potential conflict of interest relevant to this article was reported.
Conception or design: DGL, OYB, TKJ.
Acquisition, analysis, or interpretation of data: DGL, NJH, TKJ.
Drafting the work or revising: DGL.
Final approval of the manuscript: DGL, OYB, NJH, JC, TKJ.
(A) Brain computed tomographic angiography showing multiple stenosis and dilatation in the left internal carotid artery (arrow). (B) Digital subtraction angiography (DSA) shows vessel tortuosity and string-of-beads sign from the left petrous portion to the internal carotid artery bifurcation. (C) DSA showing bilateral normal renal artery at the renal-level aortogram.
High-resolution magnetic resonance imaging showing concentric wall thickening and saccular enhancement with dystrophic calcification (arrows).
(A) Magnetic resonance angiography showing dilatation and tortuosity in the right internal carotid artery (arrow). (B) Aorta computed tomographic angiography showing no stenosis or dilatation. (C) Minimal wall thickening can be seen in the right internal carotid artery (ICA) in T1-weighted images (arrow). (D) No enhancement is visible in right ICA in T1-weighted contrast-enhanced images (arrow).