String of beads sign (renal artery)

The
"string-of-beads" feature in medial fibromuscular dysplasia. The sign is caused by areas of relative stenoses alternating with small aneurysms. The diameters of the aneurysms exceed the normal diameter of the artery. The sign is characteristic of medial FMD. A similar bead appearance may be seen in perimedial FMD, but the diameters of the beads do not exceed the normal diameter of the artery [10]. Note the involvement of branch renal arteries.
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The clothes
maketh the sign. Digital subtraction angiogram in a 35-year-old woman with uncontrolled hypertension demonstrates contiguous relative stenoses alternating with fusiform aneurysmal dilatation of the right renal artery due to fibromuscular dysplasia resembling a string of beads (inset). Fibromuscular dysplasia is characterized by fibrous or muscular hyperplasia in one or more layers of the renal artery wall, producing this appearance
insightsimaging.springeropen.com • Open Access
String of
beads sign (vascular) • Segmental arterial mediolysis with string of beads sign - Ganzer Fall bei Radiopaedia
Snow, T. Segmental arterial mediolysis with string of beads sign. Case study, Radiopaedia.org. (accessed on 02 Nov 2022) https://doi.org/10.53347/rID-30330 • CC by-nc-sa 3.0 (modified)
Fibromuscular
dysplasia • Spectrum of fibromuscular dysplasia - acute vertebral artery occlusion, internal carotid and renal artery involvement, and renal infarct - Ganzer Fall bei Radiopaedia
Hartung, M. Spectrum of fibromuscular dysplasia - acute vertebral artery occlusion, internal carotid and renal artery involvement, and renal infarct. Case study, Radiopaedia.org. (accessed on 24 Oct 2022) https://doi.org/10.53347/rID-61031 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses resulting from the disease alternating with aneurysmal dilatation .

It was originally described from its appearances on digital angiography, but is equally well seen on contemporary CTA and MRA. It is also referred to as the string of pearls . Fibromuscular dysplasia is one of the renovascular causes of secondary hypertension, whilst segmental arterial mediolysis is the most common cause of spontaneous intraperitoneal or mesenteric hemorrhage in the middle-aged and elderly.

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