String of beads sign (renal artery)
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.