Alternating stenoses and dilatations ("string of beads") in the mid and distal renal or internal carotid arteries of a young or middle-aged woman — distinct from ostial atherosclerosis.
Orient first
- Multifocal FMD (string of beads) is the common form; focal FMD is a single tubular stenosis.
- Renal and extracranial carotid/vertebral arteries are the usual beds; it is often multi-bed.
- Complications: dissection, aneurysm, renovascular hypertension, stroke.
Acquire the study
- CT angiography of the renal arteries (and head and neck when one bed is affected) with thin sections, MIP and curved reformats.
The manoeuvre
- Renal arteries on curved reformats from the ostium to the hilum: mid and distal segment beading vs ostial plaque.
- Internal carotid arteries at the C1–C2 level: beading, dissection, aneurysm.
- Measure aneurysms in mm; note dissection flaps.
- Kidney: segmental infarcts, size asymmetry in cm.
- Screen the other beds when one is affected.
What confirms it
- String-of-beads morphology in the mid-distal renal or cervical internal carotid artery.
What licenses you to exclude it
- Smooth arteries on curved reformats reduce the likelihood; CTA can miss mild beading, and catheter angiography remains the reference.
The classic misread
- Calling stair-step or motion artefact beading.
- Calling ostial atherosclerotic stenosis FMD.