A nodule or serpiginous mass with an enlarged feeding artery and draining vein; the feeding artery diameter (≥ 2–3 mm) decides embolisation, and multiple PAVMs mean hereditary haemorrhagic telangiectasia.
Orient first
- Right-to-left shunt: paradoxical stroke and brain abscess are the dangers.
- Most are simple (one segmental feeding artery); complex ones have several.
- HHT screening uses contrast echocardiography; CT maps for treatment.
Acquire the study
- Thin-section CT angiography of the chest (pulmonary arterial phase) with MIP and 3D reformats.
The manoeuvre
- Find the sac: nodule contiguous with a vessel on MIP.
- Feeding artery diameter in mm and number of feeders.
- Draining vein into the left atrium; sac size in mm.
- Count all PAVMs (both lungs) and note HHT.
- After embolisation: sac shrinkage and no reperfusion on follow-up CT at the same phase.
What confirms it
- A sac with a feeding artery and a draining vein on CT angiography.
What licenses you to exclude it
- A nodule without an afferent artery and efferent vein on MIP is not a PAVM.
The classic misread
- Calling a PAVM a nodule on a thick-slice CT.
- Missing reperfusion via a recanalised or new feeder after coiling.