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Vasculitis

Summary

  • Vasculitis is inflammation of blood vessel walls, leading to organ damage
  • Classified by vessel size affected and underlying aetiology (e.g. autoimmune, infectious)
  • Imaging findings vary but often show vessel wall thickening, stenosis, or aneurysms1

Pathophysiology

  • Inflammation of blood vessel walls leads to:
    • Vessel wall thickening and narrowing of lumen
    • Weakening of vessel walls, potentially causing aneurysms
    • Tissue ischaemia due to compromised blood flow
    • Vessel occlusion from thrombosis
  • Immune-mediated mechanisms often involved:
    • Antineutrophil cytoplasmic antibodies (ANCA)
    • Immune complex deposition
    • T-cell-mediated inflammation

Demographics

  • Incidence varies by specific type of vasculitis
  • Generally affects all age groups, but some types more common in certain demographics:
    • Giant cell arteritis: typically affects those >50 years
    • Kawasaki disease: primarily affects children <5 years
    • Takayasu arteritis: more common in young women
  • Some types show geographical or ethnic predilections:
    • Behçet's disease: more prevalent along the ancient Silk Road

Diagnosis

  • Clinical presentation varies widely depending on affected vessels and organs
  • Laboratory tests:
    • Elevated inflammatory markers (ESR, CRP)
    • ANCA testing for certain types (e.g. granulomatosis with polyangiitis)
    • Complement levels
  • Tissue biopsy: often considered the gold standard for diagnosis
  • Imaging plays a crucial role in diagnosis and monitoring

Imaging

  • Modalities used:
    • Ultrasound: for superficial vessels and temporal arteries
    • CT angiography: excellent for medium and large vessel evaluation
    • MR angiography: useful for follow-up and reducing radiation exposure
    • PET-CT: can detect early inflammatory changes and assess disease activity
  • Common findings:
    • Vessel wall thickening and enhancement
    • Luminal narrowing or occlusion
    • Aneurysm formation
    • Vessel wall calcification in chronic cases
    • Surrounding soft tissue inflammation
  • Specific patterns:
    • Large vessel vasculitis: aorta and major branch involvement
    • Medium vessel vasculitis: renal, hepatic, and mesenteric artery involvement
    • Small vessel vasculitis: often manifests as end-organ damage

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  • A 35-year-old patient presenting with photophobia and headache was diagnosed with HIV with a CD4 count of 80.
  • Baseline MRI showed an old infarct in the left thalamus. VWI imaging showed concentric enhancement within stenosis in the terminal ICA and MCA.
  • Over the following 4-6 weeks, the mural enhancement was static. The stenoses only minimally progressed but the perfusion to the left and, to a lesser extent, right cerebral hemisphere worsened.
  • With worsening perfusion, an angioplasty successfully widened the stenosis and significantly improved perfusion.

Treatment

  • Corticosteroids and immunosuppression (agent depends on subtype). High-resolution vessel wall imaging showing concentric, smooth, enhancing wall thickening supports vasculitis and distinguishes it from atherosclerosis (eccentric) and RCVS (no enhancement, reversible)

Differential diagnosis

Differential diagnosis Differentiating feature
Reversible cerebral vasoconstriction syndrome (RCVS) Multifocal segmental arterial narrowing that resolves on follow-up MRA within 12 weeks; no vessel wall enhancement on high-resolution MRI
Moyamoya disease Bilateral ICA terminus and proximal MCA/ACA stenosis with "puff of smoke" lenticulostriate collaterals on DSA; no small vessel beading
Atherosclerosis Calcified eccentric plaques on CTA; diffuse large vessel involvement; no small vessel beading pattern
Fibromuscular dysplasia "String of beads" alternating narrowing and dilatation primarily in renal and cervical arteries; no intracranial small vessel involvement
Sarcoidosis Leptomeningeal and perivascular enhancement; cranial nerve involvement; vessel narrowing from periarterial inflammation; hilar lymphadenopathy on chest CT
Takayasu arteritis Concentric vessel wall thickening and enhancement of large arteries on MRI/CTA; no intracranial small vessel involvement; predominantly extracranial

  1. Cacoub et al. Large-vessel vasculitis. 2025. Lancet (London, England) - Open in new tab. ↩