What is the role of cerebral angiogram in diagnosing and managing cerebral vasculitis?

Role of Cerebral Angiography in Diagnosing and Managing Cerebral Vasculitis

Cerebral angiography is the most sensitive imaging method for assessing large-to-medium vessel cerebral vasculitis but has limited utility in small vessel vasculitis, which often requires brain biopsy for definitive diagnosis. 1

Diagnostic Algorithm for Suspected Cerebral Vasculitis

Initial Imaging

1. MRI Brain with Contrast

   • First-line imaging modality with sensitivity approaching 100% when normal 2
   • Characteristic findings:
     • Multiple infarcts of variable ages (seen in up to 50% of cases) 1
     • Progressive confluent white matter lesions
     • Cortical and subcortical T2 lesions
     • Multiple microhemorrhages
     • Enhancing mass lesions
     • Enhancing small vessels/perivascular spaces 1

2. MRA Head

   • Abnormal in 81% of patients with angiographic findings of vasculitis 1
   • Limited by resolution for small vessel involvement 2
   • Shows multifocal stenosis and dilatation of intracranial vasculature 2

Advanced Imaging

1. Vessel Wall Imaging (Contrast-enhanced MRI)

   • Increases diagnostic accuracy to 89% compared to 36% with luminal imaging alone 1, 2
   • Helps differentiate vasculitis from other cerebrovascular diseases by showing characteristic inflammatory changes 2

2. Cerebral Angiography (Digital Subtraction Angiography)

   • Gold standard for radiologic evaluation of large-to-medium vessel vasculitis 1
   • Key findings:
     • Areas of stenosis
     • Vessel dilatation
     • Occlusions
     • Pseudoaneurysm formation 1
   • Typically negative in small vessel vasculitis 1

Vasculitis Classification and Imaging Approach

Large-to-Medium Vessel Vasculitis

• Imaging of choice: Cerebral angiography or CTA/MRA
• Findings: Beaded appearance of vessels, stenosis, occlusion, vessel wall enhancement
• Utility of angiography: High sensitivity for detecting abnormalities

Small Vessel Vasculitis

• Imaging of choice: MRI brain (for parenchymal changes)
• Findings: Multiple infarcts in different vascular territories
• Utility of angiography: Limited - typically negative 1
• Definitive diagnosis: Often requires brain biopsy 1

Limitations and Pitfalls

1. False Negatives

   • Small vessel vasculitis is below resolution threshold of angiography 2
   • In a study at Jackson Memorial Hospital, some patients with normal DSA were still treated based on clinical symptoms and laboratory findings 3

2. Overlap with Other Conditions

   • Findings may overlap with atherosclerosis, reversible cerebral vasoconstriction syndrome, and other non-inflammatory vascular conditions 1, 2
   • Persistent wall thickening may be seen in up to 49% of patients despite clinical response to treatment 2

3. Evolving Role of Non-invasive Imaging

   • Advances in MRA and CTA may reduce the need for invasive catheter angiography 3
   • High-field strength (7T) MRA offers possibility of directly evaluating small vessel vasculitis 4

Management Implications

• Positive angiographic findings in the appropriate clinical context support immunosuppressive therapy 5
• Treatment typically includes combination of steroids and cyclophosphamide for induction 5
• Serial imaging is important for monitoring treatment response, though vessel wall changes may persist despite clinical improvement 2

Key Points for Clinical Practice

• A normal MRI effectively rules out CNS vasculitis with near 100% sensitivity 2
• Cerebral angiography remains valuable for large-to-medium vessel vasculitis but has limited utility in small vessel disease
• The combination of clinical, laboratory, and imaging findings is essential for diagnosis, as no single test is pathognomonic 6
• Protect patients from unnecessary immunosuppressive therapy when non-inflammatory differential diagnoses haven't been excluded 6