From the Guidelines
Brain biopsy is the most specific diagnostic test for Secondary Central Nervous System (CNS) Vasculitis, but its yield increases if it can be carried out in an area that is demonstrably abnormal on imaging studies, including MRI and angiography 1.
Diagnostic Yield Comparison
- The diagnostic yield of Magnetic Resonance Imaging (MRI) and Angiography is lower compared to brain biopsy, but they are useful in supporting the diagnostic process and directing biopsy 2, 3.
- MRI head is a useful examination in the evaluation of CNS vasculitis, with sensitivity of a normal MRI for CNS vasculitis approaching 100% 3.
- Angiography, including cerebral arteriography, has low specificity for vasculitis due to significant overlap of findings with other cerebrovascular diseases 4.
Key Findings
- Characteristic vessel imaging findings on MRI and angiography include multifocal stenosis and dilatation of the intracranial vasculature, as well as characteristic pattern of vessel wall inflammation 2, 3.
- Recent advances in MRI intracranial vessel wall imaging show promise in helping to differentiate CNS vasculitis from other cerebrovascular diseases 3.
- The addition of contrast-enhanced MRI vessel wall imaging to luminal imaging increased radiological diagnostic accuracy to 89% in differentiating among nonocclusive cerebrovascular diseases 3.
From the Research
Diagnostic Yield Comparison
The diagnostic yield of Magnetic Resonance Imaging (MRI) and Angiography in comparison to brain biopsy in Secondary Central Nervous System (CNS) Vasculitis is a complex topic.
- The study 5 found that cerebral angiography findings are not associated with biopsy findings and should be used cautiously in the diagnostic work-up of PCNSV.
- Another study 6 reported that when both cerebral angiography and histopathologic testing were performed, disagreement between them was more than 5 times more likely than agreement.
- A study 7 noted that multiple leaps in the caliber of intracranial arteries in cerebral angiography and multiple, small contrast medium-enhanced lesions in MRI of the brain are typical findings, but can also be found in other forms of vasculitis.
- The research 8 determined the diagnostic accuracy for high-resolution vessel wall image (HR-VWI) and brain biopsy according to angiographical classification in patients with primary central nervous system vasculitis (PCNSV), and found that brain biopsy remains the gold standard for proving PCNSV with small vessel variant (SVV).
- A systematic review 9 examined the frequency of symptoms, laboratory, and radiological features associated with PCNSV, and identified distinct clinical features between biopsy and angiography defined PCNSV.
Key Findings
- Brain biopsy is considered the gold standard for diagnosing PCNSV, especially for small vessel variant (SVV) 8.
- Cerebral angiography findings are not always correlated with biopsy findings 5, 6.
- MRI findings can be abnormal in a high percentage of patients with PCNSV, but are not specific to the disease 6, 8.
- The diagnostic approach for PCNSV differs concerning the affected vessel size, with HR-VWI being a useful imaging modality for the diagnosis of large-medium vessel variant (LMVV) 8.
Diagnostic Approaches
- Brain biopsy is diagnostic of PCNSV in a significant percentage of cases, and can also demonstrate an alternative diagnosis 9.
- Cerebral angiography and MRI are important diagnostic tools, but should be used in conjunction with clinical features and laboratory results to confirm a diagnosis of PCNSV 5, 6, 7, 8, 9.