Digital Subtraction Cerebral Angiography (DSCA) in Stroke Evaluation
Digital subtraction cerebral angiography (DSCA) is indicated for detecting distal branch occlusions, evaluating subacute to chronic stenoses, vasospasm, and vasculitis, where it surpasses other imaging modalities due to its superior spatial and temporal resolution. 1
Primary Indications for DSCA
- DSCA is the gold standard for determining the degree of stenosis and patient eligibility for carotid endarterectomy (CEA) or carotid angioplasty and stenting 1
- For detection of vascular stenoses and aneurysms, DSCA and CTA are recommended as first-line imaging modalities (Class I, Level of Evidence: A) 1
- DSCA is superior for demonstrating distal acute branch occlusions that may not be visible on other imaging modalities 1
- DSCA is indicated for evaluation of subacute to chronic stenoses, vasospasm, and vasculitis where it outperforms CTA and MRA 1
Timing of DSCA in Stroke Evaluation
In patients presenting within 3 hours of symptom onset (acute window):
- DSCA may be considered if it doesn't delay administration of IV thrombolysis and if an endovascular team is available (Class IIa, Level of Evidence: B) 1
- In some cases with clear signs of large vessel occlusion on non-contrast CT, proceeding directly to DSCA may be appropriate to rapidly convert to endovascular therapy 1
In patients presenting beyond 3 hours from symptom onset:
- DSCA is strongly recommended during initial imaging evaluation, especially if intra-arterial thrombolysis or mechanical thrombectomy is being considered (Class I, Level of Evidence: A) 1
DSCA vs. Other Vascular Imaging Modalities
- While CTA and MRA show general agreement with DSCA in 85-90% of cases, DSCA remains the definitive standard for certain conditions 1
- For patients with suspected large vessel occlusion who may benefit from endovascular therapy, DSCA offers the advantage of immediately transitioning from diagnostic to therapeutic intervention 1
- When evaluating the extracranial vasculature for revascularization procedures, ultrasound alone is insufficient and should be supplemented with DSCA or other advanced imaging 1
Clinical Scenarios Where DSCA is Particularly Valuable
- When there is discordance between clinical presentation and findings on non-invasive imaging 1
- For patients with suspected vasculitis or other inflammatory arteriopathies 1
- In cases where precise measurement of stenosis is critical for treatment decisions (e.g., borderline stenosis cases being considered for intervention) 1
- For assessment of collateral circulation patterns, which may influence treatment decisions and prognosis 1
Important Considerations and Limitations
- DSCA is invasive and carries risks including stroke, arterial injury, and contrast nephropathy 1
- Due to its invasive nature, DSCA is typically not the first-line vascular imaging study in the initial workup for stroke unless rapid conversion to endovascular therapy is anticipated 1
- In most acute stroke protocols, non-invasive vascular imaging (CTA or MRA) is performed first, with DSCA reserved for specific indications or when non-invasive studies are inconclusive 1
Integrated Approach to Vascular Imaging in Stroke
- Initial non-contrast CT to exclude hemorrhage is essential before any reperfusion therapy 1
- For patients within the therapeutic window for IV thrombolysis, vascular imaging should not delay treatment 1
- For patients being considered for endovascular therapy, rapid assessment of vascular status is critical, which may be accomplished through CTA, MRA, or direct DSCA depending on institutional capabilities and time constraints 1
- For secondary stroke prevention, evaluation of both intracranial and extracranial vasculature is recommended, with DSCA reserved for cases requiring definitive assessment 1