Neurointervention · IR Playbook

Diagnostic Cerebral Angiography (DSA)

Diagnostic cerebral angiography is selective catheter angiography of the cervicocerebral circulation using digital subtraction imaging. It provides unmatched spatial and temporal resolution when CTA or MRA is inconclusive, detailed flow assessment is required, or treatment planning and follow-up demand precise vascular anatomy. The reported technical success benchmark is 98%; thromboembolic stroke is the most feared complication, with permanent disabling stroke reported in approximately 0.13–0.14% in large series.

Learning objectives

• Select appropriate indications for catheter angiography after reviewing available CTA, MRA and Doppler studies
• Choose femoral or radial access and an appropriate diagnostic catheter for the aortic-arch anatomy
• Perform selective angiography while minimizing thromboembolism, dissection, contrast dose and radiation
• Recognize normal vascular variants, collateral pathways and the arterial-to-venous phases of vascular lesions
• Detect and initiate management of neurological and access-site complications

Indications

• Evaluation of suspected intracranial aneurysm, subarachnoid haemorrhage or other vascular lesion when CTA or MRA is negative, equivocal or technically limited but suspicion remains
• Characterization of aneurysm morphology, branch incorporation, collateral circulation and access anatomy before treatment
• Dynamic assessment of brain arteriovenous malformation, dural arteriovenous fistula or carotid-cavernous fistula, including feeders, nidus or fistulous point and venous drainage
• Evaluation of extracranial or intracranial stenosis, occlusion, dissection, vasospasm or other vasculopathy when non-invasive imaging is inconclusive or intervention is contemplated
• Preoperative vascular mapping of hypervascular head-and-neck or intracranial lesions and assessment of collateral pathways
• Assessment after surgical or endovascular treatment of an aneurysm, vascular malformation, fistula or stenosis when non-invasive follow-up is inadequate
• Determination of cervicocerebral flow for brain-death assessment only where accepted by applicable law and a validated institutional protocol

Relative contraindications

• Uncorrected coagulopathy or thrombocytopenia
• Uncontrolled severe hypertension, hypotension or significant cardiac instability
• Clinically significant renal impairment, dehydration or decompensated heart failure
• Previous severe allergic-like reaction to iodinated contrast material
• Pregnancy unless the expected benefit justifies fetal radiation exposure
• Severe aortic-arch atherosclerosis, marked vessel tortuosity or hostile access anatomy
• Vascular connective-tissue disorder such as vascular Ehlers-Danlos syndrome, in which non-invasive imaging is preferred whenever possible

Equipment

• Ultrasound machine with high-frequency linear transducer and sterile cover
• 21 G micropuncture needle, 0.018-inch wire and 4–5 Fr micropuncture introducer
• 4–5 Fr short femoral or radial arterial sheath
• 0.035-inch 150 cm J-tip or Bentson wire
• 0.035-inch angled hydrophilic guidewire for difficult vessel selection
• 4–5 Fr 90–100 cm Vertebral, angled taper, Headhunter or JB1 diagnostic catheter
• 4–5 Fr Simmons 1 or Simmons 2 catheter for a type II or III arch, bovine configuration or difficult left common carotid selection
• 120–130 cm Simmons 2 or equivalent catheter when using radial access
• Pressurized heparinized-saline flush system, manifold and three-way stopcocks
• Non-ionic low-osmolality iodinated contrast medium and programmable power injector
• Biplane DSA system with road-mapping and optional 3D rotational angiography
• Femoral closure device or manual-compression equipment and radial compression band
• Emergency drugs, resuscitation equipment and devices for urgent neuroendovascular treatment

Procedure steps

1. Perform a time-out, confirm the indication and define the vessels, projections and phases required. Document the baseline neurological examination and distal pulses.Pearl: A targeted diagnostic study is safer than automatically performing unnecessary vessel injections.
2. Prepare the groin or wrist using full sterile technique and infiltrate local anaesthetic. Under ultrasound guidance, puncture the common femoral artery over the femoral head or the radial artery using a micropuncture technique.
3. Insert a 4–5 Fr arterial sheath, confirm free backflow and connect a pressurized heparinized-saline flush. Maintain a closed, air-free system throughout the procedure.Pearl: Meticulous flushing and elimination of air or thrombus are fundamental stroke-prevention measures.
4. Advance the diagnostic catheter over a guidewire under continuous fluoroscopy. Use an arch roadmap or non-selective arch run when origins are uncertain, but avoid routine arch injection when selective catheterization is straightforward.
5. Select the common carotid, internal carotid, external carotid or vertebral artery according to the planned study. Keep the catheter tip proximal to significant stenosis, tortuosity or diseased plaque and avoid wedging the vessel.Pearl: A Simmons catheter is often helpful for a type III arch, bovine configuration or difficult left common carotid origin.
6. Remove the wire, aspirate and flush the catheter, then perform a gentle manual test injection. Confirm stable position, brisk antegrade flow and absence of contrast stagnation, reflux, dissection or pain before power injection.
7. Obtain AP and lateral projections with the head immobilized and the detector close to the patient. A typical adult internal carotid or vertebral injection is approximately 6–8 mL at 3–5 mL/s, but reduce the rate for smaller vessels and tailor every injection to catheter position and haemodynamics. Continue acquisition through the venous phase when evaluating shunts or venous drainage.Pearl: For AVM or dural fistula assessment, premature termination before the venous phase can miss dangerous venous restriction or cortical venous reflux.
8. Use oblique, magnified or selective external carotid views to separate overlapping branches and define lesion anatomy. Perform 3D rotational angiography when precise aneurysm neck, branch incorporation or complex vascular relationships cannot be resolved on planar DSA.
9. Confirm that the study answers the clinical question and adequately shows the relevant arterial, capillary and venous phases. Before removing the catheter, review for new occlusion, dissection, vasospasm or contrast extravasation and repeat the neurological examination.Pearl: A technically complete angiogram is not merely successful vessel selection; it must establish or exclude the suspected pathology.
10. Remove the catheter and sheath when clinically appropriate. Obtain femoral haemostasis using manual compression or a closure device, or radial patent haemostasis using a compression band. Recheck the access site and distal perfusion before transfer.

Complications

• Thromboembolic TIA or stroke
• Iatrogenic cervicocerebral arterial dissection or perforation
• Access-site haematoma or retroperitoneal haemorrhage
• Femoral pseudoaneurysm or arteriovenous fistula, reported major-event rate 0.01–0.22%
• Access-artery occlusion and limb ischaemia, reported major-event rate 0–0.4%
• Allergic-like or physiologic iodinated-contrast reaction
• Post-contrast acute kidney injury
• Radial-artery occlusion

Exam pearls

• DSA is a technique; diagnostic cerebral angiography is the complete selective catheter examination and interpretation.
• Four-vessel angiography evaluates both internal carotid and both vertebral arteries; six-vessel angiography adds both external carotid arteries.
• Never power-inject until a gentle test injection confirms a non-wedged catheter, stable position and unrestricted antegrade flow.
• For AVM or dural fistula assessment, the venous phase is as important as the arterial phase.
• The key stroke-prevention triad is gentle manipulation, meticulous aspiration and flushing, and an air-free continuously flushed system.
• A Simmons catheter is high yield for a type III arch, bovine configuration or difficult left common carotid selection.
• New neurological symptoms during or after angiography are a stroke emergency until proved otherwise.

Viva questions

Why is catheter cerebral angiography still considered the reference standard?

It provides the highest spatial and temporal resolution, selective vessel assessment and direct visualization of arterial, capillary and venous phases. It is especially valuable for small aneurysms, collateral circulation and the haemodynamics of AVMs or dural fistulas.

What is the difference between four-vessel and six-vessel cerebral angiography?

Four-vessel angiography consists of bilateral internal carotid and bilateral vertebral injections. Six-vessel angiography adds bilateral external carotid injections, which are essential when evaluating dural fistulas, vascular malformations and hypervascular tumours.

What is the most feared complication and how do you prevent it?

The most feared complication is thromboembolic stroke. Prevention requires continuous air-free heparinized flushing, aspiration and flushing after wire removal or catheter exchange, gentle catheter manipulation, avoidance of diseased plaque and repeated neurological assessment.

Which catheter is useful in a type III aortic arch?

A Simmons 2 or another reverse-curve catheter is commonly useful because its secondary curve provides support for selecting superiorly directed great-vessel origins. It must be reformed and manipulated under fluoroscopy without force.

Why should a diagnostic cerebral angiogram include the venous phase?

The venous phase defines drainage pattern, stenosis, outflow obstruction and cortical venous reflux. These findings are essential for classifying AVMs and dural fistulas and estimating haemorrhagic risk.

How is carotid stenosis measured by the NASCET method?

Percentage stenosis equals **1 minus the minimum residual lumen divided by the normal distal cervical ICA lumen, multiplied by 100**. The distal reference artery must be beyond the bulb where the walls are parallel.

What should you do if contrast stagnates during a test injection?

Stop injecting immediately because the catheter may be wedged or the vessel may be in spasm or dissected. Withdraw to a larger-calibre segment and exclude injury with a gentle proximal injection before proceeding.

What is the immediate response to a new neurological deficit during angiography?

Stop the diagnostic study, stabilize airway and haemodynamics, perform a focused neurological examination and identify an angiographic occlusion or dissection. Activate the institutional stroke and neurointerventional rescue pathway without delay.

References