Interventional neuroradiology

Main types of endovascular interventions

Interventional neuroradiologists use various techniques to treat vascular pathologies of the head and neck, utilizing digital subtraction angiography (DSA) as the primary imaging and guidance method.

• Ischemic stroke: thrombectomy is performed on an emergency basis for large vessel occlusion.
• Aneurysms: coil embolization (coiling), stenting, and deployment of flow-diverting devices (flow diversion) are used.
• Arteriovenous malformations (AVMs) and fistulas: treatment is carried out via embolization using specialized coils, medical glue, or other liquid agents.
• Arterial stenoses and vasospasm: intracranial and carotid artery stenting, angioplasty, or intra-arterial administration of vasodilators is performed.
• Tumors: preoperative embolization of vessels feeding the neoplasm significantly reduces blood loss during surgery.
• Venous pathology: venous interventions are performed for life-threatening sinus thrombosis, AVMs, and dural fistulas. In intracranial hypertension caused by dural sinus stenosis (identified by the pressure gradient during venous angiography), sinus stenting is possible.

Contraindications and risks of angiography

Absolute contraindications to cerebral angiography are practically nonexistent.

Significant limitations include:

1. Contrast anaphylaxis: an absolute contraindication if a severe reaction unresponsive to medical management is documented in the history.
2. Severe renal failure: considered a relative contraindication (in emergency cases, hemofiltration is performed after the procedure).

Anticoagulant therapy is not a contraindication for emergency endovascular interventions, but may be a reason to postpone elective procedures.

Specific risks of neck artery and aortic arch catheterization include cerebral thromboembolism, stroke, and vascular wall injury by the instrument (dissection, spasm, thrombosis). Special caution must be exercised in elderly patients with advanced atherosclerosis due to the high risk of embolic complications.

Computed tomography angiography (CTA)

CTA has revolutionized the diagnosis of vascular pathology. Modern multislice computed tomography (MSCT) scanners can assess the vascular bed from the aortic arch to the Circle of Willis or the convexital surface of the brain in a single scan.

Method features:

• Timing: automatic bolus tracking is used for optimal arterial opacification, allowing adjustment for individual blood flow velocity.
• Protocol: in stroke, 50–70 ml of contrast is typically injected at a rate of 4–5 ml/s, followed by a saline flush.
• Dual-energy CT: allows automatic bone removal from images, dramatically improving the visualization of complex vascular anatomy (e.g., at the skull base) and facilitating the evaluation of carotid plaques.

CTA is used in stroke to detect aneurysms in subarachnoid hemorrhage (sensitivity >90%), and to evaluate dissections, stenoses, and active contrast extravasation in intracerebral hematomas. Compared to MR angiography, CTA is faster and suitable for patients with claustrophobia and pacemakers, but involves radiation exposure and the administration of iodinated contrast.

CT venography (CTV) and CT perfusion (CTP)

In addition to the arterial phase, methods for assessing the venous bed and tissue perfusion are used.

CT venography: Performed similarly to CTA, but with a scan delay to opacify veins. Dual-source CT allows CTA and CTV to be obtained with a single contrast injection. The method is indicated for suspected cerebral venous thrombosis, tumor invasion (e.g., meningiomas) into the sinuses, evaluation of the venous phase of AVMs, and detection of dural sinus stenoses.

CT perfusion: The standard in acute stroke. The main goal of CTP is to identify the penumbra (zone of reversible ischemia), which can be salvaged via thrombectomy or thrombolysis. The method is also used to diagnose delayed vasospasm following subarachnoid hemorrhage and to assess cerebrovascular reserve (with acetazolamide administration).

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Clinical examples of aneurysm treatment (e.g., use of intrasaccular flow diverters)
• Post-processing and 3D reconstruction of DSA data
• Follow-up protocols after treatment of AVMs and aneurysms
• Vasospasm after subarachnoid hemorrhage: mechanisms and endovascular treatment
• Multiplanar reconstructions (MPR) in standard CTA

Other topics in the Neuroimaging section

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