Head and neck MR angiography

Comparison of methods: CTA, MRA, and DSA

CT angiography (CTA / CTA) is a key tool in emergency neurology. Unlike MR angiography (MRA / MRA), CT is performed significantly faster, does not cause issues in claustrophobic patients, and is completely safe in the presence of pacemakers. The method allows for simultaneously obtaining images from the superior mediastinum and lung apices to the brain parenchyma. The main disadvantages of CTA are ionizing radiation exposure and the mandatory use of iodinated contrast.

Digital subtraction angiography (DSA) is an invasive procedure with potential risks. It is used primarily for endovascular interventions (e.g., stenting for post-traumatic arterial dissection). Following successful aneurysm treatment with intrasaccular flow diverter devices, occlusion control at 6 months is usually performed using MRA.

CT venography and CT perfusion

To assess the venous system, CT venography (CTV / CTV) is used. It is performed with a mandatory prescanning delay. If a dual-source CT scanner is used, high-quality bone subtraction of the skull base structures can be achieved. CTV is indicated when thrombosis is suspected, for assessing the venous phase of vascular malformations, and in dural venous sinus invasion by tumors (falx meningiomas).

CT perfusion (CTP / CTP) is a routine standard in major stroke centers. Its main objective is to identify the zone of reversible ischemia, or penumbra, which can be salvaged via thrombolysis or thrombectomy. Additionally, perfusion is used to detect vasospasm following subarachnoid hemorrhage (usually a delayed phenomenon occurring after one week).

Vascular injury and Denver criteria

In acute blunt trauma, the need for CT or MR angiography is determined by the Denver criteria (Denver criteria). Vascular screening is indicated in:

• Le Fort type II or III facial fractures.
• Skull base fractures involving the carotid canal.
• Diffuse axonal injury with a Glasgow Coma Scale score < 6.
• Neck injuries involving the C1–C3 vertebrae or their foramen transversarium.
• Post-strangulation asphyxia.

Additionally, angiography is required if the patient presents with arterial bleeding, a cervical bruit under the age of 50, an expanding hematoma, or new neurological symptoms unexplained by standard CT findings. Clival fractures require special attention: high-energy axial loading carries the risk of basilar artery rupture, while transverse fractures threaten internal carotid artery injury.

Vascular screening in Horner syndrome

The development of oculosympathetic paresis requires precise lesion localization. The sympathetic pathway consists of three neurons, and the choice of imaging modality depends on the level:

1. 1st-order neurons (from the hypothalamus to the cervicothoracic junction): MRI of the brain and cervical spine is indicated.
2. 2nd- and 3rd-order neurons (C8-T2 ventral roots, lung apex, cavernous sinus, and orbit along the internal carotid artery): CTA from the aortic arch to the vertex becomes the gold standard. This allows for ruling out dissection, aneurysms, as well as lung apex or thyroid tumors.

Class and exam questions

What else to study on this topic

• Post-radiation neurotoxicity: MRI findings and classification
• Radiation necrosis of the cerebral white matter
• Neuroimaging of TBI using temporal bone fracture as an example
• Anatomical assessment of cranial nerves in ophthalmoplegia
• Differential diagnosis of congenital orbital pathologies (Coats disease

Other topics in the Neuroimaging section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.