What it is (overview)

An MRI Head Angio with/without contrast (also called MR angiography or MRA of the brain) is a non-invasive imaging test that uses a strong magnetic field and radio waves to create detailed pictures of the brain blood vessels. Unlike an X-ray or CT scan, MRI does not use ionizing radiation. The goal of head angiography is to look closely at the arteries (and sometimes veins) that supply the brain to check for narrowing, bulges, blockages, or abnormal connections.

The “with/without contrast” part means the exam may be performed using one or both of these approaches:

• Without contrast: Many MR angiography techniques can show blood flow and vessel shape without any injection. This is often sufficient to screen for certain vascular abnormalities.
• With contrast: A contrast agent (usually a gadolinium-based dye) may be injected through an IV to make the blood vessels appear even clearer and to improve detail—especially for small vessels or complex findings.

What it measures/looks for: This test evaluates the structure of the vessels (their size and shape) and blood flow patterns. It helps detect issues such as an aneurysm (a weak, bulging area in a vessel), stenosis (narrowing), occlusion (blockage), or vascular malformations (unusual vessel connections).

What the results mean in plain language:

• Normal/negative: The major brain arteries look open and normal in shape, with no significant narrowing, blockage, or abnormal bulges.
• Narrowing (stenosis): One or more vessels are tighter than expected, which can reduce blood flow and increase stroke risk.
• Blockage (occlusion): A vessel may be partly or fully blocked, which may correlate with stroke symptoms or transient ischemic attack (TIA) concerns.
• Aneurysm seen: A bulge in a vessel wall is detected; the report typically describes its size and location to guide monitoring or treatment.
• Vascular malformation: An abnormal tangle or connection of blood vessels may be present and may require specialist review.

When & why it's usually done

Doctors order an MRI/MRA head imaging exam when they need a detailed look at the brain’s circulation—often to investigate symptoms, confirm a suspected diagnosis, or monitor a known vascular condition. It is commonly used for stroke detection and to evaluate possible causes of neurological symptoms.

This test may be recommended if you have:

• Stroke-like symptoms such as sudden weakness or numbness on one side, facial droop, trouble speaking, confusion, or sudden vision changes
• Transient ischemic attack (TIA) (“mini-stroke”) symptoms that resolved but need urgent evaluation
• Severe or unusual headaches, including “worst headache of your life,” sudden-onset thunderclap headache, or headaches with neurological changes
• Dizziness, balance problems, or fainting when a vascular cause is suspected
• Unexplained neurological symptoms (e.g., seizures, new neurologic deficits) where a blood vessel abnormality is possible

It’s also often done if you have known risk factors or prior findings, such as:

• Known or suspected brain aneurysm, or a family history of aneurysms/hemorrhagic stroke
• Known vascular abnormalities (e.g., arteriovenous malformation) needing follow-up
• Carotid or intracranial artery disease, high blood pressure, diabetes, high cholesterol, or smoking history—especially when symptoms suggest reduced brain blood flow
• Monitoring after treatment (e.g., aneurysm coiling/clipping, stenting, or other vascular procedures) to confirm vessel patency and blood flow

Why contrast may be used: Adding a contrast agent can improve visualization of smaller vessels and complex anatomy, help clarify questionable areas seen on non-contrast images, and sometimes better define vascular malformations or post-treatment changes.

Common diseases related to it

• Brain (intracranial) aneurysm
• Ischemic stroke
• Transient ischemic attack (TIA)
• Intracranial arterial stenosis (narrowing of brain arteries)
• Arteriovenous malformation (AVM)
• Dural arteriovenous fistula (dAVF)
• Cerebral vasculitis (inflammation of brain blood vessels)
• Carotid artery disease affecting brain blood flow
• Cerebral venous thrombosis (when venous imaging is included/considered)
• Moyamoya disease

Health goals where it may help

• Stroke prevention and risk assessment by identifying vessel narrowing or blockage early
• Evaluating neurological symptoms (headaches, vision changes, weakness, speech difficulty) to rule in/out vascular causes
• Monitoring known aneurysms or vascular malformations to guide treatment timing and follow-up
• Post-procedure follow-up after aneurysm repair or vascular stenting to confirm good blood flow
• Managing cardiovascular risk factors (high blood pressure, diabetes, high cholesterol, smoking) by assessing end-organ effects on brain blood vessels
• Peace of mind and targeted care planning when there is a strong family history of aneurysm or prior abnormal head imaging