Understanding Your MRI - A Patient's Complete Guide

Your doctor has ordered an MRI scan—a powerful imaging tool that helps diagnose conditions affecting your eyes, optic nerves, and brain. If you've never had an MRI before, or if you're nervous about the procedure, this guide will explain what to expect and help you prepare.

What Is an MRI?

MRI stands for Magnetic Resonance Imaging. It creates detailed pictures of the inside of your body using:

• A powerful magnet
• Radio waves
• Computer processing

Unlike CT scans, MRI doesn't use ionizing radiation, making it very safe for most people.

Why Your Doctor Ordered an MRI

In neuro-ophthalmology, MRI of the brain and orbits is commonly used to evaluate:

Optic Neuritis

• Shows inflammation of the optic nerve
• Reveals brain lesions that suggest MS risk
• Helps distinguish from other causes of vision loss

Pituitary Tumors

• Visualizes tumors pressing on the optic nerves
• Shows extent and relationship to surrounding structures
• Essential for treatment planning

Idiopathic Intracranial Hypertension (IIH)

• Rules out other causes of papilledema
• May show characteristic signs of elevated pressure
• Includes MRV to check the brain's veins

Other Conditions

• Brain tumors affecting vision
• Strokes involving visual pathways
• Aneurysms (may require MRA)
• Inflammatory conditions
• Thyroid eye disease (orbital MRI)

Types of MRI Scans

MRI Brain and Orbits

The most common MRI in neuro-ophthalmology:

• Images the brain, optic nerves, and eye sockets
• Special sequences highlight the optic nerves
• Usually includes contrast (gadolinium)

MRA (Magnetic Resonance Angiography)

• Focuses on blood vessels
• Shows arteries in the brain
• Used to look for aneurysms or vessel abnormalities

MRV (Magnetic Resonance Venography)

• Images the veins draining the brain
• Important in IIH evaluation
• Checks for blood clots or narrowing

With and Without Contrast

• Without contrast: Basic MRI images
• With contrast (gadolinium): Injected into a vein, highlights certain abnormalities like inflammation, tumors, and active disease

Preparing for Your MRI

Before Your Appointment

Scheduling considerations:

• Appointment typically lasts 30-60 minutes (longer for multiple types)
• Arrive 15-30 minutes early for check-in
• Wear comfortable clothes without metal (or change into a gown)

Important to tell the scheduling team:

• If you have claustrophobia or anxiety
• Any implanted devices
• If you're pregnant or might be pregnant
• Kidney problems (relevant for contrast)
• Previous allergic reactions to contrast

Metal Safety

The MRI magnet is extremely powerful. You cannot have an MRI if you have:

• Older cardiac pacemakers (newer ones may be MRI-safe—check with your cardiologist)
• Certain cochlear implants
• Some types of brain aneurysm clips
• Metal fragments in your eyes (from welding, etc.)
• Certain implanted pumps

Safe in MRI (usually):

• Joint replacements
• Dental fillings
• Most stents and filters (check timing since placement)
• Newer cardiac devices (need verification)

When in doubt, inform the MRI team—they'll verify safety.

What to Bring

• Insurance card and photo ID
• List of medications
• List of implants/surgeries
• Previous MRI images if done elsewhere (on CD or uploaded)
• Reading material or headphones for waiting

What to Leave Home

• Watches, jewelry, piercings
• Credit cards (magnet can erase them)
• Hearing aids
• Coins, keys, cell phones

Managing Claustrophobia

Many people feel anxious about MRI, especially lying in a narrow tube. Here's how to cope:

Before Your Scan

Ask about an open MRI: These machines have more open designs, though image quality may be lower.

Request medication: Your doctor can prescribe a mild sedative (like lorazepam or alprazolam) to take before the scan. You'll need someone to drive you.

Visit the facility beforehand: Some centers allow you to see the machine and practice lying down.

Practice relaxation techniques: Deep breathing, visualization, and progressive muscle relaxation help.

During the Scan

Keep your eyes closed: Many people find this easier than seeing the tight space.

Use the call button: You're given a squeeze ball that alerts the technologist immediately. Knowing you can stop gives control.

Listen to music: Most facilities offer headphones with music of your choice.

Focus on breathing: Slow, deep breaths activate your calm response.

Count or visualize: Mental activities distract from anxiety.

Remember it's temporary: Scans typically last 20-40 minutes. Each sequence is just a few minutes.

What Happens During the MRI

Arrival and Check-In

1. Complete safety questionnaire about metal implants
2. Remove all metal objects and possibly change into a gown
3. Secure belongings in a locker
4. Review any concerns with the technologist

The Scanning Process

1. Positioning: You lie on a padded table, usually face-up
2. Head coil: For brain scans, a frame is placed around your head (doesn't touch your face)
3. Table movement: Slides you into the scanner
4. Holding still: Essential for clear images—even small movements blur the pictures
5. Sounds: MRI is loud—knocking, buzzing, and thumping sounds. Earplugs or headphones are provided
6. Communication: Two-way intercom lets you talk to the technologist

If Contrast Is Used

• An IV is placed in your arm before or during the scan
• Gadolinium contrast is injected midway through
• You may feel cool or warm sensation briefly
• Allergic reactions are rare but possible

After the Scan

• No recovery time needed (unless sedated)
• You can eat, drink, and drive normally
• If you received contrast, drink extra water to flush it out
• Results are usually sent to your doctor within a few days

Understanding Your Results

The MRI produces many images that a radiologist (imaging specialist) interprets. Your doctor then explains what the findings mean for your condition.

Common Findings in Neuro-Ophthalmology

White Matter Lesions

• Bright spots on certain MRI sequences
• Can indicate MS, small vessel disease, or other conditions
• Location and pattern help determine significance

Optic Nerve Enhancement

• The optic nerve "lights up" with contrast
• Indicates active inflammation (optic neuritis)

Optic Nerve Atrophy

• Thinned optic nerve from previous damage
• Does not enhance with contrast

Brain Tumors

• Masses with various characteristics
• Location determines visual and other symptoms

Empty Sella

• Flattened pituitary gland
• Often associated with IIH

Venous Sinus Stenosis

• Narrowing of brain drainage veins
• Common in IIH

What If Findings Are Abnormal?

Don't panic if your MRI shows something abnormal. Many findings are:

• Incidental (present but unrelated to your symptoms)
• Benign (not dangerous)
• Treatable

Your doctor will explain what the findings mean for you specifically and what, if anything, needs to be done.

Getting a Second Opinion

If you want another interpretation:

• Request a copy of your images (usually on CD or through a portal)
• Images can be reviewed by another radiologist
• Your doctor may consult with specialists

Special Situations

Pregnancy

• MRI does not use radiation and is generally considered safe in pregnancy
• Gadolinium contrast is avoided during pregnancy when possible
• Discuss the necessity with your doctor if you're pregnant

Kidney Disease

• Gadolinium contrast is processed by the kidneys
• In severe kidney disease, a rare reaction (nephrogenic systemic fibrosis) can occur
• Blood tests may be needed to check kidney function before contrast

Anxiety Disorders

• Let the team know if you have diagnosed anxiety
• Medication, support person (sometimes), and breaks can help
• Some patients do best with general anesthesia, though this requires special arrangements

Children

• May need sedation to remain still
• Pediatric MRI protocols minimize scan time
• Parent can usually stay in the room (after metal screening)

Frequently Asked Questions

Is MRI safe?

Yes, MRI is very safe for most people. It doesn't use radiation. The main risks are related to metal implants and, rarely, reactions to contrast dye.

How long does an MRI take?

Brain MRI typically takes 30-45 minutes. With orbits, MRA, or MRV, it may take up to an hour. More complex protocols can be longer.

Why is it so loud?

The knocking sounds are created by the rapid switching of magnetic gradients. It's a normal part of how MRI creates images. Earplugs or music help.

Can I bring someone into the room?

Usually yes, as long as they pass metal screening. They must also remove all metal objects. This can be helpful for anxious patients.

What if I can't finish the scan?

The technologist can pause the scan and give you a break. If you're too uncomfortable, the scan can be stopped—your health comes first. Discuss options with your doctor if this happens.

Will I feel anything?

The scan itself is painless. You'll hear loud noises and may feel some warmth. If contrast is given, you might feel a cool sensation during injection. Some people experience tingling from the magnetic field—this is normal.

How do I get my results?

Results go to your ordering doctor, usually within 1-3 days. Some facilities offer patient access to reports through online portals. Always discuss results with your doctor rather than interpreting them yourself.

Can I have an MRI if I'm claustrophobic?

Yes. Options include medication, open MRI machines, and coping techniques. Many claustrophobic patients successfully complete MRIs with proper preparation.

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