Diagnosis and Tests

MRI Scan: Complete Guide, Safety (No Radiation) & Procedure

Published: 14 February 2026 - 15:00 | Update: 15 February 2026 - 11:08

# Imaging Tests

MRI Scan: Complete Guide, Safety (No Radiation) & Procedure

💡 What You Need to Know Right Away

An MRI scan is an imaging test that uses magnetic fields and radio waves to create detailed pictures of your organs, bones, and tissues, helping doctors detect tumors, strokes, injuries, and infections without radiation.

Also known as: Magnetic Resonance Imaging, MR imaging, Nuclear Magnetic Resonance imaging, NMR imaging

In people with suspected stroke, a specific MRI sequence correctly detected stroke in 9 to 10 out of 10 cases[Evidence: A]^[10]
In people with suspected herniated disc in the lower back, MRI correctly identified disc herniation in about 9 out of 10 cases[Evidence: A]^[5]
In people with severe kidney disease receiving newer MRI contrast agents, serious complications occurred in 0 out of nearly 5,000 cases[Evidence: A]^[11]
Research shows cardiac MRI is the most accurate test for measuring how well the heart pumps blood[Evidence: A]^[6]

If your doctor has recommended an MRI scan, you probably have questions. It's normal to feel anxious about medical tests, especially ones involving loud machines and enclosed spaces. The good news is that MRI is one of the safest and most accurate imaging tests available, with no radiation exposure.

This guide explains what MRI actually feels like, how to prepare, and what the results mean. Whether you're worried about claustrophobia, curious about costs, or just want to understand what to expect, you'll find clear, evidence-based answers below.

❓ Quick Answers

What is an MRI scan used for?

An MRI scan creates detailed images of soft tissues, organs, and bones to help doctors diagnose conditions. It detects brain tumors, strokes, herniated discs, joint injuries, heart problems, and cancer. In people with suspected herniated disc, MRI correctly identified the problem in about 9 out of 10 cases[Evidence: A]^[5].

Is MRI scan safe?

MRI is very safe because it uses magnetic fields and radio waves instead of radiation. In people with severe kidney disease receiving newer contrast agents, serious complications occurred in 0 out of nearly 5,000 cases[Evidence: A]^[11]. Clinical guidelines recommend comprehensive safety screening before MRI, including checking for metallic implants[Evidence: D]^[14].

How long does an MRI take?

Most MRI scans take 30 to 60 minutes, depending on the body part being imaged. Brain scans typically take 30-45 minutes. Spine scans take 45-60 minutes. Knee or shoulder scans are faster at 20-30 minutes. Add 10-15 minutes if contrast dye is needed. You must remain completely still during the scan.

What can an MRI detect?

MRI detects soft tissue abnormalities with high accuracy. In people being tested for prostate cancer, MRI with PI-RADS score of 3 or higher correctly detected cancer in over 95 out of 100 cases when present[Evidence: A]^[8]. It also detects multiple sclerosis lesions, brain metastases, uterine tumors, and spinal cord injuries.

Can I eat before an MRI?

For most MRI scans, you can eat and drink normally. Exceptions include abdominal or gallbladder scans (MRCP), which may require 4-6 hours of fasting. Your imaging center will provide specific instructions when you schedule. Continue taking regular medications unless otherwise directed.

Why is MRI so loud?

MRI machines produce loud knocking and banging sounds reaching 100 decibels, similar to a jackhammer. This noise comes from the rapid switching of magnetic field gradients inside the scanner. Earplugs or headphones are provided to reduce noise by 20-30 decibels. Many centers offer music during the scan.

MRI with contrast vs without contrast?

Contrast MRI uses gadolinium dye injected into a vein to enhance image quality. Studies indicate newer Group II contrast agents are very safe, with the upper risk estimate for serious complications below 1 in 1,000 cases[Evidence: A]^[11]. About 85% of MRIs are performed without contrast. Your doctor decides based on what they need to see.

Medical Guide

MRI Scan

A comprehensive guide to understanding Magnetic Resonance Imaging. Learn about the process, safety protocols, and what to expect before, during, and after your examination.

Scientific Overview

Interactive Learning Module

🔬 How Does an MRI Work?

Think of your body as containing trillions of tiny compasses. These compasses are hydrogen atoms in the water that makes up about 60% of your body. Normally, these atomic compasses point in random directions. But when you enter the MRI scanner, its powerful magnetic field makes all these compasses line up in the same direction, like iron filings near a magnet.

The scanner then sends radio waves through your body. These waves cause the lined-up hydrogen atoms to wobble. When the radio waves stop, the atoms release energy as they return to their original position. The scanner detects this released energy and uses it to create detailed images.

Different tissues contain different amounts of water and release energy at different rates. This is why MRI excels at showing soft tissue detail. Fat, muscle, tendons, brain tissue, and tumors all appear differently on the image, allowing radiologists to identify abnormalities.

Research shows cardiac MRI is the most accurate test for measuring how well the heart pumps blood[Evidence: A]^[6]. In healthy men, normal heart pumping function measured by MRI ranges from about 52% to 73%[Evidence: A]^[7]. In healthy women, the normal range is about 54% to 75%[Evidence: A]^[7].

The scanner is essentially a giant, very precise listening device. It hears the signals your hydrogen atoms send back and translates them into pictures your doctor can read.

🧪 What to Expect: The Real User Experience

During the Procedure

When you enter the MRI room, you'll notice it's kept cool at 65-68°F to prevent the equipment from overheating. You may feel cold in the hospital gown. You'll lie on a narrow table that slides into a tunnel about 23-26 inches wide. For brain scans, a helmet-like head coil is placed around your head, which feels confining but isn't painful. Foam supports and wedges keep your body still.

The noise is the most striking sensation. The machine makes loud knocking, thumping, and banging sounds reaching 100 decibels, similar to a jackhammer or motorcycle engine. Some sequences cause the table to vibrate, which you can feel in your chest and bones. You'll wear earplugs or headphones, and a technologist communicates with you through an intercom between sequences every 3-5 minutes.

If you receive contrast dye, expect a brief needle prick similar to a blood draw, followed by a warmth sensation at the injection site lasting 10-15 seconds. Some people notice a metallic taste that lasts 15-30 minutes.

What You'll Feel After

After the scan, you may notice mild ear ringing from the noise exposure, which typically resolves within hours. If you lay still for more than 45 minutes, expect some back, neck, or joint stiffness. Fatigue from the stress of the procedure is normal. If you had contrast, the injection site may be slightly sore for 1-2 days.

How to Make It Easier

For the noise: Ask for earplugs AND headphones with music for double protection
If claustrophobic: Request an open MRI or wide bore (70cm) scanner if available
To stay calm: Close your eyes before entering the tunnel and practice slow, deep breathing (4 seconds in, 6 seconds out)
If you need to stop: You'll have an emergency squeeze ball that immediately stops the scan and brings the technologist to you
For comfort: Ask for a blanket if you get cold, and use the bathroom immediately before your scan
For severe anxiety: Ask your prescribing doctor about sedation medication before your appointment (not the MRI center)

📊 Preparation and Procedure

Before Your Appointment

Arrive 30 minutes early to complete paperwork
Bring your insurance card, photo ID, and prescription/referral
List all medications you currently take
Inform staff about any metal implants, devices, or foreign objects in your body
Bring previous imaging results if available

What to Wear

Loose clothing without metal zippers, buttons, or underwire
Remove all jewelry, watches, hairpins, hearing aids, and glasses
Remove medication patches, glucose monitors, and metal-containing makeup
The facility may provide a hospital gown

MRI Duration by Body Part

Body Part	Average Duration	Notes
Brain	30-45 minutes	Add 10 minutes if contrast used
Spine (cervical, thoracic, lumbar)	45-60 minutes	Cervical tends to be faster than lumbar
Knee or Shoulder	20-30 minutes	Among the fastest MRI scans
Abdomen/Pelvis	45-75 minutes	Requires breath-holding during sequences
Cardiac	45-90 minutes	Complex imaging with multiple sequences
Whole Body	60-90 minutes	Screening scan covering multiple regions

What Happens During the Scan

The technologist positions you on the scanner table with foam supports to keep you comfortable and still. The table slides into the scanner bore. You must remain completely motionless during imaging sequences, which last 2-5 minutes each. Between sequences, you can relax slightly. The technologist communicates through an intercom and can see you through a window at all times.

⚠️ Risks, Side Effects, and Warnings

The MRI scan itself is painless. Unlike CT scans or X-rays, MRI uses no ionizing radiation. The magnetic fields and radio waves have no known harmful effects on the body. It's normal to feel anxious about medical tests, but most people tolerate MRIs well.

Common Experiences (Not Side Effects)

Noise discomfort: The loud sounds can be startling. Earplugs or headphones are always provided.
Claustrophobia: About 15% of patients feel anxious in the enclosed space. Open MRI reduces claustrophobia rates significantly.
Lying still: Remaining motionless for 30-60 minutes can cause stiffness.
Warmth: Some patients feel mild warmth during the scan from the radio waves.

Contrast-Related Reactions

If you receive gadolinium contrast dye:

Common (mild): Injection site soreness, brief warmth, metallic taste lasting 15-30 minutes
Uncommon: Headache, nausea, dizziness (resolve within hours)
Rare: Allergic-type reactions (hives, shortness of breath) occur in approximately 0.04-0.4% of patients

Expert consensus confirms Group II contrast agents are safer for people with kidney disease, with specific dosing protocols based on kidney function. In people with severe kidney disease receiving newer Group II contrast agents, nephrogenic systemic fibrosis (a rare skin condition) occurred in 0 out of nearly 5,000 cases, with the upper risk estimate below 1 in 1,000[Evidence: A]^[11].

🥗 Practical Ways to Prepare for Your MRI

The Day Before

Confirm your appointment time and arrive 30 minutes early
If you're anxious, practice the deep breathing technique: 4 seconds in through your nose, 6 seconds out through your mouth
Prepare loose, comfortable clothing without metal
Gather your insurance card, ID, and referral paperwork

Managing Anxiety

Many people worry about claustrophobia. Here are evidence-based strategies:

Request an open MRI: If your facility offers it, open MRI machines have sides open to the room
Ask for a wide bore scanner: 70cm opening instead of standard 60cm provides more space
Close your eyes before entering: Prevents the visual trigger of seeing the tunnel
Focus on breathing: Counting breaths gives your mind something to focus on
Use the emergency button: Knowing you can stop anytime reduces anxiety
Request sedation: For severe anxiety, ask your prescribing doctor about oral medication before your appointment

What NOT to Do

Don't forget to remove metal: Check pockets for keys, coins, phones. Remove all jewelry.
Don't skip the screening questionnaire: Detailed answers protect your safety.
Don't assume you can't have MRI: Many implants are MRI-safe. Bring documentation of your device.
Don't hold your breath (unless asked): Breathe normally. The technologist will tell you when breath-holding is needed.

What to Look for When Choosing an MRI Provider

The quality of your MRI results depends on the equipment, facility, and radiologist interpreting your images. Here's what to consider:

Facility Quality Markers

ACR Accreditation: American College of Radiology accreditation indicates quality standards Why it matters: ACR-accredited facilities meet rigorous equipment and personnel requirements
Scanner Strength: 1.5 Tesla is standard; 3 Tesla provides higher resolution for brain, spine, and joint imaging Why it matters: Higher field strength can mean better image quality for certain conditions
Board-Certified Radiologists: Verify radiologists are board-certified with subspecialty training if needed Why it matters: Subspecialists in neuroradiology, musculoskeletal radiology, or cardiac imaging may provide more accurate reads
Turnaround Time: Ask about typical results timeline (1-2 days for routine, 24-48 hours for urgent) Why it matters: Faster results enable quicker treatment decisions

Questions to Ask Before Scheduling

Is your facility ACR accredited?
What Tesla strength is your scanner? Do you have open MRI or wide bore options?
Who will interpret my images, and what are their subspecialty qualifications?
How long until results are available?
What is the out-of-pocket cost with my insurance?
Do you offer sedation for claustrophobic patients?

Red Flags to Avoid

No accreditation: Unaccredited facilities may lack quality oversight
Unusually cheap pricing: May indicate outdated equipment or less experienced radiologists
No radiologist report: Images should always be interpreted by a board-certified radiologist
Pressure to add unnecessary tests: Your doctor should determine what imaging is needed

How MRI Compares to CT Scan: What to Know

MRI and CT scans are both valuable imaging tools, but they work differently and excel at different tasks. Your doctor chooses based on what they need to see and your specific situation.

Feature	MRI	CT Scan
How It Works	Magnetic fields and radio waves	X-rays from multiple angles
Radiation Exposure	None ✓	Low to moderate radiation dose
Typical Duration	30-60 minutes	5-15 minutes ✓
Best For	Soft tissues (brain, spine, joints, organs)	Bones, lungs, acute bleeding, emergencies
Noise Level	Loud (100 dB, requires ear protection)	Quiet
Claustrophobia Risk	Higher (enclosed tunnel)	Lower (open ring design) ✓
Metal Implants	Some restrictions (pacemakers, clips)	Generally no restrictions ✓
Emergency Use	Limited (takes longer)	Preferred for emergencies ✓

When MRI Is Better

Brain and spinal cord: In people with suspected stroke, MRI (DWI sequence) correctly detected stroke in 9 to 10 out of 10 cases[Evidence: A]^[10]
Joint injuries: In people with torn ACL, MRI correctly ruled out meniscal tears in about 9 out of 10 cases when not present[Evidence: A]^[4]
Multiple sclerosis: Clinical guidelines now recommend including the optic nerve as a fifth location when diagnosing MS with MRI[Evidence: D]^[12]
Soft tissue tumors: In women with uterine masses, MRI correctly identified the difference between benign tumors and cancer in 9 out of 10 cases[Evidence: A]^[3]

When CT Is Better

Emergency situations: CT takes 5-15 minutes versus 30-60 for MRI
Bone fractures: CT provides excellent bone detail
Lung imaging: CT is preferred for lung nodules and pneumonia
Patients with pacemakers: CT has no magnetic field restrictions

What The Evidence Shows (And Doesn't Show)

What Research Suggests

MRI is highly accurate for detecting soft tissue abnormalities, with sensitivity ranging from 70% to 96% depending on the condition being diagnosed^[1-10]
In people with suspected stroke, MRI (DWI sequence) correctly detected stroke in 9 to 10 out of 10 cases[Evidence: A]^[10]
Cardiac MRI is established as the reference standard for measuring heart pumping function, with normal left ventricular ejection fraction ranging 52-73% in men and 54-75% in women[Evidence: A]^[6]^[7]
Newer Group II gadolinium contrast agents show excellent safety profile, with 0 cases of nephrogenic systemic fibrosis in nearly 5,000 patients with severe kidney disease[Evidence: A]^[11]
Machine learning-enhanced MRI improved diagnostic accuracy for breast cancer detection, achieving 86% sensitivity and 90% overall diagnostic performance[Evidence: A]^[1]

What's NOT Yet Proven

100% detection is not guaranteed: About 7 out of 100 people with stroke may have normal initial MRI, particularly for posterior circulation strokes[Evidence: A]^[10]
Sensitivity varies by condition: MRI for meniscal tears in ACL-deficient knees has 70% sensitivity, meaning 3 out of 10 tears may be missed[Evidence: A]^[4]
PI-RADS specificity is moderate: Prostate MRI with PI-RADS ≥3 has 43% specificity, meaning more than half of positive findings may not be cancer[Evidence: A]^[8]
Long-term prognostic value: Early research suggests MRI findings predict long-term outcomes in MS patients, but individual variation is significant[Evidence: C]^[17]

Where Caution Is Needed

Contrast in kidney disease: While Group II agents are safer, expert consensus still recommends specific dosing protocols based on kidney function
Metal implant screening: Comprehensive safety screening is essential. Ferromagnetic materials can move or heat in the magnetic field[Evidence: D]^[14]
Clinical correlation required: MRI findings must be interpreted in context with clinical symptoms. Not all abnormalities seen on MRI cause symptoms.
Operator and reader variability: Image quality and interpretation accuracy depend on technologist skill and radiologist expertise

Should YOU Get an MRI?

Best suited for: People with suspected soft tissue injuries, neurological symptoms, unexplained pain, or conditions requiring detailed imaging of brain, spine, joints, or organs. Clinical guidelines provide evidence-based recommendations for when MRI is appropriate across over 200 medical conditions.

Not recommended for: People with ferromagnetic aneurysm clips, non-MRI-safe pacemakers, or metallic foreign bodies in the eyes. Consult with your physician if you have any implanted devices.

Realistic timeline: Most scans take 30-60 minutes, with results available in 1-2 business days. Urgent findings are communicated within 24-48 hours.

When to consult a professional: Your doctor should order MRI based on clinical need. If you're unsure whether MRI is right for your situation, discuss the potential benefits and alternatives with your healthcare provider.

Frequently Asked Questions

Can I have an MRI with metal implants?

It depends on the type of implant. Titanium joint replacements, most dental work, and surgical plates are generally MRI-safe. However, ferromagnetic cerebral aneurysm clips, metallic eye foreign bodies, and older pacemakers/ICDs may be contraindicated. Clinical guidelines recommend comprehensive safety screening, including checking all metallic implants. Always bring documentation of your implant to your appointment. Modern pacemakers are often 'MRI-conditional,' meaning they can be scanned under specific protocols.

Is MRI safe during pregnancy?

MRI without contrast is generally considered safe during pregnancy and may be used when the diagnostic information is needed. Unlike X-rays and CT scans, MRI uses no ionizing radiation. Gadolinium contrast agents are typically avoided during pregnancy as a precaution, although evidence of harm is limited. Your doctor will weigh the benefits of the information needed against any theoretical risks. If MRI is medically necessary, it can be performed in any trimester.

What is an open MRI and should I request one?

Open MRI machines have open sides instead of an enclosed tunnel, reducing claustrophobia significantly. They're an excellent option if you're anxious about enclosed spaces. The trade-off is that open MRIs typically use lower magnetic field strength (0.3-1.0 Tesla versus 1.5-3.0 Tesla for closed), which may produce slightly less detailed images for some conditions. For many routine scans, open MRI provides adequate image quality. Discuss with your doctor whether open MRI is appropriate for your specific diagnostic needs.

Can I have an MRI with a tattoo?

Modern tattoo inks are generally MRI-safe. Older tattoos (before 1990s) or those with metallic-based inks may cause mild warmth or tingling during the scan, but serious reactions are rare. If you have concerns, inform the technologist before your scan. They may place an ice pack over the tattoo as a precaution. Tattoos do not prevent you from having an MRI.

How much does an MRI cost?

MRI costs vary widely depending on the body part scanned, facility type, and insurance coverage. Without insurance, prices range from $400 to $3,000 at imaging centers, and up to $12,000 at hospitals. With insurance, typical out-of-pocket costs range from $100 to $500 depending on your deductible and coinsurance. Freestanding imaging centers are often 40-60% less expensive than hospital-based facilities for the same scan. Ask for pricing before scheduling.

How long does it take to get MRI results?

For routine scans, expect results within 1-2 business days. The radiologist reviews the images and sends a written report to your ordering physician. For urgent findings (such as suspected stroke or tumor), the radiologist typically contacts your doctor within 24-48 hours or immediately for critical findings. Ask your doctor when to expect a call about your results. Many facilities also provide patient portal access to imaging reports.

What happens if I move during an MRI?

Movement during MRI sequences causes blurred images. The technologist may need to repeat that particular sequence, extending your total scan time. Minor movements between sequences (when the machine is quiet) are acceptable. If you feel you cannot remain still, communicate with the technologist through the intercom. For patients who have difficulty staying still, sedation may be an option. Children under 7 typically require sedation because they cannot remain motionless for 30-60 minutes.

Can children have an MRI?

Yes, MRI is safe for children of all ages. The challenge is keeping them still during the scan. Children under 7 typically need sedation or general anesthesia to remain motionless for 30-60 minutes. Many pediatric centers use child life specialists who prepare children with age-appropriate explanations and distraction techniques. Some facilities offer 'mock MRI' experiences where children can practice before their actual scan. For older children, headphones with music or movie goggles can help.

How accurate is an MRI scan?

MRI accuracy varies by condition. In people with suspected herniated disc, MRI correctly identified disc herniation in about 9 out of 10 cases. For prostate cancer, MRI with PI-RADS 5 lesions shows cancer in about 84 out of 100 cases. However, about 7 out of 100 people with stroke may have normal initial MRI results, particularly when stroke affects the back of the brain. MRI is one of the most accurate imaging tests available, but no test is 100% accurate.

Can I have an MRI if I'm claustrophobic?

Yes. About 15% of patients experience some claustrophobia during MRI, but most complete the scan successfully. Options include: open MRI (open sides, less confinement), wide bore scanners (70cm vs 60cm opening), sedation medication (ask your prescribing doctor beforehand), breathing techniques, blindfolds or eye masks (prevents seeing the tunnel), and having a support person in the room. The emergency button allows you to stop the scan at any time. Most people find that knowing they can stop helps reduce anxiety.

Our Accuracy Commitment and Editorial Principles

At Biochron, we take health information seriously. Every claim in this article is supported by peer-reviewed scientific evidence from reputable sources published in 2015 or later. We use a rigorous evidence-grading system to help you understand the strength of research behind each statement:

[Evidence: A] = Systematic review or meta-analysis (strongest evidence)

[Evidence: B] = Randomized controlled trial (RCT)

[Evidence: C] = Cohort or case-control study

[Evidence: D] = Expert opinion or clinical guideline

Our editorial team follows strict guidelines: we never exaggerate health claims, we clearly distinguish between correlation and causation, we update content regularly as new research emerges, and we transparently note when evidence is limited or conflicting. For our complete editorial standards, visit our Editorial Principles page.

This article is for informational purposes only and does not constitute medical advice. Always consult qualified healthcare professionals before making changes to your health regimen, especially if you have medical conditions or take medications.

References

Medical Disclaimer

This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers are advised to consult their doctors or qualified health professionals regarding specific health questions and before making any changes to their health routine, including starting new supplements.

Neither Biochron nor the author takes responsibility for possible health consequences of any person reading or following the information in this educational content. All readers, especially those taking prescription medications, should consult their physicians before beginning any nutrition, supplement, or lifestyle program.

If you have a medical emergency, call your doctor or emergency services immediately.

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