Is MRI safe? Common myths, and the few real concerns

Every week we get the same anxious questions before a first MRI. Most are based on confusing MRI with CT or X-ray. Here's a quick myth-busting round with the real concerns separated from the imagined ones.

Myth 1: "MRI uses radiation"

False. MRI uses a strong magnetic field and radio waves. There is no ionising radiation involved. You can have an MRI scan every day for the rest of your life and it would not affect your cancer risk.

This is the single biggest advantage of MRI over CT and X-ray.

Myth 2: "The magnetic field damages your body"

False. Decades of MRI research have found no harmful long-term effects from the magnetic field on human tissue. Pregnant women have been scanned safely since the 1980s.

The only real concern with the magnet is physical — anything ferromagnetic in your body or pocket can move. That's why we screen carefully for metal beforehand.

Myth 3: "MRI can rearrange tooth fillings or dental implants"

Mostly false. Modern dental amalgams and titanium implants are non-magnetic and stay put. They may cause minor artefact (distortion) in nearby images but they don't move. Older steel orthodontic wires can heat slightly during a brain MRI — your orthodontist or our team will assess.

Myth 4: "The contrast dye is dangerous"

Mostly false, with one specific concern. MRI contrast is gadolinium-based, which is generally well-tolerated. The well-known concern is in patients with advanced kidney disease (eGFR under 30) — gadolinium can rarely cause a serious skin condition called nephrogenic systemic fibrosis. We test kidney function before any contrast study in anyone with known kidney issues, diabetes, or over age 60.

For people with normal kidneys, gadolinium contrast is safe.

Myth 5: "MRI is unsafe in pregnancy"

Mostly false. No evidence has shown harm from MRI in pregnancy. The general principle is to avoid any non-essential imaging in the first trimester (12 weeks), but if your obstetrician decides MRI is needed, it is considered safe across all trimesters. Contrast is usually avoided in pregnancy as a precaution.

Myth 6: "It will affect my pacemaker"

Was true, mostly not now. Older pacemakers and ICDs are not MRI-compatible. Most pacemakers implanted in the last 10 years are "MR-conditional" — meaning they can safely undergo MRI under specific protocols. Always bring your pacemaker card. We'll confirm the model and ensure the scan settings are appropriate.

Myth 7: "I might get stuck in the machine"

False. You're never locked in. The technician can pull you out within seconds. You have a panic button to press at any time. The opening at the other end of the tunnel is clear — light comes through. If at any point you want to stop, the scan stops.

The real things to actually worry about

These are the genuine concerns we screen for:

1. Implanted metal that hasn't been confirmed MRI-safe

This includes:

Older pacemakers and ICDs
Some cochlear implants
Some aneurysm clips placed before 2000
Metal fragments in the eye (from welding accidents — easy to miss)
Some neurostimulators

We'll ask about every past surgery and implant before the scan.

2. Claustrophobia

The tunnel is real and not everyone is comfortable. If you know you're claustrophobic:

Tell us at booking
Ask your doctor about a mild sedative (taken 1 hour before the scan)
Practice deep breathing for the few minutes you're inside
Use the panic button if you need to come out

Our 3T MRI has a wider bore than older machines, which helps.

3. Noise

The machine knocks loudly during scanning — up to 100 decibels. We provide earplugs and music headphones. Noise exposure during an MRI does not cause hearing damage with these protections.

4. Heating

The radio-wave pulses can mildly warm tissue. The machine has safety limits built in. The only concern is if you have certain types of tattoos with metallic ink (rare but possible heating) or certain medication patches (we ask you to remove them).

5. Contrast allergy

Rare but possible. Mild reactions (itching, mild rash) happen in less than 1 in 1000 scans. Severe reactions are very rare. We always ask about previous contrast reactions and have anaphylaxis-trained staff and equipment ready.

The bottom line

MRI is one of the safest imaging tests we have. The main reasons to avoid it are specific (incompatible implants, severe claustrophobia, very poor kidney function with contrast) — not general.

If you're anxious before a first MRI, ask us to walk you through what to expect. Knowing the process removes most of the worry.