If your doctor has recommended an MRI, you may have questions about MRI scan side effects, radiation exposure and whether the procedure is safe.
One of the most important things to understand is that MRI does not use X-rays or ionising radiation.
Instead, Magnetic Resonance Imaging (MRI) uses a powerful magnetic field, radiofrequency signals and computer processing to produce detailed images of structures inside the body.
MRI is routinely used around the world, particularly for examining the brain, spine, joints, muscles and soft tissues. However, as with any medical procedure, there are certain precautions and possible side effects patients should understand.
Does an MRI Scan Use Radiation?
No. MRI scans do not use ionising radiation.
This is a major difference between MRI and imaging techniques such as:
- CT scans
- Conventional X-rays
- Mammography
- PET/CT scans
CT and conventional X-ray imaging use X-rays. MRI uses a strong magnetic field and radiofrequency energy to generate images.
Therefore, there are no “MRI radiation side effects” in the same sense as imaging examinations that involve ionising radiation.
This makes MRI particularly useful when detailed soft-tissue imaging is required.
How Does an MRI Work Without Radiation?
An MRI scanner contains a powerful magnet.
The human body contains a large amount of water, which contains hydrogen atoms. When you enter the MRI scanner, the magnetic field influences the alignment of hydrogen nuclei within the body.
Radiofrequency pulses temporarily alter this alignment.
As the nuclei return toward their previous state, they produce signals that are detected by the MRI system. Computer processing converts these signals into detailed images.
Different tissues produce different signal characteristics, allowing radiologists to distinguish structures such as muscles, ligaments, nerves, organs and abnormalities.
Does an MRI Scan Have Side Effects?
For most people, an MRI examination does not cause significant side effects.
Because the procedure itself is non-invasive, you normally won’t feel the magnetic field or radiofrequency signals.
However, some patients may experience temporary discomfort associated with the scanning environment rather than the imaging technology itself.
These can include:
Feeling Claustrophobic
MRI scanners require the part of the body being examined to be positioned within the scanner.
Some people may feel anxious or claustrophobic, particularly during longer examinations.
If you have significant claustrophobia, tell the imaging centre when scheduling your appointment. Depending on the situation, additional support or medical advice may be appropriate.
Loud Scanner Noise
MRI scanners produce loud knocking, tapping or buzzing sounds while images are being acquired.
This is normal.
Patients are generally provided with hearing protection such as earplugs or headphones to reduce the noise.
Temporary Discomfort From Remaining Still
MRI examinations can take longer than some other imaging tests.
You may need to remain still in a particular position for an extended period. This can occasionally cause temporary stiffness or discomfort.
If you are uncomfortable, inform the MRI technologist.
What Are the Side Effects of MRI Contrast?
Not every MRI requires contrast.
For certain examinations, a gadolinium-based contrast agent may be injected through a vein to make particular tissues, blood vessels or abnormalities more visible.
Most patients tolerate MRI contrast well.
When reactions occur, they may include symptoms such as:
- Nausea
- Headache
- Dizziness
- Discomfort at the injection site
- Mild allergic-type reactions
Serious reactions are uncommon, but appropriate medical assessment is important before contrast administration.
People with significant kidney disease may require additional evaluation before receiving certain gadolinium-based contrast agents.
Tell the imaging team about kidney problems, previous contrast reactions and other relevant medical conditions before the examination.
Is MRI Safe If You Have Metal in Your Body?
This is one of the most important MRI safety considerations.
Because MRI uses a very powerful magnetic field, certain metallic objects or implanted devices can create safety concerns or interfere with image quality.
Before entering the MRI area, you will normally complete a detailed safety questionnaire.
Tell the imaging team if you have:
- A pacemaker
- Cochlear implants
- Aneurysm clips
- Neurostimulators
- Insulin pumps
- Artificial joints
- Surgical clips
- Metal fragments
- Previous major surgery
- Any implanted medical device
Having an implant does not automatically mean you cannot undergo MRI.
Many modern medical implants are classified as MR Safe or MR Conditional, meaning MRI may be possible under specified conditions.
However, the exact manufacturer and model of an implanted device may need to be verified before scanning.
Never enter an MRI scanner without informing the staff about implants or possible metallic objects in your body.
Why Must Metal Objects Be Removed Before MRI?
Loose metallic objects can be attracted by the scanner’s powerful magnetic field.
Before an MRI, patients may therefore be asked to remove items such as:
- Jewellery
- Watches
- Keys
- Coins
- Hair accessories
- Removable dental items
- Hearing aids
- Mobile phones
- Certain clothing containing metal
The MRI team will tell you what needs to be removed before entering the scanning room.
These precautions are an essential part of MRI safety.
Is MRI Safe During Pregnancy?
MRI does not use ionising radiation and may be used during pregnancy when medically necessary.
However, the decision to perform an MRI during pregnancy depends on the clinical situation.
The use of gadolinium contrast during pregnancy requires additional consideration and is generally approached cautiously.
If you are pregnant or think you may be pregnant, always tell your doctor and the MRI team before the examination.
Your healthcare team can then determine whether MRI is appropriate and whether contrast is necessary.
Can Children Have MRI Scans?
Yes.
MRI can be used to examine children because it does not expose them to ionising radiation.
The main challenge is that patients need to remain still during image acquisition.
Young children who cannot remain still for the required period may sometimes require specialised preparation or sedation under appropriate medical supervision.
Whether this is necessary depends on the child’s age and the type of examination.
Is It Safe to Have Multiple MRI Scans?
Because MRI does not use ionising radiation, repeated MRI examinations do not accumulate radiation exposure in the way repeated X-ray or CT examinations can.
However, every medical imaging test should still have a clinical reason.
Doctors generally recommend repeat imaging when it is useful for diagnosis, treatment planning or monitoring a medical condition.
If contrast is required repeatedly, additional considerations may apply depending on the patient’s medical history and kidney function.
MRI vs CT: Which Has More Radiation?
MRI itself uses no ionising radiation.
CT scans use X-rays and therefore involve ionising radiation exposure.
However, this doesn’t mean MRI should always be chosen instead of CT.
The two technologies provide different diagnostic information.
CT can be particularly useful for evaluating the lungs, bones, trauma and many emergency conditions. MRI provides excellent soft-tissue contrast and is widely used for the brain, spine, joints and many other structures.
Doctors choose between MRI and CT according to the clinical question rather than radiation exposure alone.
Is MRI Safe for the Brain?
MRI is one of the most commonly used imaging techniques for detailed evaluation of the brain.
It can provide detailed images of brain tissue without ionising radiation.
Depending on the patient’s symptoms, brain MRI may be used when investigating conditions involving the brain, nerves, blood vessels and surrounding structures.
There is no evidence that the magnetic fields and radiofrequency energy used appropriately in clinical MRI cause the type of biological damage associated with ionising radiation.
The U.S. Food and Drug Administration provides further information about MRI benefits and risks for patients.
How Can You Prepare for a Safe MRI Scan?
The most important part of MRI preparation is providing accurate information to the imaging team.
Before your examination:
- Inform staff about implants or medical devices
- Mention previous surgeries
- Tell them if you may have metal fragments in your body
- Inform them about kidney disease if contrast may be required
- Tell them about previous contrast reactions
- Mention pregnancy or possible pregnancy
- Inform them if you have severe claustrophobia
You should also follow any specific preparation instructions provided for your particular MRI examination.
MRI Scanning at Elite Scan Centre, Thrissur
MRI is an important diagnostic imaging technology capable of producing detailed images without ionising radiation.
At Elite Scan Centre, Thrissur, MRI examinations are performed with appropriate screening and preparation according to the type of investigation requested.
Before an MRI, patients are screened for implants, metallic objects and other factors that may affect MRI safety.
If your doctor has recommended an MRI and you have questions about an implant, previous surgery, contrast administration or preparation, contact Elite Scan Centre before your appointment so these details can be reviewed.
Frequently Asked Questions
Does MRI have radiation side effects?
No. MRI does not use ionising radiation, so there are no radiation-related side effects from the MRI itself.
Can MRI cause cancer?
MRI does not use the ionising radiation associated with CT scans and X-rays. There is no established evidence that appropriately performed clinical MRI causes cancer.
Does MRI contrast have side effects?
Some people may experience temporary symptoms such as nausea, headache or injection-site discomfort. Serious reactions are uncommon. Patients with kidney disease require appropriate assessment before certain contrast agents are used.
Is MRI painful?
MRI itself is generally painless. Some patients may experience discomfort from remaining still, scanner noise or claustrophobia.
Can I have an MRI with a pacemaker?
Some modern pacemakers are MR Conditional and may be scanned under specific conditions, while others may not be suitable. The exact device must be evaluated by the medical team before MRI.
Which is safer, MRI or CT?
Both are established medical imaging techniques when appropriately used. MRI does not use ionising radiation, while CT does. However, they provide different diagnostic information, so the appropriate examination depends on the medical condition.
