MRI scans: when they help and what they can show

An MRI scan uses strong magnetic fields and radio waves to create detailed images of soft tissues inside the body. In UK general practice, MRI is used selectively when detailed imaging is needed to support diagnosis or guide referral.

This page explains what MRI scans can and cannot show, how GPs decide when MRI is appropriate, safety considerations, and what to expect before and after your scan.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help or advice on medical scans, please book a GP appointment.

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How MRI scans are used in GP care

MRI is particularly helpful when a GP needs detailed information about soft tissues, nerves, or joints that cannot be seen clearly on X-ray or ultrasound.

MRI is commonly considered to:

Clarify persistent or complex symptoms
Assess nerve involvement
Support specialist referral decisions
Exclude serious but less common causes of symptoms

MRI is not used routinely for early or uncomplicated symptoms.here the suspected problem is in soft tissues such as muscles, tendons, ligaments, or discs.

What an MRI scan can and cannot show

What MRI is useful for

MRI provides detailed images of:

Discs, nerves, and spinal structures
Joints, cartilage, ligaments, and menisci
Muscles and soft tissues
Some internal organs, depending on the scan type

It is often the most informative scan for neurological symptoms or complex joint problems.

What MRI is less helpful for

MRI may be less useful for:

Simple muscle strains that are improving
Early back pain without red flags
Conditions where findings would not change management
Problems better assessed with CT or ultrasound

A normal MRI does not rule out all causes of pain.

Common reasons a GP may recommend an MRI

Back or neck symptoms

MRI may be considered if there is:

Persistent pain not improving with appropriate management
Symptoms suggesting nerve involvement, such as weakness or progressive numbness
Concern about serious underlying causes

MRI is not routinely recommended for early back pain without red flags.

Joint problems

MRI may be used for:

Suspected meniscal or ligament injuries
Ongoing joint symptoms not explained by X-ray
Planning specialist referral

Neurological symptoms

MRI may be considered for:

Unexplained neurological symptoms
Progressive weakness
Certain headache patterns, when clinically indicated

MRI is requested based on symptom pattern rather than reassurance alone.cough. The decision depends on the pattern, duration, and risk factors.

How a GP decides whether an MRI scan is appropriate

A GP will consider:

Duration and progression of symptoms
Examination findings
Presence of red flags
Whether MRI findings would change treatment or referral
Whether another test is more suitable

For the GP approach to imaging decisions, see:
How GPs use medical imaging in practice

Safety and suitability of MRI scans

MRI does not use ionising radiation.

However, MRI is not suitable for everyone. Important considerations include:

Certain implanted medical devices
Some metal fragments or implants
Severe claustrophobia
Ability to lie still for the duration of the scan

You should always inform the scan provider about implants or previous surgery.

Contrast MRI scans

Some MRI scans use contrast dye to improve image detail.

Contrast may be considered to:

Clarify inflammation or infection
Assess certain neurological conditions
Improve visualisation of specific structures

Contrast is usually safe but may not be suitable for everyone. Kidney function and allergy history may be relevant.

What happens after an MRI scan

If the MRI explains symptoms

A GP may:

Confirm the likely diagnosis
Adjust treatment or rehabilitation
Refer to a specialist where appropriate

If the MRI is normal or inconclusive