What’s the Difference Between MRI, CT and Ultrasound?

Being referred for any type of scan can feel daunting, especially if you’re not sure what to expect. Understanding the difference between magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound scans can help you feel more confident and at ease about your appointment.

At King Edward VII’s Hospital, we use advanced diagnostic imaging to investigate and monitor a wide range of conditions. This guide explains how MRI, CT and ultrasound scans work, as well as the key differences, so you can feel reassured and prepared for your appointment.

What is diagnostic imaging?

Diagnostic imaging lets doctors see inside your body without the need for surgery or invasive procedures. It creates clear images of your bones, organs and soft tissues – helping your care team spot problems, track changes and plan effective treatment.

The best scan for you will depend on which part of your body needs to be looked at, and what your doctor needs to find out. 

We understand that having a scan can feel worrying, but we’ll be here to support you at all times. We offer fast access to private MRI, CT and ultrasound scans in London that are delivered by expert radiographers and supported by consultant-led care.

What is an MRI scan?

MRI scans use a strong magnetic field and radio waves to produce detailed images of the inside of the body. Unlike X-rays or CT scans, an MRI does not use radiation.

The scanner is a large cylindrical machine. You’ll lie on a flat bed that moves slowly into the scanner. It’s a painless scan, but it can be quite loud. Most scans take 15 to 90 minutes, depending on the area being looked at.

What can an MRI scan check?

MRI scans are used when doctors need clear images of soft tissues. They’re particularly useful for spinal problems, joint injuries or neurological symptoms.

An MRI scan can be used to check or investigate:

• Persistent or unexplained headaches
• Joint or soft tissue injuries
• Neurological symptoms such as dizziness or numbness
• Spinal problems or slipped discs
• Certain tumours or lesions

It’s often used when your doctor needs highly detailed images or when other types of scans haven’t provided enough information. It is safe for most people, although some implants or medical devices (like a pacemaker) may mean MRIs aren’t right for you.

Book a private MRI scan in London with the support of our expert imaging team.

What is a CT scan?

A CT scan uses X-rays and computer technology to create cross-sectional images of the body, showing bones, organs and blood vessels in detail. They can also be useful to guide procedures such as biopsies (tissue sample collection).

You’ll lie on a bed that moves slowly through a short, doughnut-shaped scanner. The scan is painless and usually takes just a few minutes. 

Sometimes, a contrast dye may be used to make images clearer. This dye is a safe solution that’s injected into your veins to highlight certain areas of your body.

What can a CT scan assess?

CT scans are particularly helpful in urgent cases, when quick and accurate imaging is needed to make fast decisions. They are useful for viewing dense structures such as bones or lungs, and for identifying bleeding, infections or tumours.

Your doctor may recommend a CT scan to look at:

• Head injuries or suspected fractures
• Chest problems, such as lung infections or blood clots
• Abdominal or pelvic pain
• Suspected cancer
• Bone fractures or trauma

CT scans involve a small dose of radiation, so they are only recommended when the benefits outweigh any potential risks.

Book your private CT scan in London today with our trusted radiology specialists.

What is an ultrasound scan?

An ultrasound scan uses high-frequency sound waves to create images of the inside of the body. 

A handheld device, called a transducer, is moved over the skin or placed internally, depending on the area being examined.

Ultrasounds provide real-time imaging, which makes them useful for guiding certain procedures such as biopsies or injections. The scan usually takes 15 to 45 minutes, depending on which part of the body is being examined.

What does an ultrasound scan check?

Ultrasound is safe, painless and does not use radiation. It is especially helpful for examining soft tissues and is widely used in pregnancy, as well as to assess abdominal and pelvic organs.

Ultrasound scans are used to check:

• Pregnancy and the development of your baby
• Gallbladder or kidney stones
• Liver, bladder, uterus and ovaries
• Blood flow and vein health
• Lumps or abnormalities under the skin

Doctors may use ultrasound alongside other scans to provide a more complete picture of what’s going on.

Arrange your private ultrasound scan in London with support from our experienced imaging specialists.

Which diagnostic scan might be right for me?

The right scan for you will depend on your symptoms and the part of your body that needs to be checked.

For detailed images of soft tissue, such as torn ligaments or spinal problems, an MRI scan is often the most suitable option. If there is a suspected injury, internal bleeding or an issue affecting the bones, a CT scan may be more appropriate. When it comes to monitoring pregnancy or assessing abdominal organs, an ultrasound scan is usually the first choice.

Sometimes, your consultant may advise more than one type of scan to provide the clearest possible picture of what’s going on.

Choose King Edward VII’s Hospital for private diagnostic imaging

At King Edward VII’s Hospital, we combine modern diagnostic technology with personalised, consultant-led care. Our radiology department provides prompt access to MRI, CT and ultrasound scans, with flexible appointments and minimal waiting.

Each scan is reviewed by a specialist consultant radiologist. If further care is needed, we offer smooth referrals to leading UK radiologists and consultants. Whether you are investigating new symptoms or monitoring an ongoing condition, you can expect expert, compassionate care throughout.
If you’ve been referred for a scan or would like to speak to a specialist about your symptoms, get in touch today to book your appointment at King Edward VII’s Hospital.