Which Scan Do You Need? MRI, CT, Ultrasound or X-ray Explained, and How to Get the Right One Quickly in London
The best scan is the one that answers your question with the least risk, and that is often not the most expensive one. Ultrasound uses sound waves, involves no radiation and is the first test for most problems in the gallbladder, liver, kidneys, thyroid, pelvis and leg veins. MRI uses a strong magnet, also involves no radiation, and shows soft tissues such as the brain, spinal cord, joints and prostate in fine detail. CT uses X-rays to build cross-sectional images quickly and is the workhorse for the chest, abdomen and urgent problems, but a CT of the abdomen and pelvis delivers a radiation dose comparable to several years of natural background radiation. A plain X-ray is quick and very low dose, and suits bones and the chest. In the UK, any scan using radiation must be justified by a referrer under the Ionising Radiation (Medical Exposure) Regulations 2017, which is why a doctor’s assessment comes first. For some problems the right answer is no scan at all. NICE advises against routine imaging for low back pain without warning signs, because scans often show age-related changes that do not explain the pain. At The Wellness you are assessed first, by video or in person, and the right scan is arranged at the London centre best equipped for the question, performed by an experienced sonographer or radiographer and reported by a consultant radiologist, usually within days. Fees appear further down this page.
Reviewed by the medical team at The Wellness. Last updated 9 October 2026.
Ask which scan you need on WhatsApp or email team@thewellnesslondon.com or call 020 3951 3429.
Key facts about choosing a scan
Ultrasound and MRI use no ionising radiation, while CT and X-ray do.
Ultrasound is the first test for the gallbladder, liver, kidneys, thyroid, pelvis and leg veins.
MRI is best for the brain, spinal cord, joints, soft tissues and the prostate.
CT is fast and detailed for the chest and abdomen, at a higher radiation dose.
Every scan using radiation must be justified by a referrer under UK law.
Not every problem needs a scan, and an unnecessary scan can find harmless things that lead to more tests.
When is ultrasound the right scan
Ultrasound is quick, painless and safe, and it can be repeated without concern. It is the first-line test for gallstones and abdominal pain in the upper right side, fatty liver, kidney problems, thyroid lumps, pelvic pain and heavy periods, testicular lumps, lumps under the skin, and suspected clots in the leg veins.
Its limits are air and bone, which block the sound waves, so it is less useful for the lungs, bowel and brain. Image quality depends on the skill of the person scanning, which is why experienced sonographers and consultant reporting matter.
When is MRI the right scan
MRI gives the most detailed images of soft tissue. It is used for the brain and spinal cord, joints such as the knee and shoulder, muscles and tendons, the pelvis, and the prostate, where NICE recommends MRI before biopsy for men with a raised PSA or an abnormal examination.
An MRI takes longer, often 20 to 45 minutes, inside a narrow tunnel that some people find uncomfortable. Some pacemakers, implants and metal fragments are unsafe in the scanner, so a safety questionnaire comes first.
Book an assessment by video on WhatsApp or email team@thewellnesslondon.com.
When is CT or X-ray the right scan
CT builds detailed cross-sectional images within seconds. It is used for the chest, including lung nodules, for abdominal problems, kidney stones and urgent assessment, and for coronary artery calcium scoring, which measures calcified plaque in the heart arteries to refine cardiovascular risk.
The trade-off is radiation. A CT of the abdomen and pelvis gives a dose comparable to several years of natural background radiation, while a chest X-ray gives roughly the same as a few days. The risk from a single justified scan is small, but it is real, which is why UK law requires every exposure to be justified.
Plain X-ray remains the right first test for many suspected fractures and some chest problems.
When is no scan the right answer
For low back pain without warning signs, NICE advises against routine imaging. Scans of healthy backs commonly show disc bulges and wear that do not cause pain, and finding them can lead to unnecessary worry and treatment.
The same is true of scanning the whole body in people without symptoms. Incidental findings are common, most are harmless, and investigating them can lead to further scans, biopsies and anxiety.
A doctor’s assessment decides whether a scan is needed, which one, and which area, so the result answers your question.
What happens after the scan
The images are reported by a consultant radiologist, a doctor who specialises in interpreting scans. The report comes back to the doctor who arranged it, and you go through the findings together, what they mean, what needs action and what does not.
Where a scan shows something that needs a specialist, a referral is made to a named consultant with the appointment arranged.
What does a private scan cost in London
At the top of the London market, whole-body MRI packages run from around £2,000 to beyond £32,000, and comprehensive imaging programmes commonly cost several thousand pounds.
At The Wellness you are assessed first, so you pay for the scan that answers your question. All figures are from prices.
Executive Body Scan, consultant-reported imaging of the organs that matter for you with bloods and review, from £5,995.
Body scan programmes for men, women and heart health, from £3,495.
Targeted ultrasound, 3 regions from £1,795, 2 regions from £1,495, and a single region from £995.
MRI and CT arranged at specialist London centres, with the fee confirmed before you book.
In-person consultation, 30 minutes with examination, from £220. Same-day video consultation to decide on the right scan, from £150.
Appointments are usually available the same week at our London clinics, including Marylebone and Belgravia, or by video.
Why patients choose The Wellness for imaging
Because you are assessed first, so the scan is chosen to answer your question.
Because we own no scanner, so there is no machine to keep busy, and the scan goes to the London centre best equipped for it.
Because every scan is reported by a consultant radiologist.
Because results are explained by a doctor, not left in a report you have to decipher.
And because a finding leads somewhere the same week, with treatment or a referral to a named consultant.
Related reading
Private ultrasound scans in London covers ultrasound in detail, ultrasound packages and body scans covers our programmes, full body scan London covers whole-body imaging, and back pain and joint pain covers when imaging is and is not needed.
Book your scan today on WhatsApp or call 020 3951 3429.
Frequently asked questions
What is the difference between MRI and CT
MRI uses a magnet and radio waves, involves no radiation and gives the most detail of soft tissues such as the brain, spine and joints. CT uses X-rays, is much faster and suits the chest and abdomen, but involves a radiation dose.
Is ultrasound as good as MRI
For some organs it is the better first test, including the gallbladder, liver, kidneys, thyroid, pelvis and leg veins. For the brain, spine and many joints, MRI shows more.
Do I need a referral for a private scan in the UK
Scans using radiation, such as CT and X-ray, must be justified by a referrer under UK law. A doctor’s assessment, by video or in person, also makes sure you have the right scan of the right area.
Should I have an MRI for back pain
Usually not, unless there are warning signs or the result would change treatment. NICE advises against routine imaging for low back pain, because scans often show harmless age-related changes.
How quickly can I get a private scan in London
At The Wellness scans are usually arranged within days of your assessment, at the London centre best equipped for the question.
How much does a private ultrasound cost in London
At The Wellness a targeted ultrasound of a single region is from £995, with 2 regions from £1,495 and 3 from £1,795, each reported by a consultant radiologist.
The Wellness is a doctor-led private healthcare group providing medical care from our London clinics, including Marylebone and Belgravia. All doctors are GMC-registered. Imaging is arranged at specialist centres, performed by experienced sonographers and radiographers and reported by consultant radiologists. In an emergency call 999. This article is general information and not a substitute for medical advice about your own health.
Enquire now on WhatsApp or email team@thewellnesslondon.com or call 020 3951 3429.
References
UK Health Security Agency, patient dose information guidance
NICE guideline NG131, prostate cancer, diagnosis and management
NICE guideline CG188, gallstone disease
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