Understanding Your Scans (X-ray, Ultrasound, MRI, CT) PDF

What X-rays, ultrasound, MRI and CT each show, and why your surgeon chooses one over another.

When your surgeon orders a scan, it can feel like alphabet soup — X-ray, ultrasound, MRI, CT. Each one is a different tool that shows a different thing, a bit like the difference between a photograph, a video and a 3D model. None of them is simply "better" than the others; the right choice depends entirely on what we need to see. Knowing what each scan is good at takes a lot of the mystery out of the instructions you're given, and helps you understand why we sometimes ask for more than one.

Why different scans? Each one sees something different

The single most useful thing to understand is that every type of scan is suited to a particular kind of tissue. Bone, tendons, ligaments, cartilage and nerves all show up differently — and no single scan shows all of them perfectly. An X-ray is superb for bone but almost blind to a tendon; an ultrasound shows a tendon beautifully but can't see deep inside a joint. So when we pick a scan, we're really asking a question: is the problem in the bone, or in the soft tissues, or both? The answer decides the tool.

That's also why you might have one scan, then be sent for another. It usually doesn't mean anything was wrong with the first one — it means we've narrowed down the question and now need a different kind of picture to answer it.

X-ray — the picture for bone

An X-ray is the quickest and most familiar scan, and it remains the first test for most bone problems. It passes a small amount of radiation through the area and the dense bone shows up clearly white, which makes it excellent for spotting fractures (broken bones), arthritis, the alignment of bones, and dislocations. It's fast, inexpensive and widely available, and the radiation dose is small.

Its limitation is the flip side of its strength: X-rays see bone well but show soft tissues — tendons, ligaments and cartilage — only as vague grey shadows. So a normal X-ray doesn't rule out a soft-tissue injury; it simply tells us the bone looks intact, which is often exactly the reassurance we need first.

Ultrasound — a live view of soft tissues near the surface

Ultrasound uses high-frequency sound waves rather than radiation, so there's no dose at all. A small probe is moved over the skin with a little gel, and it's particularly good at showing soft tissues that sit fairly close to the surface — tendons, ganglion cysts, pockets of fluid, and inflammation.

Its special trick is that it works in real time. Because we can watch the picture live, we can ask you to move your hand or shoulder and watch a tendon glide as it happens — something a still image can't show. This makes it very useful for tendon problems around the wrist, hand and shoulder. The main thing to know is that ultrasound is operator-dependent: the quality depends on the skill of the person holding the probe, and it can't see deep inside a joint or through bone.

MRI — the detailed all-rounder for soft tissue and bone

An MRI uses a strong magnet (no radiation) to build remarkably detailed pictures. It is the all-rounder, because it shows both soft tissue and bone in fine detail — ligaments, cartilage, nerves, bone marrow, and even hidden fractures that don't show on a plain X-ray. When we're planning surgery or chasing a problem that the other scans can't quite pin down, MRI is often the deciding test.

A few practical things are worth knowing so it isn't a surprise:

• It takes longer — usually around 20 to 40 minutes — and you need to lie fairly still for clear images.
• You lie inside a tunnel, and the machine is noisy, making knocking and banging sounds while it works. You'll be given earplugs or headphones.
• If you're very claustrophobic, please tell us beforehand — there are ways to make it easier, and sometimes a different machine or a mild sedative can help.
• If you have certain metal implants (such as a pacemaker, or older metalwork), let us know. Many implants such as plates and screws are perfectly safe, but we always check first, so mention anything you have.

CT — 3D detail for complicated bone

A CT scan takes many X-rays from different angles and a computer builds them into detailed cross-sections, and even a 3D model. Like a plain X-ray it is built around bone, but with far more detail — which makes it superb for complex fractures (where bone is broken into several pieces) and for planning surgery in three dimensions. For tricky breaks around the wrist, elbow or shoulder, a CT can show exactly how the fragments sit so we can plan the repair precisely. The trade-off is that it uses more radiation than a plain X-ray, so we order it when that extra detail genuinely changes the plan.

A different kind of test — nerve studies

Not every test is a picture. If the concern is a nerve — numbness, tingling or weakness — we may arrange nerve conduction studies or an EMG. Rather than photographing the body, these measure how well the nerves and muscles are actually working, by sending tiny electrical signals along a nerve and recording the response. It answers a different question entirely. You can read more on our nerve tests and conduction studies page.

Putting it together — what to expect

The reassuring bottom line is that the team chooses the scan based on exactly what we need to see, and most scans are quick and painless. An X-ray or ultrasound is often all that's needed; an MRI or CT comes in when we need finer detail or a surgical plan. Whatever you have, the results will be explained to you in plain language, alongside what they mean for your treatment.

If you'd like, these are good questions to ask:

• What is this scan looking for, and which tissue does it show?
• Will I need anything else after it, and roughly how long will it take?
• Is there anything I should mention first — claustrophobia, metal implants, or being pregnant?
• When and how will I get the results explained?

There are no silly questions here. Understanding why a particular scan was chosen often makes the whole process feel a good deal less daunting.

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Reviewed by Dr Kieran Hirpara · 2026-06-24 11:29:51.781250+00:00.

Talk to your treating clinician for advice specific to you.

For an appointment with the CQ Hand + Upper Limb team, ask your GP about a referral or visit www.cqupperlimb.com.