About a thumb MRI scan
The thumb has two bones of its own and joins the wrist at the base through a saddle-shaped joint (the CMC joint), which lets it move in many directions to pinch and grip. Strong ligaments on each side of the joints keep the thumb stable. A thumb MRI uses a strong magnetic field and radio waves, not X-rays, to show the bones, joints, ligaments and tendons in detail.
One of the most common reasons for a thumb MRI is an injury to the ulnar collateral ligament (UCL), on the inner side of the knuckle at the base of the thumb. This is known as skier’s thumb, or gamekeeper’s thumb when it develops over time, and often happens when the thumb is bent backwards or sideways in a fall. If the ligament is completely torn, its end can become trapped behind a nearby tendon (a Stener lesion), so it cannot heal on its own and usually needs surgery. MRI can show whether the tear is partial or complete and whether a Stener lesion is present, which helps your specialist decide on the right treatment. Ultrasound can also be used for this.
MRI is also used to look at hidden fractures, pain and arthritis at the base of the thumb, tendon problems, and lumps such as ganglion cysts. For problems across the whole hand, see hand MRI. You can read more in our article on hand MRI. When you book, choose the left or right side.
What happens during the scan
Depending on the scanner, you either lie on your back with your hand by your side, or lie on your front with your arm stretched above your head. Your thumb and hand are placed in a small coil and held still with pads. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can talk to you throughout. You need to keep your hand completely still while the pictures are taken. Contrast dye is not usually needed; where contrast is needed, it is charged separately.
What the scan can show
A thumb MRI can help to look at:
- skier’s thumb (UCL tears) and Stener lesions
- other ligament sprains and tears
- hidden fractures and bone bruising
- arthritis at the base of the thumb
- tendon problems, including tenosynovitis and trigger thumb
- ganglion cysts and other lumps
- inflammatory arthritis, such as rheumatoid arthritis
Preparing for your scan
No special preparation is needed, and you can eat and drink normally. Remove any rings before your appointment. Upload any previous X-ray or scan reports when you book, and remember to choose the correct side.
You can usually eat, drink and take your normal medicines unless the scanning centre tells you otherwise. Wear loose, comfortable clothing without metal zips or buttons, and leave jewellery at home. You will be asked to remove metal items such as hair clips, hearing aids, coins and keys, and you may be asked to change into a gown.
Before the scan you will complete a safety questionnaire. Tell the team if you have a pacemaker, any metal implant, surgical clips or other device, if you have kidney problems or allergies, or if you are, or might be, pregnant or breastfeeding. If you feel anxious in enclosed spaces, let us know when you book. Some centres can offer a relaxant, and if you take one you will need someone to take you home and must not drive for 24 hours.
Frequently asked questions
Do I need a scan for skier’s thumb?
If your thumb is very loose or painful after an injury, a scan can show whether the ligament is completely torn and whether it is trapped (a Stener lesion). This affects whether you need a splint or surgery, so it is best done soon after the injury.
Should I have a thumb or hand MRI?
A thumb MRI focuses closely on the thumb and its joints, which gives more detail. A hand MRI covers a wider area. Your referrer will say which is needed; if you are unsure, contact us before booking.
Do I need to choose a side?
Yes. Choose the left or right thumb when you book. If both thumbs need scanning, contact us so the centre can plan the appointment.
Do I need a referral?
You can tell us if you have a referral from your GP, physiotherapist or consultant and upload it when you book. If you do not have one, select “no referral” when you book and the scanning centre will confirm the next steps with you.
Sources
- Injury to the ulnar collateral ligament of the thumb (PMC)
- The Stener lesion (PMC)
- NHS – Hand pain
- NHS – Osteoarthritis
- RadiologyInfo.org – Musculoskeletal MRI
- NHS – MRI scan
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.