About a femur (thigh) MRI scan
The femur, or thigh bone, is the longest and strongest bone in the body, running from the hip to the knee. It is surrounded by large muscle groups: the quadriceps at the front, the hamstrings at the back and the adductor (groin) muscles on the inner side. A femur MRI uses a strong magnetic field and radio waves, not X-rays, to show the bone, the bone marrow inside it and these soft tissues in detail.
One common reason for the scan is a suspected stress fracture, a small crack caused by repeated stress such as running or a sudden increase in training. Early stress fractures are often not visible on an X-ray, while MRI is the most sensitive test and can show swelling in the bone marrow before a crack appears. Stress fractures of the femoral neck (near the hip) are considered high-risk, so prompt assessment matters.
MRI is also used for muscle injuries. Mild hamstring strains usually get better with rest and self-care, but if a severe tear is suspected, if you felt a “pop”, or if recovery is slower than expected, an MRI can show where the injury is and how severe it is, which helps guide rehabilitation and decide whether surgery is needed. Left and right thighs are separate scans. The hip and knee joints have their own scans, so choose those if your pain is mainly in a joint.
What happens during the scan
You lie on your back on the scanner bed, usually feet first, with a coil placed over your thigh. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can talk to you throughout. You need to keep still while the pictures are taken. Contrast dye is not usually needed, but may be used to look at a lump or infection; where contrast is needed, it is charged separately.
What the scan can show
A femur MRI can help to look at:
- stress fractures and bone stress injuries, including those not visible on X-ray
- hamstring, quadriceps and adductor muscle strains and tears
- tendon injuries, including a hamstring tendon pulling away from the bone
- bone bruising and bone marrow swelling (oedema)
- bone and soft-tissue infection
- lumps and tumours of the bone, muscle or fat
- inflammation of the muscles (myositis)
Preparing for your scan
No special preparation is needed, and you can eat and drink normally. Wear comfortable clothing without metal; you may be asked to change into a gown. If you have had previous X-rays of your thigh, hip or knee, upload the reports when you book.
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
Can an MRI show a stress fracture that was missed on an X-ray?
Yes. Early stress fractures often do not show on X-ray. MRI is the most sensitive test for them and can show swelling in the bone marrow before a fracture line is visible.
Do I need an MRI for a pulled hamstring?
Most mild hamstring strains get better with rest and self-care and do not need a scan. An MRI may help if the injury is severe, you felt a pop, you have large bruising or weakness, or it is not improving as expected.
Do I need to book the left or right side?
Yes. Each thigh is a separate scan. If you need both, book them together, as two or more areas booked together qualify for the lower clubbed price.
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
- Radiopaedia – Stress fracture
- NHS – Hamstring injury
- MRI Master – MRI thigh (upper legs) protocols and planning
- 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.