About a lumbar spine MRI scan
The lumbar spine is the lower part of the back, made up of five vertebrae (L1–L5) separated by cushioning discs. The spinal nerves that supply the legs pass through this area. A lumbar spine MRI uses a strong magnetic field and radio waves, not X-rays, to show the bones, discs, nerves and spinal canal in detail.
Most lower back pain is caused by a strain and gets better within a few weeks without a scan. An MRI is more often used when pain persists, when pain spreads down the leg (sciatica), or when there is numbness or weakness, to look for a slipped (herniated) disc or narrowing of the spinal canal (spinal stenosis) pressing on a nerve. MRI is also the preferred test after back surgery, to look for scarring, infection or a recurrent disc problem, and to help plan treatments such as injections or surgery.
Disc and joint wear is common and often shows on MRI in people without back pain, so your doctor will look at the results alongside your symptoms. You can read more in our article on lumbar spine MRI.
What happens during the scan
You lie on your back on the scanner bed, with the coil built into the bed under your lower back. A cushion under your knees can make this more comfortable. 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 after previous spinal surgery or to look for infection; where contrast is needed, it is charged separately.
What the scan can show
A lumbar spine MRI can help to look at:
- slipped (herniated or prolapsed) discs and disc wear
- sciatica and trapped nerves
- spinal stenosis (narrowing of the spinal canal)
- arthritis of the facet joints
- spondylolisthesis (a vertebra slipping forward) and stress fractures
- scarring, infection or a recurrent disc after spinal surgery
- infection, inflammation and tumours
When to get urgent help: call 999 or go to A&E if you have back pain with numbness around your genitals or bottom, new problems controlling your bladder or bowel, or pain, numbness or weakness in both legs. These can be signs of cauda equina syndrome, which needs emergency treatment.
Preparing for your scan
No special preparation is needed, and you can eat and drink normally. If lying flat is painful, you may want to take your usual painkillers before your appointment. If you have had previous spinal surgery or scans, 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
Do I need an MRI for back pain?
Most lower back pain gets better within a few weeks and does not need a scan. An MRI may help if the pain lasts, spreads down your leg, or comes with numbness or weakness.
Will the MRI show a slipped disc?
Yes. MRI is the best test for slipped discs and shows whether a disc is pressing on a nerve. Disc changes are also common in people without symptoms, so your doctor will look at the results alongside your symptoms.
What if lying still is painful?
Tell the radiographer. They can use cushions under your knees and pads to make you more comfortable. Taking your usual painkillers beforehand can also help.
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
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.