About a kidney MRI scan
The kidneys are two bean-shaped organs at the back of the abdomen that filter waste from the blood to make urine. A kidney (renal) MRI uses a strong magnetic field and radio waves, not X-rays, to make detailed pictures of the kidneys, the tubes that drain them, the adrenal glands above them and the nearby blood vessels.
Kidney cysts and lumps are often found by chance on an ultrasound or CT scan done for another reason. Most are harmless simple cysts, but some need a closer look to decide whether they need follow-up or treatment. MRI, CT with contrast and contrast-enhanced ultrasound are all used for this and are broadly equivalent, so usually only one is needed. MRI is particularly useful for people who should avoid the iodine-based contrast used in CT, or to avoid radiation.
To show how a lump takes up blood, a kidney MRI often includes an injection of gadolinium contrast dye into a vein in your arm. MRI can also be done without contrast if contrast is not suitable for you.
Availability: this scan is currently offered at 3T MRI Scan – Orpington, which also lists a separate charge for contrast.
What happens during the scan
You lie on your back on the scanner bed, with a coil placed over your abdomen. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can talk to you throughout. You will be asked to hold your breath for short periods, often around 15–20 seconds, so the pictures are not blurred by breathing. If contrast is used, it is injected through a small cannula partway through the scan.
What the scan can show
A kidney MRI can help to look at:
- cysts, including complex cysts that need a closer look
- solid lumps (masses), and whether they may need follow-up or treatment
- the spread of a known kidney tumour into nearby veins or tissues
- the drainage system of the kidneys and ureters
- the blood vessels to the kidneys
- the adrenal glands and nearby structures
Preparing for your scan
Some centres ask you not to eat for around 4 hours before an abdominal MRI, to reduce movement of the bowel; the centre will confirm this when you book. If contrast is likely, you may be asked about your kidney function, and a recent blood test (eGFR) may be needed, especially if you have kidney disease, diabetes or are over 65. Tell the centre if you have had a previous reaction to contrast dye. Upload previous ultrasound or CT reports when you book so the radiologist can compare.
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
A cyst was found on my kidney. Do I need an MRI?
Most kidney cysts are simple and harmless and need no further scans. If a cyst looks complex, or a solid lump is seen, your doctor may suggest an MRI, CT or contrast ultrasound to look more closely.
Will I need a contrast injection?
Often, yes. Contrast helps show how a lump or cyst takes up blood. It is charged separately. If contrast is not suitable for you, an MRI can still be done without it.
Do I need a blood test before the scan?
If contrast is planned and you have kidney problems, diabetes or are older, the centre may ask for a recent kidney function blood test (eGFR) to make sure contrast is safe for you.
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.