About a pituitary MRI scan
The pituitary gland is a pea-sized gland at the base of the brain, just behind the bridge of the nose. It sits in a small bony pocket called the pituitary fossa (sella turcica) and controls many of the body’s hormones, including those for growth, thyroid function, periods and fertility, breast milk and the stress hormone cortisol. The nerves from the eyes cross just above it. A pituitary MRI uses a strong magnetic field and radio waves, not X-rays, to show the gland in fine detail.
The scan is usually requested by a GP or hormone specialist (endocrinologist) when blood tests show a hormone level that is too high or too low, or when there are symptoms such as headaches or loss of the outer field of vision. The most common finding is a pituitary adenoma – a non-cancerous growth. A prolactinoma, which makes too much of the hormone prolactin, can cause missed periods, breast milk production, low sex drive or erectile problems, and is usually treated with tablets; MRI shows its size and is used to check that it shrinks. MRI is also used for suspected acromegaly and Cushing’s disease, and to follow up a pituitary lump found by chance on another scan.
Pituitary tumours can be just a few millimetres across, so this scan uses thin, detailed slices focused on the gland rather than a standard brain MRI.
What happens during the scan
You lie on your back on the scanner bed with a coil placed around your head. 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 head very still. Most pituitary scans include an injection of contrast dye (gadolinium) into a vein in your arm; pictures are often taken while the dye is being given, as small tumours take up the dye more slowly than the normal gland. Where contrast is needed, it is charged separately.
What the scan can show
A pituitary MRI can help to look at:
- pituitary adenomas, including small microadenomas (under 10 mm)
- prolactinomas, and how they respond to treatment
- causes of acromegaly and Cushing’s disease
- pituitary lumps found by chance on other scans
- cysts, inflammation and other growths near the gland
- the optic nerves, if a growth is pressing on them
- the pituitary area after surgery
When to get urgent help: call 999 or go to A&E if you have a sudden, severe headache with vomiting, sudden loss of vision or double vision.
Preparing for your scan
No special preparation is usually needed, and you can eat and drink normally. Upload your recent hormone blood test results, any eye field (visual field) test results and previous scan reports when you book. As contrast is usually used, tell the centre if you have kidney problems or have had a reaction to contrast dye before.
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
Is a pituitary tumour a brain tumour or cancer?
Almost all pituitary tumours are non-cancerous (benign) adenomas. They do not spread to other parts of the body, and many are treated with tablets or simply monitored.
Why do I need a pituitary scan rather than a brain scan?
The pituitary gland is very small, and some tumours are only a few millimetres across. A pituitary MRI takes thin, detailed pictures focused on the gland, which a standard brain MRI may miss.
Will I need a contrast injection?
Usually, yes. Pictures taken while the contrast is given help show small tumours. It is charged separately.
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 Pituitary Foundation – Prolactinoma
- The Pituitary Foundation – Non-functioning tumour
- NHS – Acromegaly
- Radiopaedia – Pituitary microadenoma
- 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.