A magnetic resonance imaging (MRI) scan is a powerful diagnostic tool that uses a strong magnetic field to produce high-quality images in multiple planes or directions. The images are generated using superconducting magnets and pulsed radio waves. It has been in use since the early 1980s and has no known side-effects.

MRI has become the investigation of choice for many neurological and musculoskeletal conditions and is used in all areas of the body. It helps identify problems in soft tissue in particular nerves, muscles, ligaments and tendons. 

Having an MRI scan

If you’ve never had an MRI scan you might not know what to expect and this brief guide is designed to answer the questions that might be in your mind.

Important things to tell us

It’s important that you tell us before the scan if you:

  • are (or might be) pregnant
  • have a heart pacemaker or an artificial heart valve
  • have any electro-mechanical devices used for drug delivery
  • have any surgical clips
  • have a cochlear implant, a neurostimulator or a programmable hydrocephalus shunt
  • have had any operations on your head
  • have any metal implant in your body
  • have had an injury to your eyes involving metal or metal fragments

Could you have metal fragments in your eyes?

If there is a possibility that you might have metal fragments in your eyes, as a result of a penetrating injury, or from working with metal at high speed, you may need to have an X-ray to ensure that there are no particles present. This is because the MRI magnet can exert a pull on small fragments of metal. Such metal fragments can remain unchanged for many years so we will need to be absolutely sure, regardless of how long ago a possible injury might have occurred.

Before you arrive

  • We will make sure that it’s appropriate for you to have an MRI scan. We’ll ask you some basic questions when you book and you’ll be required to complete a questionnaire before your appointment.
  • Unless we let you know otherwise, you don't need to make any special preparations before the scan. You can eat and drink as normal and take any prescribed medicine.
  • Please wear clothing without zips or metal buttons, and leave jewellery and watches at home if possible.
  • Please confirm your appointment by phone 24 hours before your scan and arrive in plenty of time.
  • Please let us know if you have any disabilities so that we can ensure we are able to offer you the highest quality service.
  • You’re welcome to bring a friend or a relative with you, but for safety reasons we won’t normally allow them into the examination room.
  • Don't forget to bring your appointment letter with you

Preparation for the scan

  • Once you’ve checked in at reception a member of the radiography team will meet you, explain the procedure, go through your safety questionnaire with you and ask you to sign a consent form. You'll have the opportunity to ask any questions about the scanning process.
  • We might ask you to change into a hospital gown. We’ll provide somewhere to store your personal possessions.
  • Throughout the procedure you will be looked after by the radiography team. They will explain what’s happening and will be there if you experience any discomfort.
  • We might need to give you an injection (known as a contrast medium) to increase the amount of information we can get from the scan, depending on the area we're scanning.

During the scan

  • The radiographer operating the scanner will be able to see and hear you throughout the procedure.
  • The examination consists of several scans, each lasting a few minutes with a short pause between each. The whole procedure will take between quarter of an hour and one hour, depending on which part(s) of your body we’re scanning.
  • We’ll ask you to lie down on the scanner bed and we'll make sure you're comfortable so you can stay as still as possible. You won’t feel anything, but there is some mechanical noise from the equipment so we’ll provide you with some ear defenders or ear plugs.
  • For safety reasons, we won’t normally allow anyone accompanying you to come into the examination room whilst the scan is in progress. However if this is necessary we will have to carry out the same safety checks for them as we have done for you.

After the scan

  • There are no restrictions on normal activity, you can eat and drink normally, drive and return to work immediately after the scan.
  • If we’ve given you a contrast injection we will check you before you leave the scanner.
  • A radiologist will examine the images shortly after your visit and send a report to your doctor or consultant, normally within a few days.
  • For ethical and professional reasons, we cannot discuss results with you. Only your doctor or consultant can do this.

More MRI scan facts

MRI – a brief technical explanation

Magnetic Resonance Imaging (MRI) is a diagnostic scanning technique based on the principles of magnetic resonance. MRI uses no radioactivity or X-rays which is why it's often described as being such a safe modality.

The human body is predominately made of water molecules that contain hydrogen protons. When you're placed in a strong magnetic field the tiny magnetic fields of the hydrogen protons, which normally move around randomly, are aligned to the magnetic field

A brief radio pulse is rapidly switched on and off. This makes the protons' magnetic fields spin round in unison and emit a weak radio signal. By altering the timing of the radio wave applications it's possible to produce images that show up the various body tissues as shades of grey. The contrast on MRI images is very good and the operator can change the parameters to give images that can demonstrate the anatomy of the area and also, in many cases, highlight common disease processes

This contrast (grey scale) on an MRI scan depends upon whether the hydrogen protons are linked to fat, muscle, water, etc. Depending on the area scanned with the MRI and what your doctor wants to find out, the contrast can be altered slightly by giving an injection of an agent into a vein that makes it easier to visualise certain structures.

During the MRI scan, the main magnetic field strength is altered using electromagnets. This causes a wide range of sounds during the scan procedure including banging, buzzing and rumbling noises which can be quite loud. You'll be offered ear protection during the scan and in some centres music is available.

MRI and safety

MRI has been in use since 1977 and it has the major advantage that it doesn't use ionising radiation such as X-rays. However, because the scanner contains a powerful magnet, it must not be used on people with certain implants or metal fragments in their bodies.

If you have an implant, a medical device or metal in your body

If you have a device such as a heart pacemaker, aneurysm clip, a cochlear implant, electromechanical devices like drug delivery systems, surgical clips or certain varieties of metal artificial heart valves you should tell the MRI staff about this immediately. 

When you arrive at the scan department, you'll be asked to fill out a safety questionnaire to verify your personal safety. Please ensure that you answer the questions carefully and accurately. It's absolutely essential that you don't enter the scan room if you have a heart pacemaker.

If you've ever had metal fragments in your eyes due to a penetrating injury or worked with metal at high speed, you may need to have an X-ray of your eyes to ensure there are no particles still remaining. This is important because even small fragments of metal can be pulled strongly by an MRI magnet. The time elapsed since any metal related injury makes no difference as metal fragments can remain unchanged in the body for years.

You might need an injection

In some instances, you may need an injection to enhance the images of parts of the body that can have poor natural contrast. Most of the time, the injection is given in the vein in your elbow, the same place as a blood test.

If you have known renal (kidney) disease please tell the MRI staff before any injection as there is an extremely small risk of developing a condition called nephrogenic systemic fibrosis. We undertake screening to reduce the chances of this occurring. 

The injection is unlikely to have side effects. This isn't the same kind of injection that you may have had before X-ray procedures such as a CT scan. Unlike traditional radiological contrast media which often contains iodine, MRI contrast media usually contains gadolinium or iron oxide combined with other products to reduce toxicity and make them safer to inject. The composition and low dose of MRI contrast injections leads to very few adverse reactions. If you have any concerns about your injection or have any serious allergies, particularly to previous injections of MRI contrast media, gadolinium or iron, please let us know in advance.

Sometimes, the contrast agent may be given as a drink (in abdominal scan procedures) or as a very small injection into a joint (in orthopaedic scans). Again, there are usually no noticeable side effects to worry about. As always, if you have any concerns about your injection or have any serious allergies, particularly to previous injections of MRI contrast media (gadolinium or iron) please let us know in advance.

The results of your scan

During an MRI scan there may be literally hundreds of images taken. As this procedure doesn't use X-rays, from a safety viewpoint there is no real limit to the number of images we can take.

The digital images are stored onto a computer hard drive and the operator will check the images for technical quality and to ensure that every view required has been taken during the procedure.

The images are then reported by a radiologist , a doctor who specialises in the interpretation of diagnostic images. The report is usually done soon after the scan, often on the same day and the images may also be sent to the referring clinician or consultant.

The report will be sent to, and available at, your follow-up appointment with the consultant that referred you for an MRI scan. Reporting the scan is a process that requires time and expertise so please don't ask the radiographer for a result at the end of your scan, because they're simply unable to give a report.

Please remember, just because the radiographer can't give an answer, this doesn't mean that there is anything wrong with you or the scan.

AML Quality Account 2020/21

The report has now been finalised and is ready for download


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Alliance Medical are Europe’s leading independent provider of medical imaging services. 

We combine service excellence and innovative imaging technologies to improve patient care and support NHS and independent sector organisations with their ongoing imaging requirements. Our approach has delivered consistent company growth for more than 25 years.


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Carrying out over 2 million scans per year, we set our standards high when it comes to our people and their careers. Investment in integrated systems and individual expertise allows the development of services and long term partnerships to be forged which has seen us grow to be the imaging healthcare provider of choice for patients, referrers and employees.
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Alliance Medical is Europe’s leading diagnostic and molecular imaging services provider delivering high quality diagnostic solutions in partnership with public organisations.  

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