Magnetic resonance imaging (commonly known as MRI) is a diagnostic scan that uses radio waves and strong magnetic fields to create detailed cross-sectional imaging of the inside of your body. MRI can provide a level of detail that other diagnostic imaging may not be able to replicate, particularly for soft tissues such as muscles, nerves, ligaments and tendons.
An MRI scan can aid diagnosis of a range of medical conditions and help when planning certain treatments and/or assessing the effectiveness of previous treatments.
Call us on 02070345250 to book an MRI scan at a Circle hospital.
MRI is an incredibly useful diagnostic tool as it can be used to examine most parts of the human body. Due to the way it works, any part of the body that contains water can be imaged using MRI. This means that the only part of the body that an MRI can’t examine is the lungs, as they don’t contain water.
MRI is particularly useful for examining:
- Bones and joints
- Neurological problems, including diseases affecting the brain and spinal cord.
- The circulatory system, meaning your blood vessels and heart.
- The eyes and inner ear.
- Internal organs, such as the liver.
The most common conditions we see here at Circle for an MRI scan include injuries in the knee, spine and ankle. These conditions often result from sports injuries, but also occur as a result of trauma or degenerative changes.
Soft tissue imaging
MRI scans are particularly useful for visualising soft tissue, a term used to describe tissues that connect, support or surround organs and structures in the body. Found throughout the body, soft tissues include muscles, tendons, ligaments, nerves and blood vessel. Being able to obtain accurate images of these tissues can aid diagnosis of a range of conditions, diseases and injuries.
MRI scans of the bowel and female pelvis are also common, and these help to check for conditions such as lesions and tumours and to assess progress or the effectiveness of any treatment.
A number of diagnostic tests and scans that are routinely carried out in a hospital use ionising radiation in the form of X-rays. While the amount of radiation you are exposed to from an X-ray is usually very low, any exposure to radiation carries with it a corresponding risk. As an MRI scan does not use radiation, it is generally considered safer than a scan or test that uses X-rays.
An MRI scanner is shaped like a large, elongated tube. There are a number of different makes and models available, depending on where you have your scan. All Circle scanners are 1.5 Tesla, this number referring to the strength of the magnet in the scanner. By way of example, the scanner at Circle Reading is a GE Signa HDxt 1.5 T.
Your scan will be carried out by a diagnostic radiographer, a healthcare professional registered with the Health and Care Professions Council (HCPC). They will usually be supported by a radiography assistant, who will help you get ready for the scan. The scan is overseen by a consultant radiologist, a doctor who specialises in interpreting diagnostic images. It is the radiologist who will write the full report on what the scan shows.
The radiographer will talk through the scan with you beforehand, to ensure you know what to expect. They will ask you a number of questions to check that the MRI scan will be safe for you (details of some of the things that may preclude an MRI scan are described below in the section titled ‘Things to be aware of before your MRI scan’).
We appreciate it can sometimes be worrying having a scan, and we want to help reduce any concerns you may have. Should you have any questions or concerns before the scan, you will be able to talk with the radiographer about them.
As an MRI scanner uses magnets, you will need to remove any clothing that has metal clips, fasteners or zips before your scan. If your clothes do not contain any metal, you will be able to wear them for the scan. If you do need to remove items of clothing, you will be provided with a gown to wear for the scan. We will also ask you to remove your watch as well as any jewellery, bank cards and loose change, all of which will be locked securely in a private locker for the duration of your scan.
Upon entering the MRI scanner room, you will be asked to lie on the scanning table. During the scan this table will move into the scanner, but before your scan it will be extended to a position outside the scanner to allow you to get up onto it more easily.
Once the radiographer and radiography assistant have ensured you are comfortable on the table, they will give you a pair of ear defenders (headphones) to put on, to help reduce the volume of the scanner noises you will hear while having your scan. The table will then be moved to the relevant position in the scanner. Ordinarily this means that you enter the scanner head first, although the exact positioning will be determined by the area of your body that is being imaged.
Once the table has been positioned in the correct place, the radiographer will leave the room before the scan. They will be able to see and hear you the entire time from the control room and should you require help at any time, you can speak with them from the scanner or press a handheld buzzer to let them know you are feeling uncomfortable.
The scan itself will take between 15-60 minutes, depending on where in the body is being scanned. As a guide, a scan of a knee might take around 25 minutes while a scan of the spine could take one hour.
To help obtain the highest quality images it is important you keep as still as possible throughout the scan. You may be asked by the radiographer to breathe in and hold your breath for a few seconds at various times during the scan. If this is going to be required for your scan, it will always be fully explained to you in advance.
During the scan, the table you are lying on will move slowly through the middle of the scanner. This can be a bit of an unusual feeling and you may find it more relaxing to close your eyes during the scan, although you do not need to do so if you would prefer not to.
Sometimes, to help accurately visualise specific parts of the body, it may be necessary to introduce a special ‘dye’ into your body. This dye is known as a contrast agent (also sometimes referred to as a ‘contrast media’), and it helps to show up parts of your body more clearly on the MRI scan. For MRI scans, the contrast agent used is normally a gadolinium-based one.
Should you require a contrast agent, it will be introduced into your body either by drinking it or via intravenous injection during the scan. Generally, if the contrast agent is being administered to help visualise blood vessels, it will need to be injected. If the agent is being administered to help visualise your gastrointestinal tract, it will usually be given orally. This will have been explained to you before the scan, and the staff will talk with you as they administer the contrast agent. The contrast agent is filtered out and will be naturally excreted by your body following your scan. We always advise drinking fluids after your scan to help flush the contrast agent from your body.
After the scan
You will usually be able to go home straight after your scan. If you had an injection as part of the scan, whether contrast agent or relaxant, you may be asked to sit and wait in a quiet waiting area for 15 minutes to make sure that you have fully recovered before you are allowed home. This is for your safety, and to make sure you don’t experience any delayed side effects.
Following your scan, the results will be sent to the doctor who referred you for the scan, so the next time you see them you will be able to discuss the results.
Metal and electronic implants
The use of magnets within an MRI scanner means that certain precautions need to be taken before you enter the scanning room.
Items of clothing or jewellery containing metal will need to be removed. This includes earrings and belts, although finger rings are usually not required to be removed.
If you have any electronic devices or pieces of metal in your body, you will need to let the staff know about this at the earliest opportunity. This includes items such as:
- a pacemaker, used to correct an irregular heartbeat
- metallic joint replacement, most common in the hip and knee
- metallic fragments in or near you eye; this is most commonly seen in people who work with metal for a living, such as welders
- metal plates or screws, which are often used in orthopaedic surgery to realign fractured bones and to fix them securely in place
- An artificial heart valve
- A neurostimulator
- A cochlear implant in your ear
Should you have any of the above, staff will need to assess the suitability of an MRI scan for you. To aid them in this, you may require an X-ray before your scan in order to determine the size and/or position of any metal in your body. Safety is paramount at Circle, and we will always ensure that it is safe for you to have an MRI scan before proceeding.
You will need to let staff know if there is any chance you could be pregnant at the time of your scan. Although MRI scans are considered to be safe, they are not normally advised during pregnancy due to uncertainty about the effects that the strong magnetic fields may have on the baby.
While an MRI scan is a safe procedure, some people do find the experience of entering the scanner unnerving. Staff will be monitoring you the entire time, able to speak to you and hear you via microphones and speakers in the scanner, but if you suffer from claustrophobia do let Circle staff know in advance and they will do everything they can to help put you at ease before your scan. In severe cases of claustrophobia or anxiety, you may be advised to have anti-anxiety medicine or a gentle sedative to help calm you for the scan. Should this be recommended, the consultant and radiographer will discuss it fully with you in advance of the scan.
The way an MRI scanner works means that it is quite noisy at certain points during a scan, with bumps and knocking noises occurring. These noises are caused by the electric current in the scanner coils alternating between ‘on’ and ‘off.’. To reduce the noise, you will be given some ear defenders to wear. These resemble headphones and help to protect your ears from the loud noises.
An MRI scan needs to be requested by a doctor or suitable healthcare professional. Upon being referred for an MRI scan, your closest Circle hospital will be able to schedule an appointment for you at a time of your convenience. Contact our friendly team today, who will be happy to book you an appointment.
As a general guide, our private and self-pay patients are typically offered a scan appointment within two working days. Scans are then reported on by a consultant radiologist, with the report then sent back to the referring clinician within 48 hours of the scan. You can expect to receive the results from your scan when you next see your doctor.
As always, should you have any questions, please contact Circle today on 02070345250 to book an MRI scan at a Circle hospital or find out more.