To make an appointment for MRI call (495)-741-06-41
This page tells you about MRI scans. There is information on:
- How an MRI scanner works
- Preparation for the scan
- What will happen
- Injections before the scan
- Is MRI safe?
- The results
MRT stands for Magnetic Resonance Imaging. Sometimes especially in Russia a term MRT - Magnetic Resonance Tomography is used This type of scan uses magnetism to build up a picture of the inside of the body instead of X-rays.
MRT is completely painless, but rather noisy. The MRT scanner can be used for cross section views of the body, like the CT scanner. The main advantages of MRT scans are that they use no X-ray radiation, they can show up soft tissues very clearly and a single scan can produce many pictures from angles all round the body. The drawbacks are that they are very noisy and they can be affected by movement. So they aren't used so often for some mouth tumours, for example, because coughing or swallowing will make the scan less clear. MRT can be used on most of the body. For some parts of the body and for some types of tissues, it can produce clearer results than CT scan. For other situations, CT scan is better. Your own doctor will be best placed to decide the best type of scan for you.
MRT is particularly good for some types of brain tumour , for primary bone tumours and soft tissue sarcomas and for tumours affecting the spinal cord . In some situations, your doctor may suggest MRI if a CT scan hasn't been able to give all the information they need. In some early cancers, for example cervix or bladder cancer, MRT is better than CT at showing how deeply the tumour has grown into body tissues. It can be particularly useful for showing whether tissue left behind after treatment is tumour or not. As well as being used to find or stage tumours, MRI can be used to measure blood flow. As with CT scans, you may have a type of special dye by injection before the scan to help make the pictures clearer.
MRI scanner is a large cylinder with a couch that can move backwards and forwards through the cylinder. The pictures are taken inside the cylinder. The MRT is in a protected room to keep out radio waves as these interfere with the scan .
Preparation for the scan
Some MRI scans need preparation beforehand. If there are special preparations, you will be told about them in plenty of time. You can take all your medicines as normal beforehand so don't worry about that. You may be asked not to eat for at least an hour before your scan .
What will happen
Once you have checked in, the receptionist will ask you to take a seat in the waiting room until the radiographer or helper calls you. At this point, you will have to complete and sign a checklist for safety. This will ask you about any medical conditions you may have, mainly those that may involve any metal implants. This includes pacemakers, surgical clips, pins or plates and cochlear implants (for deafness). If you have your ears pierced (or any other part of your body), you will have to take out your rings or studs before your scan . If you have a contraceptive coil (IUD) fitted, you must tell the radiographer as some have copper wire in them. You should also tell them if you think you may have any metal fragments anywhere - this sounds odd but is common in those who do metalwork or welding for a living. If you think this is possible, you'll need an X-ray before the MRT to check.
When it is time for your scan , you may first go to a cubicle to take off your outer clothing down to your underwear and put on a hospital gown. Don't forget to remove jewellry, watch and hair clips. If you are just having an MRI of your head, you may not have to undress.
The scan uses a very powerful magnet. If you still have your clothes on, it is best to empty your pockets. You need to remove all coins, keys and credit cards so it might be easier to take everything out. Because there is no radiation, it is safe to take a relative or friend into the scanning room with you if you like. They will also have to take off everything metal. Remember little things like hairslides, cufflinks and belt buckles.
When you are ready, the radiographer will take you into the scanning room. You will need to lie down on the machine couch. Most MRT scans are done with you lying on your back. You have to lie as still as you can, but breathe normally. Your radiographer will explain any instructions beforehand. You may have to hold your breath at points during the scan so that you move as little as possible. Any movement can blur the scan .
The radiographer may offer you ear plugs or headphones to wear. MRI scans are very noisy. The noise is like a loud clanging inside the cylinder and it goes on throughout the scan . The radiographers do prefer that you wear some sort of ear protection to safeguard your hearing and for your own comfort. And if you wear headphones, you can listen to music while the scan is going on.
Once you are positioned in the scanner, the radiographer will go out to the control panel. They will be able to see the scanning room through a window or on a TV screen and you can talk to each other through an intercom. They will tell you that they are about to start the scan and remind you to keep as still as you can.
When the scan is over, the radiographer will come back into the room and help you down from the couch.
An MRT scan can take anything from half an hour to an hour and a half. Lying still for that long can be uncomfortable. If you are getting stiff and need to move, tell the radiographers through the intercom. It is very important to keep as still as you can, otherwise parts of the scan may have to be done again and the whole thing will take even longer. You should be able to go home as soon as the scan is over.
Some people feel a bit claustrophobic ('closed in') when they
are having a scan. If you think you are likely to feel
this way, tell the radiographers before the day of your scan.
If necessary, you can have a tablet or injection to calm you down before the scan. If you need a sedative, it needs to be organised in advance so if you think you'll need one, do ring the department as soon as your appointment comes through. If your radiographers know you are nervous, they will take extra care in making sure you are comfortable and understand what is going on. Keeping your eyes closed sometimes helps. Or you can bring in a tape or CD of some favourite music that the radiographers can play through your headphones to help pass the time.
Injections before the scan
As with CT scans, you may have an injection of a type of dye (called contrast medium) just before the scan. This helps to make the scan clearer. This is particularly likely if you are having a body scan as the dye makes the body organs show up more clearly.
Is MRI safe?
MRT is very safe - because of the checklist you complete beforehand. There are some people who cannot have an MRT but the checklist will make sure this is picked up. The scan uses magnetism, so metal will affect it. If you have certain types of metal surgical clips, metal pins or plates or a pacemaker inside your body, you cannot have an MRT scan.
Very, very rarely, someone has an allergic reaction to the contrast medium injection. The reaction most often starts with sweating, rash and difficulty breathing. It is possible to react to any injection in this way, and the doctors and radiographers will know what to do if you should have this type of reaction.
Generally you won't be given an MRT scan if you are pregnant, but it can be done if absolutely necessary.
It can take time for test results to come through. How long will depend on why you are having the scan. Usually, a specialist in MRT sees the scan and dictates a report to be typed up. The report then goes to your specialist, who gives the results to you. If your GP has sent you for the test, the results will be sent directly to the GP surgery.
Understandably, waiting for results can make you anxious. It usually takes a couple of weeks for the results to come through. If your doctor needed the results urgently, it would have been noted on the scan request form and the results will be ready sooner than that. Try to remember to ask your doctor how long you should expect to wait for the results when you are first asked to go for the test. If it is not an emergency, and you have not heard a couple of weeks after your test, ring your doctor's secretary to check if they are back.