MRI scan

What an MRI scan is?

MRI stands for Magnetic Resonance Imaging. This type of scan uses magnetism to build up a picture of the inside of the body.

                    

MRI is completely painless, but the scanner is very noisy. The MRI scanner creates cross section pictures of the body. It can show up soft tissues very clearly and a single scan can produce many pictures from angles all round the body. The pictures can be affected by movement so they aren't used very often for some tumors because coughing, swallowing or breathing will make the scan less clear.

MRI can be used on most areas of the body. For some parts of the body and for some types of tissues, it can produce clearer results than a CT scan. For other situations, the CT scan is better. Your own doctor will know which the best type of scans is for you.

MRI is particularly good for some types of brain tumour, primary bonetumours, soft tissuesarcomas and for tumors 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, such as cervix or bladder cancer, MRI is better than CT at showing how deeply the tumor has grown into body tissues. It can be particularly useful for showing whether the tissue left behind after treatment is cancer or not.

As well as being used to find or stage tumors, MRI can be used to measure blood flow. You may have an injection of a special dye before the scan to help make the pictures clearer.

The photo above shows an MRI scanner. It is a large cylinder with a couch that can move backwards and forwards through the cylinder. The pictures are taken inside the cylinder. The MRI is in a protected room to keep out radio waves as these interfere with the scan.

Is MRI safe?

MRI is very safe - because of the checklist you fill in beforehand. There are some people who cannot have an MRI 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 MRI 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. The doctors and radiographers will know what to do if you have this type of reaction.

Generally you won't be given an MRI scan if you are pregnant, but it can be done if absolutely necessary.