MR Imaging is the formation of images using magnetic fields and radio waves. No harmful rays are used. MR is appropriate for diagnosing illnesses in the brain. The MR examination is experienced by some patients as being very uncomfortable.
What is MR imaging?
MR is short for Magnetic Resonance and is the formation of images using magnetic fields and radio waves. MR imaging of the brain gives the same or broader information about illnesses in the brain as a CT scan but without the use of harmful radiation.
What is an MR examination used for?
MR imaging is appropriate for producing a detailed image of the brain. Thereby, making it easier to detect brain tumours, thromboses, inflammation and congenital illnesses in the brain. Especially in the case of the illness sclerosis (multiple), MR imaging is of great value.
MR imaging is often used as a first examination in the case of injuries to the knee – especially if there is suspicion of damage to the meniscus or the cruciate ligament. From an x-ray the doctor can look for damages to the bones but not to the ligaments or meniscus – this is possible to detect from an MR.
Compared to a CT scan, MR imaging has some advantages but also some disadvantages. The advantages with MR imaging are biggest when it concerns illnesses in the brain. MR imaging is more expensive and very sensitive to even the slightest uneasiness with the patient. Claustrophobia is experienced more frequently during MR imaging than during a CT scan.
What is going to happen?
During MR imaging, the patient lies on a moveable bed. Most MR scanners are tunnel shaped with an opening in both ends. When the patient is placed in the tunnel, some people are struck with anxiety or even claustrophobia. During the examination knocking sounds are heard. If you have difficulties being in small rooms or are scared of the MR examination you can be given a sedative medication. Talk to your doctor about it. Earplugs or earphones with music is recommended to muffle the knocking sounds. It is important that the patient lies absolutely still since movement will cause the examination to fail. Typically, the examination lasts 20-45 minutes.
Since magnetic fields are used, the patient is not allowed to carry any metal on his or her body. Hearing aid, dentures, jewellery, piercings, pacemaker and prostheses can cause problems. Certain types of cosmetics (mascara) contain metal and can therefore cause discomfort and disturbances on the MR imaging. Therefore, the patient is not allowed to wear make-up during the examination.
No harmful effects to the foetus have been detected but if the examination can be postponed until after the pregnancy, this is recommended as a precaution. If the examination cannot be postponed, MR imaging is preferred over a CT scan that uses ionising radiation.
What can an MR examination show?
Smaller or bigger changes of illnesses in the brain tissue can be represented at an MR examination. It can be haemorrhaging, tumours or inflammation. In most cases, MR imaging provides better information about illnesses in the brain than a CT scan.
Damages to meniscus or ligaments in the knees can be detected with MR imaging. If MR imaging is a possibility, the doctor – with patients with injuries to the knee – prefers MR imaging over an endoscopy of the knee.
Is it dangerous?
In the case of an ordinary x-ray examination and CT scan, ionised rays are used to produce an image. With an MR examination, magnetic fields and radio waves are used. No harmful effects of magnetic fields and radio waves have been proven. Therefore, MR imaging is milder for the patient.