This radiological examination uses electromagnetic fields.
Painless and reliable, Magnetic Resonance Imaging (MRI) is a radiological examination that uses a non-invasive medical imaging technique. It allows you to obtain 2D and 3D views of all tissues of the human body, whether hard tissues (bones) or soft tissues (bone marrow, central nervous system, muscles, heart). . MRI is often even more precise than x-rays, ultrasound or CT scans.
Brain MRI: definition and indications
A brain MRI may be ordered if neurological symptoms are present. The objective is then to detect possible anomalies in the brain and its vessels (tumor, vascular accident, multiple sclerosis, etc.).
How to prepare for it? No precautions are necessary before having a brain MRI. However, the long duration of the examination and the immobility it requires to obtain good image quality must be taken into consideration. The patient must also report if he or she is:
- claustrophobic so that the doctor can act and react accordingly during the examination,
- pregnant (whether the pregnancy is suspected or proven),
- carrier of an electronic system such as a cardiac pacemaker (in this case, the examination is impossible since these systems could fail) or of a metal body such as a prosthesis or implant (the examination again is impossible because these parts of metal could move under the effect of the magnet).
Spinal MRI: definition and indications
Spinal MRI is an examination that allows you to study the spinal cord and the vertebral column along their entire length. It is used in particular in cases of suspected disc herniation with compression of the spinal cord, but also in cases of multiple sclerosis.
Unlike x-rays, ultrasound or CT scans, MRI is not irradiating: it uses a magnetic field and radio waves. The technique is based on the use of a very powerful magnet which will generate a magnetic field having an action on the hydrogen ions contained in the body’s water.
The device consists of a tunnel inside which is the magnet which surrounds the examination bed where the patient lies. It weighs several tons and looks like a large cylinder with a hole in the center. A computer reconstructs the images obtained, computer analysis of the results making it possible to obtain quality images in 2D or, after computer reconstruction, in 3D.
Indications: when to perform an MRI?
MRI not only makes it possible to diagnose tumors, but also to monitor their evolution during treatment or after treatment as part of regular monitoring in order to detect relapse. “Any doctor can order an MRI“, specifies radiologist Thomas Bourdrel. For example, we can go:
- an MRI of the liver, pancreas, kidneys to characterize abnormalities such as cysts or cancers, but also to look for common bile duct stones (BiliIRM).
- an enteroMRI, which allows a good analysis of the intestine and is useful in Crohn’s disease.
- a pelvic MRI is the best test to detect endometriosis as well as to characterize an ovarian cyst.
- a prostate MRI is also increasingly replacing ultrasound and is much more sensitive than ultrasound for detecting prostate cancer. Note that the lung is the only organ that cannot be properly explored by MRI.
- an MRI is also very effective for studying joints.
In general, the patient must be in underwear and not wear any metal parts (jewelry, glasses, hearing or dental aids, etc.). It is not necessary to fast.
The patient is placed on a bed that advances mechanically inside the machine, resembling a large hose. The patient wears headphones that can allow him to listen to music because the machine makes a lot of noise. However, some centers prohibit music in order to avoid any movement of the patient, which would generate movement artifacts and affect the quality of the images acquired. In the event of a problem, a bell located inside allows you to contact the doctor.
The examination is carried out by a technician and interpreted by a doctor. The radiology technician, present in a cabin, observes the smooth progress of the examination and any reactions of the person. It is sometimes necessary to give an anxiolytic, a medication that relieves the anxiety of claustrophobic people. The examination is carried out on an empty stomach if an injection of contrast product is carried out. The exam lasts between thirty minutes and one hour. “In very young children, these examinations are carried out in hospital, using sedation with an on-site anesthetist.“, specifies Dr Bourdrel.
MRI can be performed with or without injection of a contrast agent. The contrast material can be injected into a vein in an arm to more closely observe the targeted organ.
Is it painful?
MRI is a completely painless examination, but it is not very pleasant due to the noise inside the device and its duration. Not to mention that you have to be perfectly still. “A feeling of warmth may be present“, adds Dr Bourdrel.
What are the risks?
Due to the powerful magnetic field, there are certain contraindications such as the presence of a pacemaker or the existence of certain types of heart valves comprising a metal part, brain clips, prostheses or hearing aids. Another risk: the presence of vascular stents, including if they are cerebral.
Thanks to Thomas Bourdrel, radiologist.
