MRI: indications and course of the examination

What is MRI?

MRI is an imaging technique that provides 2 or 3 D views of the inside of the body and is able to detect invisible lesions in other exams such as standard radio, CT scan or ultrasound. MRI uses a magnetic field and radio waves. Its principle is to produce images of the body by resonating the hydrogen atoms it contains through stimulation by radio waves. When this stimulation stops, these atoms will produce energy that will materialize by a signal that will be retranscribed in the form of images. The images delivered are delivered in sections of different plans and then reconstructed in 3D.

Why is an MRI prescribed?

The indications of the examination are multiple and it can be prescribed by any general practitioner or specialist. Highly sensitive, this examination can give particularly accurate images of the brain, joints and soft tissues, spine, digestive organs. It can detect tumors, infectious lesions, inflammatory diseases (such as multiple sclerosis), hernias, ligamentous lesions.

The course of the MRI and its contraindications

The machine takes the form of a tunnel in which the patient will lie down. Before performing the examination, the patient must remove all metal jewelry but also glasses, hearing aids or dental. The radio handler will tell him what clothes he needs to remove and can make him put on a blouse if necessary. Do not hesitate to ask for a blanket, these rooms are sometimes cold and the exam can be long, 30 minutes on average. The patient is then lying down and the device is positioned on the area to be visualized. If it is the brain, the head can be held to avoid movements that would falsify the examination.

A mirror is often placed just above the patient's face to allow him to see the staff and he is given a small box on which he can support if there is a problem. MRI is a noisy exam, so you usually have a headset, but you can also bring your own earplugs. Depending on what is sought and to obtain better images, a contrast medium may be injected intravenously during the examination. The product, often gadolinium is not recommended in pregnant women, people with liver failure or kidney problems. The doctor will assess the situation on a case-by-case basis.

• Contraindications to MRI

Contraindications to MRI are related to the magnetic fields used to perform the examination. It is therefore not recommended for people with mechanical heart valves, neurostimulator, cochlear implants, in case of presence of a metallic foreign body in the body (nails, screws, etc.), pregnant women.

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