Magnetic resonance imaging (MRI) is an examination that uses a magnetic field and radio waves to produce images of body structures. With the help of MRI, it is possible to obtain high-resolution images of organs, which can help in establishing an accurate diagnosis.
An examination may be needed in the following cases:
With the help of MRI, the brain and spinal cord, bone, muscle and joint system, abdominal and pelvic organs, ears, eyes, heart, blood vessel system, and in some cases the chest and lungs are examined.
How to prepare for a visit?
- A referral from a specialist is required. In the case of an MRI, a referral from a family doctor is only valid in conjunction with a referral from a specialist.
- Before an MRI, it is necessary to determine the level of creatinine in the blood, taking the result of the analysis with you.
- Be sure to take with you the results of previous examinations (radiological, functional diagnostics, especially electroencephalography data if a brain examination is performed in patients with epilepsy), including images, test results, and hospital discharges, if any. It is important to remember that it is better to take more documents with you than less. The interpretation of the examination images depends on the awareness of the radiologist.
- To reduce the child’s anxiety, explain in simple terms why an MRI is necessary. If necessary, be nearby during the procedure, it is also allowed to take your favorite book or toy with you.
- If the MRI is performed under general anesthesia, on the day of the examination (at least 3 to 4 hours before the examination), you can neither eat nor drink. This condition is mandatory because otherwise, there is a risk of getting the contents of the stomach into the respiratory tract and this may threaten the life of the patient.
- For an abdominal or whole-body MR examination, the child should not eat for 6 hours before the procedure and, if the MRI is performed without anesthesia, it may be necessary to drink a certain amount of water (1 – 2 cups) before the examination. Patients with or suspected Crohn’s disease will need to drink 1 to 1.5 liters of mannitol solution from the MRI room 1 to 2 hours before the examination.
- In the case of a pelvic exam, the bladder should be moderately full (not empty or full).
- For examination of the brain and spinal cord, blood vessels, heart, as well as musculoskeletal system, there is no need for special preparation.
- Girls on the day of the MRI are prohibited from using mascara and eye shadow, because. they may contain metal particles that stick to the device and cannot be removed.
- Before the examination, it is necessary to remove from the child and the accompanying person, if he is nearby during the MRI, all-metal objects – jewelry, piercings, hair clips, glasses, take-out keys, coins, bank cards, mobile phone from pockets.
Carrying out diagnostics
The MRI device consists of a large magnet with a tunnel in the center and a movable table on which the patient is positioned. To preserve hearing, earplugs are inserted into the ears, and headphones are put on. During the scan, the child must lie still, because. movements interfere with the examination and reduce the quality of the images. During operation, the device makes roaring sounds that are not harmful to health. During an MRI examination, several series of images are created. In certain cases, to obtain additional information, it is necessary to introduce a contrast agent through a vein, for which an intravenous catheter will be placed in the child before the examination. The total time of the procedure depends on the amount of information received – from 20 to 90 minutes. For small children (up to 7 years old) and children who are unable to lie still during the procedure, The examination is performed under general anesthesia. Such patients are placed in a day hospital before the MRI examination.
If the examination is carried out under anesthesia, you can leave the day hospital after full awakening (usually this happens within a couple of hours after the procedure), after agreeing on this with the medical staff.
During MRI, the patient is placed in a powerful magnetic field and irradiated with radio waves that do not harm tissues, so the MRI method is considered harmless for both children and pregnant women. MRI should not be performed if the patient has: an inner ear implant, artificial valves, neurostimulators, pacemakers, certain metallic foreign bodies, pregnancy before 12 weeks, not including life-threatening situations.
For MRI, gadolinium contrast is injected, which does not contain iodine, and its use is not prohibited for patients who cannot tolerate the contrast agent injected for computed tomography. In most cases, the use of a gadolinium contrast agent is safe, in some cases (1-5% of patients) transient headache, nausea, and dizziness, as well as a feeling of cold at the injection site, may occur. Allergic reactions to the administration of a contrast agent are extremely rare – in one in 10,000 patients. A rare complication of the administration of gadolinium is nephrogenic systemic fibrosis, in which thickening and tightening of the skin are formed, as well as damage to internal organs. In this regard, for patients with reduced renal function or renal failure (both acute and chronic) and hepatorenal syndrome (a pathology in which a decrease in kidney and liver function is characteristic), one should refrain from administering a contrast agent for MRI. To prevent the development of this pathology, gadolinium contrast is administered to children only after reaching 3 months of age and only if its use is justified by the clinical situation.