Magnetic resonance imaging (MRI), like computed tomography (CT), is one of the modern diagnostic methods useful in detecting a variety of diseases.
MRI allows a cross-section of the internal organs to be imaged in all planes. This is possible because the human body, like everything else in the world, is made up of atoms.
Hydrogen atoms, which are found in all human tissues, are the most important in MRI. A special apparatus that produces a magnetic field and radio waves is used to perform the test.
The patient is placed in a strong magnetic field, which is produced by the scanner. This causes the rotation axis of the hydrogen atoms to be ordered. Then, due to an alternating electromagnetic field, a resonance excitation of the atoms’ nuclei occurs. The nuclei start sending out signals (radio waves), which are picked up by a special antenna placed around the patient. The intensity of these signals varies depending on the type of tissue. These signals are processed by a computer into an image.
An MRI scan may require the administration of a contrast agent. Currently, elements such as manganese Mn2+, iron Fe2+, and gadolinium Gd3+ are most commonly used.
Preparation for magnetic resonance examination
- The patient should be fasting at least 6 hours before the test.
- Young children are given sedatives.
- The patient does not need to undress for the examination.
- The patient should inform the doctor that she is pregnant.
- It is recommended to wear no makeup or hairspray, and to wear loose clothing without metal fasteners or zippers.
No metal objects should be brought into the room where the examination room is located, as this can damage the examination room (keys, pendants, jewelry, watches, etc.).
The examining physician should be informed of the presence of:
- an artificial heart valve
- vascular prosthesis
- artificial hip
- Other metallic objects, such as filings, metal fragments, nails, plates.
Tell your doctor if you are claustrophobic or prone to bleeding.
IT IS DEFINITELY PROHIBITED TO HAVE A HEART STIMMER!!!
Patients with a pacemaker should not even enter the room where the magnet is located, as this may interfere with the pacemaker and eventually lead to the patient’s death.
Also, patients with implanted neurostimulators cannot be examined by MRI.
Relative contraindications to MRI:
- artificial heart valve
- Metal orthopedic implants
- vascular clips.
Patients with any of these devices are required to provide full documentation about the device and the operation during which it was implanted. Such documentation should include the date of device manufacture and the name of the material from which it was made.
Course of magnetic resonance examination
The patient lies down on a moving table. Then, he/she is moved to the center of the apparatus, the so-called gantry. During the examination the patient cannot move. The examination lasts from 1 to 3 hours. Lighting is installed in the tunnel to increase the patient’s comfort.
During the examination the patient has constant contact with the doctor through a camera and microphone.
Since the temperature inside rises to about 25°C, it is necessary to dress lightly. During the examination you will hear a knocking sound.
Since it is quite noisy inside the machine during the examination, the patient wears noise-cancelling headphones.
Main use of magnetic resonance imaging
The indications for magnetic resonance imaging are similar to those for computed tomography. However, it should be noted that this examination is more accurate.
- Diseases of the central nervous system
- brain tumors
- multiple sclerosis
- Alzheimer’s disease.
2.Diseases of the spine
- post-traumatic lesions
- tumours of the spinal canal.
3.Soft tissue diseases
- tumors of soft tissues
- injuries of ligaments, joints, muscles.
- heart tumors
- lung tumours.
5. Vascular diseases, e.g. aneurysms.
6. Orbital diseases
- intraocular pathologies
- Graves’ disease
- Orbital tumors.
Patient safety during MRI examination
Magnetic resonance does not use X-rays and, therefore, unlike computed tomography, it is a completely safe examination.