Sinus MRI is a diagnostic examination of the paranasal sinuses of the nose using magnetic resonance imaging. The principle of operation of the equipment is based on the movement of hydrogen protons induced by an external magnetic field (nuclear magnetic resonance). The obtained images allow us to assess the structural features of the paranasal sinuses, identify the presence of inflammation or neoplasms, determine the extent of their spread to nearby anatomical structures, etc.
Sinus MRI is considered an auxiliary (alternative) method of investigation. The procedure is carried out with unclear or questionable results of radiography or computed tomography. Indications for sinus scanning are:
- Sinusitis. MRI has a higher resolution than X-rays and CT scans, which makes it possible to detect even minor inflammatory changes in the mucous membrane of the sinuses, especially the latticed and wedge-shaped.
- Polyps of the sinuses of the nose. Soft tissue structures are better visualized on MRI, therefore, in the presence of sinus polyps, it is preferable to use this method of examination.
- Suspected tumor. It is considered the main indication for MRI of the sinuses. The technique allows you to specify the size of neoplasia, the degree of involvement of surrounding tissues. To diagnose malignant neoplasms, a contrast agent is pre-injected.
- Control of treatment. Sinus MRI is often used to evaluate the effectiveness of surgical intervention.
Despite the fact that this diagnostic method is completely harmless to the body, under some circumstances, MRI is contraindicated. Scanning is not prescribed in the following cases:
- The presence of implanted devices: artificial pacemaker (pacemaker), intracranial ferromagnetic hemostatic clips, cochlear implant, metal prosthetic stirrups.
- Pregnancy, lactation, kidney failure – MRI using contrast is prohibited.
- Epilepsy – with poor seizure control.
- Allergy to a contrast agent.
Adults and children over 6 years of age do not need special training. Children under 6 years of age are often pre-injected with sedatives or hypnotics, since in order to obtain high–quality images it is necessary to observe complete immobility during the procedure (the duration of the test is about 20-25 minutes, with the introduction of contrast – 45-50 minutes). The use of medications increases the cost of the method.
Immediately before entering the room in which the tomograph is located, it is necessary to remove the wristwatch, belt, jewelry (earrings, bracelets) and clothing with metal elements. You should get your phone, keys, and bank cards out of your pockets.
Methodology of conducting
The patient lies down on a special movable tomograph table with his face up, takes a comfortable position. Small children are fixed with belts. Since the patient is in a confined space, and a working tomograph makes a very intense noise, in case of an emergency (poor health, panic attack), the doctor or laboratory assistant gives the patient an alarm button or a warning pear in his hands.
If the study is carried out with contrast enhancement, a system for intravenous infusion of contrast is installed. Then the table is pushed into the tunnel of the tomograph. After that, the patient is forbidden to perform any actions. The introduction of a contrast agent (gadolinium) is not performed immediately, but after receiving several images – this is necessary for comparing tomographic pictures.
In the images obtained, the doctor assesses the level of pneumatization of the sinuses, the clarity of the contours, the thickness of the walls, the presence of exudate or formations, their prevalence on the surrounding tissues, the degree of contrast absorption. An important role is played by determining the intensity of the MR signal, for example, malignant tumors have a hypointensive signal, and inflammatory changes in the mucosa are hyperintensive.
An sinus MRI is harmless, since it does not use ionizing radiation. The main problem is related to the need to stay in a confined space, which is undesirable for people suffering from claustrophobia. Adverse consequences occur when contraindications are ignored. In some cases, a fatal outcome is possible, for example, cardiac arrest due to failure of a pacemaker or hemorrhage in the brain due to displacement of intracranial clips and rupture of blood vessels.
The vast majority of complications are associated with the use of contrast. During its administration, unpleasant sensations (nausea, a feeling of heat), allergic reactions (urticaria, Quincke’s edema, anaphylactic shock) may appear. More severe but rare complications of using gadolinium contrasts are pseudohypocalcemia and nephrogenic systemic fibrosis.