Contents
The temporomandibular joint (TMJ) is a paired joint that is responsible for synchronous sliding and rotational movements of the lower jaw. Due to its anatomically complex structure, the TMJ is one of the most difficult joints in the body to diagnose, but its normal functioning is an integral part of human dental health.
Internal injuries of the temporomandibular joint in combination with violations of the anatomical correspondences between the articular discs and the lower jaw cause dysfunction of the temporomandibular joint. At an early stage of damage, the articular disc retains its original shape, but over time it deforms and becomes the cause of the onset and development of various dental diseases.
To detect and evaluate injuries and pathologies of the temporomandibular joint, it is necessary to accurately establish the localization of the articular disc. Magnetic resonance imaging of the TMJ joint is a non-invasive research method that has no alternative, which allows you to get a layered image of the scanned area in high resolution with the necessary magnification.
MRI of the temporomandibular joint does not carry radiation exposure, therefore it has a limited number of contraindications and is suitable for multiple examinations of patients.
Indications for MRI of the temporomandibular joint
The temporomandibular joint is functionally connected with the teeth, therefore, it undergoes significant changes during life. The load on the TMJ is so high that it leads to the destruction of articular tissues and the occurrence of degenerative processes up to the development of osteoporosis. In addition, this joint is subject to mechanical damage due to malformed bite, extraction of teeth, prosthetics and maxillofacial injuries.
MRI of the temporomandibular joint is prescribed by a maxillofacial surgeon, dentist or ENT doctor for: joint mobility disorders, pain during movement of the lower jaw, jaw injuries, displacement and jamming of the jaw joints, swelling and numbness of half of the face, arthritis, arthrosis and ankylosis, suspicion on oncological neoplasms in the study area, the need for preliminary diagnosis before surgery and evaluation of the effectiveness of treatment.
MRI images clearly visualize inflammation of the TMJ and surrounding soft tissues, various neoplasms in the early stages, and other pathologies. MRI is no less effective for diagnosing jaw dislocations, disc displacement, and violations of the integrity of nearby vessels.
Statistical data show that MRI of the temporomandibular joint detects displacement of the articular disc in more than 30% of patients who turn to the maxillofacial surgeon with the corresponding symptoms. As a rule, MR screening is sufficient to detect TMJ dysfunction and its causes, so traumatic punctures and additional arthroscopy are not required.
Features of MRI of the temporomandibular joint
MR imaging of TMJ injuries and dysfunction is performed in two positions: with the mouth open and closed. Diagnostics can be carried out both on open and closed scanners. During an examination on a closed-type tomograph, the patient is only partially placed inside the scanner. During the screening process, it is necessary to keep the scanned area completely still, so the head can be fixed using special devices.
As a rule, the introduction of contrast agents to improve the accuracy of the result is not required, since the jaw area is clearly visualized with a simple scan. But sometimes contrast may be required to diagnose complex pathologies of the TMJ.
For contrast tomography, preparations based on the paramagnetic gadolinium are used, which do not contain iodine and do not cause an allergic reaction. Allergy tests are recommended only for those patients who suffer from intolerance to certain medications, and who have a history of severe allergic reactions in the form of anaphylactic shock or Quincke’s edema to some drugs. In the presence of renal failure, additional examinations may also be necessary before MRI with contrast.
Absolute contraindications for MRI of the TMJ: permanent pacemakers and pacemakers, intracranial clips made of ferromagnetic material, implanted cochlear devices, metal braces and dentures, foreign bodies and metal fragments in the orbits.
Absolute contraindications for MRI are the same for all types of diagnostics, since they depend on the characteristics of the scanning process. The tomograph magnet generates a powerful constant field that can disable electronic devices.
Metal prostheses and implants, when exposed to the field, can become magnetized and displaced, exposing the patient to serious danger. RF pulses, in turn, imitate heart contractions and lead to a violation of the cardiac activity of a person who needs constant pacing.
MRI is also contraindicated in women in the first trimester of pregnancy due to the fact that the effect of radio frequency waves and a strong magnetic field on the fetus has not yet been studied. MRI of the TMJ with contrast is not recommended throughout pregnancy and lactation, but simple diagnostics without contrast can be performed. If during lactation the stage of contrasting is extremely necessary, then after its use, a woman needs to refrain from breastfeeding for two days, express milk and pour it out.
Screening of the temporomandibular joint
There is no special preparation required before an MRI of the TMJ, so you can eat and take your medications as usual. If it is necessary to administer contrast agents, it is not recommended to eat at least 4-5 hours before the examination in order to avoid nausea and other possible complications.
People who suffer from claustrophobia, asthma, epilepsy, and other mental disorders that prevent them from remaining still should discuss these nuances with a radiologist. Sedatives or drug-induced sleep may be prescribed to calm the patient and relieve panic attacks.
Relative contraindications to MRI of the TMJ, which should also be reported to the specialist in advance: removable pacemakers and defibrillators, non-ferromagnetic prostheses of the inner ear and hemostatic clips, dentures, bridges, implants in non-scanned organs, the presence of tattoos, the need for physiological monitoring.
The patient can change into the proposed clothes or take with them spacious clothes without metal parts. Before the procedure, it is necessary to make sure that there are no metal objects, jewelry, accessories on the body.
It is unacceptable to be in the same room with a magnetic field of any electronic gadgets, credit cards, mobile phones, watches, etc. The same rules apply to everyone who is near the patient at the time of the scan.
The scanning procedure usually takes 30-60 minutes in the position of the open and closed mouth. The images-sections obtained as a result of screening are processed by a special computer program and stored on electronic media or as a three-dimensional image of the examined area.
Advantages and disadvantages of TMJ MRI
Among non-invasive research methods, MRI is the most accurate and safe diagnostics, but it has both positive and negative sides. MRI is best suited for examining a patient for TMJ injuries, inflammation of the joints and joint capsules, tumors, various violations of the integrity of blood vessels and soft tissues.
The advantages of MRI compared to radiography and CT are the absence of radiation exposure, accurate and detailed visualization of organs and tissues without interference in the form of bone structures. However, if necessary, the diagnosis of fractures and bone pathologies should be examined using computed tomography.