Contents
Computed tomography of the temporomandibular joint belongs to the category of non-invasive diagnostics based on the principle of X-ray examination. Briefly, this procedure is simply called CT TMJ. It is aimed at studying a potentially modified area with the involvement of radioactive radiation.
Despite the fact that the technique belongs to the category of relatively safe, it should be carried out only as directed by a doctor. Otherwise, you can increase the risks of negative effects of ionizing radiation on the sensitive parotid glands.
The test results allow you to confirm or refute medical suspicions regarding the presence of neoplasms.
Due to high-precision technology, it is possible to obtain visual information on the presence of even tumors of minimal size and low density.
Expected Outcomes
Information obtained by scanning a presumably pathological lesion in the jaw is visualized by displaying it on a computer screen. Scanning is performed in 3 projections: frontal, axial, sagittal, allowing you to assess not only the current state of the joint space, but also the shape, size, and the presence of a possible neoplasm. If, however, the study is carried out only in one plane, then determining the shape and localization of the poles of the heads of the temporomandibular joint will be very difficult.
The only significant drawback of modern diagnostics is artifacts due to the shadows of the smeared layers in the zones of the medial and lateral poles, which make it difficult to make an accurate diagnosis. In the region of the lateral pole it is an array of the zygomatic arch, in the region of the medial pole it is the petrous part of the temporal bone. The tomogram is clearer if there is a cut in the middle of the head, and the greatest changes in pathology are observed at the poles of the heads. To eliminate the risks of a false positive result, the doctor necessarily repeats the CT scan until the area under study is more clearly visible.
The mechanism for capturing a layered image of tissues is based on the use of x-rays. A potentially problematic area is affected by ionizing beams in different directions due to the rearrangement of the X-ray tube, which makes it possible to get a complete picture of what is happening.
The resulting visual picture allows you to find a number of deviations, among which the most common are:
- changes in the width of the joint space;
- pathology of bone tissue;
- displacement of the articular heads in a position with a closed and open mouth;
- anomalies of the articular disc;
- change in the size of the heads of the joint of the lower jaw.
The results obtained help to identify structural changes in the joint.
When is it time to get tested?
The doctor may prescribe computed tomography, if necessary, to urgently determine the presence of pathology, or confirm the diagnosis. Also, diagnostics will help clarify the nature of pathological changes, which in the future will lay the foundation for a successful course of therapy.
The main reasons for referral for diagnosis are:
- suspicion of oncological neoplasm;
- diagnosis of structural anomalies of the joint, both congenital and acquired;
- search for a suspected focus of inflammation;
- preparatory stage of dental implantation;
- dystrophic changes in the temporomandibular joint;
- problems with the functionality of the jaw.
In addition to the fact that the diagnosis provides information regarding the suspected affected area, it also provides data on the condition of the nearby muscle tissues. This will be useful for those patients who came for examination with a referral from an oncological dispensary, because the picture will show metastases if they are present.
Since this is a rather serious, lengthy and expensive study, it is not prescribed as a prophylaxis. The doctor will issue a referral only after a thorough history taking, patient complaints, an objective examination, the results of a standard set of tests and reading the patient’s medical record.
Typical symptoms indicating possible deviations of the system include: articular dysfunction, joint injury, pain in the jaw area, pain in the cheekbones, jaw mobility disorders, temperature failures, facial asymmetry.
But if a narrow specialist has already recommended a CT scan, then you should not postpone a visit to the diagnostic room. With some diseases, progress occurs in just a few weeks, which, if the medical prescription is ignored, is fraught with numerous complications.
Especially often, early diagnosis helps cancer patients. When the doctor “catches” the disease at the initial stage of development, the percentage of successful outcome of therapy increases several times.
Otherwise, a patient patient can reach the extent of metastatic damage to neighboring tissues and organs, which greatly complicates a favorable outcome of treatment.
Preparatory stage
Before going directly to the procedure, you should check with the attending physician whether there will be an examination with the introduction of a contrast agent, since if the doctor insists on just such an in-depth examination, the preparation may take several days.
Before applying the contrast agent used to make the CT image clearer, the person must have a blood chemistry test. Such a precautionary measure will allow you to establish the current level of urea and creatinine in the blood, in order to avoid the risk of potentially negative effects.
You can not do without standard allergic tests, which are designed to reduce the risk of an organism reaction. On the day of the diagnosis, patients refuse to drink.
If the doctor directs for tomography without the use of contrast, then no special preparatory measures are required.
Before the procedure itself, the X-ray technician will definitely ask you to temporarily remove any metal objects from the body, from jewelry to dentures, as they significantly impair visualization, which is reflected in the distortion of the finished image. Because of this, people are offered to change into cotton pajamas on the spot.
The study is carried out in a horizontal position on a comfortable table. And it is worth preparing for the fact that the doctor will ask you to lie still for a while.
Mechanism of CT
Usually, computed tomography, without taking into account preparatory measures, is done for no more than ten minutes. But if a contrasting stage is added to the examination, then it takes about half an hour. You should not be afraid of feeling nausea and dizziness, which is acceptable after the introduction of the substance.
After the patient is placed on the table, he rolls into a special hardware space, where the information is read directly. During the procedure, the table rotates in a circular mode so that the X-ray radiation can reach the supposed affected area from all sides.
As a result, a layered image of the pathological focus is displayed on the screen without the effect of superposition, which guarantees increased clarity of the boundaries of the lesion.
If the patient needs to receive a conclusion quickly, then the encrypted document can be given to him in about an hour. But usually radiologists send their report directly to the attending physician the next day. Already on the spot, the doctor, based on the results obtained, the patient’s complaints and other data, makes the final verdict.
Sometimes, in difficult cases, the doctor may additionally refer the patient to an MRI after CT scan in order to completely eliminate the risk of a possible medical error or visual error. The combination of two advanced medical technologies is especially relevant when rare genetic abnormalities or oncological tumors are suspected. Since CT is aimed primarily at studying the bone and articular structure, MRI will provide a clear picture of the state of the soft tissues. The joint results are intended to exclude the possibility of diagnostic error.
In rare cases, it may be necessary to re-diagnose on a computed tomography scanner, when a diagnosis is already made on the basis of a double study, followed by the appointment of therapeutic and restorative therapy.
Contraindications for use
Despite the fact that the presented non-invasive method is classified as safe for health, there are some contraindications for its use. This is especially true for pregnant women, whom even minimal radiation exposure can seriously harm, provoking pathologies in the development of the fetus. According to the same principle, women should refuse treatment during lactation.
Also, before prescribing a diagnosis, the doctor must clarify with the patient, or check with the medical card, in order to exclude other factors of contraindications, such as:
- body weight over 120 kg;
- individual intolerance to the components of the contrast agent;
- renal insufficiency.
Separately, cases are considered when the benefits of the procedure are many times greater than the relative contraindications. Here everything happens at the discretion of the attending physician, who knows the characteristics of the organism of the ward and his medical history.
Useful Tips
Experienced doctors say that during testing for the TMJ, some patients experience mild discomfort.
To avoid situations when, in an attempt to change the position, a person shifts and the rendered image is blurred, the technicians built an assistant into the device. This is a two-way microphone. If a person on the table suddenly became ill, had a seizure, or something else out of the ordinary happened, he must immediately inform the X-ray laboratory assistant about it.
It is also worth understanding with understanding the doctor’s request to hold your breath. This approach increases the information content of the results, if you follow the instructions strictly. Otherwise, you will have to re-diagnose.
Although it is not necessary to stop taking your usual medications even when using contrast, it is still worth informing the doctor about which medications the patient is taking. This is necessary to draw up a detailed clinical picture.
Against the background of the request to remain motionless for the entire scanning period, the presented method is not suitable for children and the elderly. They are more often prescribed a classic ultrasound.