Indications for conducting such a study as computed tomography can be various otolaryngological pathologies, including changes in the area of the paranasal sinuses. One of the significant advantages of the method is obtaining a spatial image, which allows an objective assessment of the nature of anatomical disorders and the choice of treatment tactics. Computed tomography of the nose and paranasal sinuses is currently one of the most informative methods of radiation diagnostics. With the help of computed tomograms, the doctor can plan a surgical intervention, reducing the invasiveness of the operation and the percentage of the risk of complications. Computed tomography is useful for both primary and differential diagnosis of various diseases.
CT in ENT practice
The variety of research methods sometimes makes you wonder: what is this or that diagnostic test for? A natural question when prescribing a CT scan of the sinuses is what is it? Are there any contraindications, restrictions on the frequency of procedures? Patients should be aware of the features of diagnostic procedures that are recommended to clarify the diagnosis.
Computed tomography (CT) of the nose and paranasal sinuses is an X-ray tomography method that works by passing a beam of X-rays through a layer of the patient's body in different directions. Different tissues absorb the radiation emitted by a movable X-ray tube in different ways - a quantitative expression of the degree of absorption is analyzed and recorded using special devices.
CT scan of the sinuses is performed if antibiotic therapy for sinusitis is ineffective.
The modern standard for computed tomography of the paranasal sinuses is multispiral CT. The examination is performed using a multispiral tomograph. The undoubted advantage is the speed of obtaining planar sections - the time spent on MSCT of the sinuses does not exceed several minutes. The method is optimal for diagnosing diseases in children, traumatized patients and patients suffering from acute pain (the likelihood of obtaining image artifacts due to patient mobility decreases).
Computed tomography of the sinuses has become widespread and recognized among specialists in the field of otolaryngology. The main indications for the study are as follows:
- Sinusitis.
- Neoplasms.
- Developmental anomalies.
- Injuries.
- The need for surgical intervention.
Methodology
How is a CT scan of the nose and paranasal sinuses done? The study is carried out in a special room where the device is installed - a computer tomograph. Before starting the procedure, the patient is interviewed by the specialists of the Department of Radiation Diagnostics. The state of health, the presence of an allergy to any drugs is clarified - this is especially important if it is planned to inject a contrast agent. Contraindications to the administration of iodine-containing contrast are:
- history of allergy to contrast media;
- the presence of bronchial asthma or other disease with an allergic component of pathogenesis in severe form;
- the presence of severe renal or liver failure;
- the presence of hyperthyroidism.
Among the risk factors for intravenous contrast enhancement are age over 70 years, the presence of diabetes mellitus (especially in the case of diabetic nephropathy), liver cirrhosis, heart failure, low systolic blood pressure (less than 80 mm Hg).
Computed tomography of the sinuses involves the following:
- Assessment of the patient's condition by specialists of the Department of Radiation Diagnostics.
- Explaining to the patient the goals and course of the procedure.
- Laying the patient in the position required for the study - on his back. Hands should be extended along the body. The head is fixed in a special pad (headrest). The doctor may ask you to press your chin to your chest, look up.
- Contrast introduction (if necessary). Contrast is usually injected through a catheter in the cubital vein. The volume of the contrast agent is about 50 ml. Some patients may experience a feeling of warmth, a change in taste perception and the appearance of a specific taste in the mouth. These are short-term phenomena that are stopped on their own without treatment.
- Installation of the movable table of the apparatus in the working position. For this, the table, together with the lying patient, is pushed directly into the tomograph. After that, the staff goes to the adjacent room, where the equipment for recording and processing the signals of the apparatus is installed. The doctor can hear the patient's voice and communicate with him through a sound device, an alternative to which, when hearing acuity is reduced, are light signals.
Removable dentures are removed before the procedure.
A CT scan of the paranasal sinuses is not a painful procedure. During the examination, the scanning device is at a distance from the patient, not in contact with the surface of his body. Moderate, quickly passing pain can be caused by injection if contrast is injected during the diagnostic procedure.
How often can a sinus CT scan be done? Any method of radiation diagnostics implies radiation exposure, that is, the effect of a certain dose of ionizing radiation on the human body being examined. It should immediately be said that the radiation exposure with CT is significantly higher than that with X-ray. At the same time, there is a concept of the total dose - each time the risk increases. Therefore, CT is not used without clear indications. It is possible to repeat the study, however, the exact time frame is indicated by the attending physician after substantiating the reasons for its conduct.
In acute inflammation, CT scan of the sinuses is performed only in urgent cases.
Assessment of anatomical changes during the active phase of the inflammatory process becomes much more complicated. Difficulties lie in the distortion of the anatomical characteristics due to edema and thickening of the mucous membranes. The expediency of performing CT scan of the paranasal sinuses in acute inflammatory diseases is determined by the attending physician.
Interpretation of results
If a CT scan of the paranasal sinuses is ordered, what can it help to find out? With computed tomography, shadows are not superimposed on the image, therefore the anatomical picture is more accurate than when using radiography. Using the method, the characteristics of the studied anatomical region are assessed, and the individual structural features of various structures are identified.
What does a CT scan of sinuses show? The method allows you to detect a number of pathologies, a list of which can be presented in the table:
| Pathology type | Visualized signs | Research features | Combination with other methods |
| Sinusitis | Thickening of the soft tissue membrane, the presence of fluid in the lumen of the affected sinuses. | CT is not the main method for diagnosing sinusitis and is only required if there is no response to treatment for differential diagnosis. | It is performed in combination with X-ray of the paranasal sinuses as an additional imaging method after receiving the results of the said study. |
| Polyps | A single polyp is visualized as a mass with a pedicle and emanating from the membrane of the sinus wall. With multiple polyps, the shape and volume of the sinus changes. | It is difficult to identify polyps localized in the alveolar bays (anatomical region of the maxillary sinus). | The primary method of examination is X-ray of the paranasal sinuses, CT is performed in order to clarify the data. |
| Sinus neoplasms | Destruction of bone tissue. The presence of a pathological formation consisting of soft tissues. | It is not always possible to immediately differentiate between malignant and benign tumors. | For the purpose of differential diagnosis, not only CT scan of the paranasal sinuses is performed, but also a biopsy of the pathologically altered tissue. |
| Odontogenic cysts of the maxillary sinus | Intense homogeneous shading with a rounded, clear top contour. Probably thickening of the mucous membrane over the cyst. | Differential diagnosis with a polyp located in the alveolar bay of the maxillary sinus may be required. | Pathology is usually detected by radiography. CT allows you to eliminate the overlap of the shadow image of bone structures, to establish the size of the cyst. In order to get an idea of the boundaries of the localization of cysts, CT is not always sufficient, therefore, the method of magnetic resonance imaging (MRI) can be used. |
| Rhinogenic cysts of the maxillary sinus | Rounded homogeneous darkening adjacent to the sinus wall. The upper contour is well defined. | No mucosal thickening due to edema. |
In tumor processes, CT is used to determine the presence and size of areas of bone destruction.
Computed tomography of the sinuses also allows you to detect the curvature of the nasal septum, to assess the nature and degree of changes in the case of traumatic injuries of the nasal region.
