Paranasal sinus sonography (synonyms: paranasal sinus sonography, ultrasound of the paranasal sinuses) is used for ultrasound diagnostics in ear, nose, and throat (ENT) medicine and dentistry. As a sonographic procedure, this examination is characterized above all as particularly low-risk or with few side effects, since no X-rays are used.The paranasal sinuses are referred to in Latin as “sinus paranasales”. Anatomically, the paranasal sinuses are air-filled cavities that protrude into the bones of the skull as mucosa-covered outpouchings of the nasal cavity. The paranasal sinuses communicate with the nasal cavity and are in pairs; according to their location, the following cavities should be named:
- Sinus maxillaris (maxillary sinus).
- Sinus frontalis (frontal sinus)
- Sphenoid sinus (sphenoidal sinus)
- Cellulae ethmoidales (ethmoidal cells).
Paranasal sinus sonography is an imaging technique used to diagnose or visualize paranasal sinus pathology.
Indications (areas of application)
- Sinusitis (inflammation of the paranasal sinuses).
- Maxillary sinus empyema – accumulation of pus in the maxillary sinuses.
- Mucoceles – accumulation of mucus due to obstruction of drainage in the excretory duct.
- Polyps (mucosal growths).
- Cysts (water-filled cavities)
- Fractures (bone fractures), of the bones bounding the sinuses after trauma (exposure to force).
- Hematosinus – bleeding into the sinus after trauma.
- Tumors
Contraindications
Due to the sound waves used, sinus sonography is absolutely free of side effects and harmless and can be repeated as often as desired. The only thing to watch out for is an intact skin surface so as not to cause pain or contamination of larger wounds.
Before therapy
No special measures are necessary before sonography is performed; the examining physician applies a transparent gel containing water to the skin to optimize the conduction of ultrasound waves into the tissue and back again.
The procedure
The examination is performed on a seated patient. Both sides are always examined in comparison in order to assess changes in a more differentiated manner.Sonography of the paranasal sinuses used to be performed mainly by A-mode ultrasonography and was the main indication for this type of ultrasound. In the meantime, however, B-mode sonography is also gaining in importance in this area. When A-mode ultrasonography is performed, the ultrasound echoes are presented as simple curve deflections, i.e., amplitudes. The newer B-mode sonography represents the further development of the A-mode. This method visualizes the amplitude of the echo as a so-called gray value. In sonography, the transducer emits ultrasound waves that are reflected by the tissue. Air, on the other hand, is shown as an echo-poor area in black on the screen. In the case of the paranasal sinuses, which are filled with air, this means that only the anterior border of the healthy paranasal sinus can be visualized with sonography. The air in the cavity causes total reflection of the sound, so the posterior boundary cannot be visualized. This process is called sound cancellation, but it only applies to the healthy sinus. If, on the other hand, there is a change, such as a tumor within the paranasal sinus, this changes the echogenicity and the posterior wall of the sinus becomes visible as a so-called backwall echo, since the ultrasound is transmitted via the foreign structure. This simple principle allows the visualization of relevant changes in the paranasal sinuses. Supplementary X-ray examinations are performed. Paranasal sinus sonography is of particular importance in:
- Sinusitis during pregnancy as a low-radiation procedure.
- The postoperative follow-up as a complementary diagnostic procedure.
- Children, since here the paranasal sinuses are only slightly filled with air
Possible complications
No side effects are expected during sinus ultrasonography.
