Paranasal Sinus Radiography

Sinus imaging methods

The modern protocol for examining patients with facial skull pathology requires the most accurate visualization possible. Computed tomography (CT) of the maxillary sinuses is performed predominantly in the axial projection, followed by mandatory image reconstruction in the coronal plane. This method has tremendous diagnostic value as it provides the physician with a comprehensive assessment of all characteristics of the pathological process—both within the sinus cavity itself and in the adjacent tissues.

In complex clinical situations, CT is of critical importance. It is indispensable when maxillary osteomyelitis is suspected or when searching for neoplasms of the maxillary sinus. Despite the limitation of relatively high cost compared to classical X-ray images, under certain conditions, tomography can completely replace both plain paranasal sinus radiography and orthopantomography.

It is important to note that all performed examinations (radiographs and CT scans of the paranasal sinuses, nasal bones, larynx, and temporal bones) must be strictly documented in medical records with the indication of the exact date they were performed.

CT anatomy in the coronal plane

When analyzing a computed tomography scan of the paranasal sinuses in the coronal projection, the radiologist sequentially identifies a number of critical anatomical structures. From top to bottom, the slice reveals:

• Crista galli (Crista galli), bordering the anterior cranial fossa.
• Orbits (Orbita).
• Ethmoid air cells (Cellulae ethmoidales).
• In the nasal cavity, the nasal septum (Septum nasi) is visualized, as well as the middle (Concha nasalis media) and inferior (Concha nasalis inferior) nasal conchae.
• Below the inferior concha, the inferior nasal meatus (Meatus nasi inferior) can be traced.
• Lateral to the nasal cavity structures are the massive maxillary sinuses (Sinus maxillaris).
• The lower boundary of the studied area is formed by the hard palate (Palatum durum), which forms the floor of the nasal cavity, and the alveolar process of the maxilla (Processus alveolaris maxillae), where tooth roots are clearly defined.

Radiological signs of sinusitis

Imaging findings directly depend on the form and localization of the inflammation.

Acute inflammation of the ethmoid labyrinth cells (acute ethmoiditis, ethmoiditis acuta) is a common pathology, ranking second in prevalence after maxillary sinus lesions (often occurring concurrently with them and the frontal sinus). It develops against the background of acute respiratory viral infections (ARVI), influenza, or acute rhinitis. Patients complain of nasal congestion, purulent discharge, a heavy sensation at the nasal root, and frontal headache. On radiographs and CT scans, this disease is characterized by opacification of the ethmoid bone cells.

A completely different picture is observed in chronic odontogenic maxillary sinusitis. Tomograms reveal almost complete filling of the air volume of the maxillary sinus by polypoid-changed mucous membrane. The main advantage of CT here is the identification of the source of infection. The images clearly show foci of bone destruction resulting from severe periodontitis in the area of the upper molars (typically teeth 16 and 17).

Intraoral radiography

In maxillofacial surgery and dentistry, in addition to extensive sinus imaging, targeted intraoral radiography of the alveolar process is widely used. This highly specific technique focuses on examining the socket of an extracted (or about to be extracted) tooth. The main purpose of such an image is to reliably rule out the presence of residual root fragments. A root may hide directly within the bone socket or be pushed into the lower part of the maxillary sinus, which will require additional therapeutic measures.

Surgical treatment planning based on imaging data

The results of instrumental imaging and endoscopic diagnostics determine further treatment tactics. Thus, in the presence of an established oroantral fistula, gimroscopy using a fiberscope is performed for direct visual assessment of the mucosa. This helps select the optimal technique and localization for the intervention, especially if the changes in the sinus are not total, but localized.

In the case of chronic frontal sinus inflammation (chronic frontal sinusitis, frontitis chronica) with a sluggish process, trepanopuncture of the anterior wall using a trephine may be indicated. A metal cannula is inserted into the created lumen for prolonged flushing and the administration of enzymes and antibiotics. If urgent surgical intervention is necessary, CT data helps the physician plan the opening of the frontal sinus, revision of its walls, radical removal of altered mucosa, and creation of an anastomosis with the nasal cavity. However, functional endoscopic surgery is currently recognized as the modern and preferred method of treatment.

Class and exam questions

What else to study on this topic

• Functional endoscopic sinus surgery
• Fibroscopic gimroscopy through an established fistula
• Frontal sinus trepanopuncture: surgical technique and patient management
• Clinical presentation and endoscopic examination in acute ethmoiditis
• Rules for maintaining medical documentation of diagnostic and instrumental examinations

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Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.