Role of radiography in maxillofacial diagnostics
In dentistry and maxillofacial surgery, X-ray examination is of paramount importance. In some cases, it is the only objective method for making a definitive diagnosis. In routine clinical practice, extraoral, intraoral, and panoramic radiography, as well as orthopantomography, are used. Their main field of application is the study of teeth, maxillofacial bones, and paranasal sinuses.
For example, if it is necessary to specifically rule out the presence of a retained root of an extracted tooth in the socket or in the lower part of the maxillary sinus, intraoral radiography of the alveolar process is used.
Methods using contrast and endoscopy
A standard non-contrast image is not always sufficient for an accurate assessment of cavity structures. In such situations, the physician may resort to methods using artificial contrast agents. For the study of the maxillary sinuses, haymorography (contrast-enhanced maxillary radiography) is used.
If an oroantral communication (fistula tract) has formed in a patient after trauma or severe inflammation, it is advisable to supplement diagnostic imaging with direct visualization—haymoroscopy. A fibroscope is inserted through the fistula for a visual assessment of the mucosal condition from the inside. This is critically important for determining indications and choosing the location of surgical intervention, especially if the pathological focus is localized.
CT of the paranasal sinuses as the modern standard
With proper technical equipment of the clinic, computed tomography (CT) can completely replace plain radiography of the paranasal sinuses and orthopantomography. The only significant limitation of the method remains its relatively high cost.
The examination of the maxillary sinuses is usually performed in the axial projection with subsequent image reconstruction in the frontal plane. CT provides a comprehensive assessment of the pathological process both in the sinus itself and in the surrounding tissues. The method is of critical importance in complex cases of differential diagnosis, especially when suspecting:
- Osteomyelitis of the upper jaw.
- Neoplasms of the maxillary sinus.
Features of the study in trauma and cerebrospinal fluid leak
In penetrating craniocerebral trauma and suspected basal cerebrospinal fluid leak (as a consequence thereof), spiral CT of the paranasal sinuses and CT of the facial skull are mandatory. The study is performed with a slice thickness of 1–3 mm.
When analyzing tomograms in bone window mode, the physician evaluates the localization and type of fracture (depressed, impression), the position of bone fragments, the state of soft tissues, and the contents of the sinuses. Different projections solve specific diagnostic tasks:
| CT projection | Diagnostic task |
|---|---|
| Coronal reconstruction | Assessment of skull base bone fractures, the nature of fragment displacement, and the presumed localization of the cerebrospinal fluid fistula. |
| Axial slices | Visualization of the posterior wall of the frontal sinus, the walls of the sphenoid sinus, and the mastoid air cells of the temporal bone. |
| Coronal slices | Verification of fractures of the cribriform plate, the walls of the ethmoid air cells, and the superior wall of the sphenoid sinus. |
| Sagittal reformation | Topography of fractures of the anterior cranial fossa base and orbital walls. |
Comparison of CT and MRI in the diagnosis of nasal bones
Despite the fact that magnetic resonance imaging (MRI) perfectly differentiates soft tissues and fluids, computed tomography is the method of choice when bone structures are involved. MRI visualizes bone elements of the maxillofacial region significantly worse than CT.
The physical principle of CT is based on the difference in X-ray absorption by tissues of varying density, which is ideal for sinus walls. MRI, on the other hand, captures the electromagnetic signal from hydrogen protons, which are sparse in dense bone tissue. In addition, MRI is contraindicated in patients with incompatible ferromagnetic implants or metal foreign bodies.
For quick memorization of CT slice targets: Axial for "Arches" (posterior walls of the frontal and sphenoid sinuses), Coronal for "Roof" (cribriform plate), Sagittal for "Walls" of the orbits.
Class and exam questions
Why is CT preferable to standard paranasal sinus radiography?
CT provides a comprehensive spatial assessment of all features of the pathological process in the sinus and surrounding tissues. Under certain conditions, it completely replaces plain radiography and orthopantomography, being indispensable in complex diagnoses (osteomyelitis, tumors).
What CT picture is characteristic of chronic odontogenic sinusitis?
The tomogram visualizes almost complete opacification of the maxillary sinus volume by polypoid-altered mucous membrane. At the same time, the odontogenic source is clearly defined—foci of bone destruction due to severe periodontitis (most often in the region of the maxillary molars—teeth 16 and 17).
How is the exact location of a cerebrospinal fluid fistula found in skull base fractures?
For initial screening, spiral CT with coronal reconstruction is used. For direct visualization of the fistula itself, computed tomographic cisternography is used—a method in which an iodine-containing radiopaque agent is injected into the spinal canal (endolumbar injection).
Can MRI be used to evaluate facial skull fractures?
MRI visualizes bone structures worse compared to computed tomography. Therefore, in trauma involving the bones of the maxillofacial region, CT remains the method of choice.
What else to study on this topic
- Methods of intraoral radiography (including periapical contact imaging).
- Diagnostic imaging of depressed skull fractures and the use of CT angiography of cerebral vessels.
- Contrast X-ray examinations in dentistry: sialography and fistulography.
- Physical foundations of the nuclear magnetic resonance (NMR) phenomenon and the principles of T1- and T2-weighted image formation.
- Specifics of scintigraphy application: selection of radiopharmaceuticals depending on the tissue and purpose of the study.
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Nasal radiography" and another 2,199 pages of the subject
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Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.