Facial Computed Tomography (CT) Scan
Facial CT scan is a diagnostic test that provides three-dimensional images of the facial structures. It is a non-invasive, painless procedure that does not affect patient health.
General Description
Facial computed tomography (CT) is a medical imaging technique that uses X-rays to capture images of the facial bones and soft tissues from different angles. This painless, non-invasive diagnostic tool also helps plan surgeries and assess treatment effectiveness. It employs very low radiation doses, posing no health risk to the patient.
A facial CT provides detailed information about various facial structures, primarily used to examine:
- Paranasal sinuses: Internal cavities in the bones around the nose connected to the nasal cavity, responsible for mucus production to keep the nose moist. These include the frontal, ethmoidal, sphenoidal, and maxillary sinuses.
- Nasal cavity: The inside portion of the nose, divided by the nasal septum, with external nostrils and internal choanae leading to the pharynx. It consists of the vestibule, respiratory, and olfactory regions.
- Maxilla: A main craniofacial bone crucial for speech, chewing, and holding teeth. It includes the upper and lower maxilla.
- Mandible: The lower jawbone, articulating with the temporal bones, essential for chewing and speech. It forms a fundamental facial support.
- Facial skeleton (viscerocranium): Comprising 13 bones including the mandible, nasal bones, zygomatic bones, vomer, maxillae, nasal conchae, palatine, and lacrimal bones.
- Orbital cavities: Housing the eyeballs, eyelids, and tear ducts, formed by the maxilla, zygomatic, frontal, ethmoid, lacrimal, sphenoid, and palatine bones.
Facial CT scans can be performed with or without contrast depending on the tissues to be examined.
When is it indicated?
A facial CT is requested for many diverse reasons depending on symptoms and the facial area examined, including:
- Paranasal sinus CT: cancer, sinusitis, inflammatory diseases, membrane thickening, or fluid retention.
- Nasal CT: benign cysts, malignant tumors.
- Maxillary or mandibular CT: cancers, prognathism (protruding upper jaw), micrognathia (small jaw), retrognathism (receded jaw), dental implants, root canals, bone regeneration, complex extractions.
- Facial skeleton CT: bone fractures, temporomandibular joint disorders, cysts, tumors.
- Orbital CT: infections, fractures, foreign bodies, hemorrhages, cysts, tumors, Graves' disease (excess thyroid hormone production).
Facial CT is contraindicated during pregnancy and lactation due to higher radiation sensitivity in children. Pediatric cases are evaluated individually. Contrast use is discouraged in patients with kidney, heart, or thyroid conditions or contrast allergies.
How is it performed?
The facial CT procedure is quick and performed in the radiology department with these steps:
- The patient lies supine on a scanning table.
- If contrast is needed, it is injected into a peripheral vein, usually in the arm.
- The table slides into the cylindrical scanner.
- X-rays are emitted, absorbed variably by different tissues. Structures appear in various shades of gray: tissues letting more radiation through appear darker; denser tissues and contrast-enhanced areas (blood vessels, tumors) appear lighter or brighter.
- The scanner (gantry) rotates around the patient, capturing images from multiple angles, each slice between 1 and 10 mm thick.
- The computer reconstructs a 3D model from all slices for detailed analysis.
Risks
Despite X-ray use, facial CT scans carry minimal risk because of low radiation doses, typically between 4 and 6 millisieverts—equivalent to about two years of natural background radiation.
Allergic reactions to contrast agents are uncommon but possible.
What to expect during a facial CT
On the day of the test, patients sign informed consent and change into a hospital gown. They remove all metal items such as jewelry, glasses, dentures, or hearing aids.
If contrast is used, a mild needle prick occurs followed by possible sensations of warmth, rapid heartbeat, and flushing in the arm, chest, and genital area, which subside after a few minutes.
The table slides inside the scanner tube. The device moves back and forth and rotates, making some noise but usually not uncomfortable.
The scan lasts 5 to 15 minutes, during which the patient must remain still. After completion, normal activities can be resumed immediately.
Specialties requesting facial CT
Radiologists perform facial CTs at the request of dentists, stomatologists, maxillofacial surgeons, endocrinologists, traumatologists, ophthalmologists, oncologists, and otolaryngologists.
How to prepare
Only facial CT with contrast requires fasting for 4 to 6 hours beforehand.
Metal objects cannot be worn in the radiology room, so it is recommended to leave them at home. Some cosmetics contain metal particles, so arriving without makeup is advised.
