A computed tomography (CT) scan of the sinuses is a medical imaging technique. This non-invasive procedure uses X-rays and computer processing to create detailed cross-sectional images of the paranasal sinus cavities. These hollow, air-filled spaces are located within the bones of the face surrounding the nasal cavity.
Why a CT Scan of Sinuses Is Performed
Healthcare providers often recommend a sinus CT scan to diagnose various conditions affecting the sinus cavities. It identifies inflammatory diseases or infections, such as acute or chronic sinusitis. The scan can also detect blockages caused by fluid accumulation, thickened sinus membranes, or growths like nasal polyps. A sinus CT provides detailed views not always available with standard X-rays, making it useful for evaluating structural abnormalities within the nasal passages and sinuses. This information is also valuable for pre-surgical planning, offering surgeons a detailed map of the anatomy and any potential issues.
How a Sinus CT Scan Works
A sinus CT scan uses a rotating X-ray source and electronic detectors. The patient lies on a table that moves through a doughnut-shaped machine called a gantry. As the X-ray tube rotates around the head, it emits narrow beams of X-rays that pass through the body. Different tissues absorb these X-rays at varying rates; denser structures like bone appear white, and air appears black. Detectors measure the X-rays, transmitting data to a computer that processes it to construct detailed cross-sectional images, or “slices,” of the sinus structures, which can also be stacked to create three-dimensional models for a comprehensive view.
What to Expect During a Sinus CT Scan
Preparation for a sinus CT scan is minimal. Patients are advised to wear comfortable, loose-fitting clothing and remove any metal objects like jewelry, eyeglasses, or hairpins, as these can interfere with image quality. Fasting is generally not required, but if contrast material is used, specific food and drink instructions may be provided. During the procedure, the patient lies on a narrow table, often on their back or face-down with the chin elevated. This table then slides into the center of the CT scanner. Straps and pillows may be used to help maintain the correct position and ensure stillness, which is important for clear images.
The actual scanning time is typically less than a minute, though the entire process takes about 10 to 15 minutes. Patients will hear subtle whirring or clicking sounds. A technologist monitors the scan from an adjacent room and communicates through an intercom. While contrast material is not commonly used for sinus CTs, it may be administered intravenously in certain situations. This enhances the visibility of specific tissues or blood vessels, particularly if tumors or inflammatory processes are suspected. If contrast is administered, patients might experience a temporary warm sensation or a metallic taste. After the scan, patients can generally resume normal activities immediately.
Interpreting Sinus CT Scan Results
Once the sinus CT scan is complete, the images are sent to a radiologist, a medical doctor specializing in interpreting medical images. The radiologist analyzes the cross-sectional images for abnormalities within the sinus cavities. They look for inflammation, such as mucosal thickening or fluid accumulation, which may appear as opacification. The detailed images allow for precise identification of blockages, structural irregularities like a deviated septum, or the presence of cysts and polyps.
The radiologist also assesses for signs of bone erosion or thickening, which can indicate more severe conditions. After review, the radiologist compiles a comprehensive report detailing their findings. This report is sent to the referring healthcare provider, who will discuss the results with the patient and determine the appropriate course of action.
Safety Aspects of Sinus CT Scans
Sinus CT scans involve the use of ionizing radiation, similar to traditional X-rays. While any exposure to radiation carries a degree of risk, the radiation dose for a sinus CT is localized and considered relatively low. Medical professionals adhere to the “As Low As Reasonably Achievable” (ALARA) principle, which means they strive to keep radiation exposure as low as possible while still obtaining diagnostic quality images. This principle guides imaging protocols to minimize patient dose. The benefits of obtaining accurate diagnostic information from a sinus CT scan often outweigh the minimal risks associated with radiation exposure, especially when the scan is medically indicated.