Primary Care Otolaryngology

How to Read a Sinus CT Scan

sinuses above, and sphenoid sinuses behind. You should carefully study every x-ray, MRI, or CT scan that you encoun- ter, so you can learn to recognize com- mon anatomic variants and distinguish them from true pathology. Here are three common anatomic variants encountered on coronal CT scans of the sinuses. Deviated nasal septum • Asymmetry of sinuses, including size, • shape, presence of septas, etc. An air cell within the middle tur- • binate (concha bullosa) Abnormalities include fluid, mucosal thickening, bony fractures, cysts, and tumors, as shown in Figures 11.1 and 11.2. The Osteomeatal Complex The most significant area to examine in a patient with sinus complaints is the osteomeatal complex (OMC) . Coronal CT scans are used in the evaluation of sinus disease because they are best for visualizing the OMC. The OMC is the region through which the maxillary, eth- moid, and frontal sinuses drain in the nose. An obstruction of the OMC will frequently lead to sinusitis, and is often due to mucosal edema or anatomic abnormalities. Neoplasm should always be on the differential diagnosis. The anterior-most ethmoid sinus—the agger nasi cell —is frequently clouded. Edema in this sinus may be associated with obstruction of the nasal frontal duct and results in frontal sinusitis. This

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Figure 11.1. A coronal CT scan of the sinuses in a patient with deviated nasal septum and an air cell (concha bullosa) within the right middle turbinate. The surgical correction of nasal obstruction in this patient would require partial middle turbinectomy, as well as correction of the deviated nasal septum.

Figure 11.2. A coronal CT scan of the sinuses demonstrating complete opacification of the nasal cavity and ethmoid and maxillary sinuses. This image represents pansinusitis with polyps; however, neoplasms may present in a similar fashion.

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