HRCT Scan of Paranasal Sinuses is an imaging test that uses a small amount of radiation to visualize details of your sinuses. Sinuses are paired (right and left) air-filled pockets that circumscribe the nasal structures. The function of the sinuses is include humidifying the air breathed through your nose and providing shape to your face. introduction of computed tomography (CT) and the wider use of it in the last 20 years have further contributed to the physician's ability to appreciate nuances of paranasal sinus anatomy and accurate disease correlation. It is also called as paranasal Sinus radiography.