A PNS CT scan, also known as a paranasal sinus CT scan, is a medical imaging procedure that provides detailed images of the paranasal sinuses. The paranasal sinuses are air-filled spaces located in the bones of the face and skull, surrounding the nasal cavity. During the procedure, you will be asked to lie down on a table that slides into a large, donut-shaped machine called a CT scanner. The scanner will rotate around your head, taking multiple X-ray images from different angles. You may be asked to hold your breath briefly during the scan to minimize motion artifacts.