Finding the right tests…
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Finding the right tests…
X-Ray
A PNS X-ray looks at the paranasal sinuses, the air-filled spaces around your nose, cheekbones, and forehead, checking for fluid, thickened lining, or blocked spaces that can come with a sinus infection. You are usually seated upright for the film, so that any fluid trapped in a sinus settles and shows as a level line on the image. It works reasonably well for the sinuses behind your cheekbones, but published research shows it picks up problems in the other sinus groups far less reliably. A normal-looking film does not rule out sinusitis, and your doctor may still ask for a CT scan if symptoms continue. It remains useful as a quick, low-cost first look.
The film shows the air-filled sinus spaces around your nose and forehead, read for fluid levels, thickened lining, or opacity that can suggest infection or blockage. It is most reliable for the sinuses behind your cheekbones and considerably less reliable for the others, so your doctor weighs it alongside your symptoms.
A PNS X-ray is taken with you sitting upright, which lets any fluid sitting in a sinus form a visible level line on the image, something that would not show the same way lying down.
The film is read for three main signs: fluid levels, thickened or swollen lining along the sinus walls, and areas of opacity where the sinus should look dark and air-filled. It performs best for the sinuses just behind your cheekbones, where published research puts its accuracy for infection at around 80 percent.
- For the sinuses near your eyebrows and between your eyes, accuracy drops sharply, reported in the range of 25 to 41 percent in comparative studies - Overlapping bone in the skull can hide or mimic sinus changes, even for an experienced reader - A normal result does not fully rule out sinusitis, particularly outside the cheekbone sinuses
Because of these limits, medical guidance notes that regular sinus X-rays often do not diagnose sinusitis well on their own. If your symptoms persist despite a normal or unclear film, your doctor may move to a CT scan, which shows the sinuses and surrounding bone in far more detail.
It can support a sinusitis diagnosis when it shows fluid or thickened lining, but research shows it misses a fair number of cases, especially outside the cheekbone sinuses. Your doctor combines it with your symptoms and exam.
Sitting up lets any fluid trapped in a sinus settle and form a visible line on the image, which helps show a blocked or infected sinus. Lying down would not show this the same way.
It is most accurate for the sinuses behind your cheekbones. For the sinuses near your eyebrows and between your eyes, published accuracy is considerably lower.
A CT scan shows the sinuses and surrounding bone in much greater detail and is more reliable, especially when an X-ray is normal but symptoms continue. Your doctor may start with an X-ray and move to CT if needed.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
There is generally no special preparation, but ask your doctor or the centre beforehand in case your situation needs something specific. You may be asked to remove jewellery or hair clips near the face.
Tell your doctor and the technologist if you are or might be pregnant before the scan. A lead apron is typically used, and your doctor will confirm whether the X-ray is needed right now.
Yes, earrings, nose studs, and glasses near the imaging area are usually asked to be removed since they can show up on the film. The technologist will tell you exactly what to take off.