Medically reviewed by Prof. Dr. Aamer Nadeem Chaudhary, M.B.B.S., D.M.R.D., F.C.P.S. (Diagnostic Radiology), Consultant, Al-Nasar Lab & Diagnostic Centre. Updated September 2026.
Quick answer: CT PNS means a CT scan of the paranasal sinuses. It shows the sinuses, the drainage channels between them and the nasal septum in fine bony detail. It is the standard test for chronic sinusitis, nasal polyps and blocked nose, and it is mandatory before endoscopic sinus surgery. The scan takes under a minute and needs no injection.
Book a CT PNS: call 0300 0341944. Performed at our main Johar Town campus.
Why is a plain X-ray not enough for sinuses?
Sinus X-rays were standard decades ago and are still occasionally requested, but they have a real weakness. The sinuses are a complex three dimensional set of air spaces stacked behind the face, and an X-ray flattens all of that into a single overlapping image.
It will sometimes show fluid in the large maxillary sinuses. It will reliably miss disease in the ethmoid cells and the sphenoid sinus, and it shows almost nothing of the osteomeatal complex, the narrow drainage channel where most chronic sinusitis actually starts.
CT shows each sinus separately in thin slices, in all three planes. That is why ENT surgeons ask for it specifically.
What does a CT PNS show?
| Finding | Why it matters |
|---|---|
| Mucosal thickening | The basic sign of chronic inflammation, and which sinuses are involved |
| Blocked osteomeatal complex | The drainage bottleneck that causes recurrent infection. This is the key surgical target |
| Nasal polyps | How extensive they are and which sinuses they fill |
| Deviated nasal septum | Direction and severity, and whether it contributes to the blockage |
| Fungal sinusitis | Characteristic dense material inside the sinus. Important in diabetics, where invasive fungal disease is dangerous |
| Concha bullosa and anatomical variants | Normal variations that narrow the drainage pathway |
| Mucocele or retention cyst | Fluid filled swellings that can expand and erode bone |
| Bony landmarks near the eye and brain | The safety map the surgeon navigates by, including the thin plate separating sinus from brain |
Why is it essential before sinus surgery?
Endoscopic sinus surgery is performed a few millimetres from the eye socket and the base of the skull. The bone separating the ethmoid sinuses from the orbit is paper thin, and its exact position varies from person to person.
The CT is the surgeon’s map. It shows where those boundaries sit in your anatomy, whether the skull base is unusually low on one side, and whether any bony wall has already been eroded by disease. Surgery is not performed without it, and image guided systems in theatre are driven directly from these scan images.
When should a CT PNS be done, and when not?
Timing changes the result, and this catches many patients out.
Do not scan during an acute infection. During a common cold or acute sinusitis, almost everyone shows mucosal thickening and fluid levels. Scanning then produces a frightening looking report that reflects a temporary infection rather than chronic disease. The usual advice is to wait 4 to 6 weeks after symptoms settle, and to complete any course of medical treatment first.
A scan is appropriate when:
- Symptoms persist beyond 12 weeks despite proper medical treatment
- Sinusitis keeps coming back repeatedly through the year
- Nasal polyps are suspected or confirmed on endoscopy
- Persistent one sided blockage, discharge or bleeding, which always needs proper assessment
- Surgery is being planned
- There are warning signs such as swelling around the eye, visual change, double vision or severe headache, where the scan becomes urgent
- Suspected fungal sinusitis, particularly in someone with diabetes or reduced immunity
Does it need contrast?
Usually not. A standard CT PNS for chronic sinusitis is a plain scan with no injection, which keeps it quick and simple.
Contrast is added when a complication is suspected, such as spread of infection into the eye socket or brain, or when a tumour is being assessed. Our guide to CT with or without contrast explains the difference.
What happens during the scan?
You lie on your back on the CT table and the scanner moves your head through a short ring. The scan itself lasts well under a minute. There is no injection, no enclosed tunnel and no loud knocking, which makes it far easier than an MRI for anyone uneasy about scans.
You will be asked to stay still and to avoid swallowing during the acquisition, since movement blurs the fine bony detail. The whole visit is usually 10 to 15 minutes.
The radiation dose is low for this study, and modern scanners use dose reduction protocols. Even so, tell the team if you are or might be pregnant, since the scan would usually be deferred.
How to prepare
- No fasting is needed for a plain CT PNS, and you can take your usual medicines
- Remove earrings, nose studs, glasses, hairpins and dentures, since metal near the face creates streaks across the images
- Reschedule if you currently have a cold or acute infection, unless your doctor specifically wants an urgent scan
- Bring your ENT referral, previous scans and any endoscopy report
- Tell the team if you are or might be pregnant
CT PNS at Al-Nasar Lab
Al-Nasar Lab & Diagnostic Centre has served Lahore since 1996 and holds ISO 15189:2022 accreditation from the Pakistan National Accreditation Council. CT of the paranasal sinuses is performed at our Johar Town campus on multislice CT with thin slice reconstructions in all three planes, which is what surgical planning requires, and reported by consultant radiologists.
Digital images are provided in a form your ENT surgeon can load directly, not just a printed film.
See the full CT scan in Lahore range, our 128 slice CT capability, or contact us to book. Find your nearest location.
Frequently Asked Questions
How long does a CT PNS take?
The scan itself is under a minute. Allow 10 to 15 minutes at the centre including positioning and checks.
Do I need an injection for a sinus CT?
Usually no. A standard sinus CT is done without contrast. It is added only if a complication or tumour is suspected.
Should I have the scan while I have a cold?
No, unless your doctor wants it urgently. An active infection makes almost every sinus look abnormal. Waiting 4 to 6 weeks after symptoms settle gives a far more meaningful result.
Is CT or MRI better for sinuses?
CT is better for routine sinus disease because it shows bone and air spaces clearly. MRI is added when a tumour, fungal invasion or spread into the brain is being assessed.
Can a CT PNS show why my nose is always blocked?
Usually yes. It identifies a deviated septum, polyps, chronic mucosal disease and anatomical variants narrowing the drainage channels, which together explain most cases of persistent blockage.
This article is for general information and is not a substitute for medical advice. Please discuss your results with a qualified doctor.
