CT perfusion shows how well blood reaches different parts of the brain in stroke. Learn how it helps choose treatment in the first hours and what the maps mean.
CT perfusion is a special CT scan done in stroke emergencies after a plain CT. It shows which parts of the brain are already badly damaged (the core) and which parts are at risk but can still be saved (the penumbra). This helps stroke doctors decide whether clot-removal treatment is worthwhile, even many hours after symptoms started.
Why Is It Used in Stroke?
In stroke caused by a blocked brain artery, brain cells die every minute. Clot-dissolving medicine and clot removal work best early, but in selected patients can help up to 24 hours when the scan shows salvageable tissue. CT perfusion finds these patients. See MRI for stroke.
MapWhat it showsCerebral blood flow (CBF)How much blood reaches each areaCerebral blood volume (CBV)Tissue that is likely already dead (core)Mean transit time (MTT) or TmaxDelay in blood arrival (area at risk)MismatchSalvageable brain tissue (penumbra)What Is Done
First, a plain CT brain rules out bleeding. Then a CT angiography finds the blocked vessel, and CT perfusion is done after a rapid contrast injection, taking images for about a minute. All together take around 10 to 15 minutes. See CT angiography of the brain and CT brain scan.
Who Benefits?
- Stroke patients who arrive late or whose onset time is unknown
- Patients with a large artery blockage who may need clot removal
- Cases where plain CT looks normal but symptoms are clear
Limits and Safety
CT perfusion uses more radiation than a plain CT and needs iodine contrast, but in stroke the benefit is high. Kidney function is checked if time allows, but treatment is never delayed for it. Movement, poor heart function and certain vessel problems can distort maps. MRI with diffusion imaging is another way to assess damage. See CT scan with contrast.
A Practical Example
Gurdeep, 64, wakes with weakness in his right arm and speech problems, so the onset time is unknown. His CT is normal, but CT angiography shows a blocked artery, and CT perfusion shows a small core and a large area at risk. A clot-removal procedure is done, and he walks out of the hospital in days. The scan helped treat him beyond the usual early window.
Know the FAST Signs
- Face drooping
- Arm weakness
- Speech difficulty
- Time to call for emergency help
After the Scan and Next Steps
Stroke treatment is a team effort led by a neurologist or neurointerventionist. After the acute phase, your care includes finding the cause, blood pressure and cholesterol control, blood thinners as advised, rehabilitation and lifestyle changes. Learn the warning signs so you or your family can act fast the next time.
Questions to Ask Your Doctor
- How much brain tissue can be saved?
- Is clot removal suitable for me?
- What caused my stroke?
- What rehabilitation do I need?
Common Mistakes to Avoid
- Waiting at home to see if symptoms pass.
- Driving yourself during a stroke.
- Stopping blood thinners after recovery.
Booking, Timing and Report
Most CT scans can be booked on the same day, and the visit takes 20 to 40 minutes. Carry your prescription, old scans and a recent creatinine report if contrast is planned. Reports are usually ready within 24 hours, and images can be provided on a CD or digital link for your doctor.
Understanding Your Report
The report describes the size of the core and the size of the at-risk area, often giving volumes in millilitres and the mismatch ratio. A small core with a large at-risk area suggests a good chance of benefit from clot removal. Your stroke team makes the decision quickly, in minutes, with these numbers and your clinical condition.
Frequently Asked Questions
What is CT perfusion?
A CT that shows blood flow in the brain.
Why is it used in stroke?
To find brain tissue that can still be saved.
Is it safe?
Yes, with a higher dose than plain CT but justified.
Does it need preparation?
No, it is done in emergencies.
How long does it take?
About 10 to 15 minutes for the full stroke scans.
Can it help late-arriving patients?
Yes, in selected cases.
Is MRI better?
MRI shows damage well, but CT is faster.
Can it detect bleeding?
The plain CT does that.
When is the report ready?
Immediately, in emergencies.
Book Your Test at Ganesh Diagnostic
Ganesh Diagnostic & Imaging Centre in Rohini, Delhi offers this test with trained radiology staff and clear reports. You can book an appointment online, check our branches across Delhi NCR, contact us for current rates, or explore all our services. Reports can be downloaded online through our patient portal, so you do not need to make a second trip just to collect them.
This article is for general information only. It does not replace advice from your doctor. Always follow your doctor's instructions for your test.
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