CT Perfusion

CT perfusion measures blood flow to brain tissue or other organs by tracking how contrast moves over time. It helps doctors distinguish tissue that can still be saved from tissue that is already damaged.

Principle of the exam

In CT perfusion, intravenous contrast is injected and the same area is scanned repeatedly over several minutes. By observing how quickly contrast arrives and leaves, doctors can calculate blood flow parameters.

The exam is often used in acute stroke assessment to estimate areas with reduced blood flow.

Use in stroke

In acute stroke, CT perfusion helps determine whether a patient is a candidate for reperfusion treatment. Doctors evaluate the infarct core (tissue already dead) and the penumbra (tissue that may still be saved).

Decisions depend on time since symptom onset, so the scan is usually performed quickly in a stroke unit.

Dose and contrast notes

CT perfusion uses a higher radiation dose because of multiple repeated scans. Doctors weigh the benefit against the risk in emergency situations.

Intravenous contrast is used, so patients with kidney disease or contrast allergy should be assessed beforehand when possible.

Key points

• Often used in acute stroke assessment.
• Requires repeated scanning with contrast.

Educational information, not a substitute for medical advice.