CT Perfusion (CTP), Key Perfusion Parameters:, CBF (Cerebral Blood Flow), CBV (Cerebral Blood Volume, MTT (Mean Transit Time),

 CT Perfusion (CTP) is an advanced CT imaging technique used to measure blood flow dynamics in tissues, most commonly in the brain, but also in other organs like the heart, liver, and tumors.

Basic Principle:

• After injecting iodinated contrast intravenously, multiple rapid CT scans are taken over time at the same slice levels.

• The changes in contrast enhancement (HU values) reflect how blood flows through tissue.

• Using specialized software, perfusion maps are generated.

Key Perfusion Parameters:

1. CBF (Cerebral Blood Flow): Volume of blood moving through a given brain tissue per minute (mL/100g/min).

2. CBV (Cerebral Blood Volume): Total volume of blood in a given brain tissue (mL/100g).

3. MTT (Mean Transit Time): Average time taken by blood to pass through a given region (seconds).

4. TTP (Time to Peak): Time from contrast injection to maximum tissue enhancement.

5. Tmax: Delay in contrast arrival compared to normal tissue.

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   perfusion parameters

   Common Clinical Uses:

• Stroke:

  • Differentiate ischemic core (irreversible damage) from penumbra (salvageable tissue).

• Brain Tumors:

  • Assess tumor vascularity and response to therapy.

• Trauma:

  • Detect perfusion deficits due to vessel injury.

• Other Organs:

  • Evaluate perfusion in heart, liver lesions, kidneys, lungs.

Advantages:

• Quick (few minutes).

• Provides functional information in addition to anatomical imaging.

• Widely available on most modern CT scanners.

Limitations:

• Radiation dose is relatively higher (due to repeated scanning).

• Requires iodinated contrast (risk of allergy/renal impairment).

• Limited coverage (though modern scanners can cover whole brain).