Perfusion CT

Perfusion CT

CT perfusion with flow and volume maps in cerebral infarction

Perfusion CT is an advanced imaging technique used in computed tomography (CT) to evaluate the blood flow characteristics of tissues, particularly in the brain. This method provides valuable information about the hemodynamics of tissues, which is crucial in diagnosing and managing various medical conditions, such as stroke, tumors, and traumatic brain injury.

Principles of Perfusion CT

Perfusion CT involves the acquisition of multiple CT images over a period of time after the intravenous injection of a contrast agent. The contrast agent enhances the visibility of blood vessels and allows for the assessment of blood flow dynamics. The key parameters measured in perfusion CT include:

• Cerebral Blood Flow (CBF): The volume of blood passing through a given amount of brain tissue per unit time, typically measured in milliliters per 100 grams of tissue per minute.
• Cerebral Blood Volume (CBV): The total volume of blood within a given amount of brain tissue, measured in milliliters per 100 grams of tissue.
• Mean Transit Time (MTT): The average time it takes for blood to pass through a given region of the brain.
• Time to Peak (TTP): The time from the start of the contrast injection to the peak concentration of contrast in the tissue.

Clinical Applications

Perfusion CT is primarily used in the evaluation of acute ischemic stroke. It helps differentiate between the ischemic core, which is irreversibly damaged, and the penumbra, which is potentially salvageable with timely intervention. This distinction is critical for determining the appropriate treatment strategy, such as thrombolysis or mechanical thrombectomy.

In addition to stroke, perfusion CT is used in:

• Tumor Assessment: Perfusion CT can help in characterizing brain tumors by assessing their vascularity and response to treatment.
• Traumatic Brain Injury: It aids in evaluating the extent of injury and guiding management decisions.
• Chronic Ischemia: Perfusion CT can assess the adequacy of collateral circulation in patients with chronic cerebrovascular disease.

Advantages and Limitations

Perfusion CT offers several advantages, including rapid acquisition, widespread availability, and the ability to provide quantitative data on tissue perfusion. However, it also has limitations, such as exposure to ionizing radiation and the potential for contrast-induced nephropathy, especially in patients with pre-existing kidney disease.

Related Pages

• Computed tomography
• Stroke
• Cerebral blood flow
• Contrast agent