CT Brain Perfusion

  • When performing a CT brain perfusion exam, it is common to first do a non-contrast head, a CTA of the head, and then perfusion imaging.

  • Brain perfusion evaluates blood flow in and out of the brain tissue. This exam is performed typically as part of a stroke protocol.
  • The goal of the exam is to determine infarcted brain tissue from potentially viable brain tissue.
  • There are several key measurements that are taken during this exam:
  • Cerebral blood volume-The quantity of blood contained within 100g of brain tissue.
  • Cerebral blood flow-The quantity of blood that moves within 100g of brain tissue in a minute.
  • Mean transit time-The average time it takes for blood to pass through a given area of brain tissue.
  • Typical protocols require at least 50mL of contrast media to be injected at a rate of 5-7mL/second.
  • Imaging takes place over the specified area of the brain for up to 60 seconds in order to completely image contrast moving through the brain.
  • In order to be able to properly calculate the measurements listed above, ROI measurements must be placed on an artery and venous outflow within brain.
  • With this, the computer will calculate the measurements during post processing.
  • Patient radiation dose is very high during this scan due to the continuous scanning, it is crucial that only the area of interest is imaged.



    Patient Position
    Patient Prep
    -IV placement
    -Xenon (Xe) gas (per department protocol)
    Clinical Indicators
    -Stroke, vasospasm, cerebrovascular reserve detection, can be used with temporary balloon occlusion.

    Scan Range
    -The area of brain tissue of interest
    – Soft tissue
    Slice Thickness
    -3mm-5 mm
    -Flow Mapping