CT Protocol For Cerebral Perfusion

CT cerebral perfusion scan image
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Protocol for Cerebral Perfusion

Indications
Suspected hyperacute stage of cerebral infarction, pretherapy evaluation, and posttherapy follow-up of the cerebral ischemia.

Patient positioning
Supine with Headfirst with Arms beside the trunk.

Topogram position/Landmark
Lateral;2-3 cm above the vertex.

Mode of Scanning
Sequential dynamic.

Scan Orientation
Caudocranial.
  • Starting Location- As decided by the radiologist depending on the site of ischemia.  
  • End location- As decided by the radiologist depending on the site of ischemia
Gantry Tilt 
As many degrees required making the plane of scanning parallel to the canthomeatal line.

Field of view
Just fitting the parenchymal brain.

Contrast Administration
Intravenous.

The volume of Contrast
40-50 mL.

Rate of Injection of Contrast
>5mL/sec

Scan Delay
0 sec.

Slice Thickness
5-10 mm

Algorithm/Kernel
Smooth

3D-Reconstructions
Nil.

Comment

  • The use of a headrest is recommended for head position
  • A noncontrast scan in sequential mode should precede the angiography protocol as it will give the baseline scans and will determine the region of interest.
  • There should be no motion between the noncontrast and contrast scans.
  • This technique requires larger venous access than usual.
  • This protocol involves utilizing special software techniques to produce time density curves for calculating different cerebral perfusion parameters as relative cerebral blood flow (rCBF) relative cerebral blood volume (rCBF) and  time to peak enhancement(TTP).

Criteria of good image quality:

  • Symmetric position with the orbital plates overlapping with each other.
  • Absence of the motion artifacts.

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