CT of the head

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Author: Mikael Häggström [notes 1]


Indications for contrast

Most CTs of the head are made without IV contrast, as there is limited advantage of contrast for initial investigations for stroke, intracranial bleeding or skeletal trauma. In the acute setting, it is also acceptable to have a CT head without contrast if a tumor is part of a list of differential diagnoses but not the most likely cause. It is then generally possible to to a complementary MRI of the head if a suspicion of a tumor remains. However, if a tumor is strongly suspected in an initial acute setting, it is usually appropriate to do a CT with and without IV contrast.

CT angiography of the head

This is indicated in identification and characterization of aneurysms, stenosis or other occlusive diseases, arteriovenous malformations, vessel dissections, sinus thrombosis, idiopathic hemorrhage, and other vascular pathologies.[1]


Also make thin slices for skeletal evaluation. Further information: CT of the head in trauma

Basic screening

Apart from any specific requests in the referral, it is appropriate to scroll through the brain in at least two planes in:

  • Parenchymal window. In people over age 50-60, the main finding to look for is ischemia or stroke in the brain. It also allows for a quick glance of extra-cranial structures, the orbits and the paranasal sinuses. In case of substantial mucus filling of one or more sinuses, also evaluate as CT of sinusitis.
  • Bleeding window (such as center at 80 HU and width 150 HU)

Also, in cases with possible head trauma:

  • Bone window for fracture, at least in emergent exams. It also facilitates a quick glance of the mastoid air cells, the middle ears and the paranasal sinuses in case of fluid/mucus filling.

Normal anatomy

CT of the head with normal anatomy.

Associated diseases and conditions




  • Questions or requests on the referral.
  • In people over age 50-60, include even the absence of stroke, preferably using "visible" in the first 24 hours after onset of symptoms to emphasize that this is generally the time needed before appearance on CT.[3]
    Example: No visible stroke.
  • In cases of possible head trauma, report even the absence of skull fracture.

A somewhat more detailed report includes even the absence of intracranial bleeding.

See also: General notes on reporting


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.


  1. Lian, K.; Bharatha, A.; Aviv, R.I.; Symons, S.P. (2011). "Interpretation Errors in CT Angiography of the Head and Neck and the Benefit of Double Reading ". American Journal of Neuroradiology 32 (11): 2132–2135. doi:10.3174/ajnr.A2678. ISSN 0195-6108. 
  2. Vermeer, Sarah E.; Hollander, Monika; van Dijk, Ewoud J.; Hofman, Albert; Koudstaal, Peter J.; Breteler, Monique M.B. (2003). "Silent Brain Infarcts and White Matter Lesions Increase Stroke Risk in the General Population ". Stroke 34 (5): 1126–1129. doi:10.1161/01.STR.0000068408.82115.D2. ISSN 0039-2499. 
  3. Majda Thurnher. Brain Ischemia - Imaging in Acute Stroke. Radiology Assistant. Retrieved on 2018-12-02.