How to approach a non-contrast CT head

Step-by-step approach

1. 1

   Orient yourself

   Axial slices are viewed from the feet: patient left is image right. Scroll the whole stack once quickly before detailed review.

2. 2

   Blood

   Acute blood is hyperdense (bright, ~50–70 HU). Check the parenchyma, the extra-axial spaces (subdural crescents, extradural lentiform collections), the sulci and cisterns (subarachnoid), and the ventricles.

3. 3

   Cisterns

   Are the basal cisterns open? Effaced cisterns signal raised intracranial pressure and impending herniation.

4. 4

   Brain

   Grey–white differentiation preserved and symmetric? Loss of the insular ribbon or an obscured lentiform nucleus are early infarct signs.

5. 5

   Ventricles

   Size and symmetry; midline shift; blood in dependent occipital horns.

6. 6

   Bone

   Switch to bone windows. Fractures, especially where they cross vascular grooves, matter enormously.