Extradural Haematoma

Biconvex (lenticular shaped), hyperdense, sharply demarcated extra-axial lesion. Limited by suture lines

Subdural Haematoma

Hyperdense cresenteric haematoma, extending across suture lines

acute (< 3 days): hyperdense crescent, central hypodensity represents active bleeding

subacute (3-21 days): over the first couple of weeks, the blood is broken down. Density approaches that of the brain - may be tricky to see

chronic (>21 days): over time, the hematoma approaches CSF density

Traumatic SAH

small volume sulcal SAH occurring at the site of impact (coup) or opposite the site of impact (contrecoup)