Non-contrast CT head of a 55-year-old hypertensive shows a hyperdense lesion in the right basal ganglia (putamen) with surrounding oedema. The CT attenuation of the acute haematoma is approximately:

• A 20–30 HU
• B 80–100 HU
• C 100–130 HU
• D 50–70 HU ✓

Explanation

Acute haematoma on non-contrast CT appears hyperdense with Hounsfield units of 50–70 HU, due to the protein content of clotted blood (especially globin). Subacute (days to weeks) haematoma decreases in attenuation and becomes isodense then hypodense. The normal brain parenchyma is 30–40 HU. Values >80 HU may indicate a fluid-fluid level in an acute hyperacute bleed with serum/clot separation, but the typical acute clot is 50–70 HU.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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