Ans: B (Extradural....) "The features of an EDH on a CT scan are a lentiform (lens-shaped or biconvex) hyperdense lesion between the skull and brain. There may be an associated mass effect on the underlying brain, with or without a midline shift. Areas of mixed density may be seen in a lesion that is actively bleeding"- L & B 25th/303"The CT appearance of an Acute SDH is hyperdense (acute blood) but the haematoma spreads across the surface of the brain giving ita ratherdiffuse and concave appearance. This occurs because there is less resistance to blood moving through the subdural space than through the extradural space1'- L & B2Sth/304"The CT appearance of a Chronic SDH is variable. Acute blood (0-10days) is hyperdense whereas subacute blood (10 days to 2 weeks) is isodense relative to brain; chronic blood (> 2 weeks) is hypo-dense. A Chronic SDH will often have areas of more recent haemor-rhage in more dependent (posterior) areas and is then termed an acute-on-chronic subdural haematoma. The extent of acute ver-sus chronic blood is important as it affects the method of haematoma evacuation"- L&B 25th/305"Cerebral contusions on CT appear heterogeneous with mixed areas of high and low density. There may be an asso-ciated mass effect. A contusion may be described as an intracerebral haematoma if the lesion contains a large amount of fresh haemorrhage and therefore appears uniformly hyperdense"- L & B 25th/305Radiographic features www.nlm.nih.gov/medlineplus/ency/ar- tide/001412.htm: WritesIn almost all cases, extradural haematomas are seen on CT scans of the brain. They are typically bi-convex (or lentiform) in shape, and most frequently beneath the squamous part of the temporal bone. They are hyperdense, somewhat heterogenous, and sharply demarkated. Depending on their size, secondary features of mass effect (e.g. midline shift, subfalcine herniation, uncal herniation) may be present.When acute bleeding is occurring at the time of CT scanning the non-clotted fresh blood is typically less hyper dense, and a swirl sign may be evident emedicine.medscape.com/artide/340527-overview# Epidural hematomas can typically be distinguished from subdural hematomas by their biconvex shape, compared with the crescent-shape of the subdural hematoma. In addition, unlike subdural hematomas, epidural hematomas usually do not cross the sutures.Intracranial HemorrhageCT FindingExtradural hematomaBiconvex lentiform opacitySubdural HematomaConcavo convex crescentric opacityIntracerebral BleedSmall hemorrahage foci at grey- white matter interfaceSubarachnoid HemorrhageSubarachnoid dots > 5x3 mm in basal dsterns or layers of blood > 1mm thick in cerebral fissures.vasospasm Intracranial BleedSource of bleedingSiteExtradural hematomaMiddle meningeal arteryMiddle cranial fossaSubdural HematomaRupture of dural venous sinusFrontotemporal regionIntracerebral BieedRupture of berry aneurysmBasalSubarachnoid HemorrhageLenticulostriate arteries Fig: An axial CT scan of a left frontal extradural haematoma. Note the biconvex shape of the haematomas