Epidural hematoma on CT scan shows -

Ans. is 'b' i.e., Biconvex hyperdense lesion o Biconvex (lens shaped or lenticular) hyperdense(2/3rd) or mixed density lesion(l/3rd)- Epidural hematomao Crescent (concao-convex) hyperdense (<2 weeks) or isodense (2-4 weeks) or hypodense (>4 weeeks) lesion - subdural hematomao Intracranial hematoma may be: -1) Epidural hematoma# Most common cause is injury to middle meningeal artery.# Radiologically it appears as:-i) Biconvex (lens shaped or lenticular)ii) In Acute cases - Hyperdense (2/3) or mixed density (1/3).iii) In chronic cases - Hypodense2) Subdural hematoma# ost common cause is stretching and tearing of cortical bridging veins.# Radiologically it appears as : -i) Crescent (Concavo-convex)ii) Hyperdense in acute (< 2 weeks)iii) Isodense in subacute (2-4 weeks)iv) Hypodense in chronic (> 4 weeks)3) Subarachnoid hemorrhage# Most common cause is rupture of berry (saccular) aneurysm.# Investigation of choice for acute subarachnoid hemorrhage is non contrast CT.# Blood in CSF on lumbar puncture is the hallmark of subarachnoid hemorrhage. If CT scan fails to diagnose SAH and there is high index of suspicion, lumber puncture is the next investigation.# Investigation of choice for chronic SAH is MRL# Investigation of choice for determining the etiology of SAH is four vessels (both carotid and both vertebral) digital substraction angiography.