"Cortical Contusion MR and CT appearance of "

Cortical contusion: - Primarily involves superficial grey matter; (cf DAI) - better prognosis then DAI; less likely to have loss of conciousness at time of injury (cf DAI) - Occurs near bony protruberances of the skull - - temporal lobe above petrous bone or posterior to greater sphenoid wing;  - - frontal lobe above the cribiform plate; planum sphenoidale; and lesser sphenoid wing -- Margins of depressed skull fractures - Usully multiple and bilateral - Commonly hemorrhagic CT: varies with age of the lesion - nonhemorrhagic - become evident in the first week as region of low density cerebral edema - Hemorrhagic: foci of high density, oftern involving cortical (superficial) grey matter - may be surrounded by larger area of low density edema; - after a week: mixed areas of hyper and hypodensity density ("salt and pepper appearance") - Old contusion: foci of encephalomalacia in the characteristic locations described MRI: Poorly marginated areas high signal on T2WI and FLAIR and PD sequences - Usually frontal and temporal lobes - "Gyral" morphology - Hemorrhage signal intensity varies based on age of lesion  -- Old blood (hemosiderin): low signal T2WI, may persist indefinately as a marker of prior hemorrhage