Pseudosubarachnoid hemorrhage

1. 원인

cerebral edema where there is a decrease in parenchymal attenuation and engorgement and dilatation of the superficial venous structures due to an increased intracranial pressure

Other causes include:
severe meningitis: breakdown of the BBB allowing mildly hyperdense proteinaceous material to leak into the subarachnoid space 
venous sinus thrombosis : bilateral large subdural hemorrhage producing effacement of sulci and basal cisterns and the false impression of blood in the subarachnoid space 
intrathecal contrast

 

2. DDX  - SAH

usually, symmetrical density confined to the basal cisterns (i.e. no sulcal density)
30-40 HU (cf. true acute subarachnoid hemorrhage ~60 HU)
often seen with generalized cerebral edema or basal cistern effacement
the appearances are thought to be due to a combination of cisternal effacement distention +/- thrombosis of vessels
adjacent brain hypoattenuation accentuating contrast difference

 

pseudo

SAH