What is penumbra?
Brian at risk after a stroke
What do the results of a perfusion CT scan tell you about a stroke?
Increased time to start or mean transit time, increased time to peak and decreased blood volume equals completed infarct.
Increased time to start, increased time to peak and normal or increased time to peak and normal or increased blood volume equals brain at risk
What is found on CT after a stroke at different time periods?
1-6 hrs: Loss of gray matter density
6 hrs-4days: Progressive swelling and hypodensity
4-14 days: return towards normal density and volume
14 days on: varying degrees of hypodensity and volume loss
MR imaging of infarcts
1 hr- 10 days: bright on diffusion weighted imaging
Swelling and increased signal on FLAIR and T2-weighted scans follows same pattern as swelling and low density on CT
DWI great for small infarcts and telling new from old
Basilar artery thrombosis
BAD prognosis so window for intervention often extended