On a CT scan of the brain, how can you tell the difference between an infarct and a haemorrhage?

Question

As above

Answer 1

Well, there you go then.  ;-)

Fresh blood on CT looks white.  So infarct will be a darker area (less blood), whereas fresh hemorrhage (I'm American, please forgive the spelling) will be white.  You do run into some difficulty with differentiating chronic infarct or bleeds on CT; for chronic problems, MRI is the preferred modality.

(Actually, studies show that MRI is at least as sensitive as CT for the detection of early hemorrhagic stroke, and maybe more so, but the problem is that CT is quicker and usually more accessible, so when you need a study done quickly, CT may be your only choice.)