CT perfusion

- Look at MTT first followed by CBV
- CBV can be normal or ↑ in penumbra
- You can also have ↑MTT and normal or ↑CBV in areas of successful auto-regulation (eg. long-standing carotid stenosis) or benign oligemia
- CBF is useful but is decreased in both penumbra and core so it may lead to overestimation of core size and underestimation of penumbra if assessed visually
- Large mismatch (ie large penumbra, small core) is more amenable to reperfusion
- DEFUSE 2 trial has some numbers and good profiles and bad profiles
- Very large core is riskier to reperfuse given risk of hemorrhage
- Hypoperfusion intensity ratio looks at ratio of Tmax >10s/Tmax >6s
- High ratio predicts poor collaterals and more growth of core
- Low ratio predicts good collaterals and less core growth