Patient with a persistent left middle cerebral artery (MCA) occlusion: 2 hours after symptom onset the Non-contrast CT (NCCT) is normal. Cerebral blood flow (CBF) is reduced by >70% in a small region of the left hemisphere (pink on the RAPID CBF map). Perfusion is substantially delayed (> 6 seconds) in a much larger region of the left hemisphere (green on the RAPID Tmax > 6 s map).

By 8 hours the early ischemic lesion is now visible on the NCCT and the volume of the lesion with > 70% reduction in CBF has grown (pink on the RAPID CBF map). The degree of perfusion delay (green on the RAPID Tmax map) is unchanged.

Despite the persistent MCA occlusion, at 24 hours the CBF values within the ischemic lesion have increased, due to improved collateral flow, and are now reduced by less than 70% and therefore no longer visible as pink on the RAPID CBF map. The full ischemic lesion is now clearly seen on the NCCT.

CBF (0.3): regions with CBF reduced by >70% are pink on CBF maps
Regions with perfusion delay >6 seconds are green on Tmax > 6 s maps


Patient with a left middle cerebral artery (MCA) occlusion and early reperfusion: 2 hours after symptom onset the non-contrast CT (NCCT) is normal. Cerebral blood flow (CBF) is reduced by >70% in a small region of the left hemisphere (pink on the RAPID CBF map). Perfusion is substantially delayed (> 6 seconds) in a much larger region of the left hemisphere (green on the RAPID Tmax > 6 s map).

Early reperfusion occurs at 4 hours (green arrow) resulting in a sudden rise in CBF values. At 24 hours the CBF values within the ischemic lesion are normal; therefore the lesion is no longer visible on the CBF map. A small ischemic lesion is now clearly seen on the NCCT in the same region as the initial CBF lesion.

Regions with CBF reduced by >70% are pink on CBF maps
Regions with a perfusion delay >6 seconds are green on Tmax > 6 s maps


Patient with a left middle cerebral artery (MCA) occlusion and large lesion with low cerebral blood flow (CBF): 2 hours after symptom onset the non-contrast CT (NCCT) is normal. CBF is reduced by >70% in a large region of the left hemisphere (pink on the RAPID CBF map). Perfusion is substantially delayed (> 6 seconds) in the same region of the left hemisphere (green on the RAPID Tmax map) that has low CBF.

Despite reperfusion at 4 hours no tissue salvage occurs. A large ischemic lesion with hemorrhagic transformation and substantial edema is seen on the 24 hour NCCT.

Regions with CBF reduced by >70% are pink on CBF map
Regions with a perfusion delay >6 seconds are green on Tmax > 6 s map