Numerous studies have shown that ADCs in ischemic areas are lower by 50% or more compared with those of normal brain areas, and they appear as bright areas (ie, hyperintensities) on DWI (see the image below). Studies have demonstrated that changes in the ADC occur as early as 10 minutes following the onset of ischemia.

The infarct remains hyperintense on T2 and FLAIR, with T2 signal progressively increasing during the first 4 days. T1 signal remains low, although some cortical intrinsic high T1 signal may be seen as early as 3 days after infarction ¹⁰. After day 5 the cortex usually demonstrates contrast enhancement on T1 C+ ¹⁰.

An acute infarct occurs when the blood flow to the brain is blocked by occlusion or due to a haemorrhage in the brain. This leads to hypoxia (deficiency of oxygen) and depletion of adenosine triphosphate (ATP) in the cells.