Which MRI findings are characteristic of the acute phase (1-7 d) of acute stroke?

Updated: Dec 09, 2020
  • Author: Souvik Sen, MD, MPH, MS, FAHA; Chief Editor: Helmi L Lutsep, MD  more...
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In this phase, edema increases, maximizing at 48-72 hours, and MRI signals become more prominent and well demarcated. The ischemic area continues to appear as an area of hypointensity on T1-WI and as a hyperintense area on T2-WI. In addition, the mass effect can be appreciated in this phase.

In contrast-enhanced images, the arterial enhancement usually persists throughout the acute phase, while the parenchymal enhancement is usually appreciated at the end of this phase in complete infarction. In incomplete infarction, the parenchymal enhancement is usually earlier.

During this period, reperfusion occurs and petechial and frank hemorrhages can be observed, typically 24-48 hours after the onset of the stroke. Usually, petechial hemorrhages cause the "fogging" phenomenon, due to hemoglobin degradation products, that masks the infarction on T1-WI and T2-WI.

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