Hemorrhage at 7 days
Hemorrhage at 21 days

These two T2-weighted MR images show a cerebellar haematoma at 7 days (top) and 21 days (bottom).

Cerebral hemorrhage may be divided into hyperacute (<24h), acute (1-3 days), subacute (3-14 days), chronic (>2 weeks) and ancient (years). T1 and T2 signal changes occur over this time as hemoglobin becomes deoxyhemoglobin, intracellular methaemoglobin, extracellular methaemoglobin, and finally iron-containing breakdown products such as hemosiderin.

The first image is essentially T2 isointense to brain and corresponds to the mid subacute stage. The high signal rim is due to edema. The hematoma is probably isointense because it contains a mixture of intracellular methaemoglobin (hypointense) and extracellular methaemoglobin (hyperintense). The second image corresponds to the chronic stage, with central hyperintensity and a rim of hypointensity. These correspond to extracellular methemoglobin (hyperintense) and hemosiderin (hypointense).

Reference: ACR Learning File: Neuroradiology
Credit: Dr Laughlin Dawes