Fig. 1

Hematoma attenuation. The left panel illustrates the changes in hematoma attenuation over time. In the hyperacute phase, within the first minutes of onset, the hematoma is iso-attenuating with gray matter. Within an hour, the attenuation in the hematoma increases to the hyperattenuating typical appearance of the acute phase, lasting for several hours. The attenuation then gradually decreases over the next days to iso-attenuating with the gray or white matter in the subacute phase, and then even further to become hypoattenuating in the chronic phase, typically within weeks of onset. Finally, the hematoma is absorbed and the lesion is healed with substance loss and gliosis in the surrounding brain parenchyma