Figure 1

Imaging data from a patient with a left hemiparesis. Diffusion weighted images (top row) and mean transit time (bottom row) at the level of the lateral ventricles from a patient who presented 4.2 hours after onset of a left hemiparesis, and who was found to have a proximal right middle cerebral artery occlusion by CT angiography. Thrombolytic therapy was not given, but normobaric oxygen was provided by face mask for 4 hours. The image abnormalities were located within the right middle cerebral artery territory. The sizes of the diffusion and MTT abnormalities are very similar at the first 2 time points and there is a large mismatch. At 24 hours after baseline imaging, a large increase in the abnormal diffusion volume is apparent accompanied by a decrease in the abnormal MTT volume, but a greater than 20% mismatch persists. At 1 week, continued increase of the abnormal DWI is observed.