Significance of the perfusion-diffusion mismatch in chronic cerebral ischemia

Purpose: To determine whether the perfusion deficit could predict brain infarction in patients with chronic cerebral ischemia who experienced recurring episodes of neurological symptoms and showed a perfusion-diffusion mismatch on magnetic resonance (MR) images. Materials and Methods: In 53 consecutive patients (38 males and 15 females, 62 +/- 13 years old) with ischemia in the middle cerebral artery (MCA) territory, lesion volumetry was performed on parametric maps of the time-to-peak, the cerebral blood volume, and diffusion-weighted (DW) images. The infarct lesions were assessed on follow-up T2-weighted (T2W) MR images after eight days. Cerebrovascular changes were determined by time-of-flight (TOF) MR angiography (MRA). Inferential and correlation statistics were used. Results: Patients with chronic ischemic brain disease (N = 39) who presented With a severe perfusion-diffusion mismatch in the presence of a normal cerebral blood volume had no or small brain infarctions as found on follow-up T2W images. MRA revealed Widespread abnormalities of the basal cerebral arteries compatible with brain perfusion abnormalities. In, contrast, in acute stroke patients (N = 14) the deficit of cerebral perfusion predicted the infarct lesion in the T2W images. Conclusion: Our results suggest that in chronic cerebral ischemia the normal blood, volume was maintained despite the depression of cerebral perfusion and recurring minor insults.