Fragmentation of the classical magnetic resonance mismatch "penumbral" pattern with time.

Background And Purpose: The classical mismatch pattern in the middle cerebral artery territory stroke on MR is defined by a central diffusion-weighted image core with surrounding mismatch tissue. Because of variable rates of tissue salvage, we hypothesized that this pattern may fragment over time and may be influenced by vessel patency, mismatch volume, and infarct core location.

Methods: Patients were recruited with MR studies performed within 48 hours of ischemic stroke.

Ischemic thresholds for gray and white matter: a diffusion and perfusion magnetic resonance study.

Background And Purpose: Although gray matter (GM) and white matter (WM) have differing neurochemical responses to ischemia in animal models, it is unclear whether this translates into differing thresholds for infarction. We studied this issue in ischemic stroke patients using magnetic resonance (MR) techniques.

Methods: MR studies were performed in patients with acute hemispheric ischemic stroke occurring within 24 hours and at 3 months.