Method for determining ischemic status or assessing stroke onset time of a brain region

A method for determining ischemic status of a brain region, comprising:

• acquiring magnetic resonance diffusion tensor matrices of the brain region and of a normal brain tissue, wherein the normal brain tissue and the brain region belong to the same brain tissue type;
• obtaining diffusion magnitude (L) of the brain region (Li) and diffusion magnitude of the normal brain tissue (Ln) from the magnetic resonance diffusion tensor matrices;
• and
• calculating a relative decrease of Li to Ln, and the ischemic status is determined by the relative decrease of Li to Ln;
• wherein the diffusion magnitude L is defined as L=√{square root over (λ12+λ22+λ32)}, wherein λ1, λ2, and λ3 are the eigenvalues of the diffusion tensor matrices, and λ is the mean diffusion;
• and
• the brain region locates in a superficial cortex, a subcortical tissue or a white matter.