Diffusion Weighted Imaging (DWI)

(from Radiology Assistant)

Diffusion Weighted Imaging (DWI)

DWI is the most sensitive sequence for stroke imaging.
DWI is sensitive to restriction of Brownian motion of extracellular water due to imbalance caused by cytotoxic edema.
Normally water protons have the ability to diffuse extracellularly and loose signal.
High intensity on DWI indicates restriction of the ability of water protons to diffuse extracellularly. 

Pseudo-normalization of DWI
This occurs between 10-15 days.
The case on the left shows a normal DWI.
On T2WI there is may be some subtle hyperintensity in the right occipital lobe in the vascular territory of the posterior cerebral artery.
The T1WI after the administration of Gadolinium shows gyral enhancement indicating infarction.