The T2WI relies upon the transverse relaxation of the net magnetisation vector (NMV). T2 weighting tend to have long TE and TR times.
Paramagnetic contrast agents, e.g. gadolinium-containing compounds, do not have nearly as significant effect as they do in T1WI.
TR: long TE: long fat: intermediate-bright fluid: bright
Quantitative T2'-mapping detects regional changes in the relation of oxygenated and deoxygenated hemoglobin and might reflect areas with increased oxygen extraction.
Motion-corrected T2'-mapping reveals significant and gradually declining values from healthy to perfusion-disturbed to apparent diffusion coefficient-restricted tissue. Current T2'-mapping can differentiate between the ischemic core and the perfusion-impaired areas but not on its own between penumbral and oligemic tissue 1).
More recent publications tend to indicate that T2 weighted signal change, particularly if multisegmental, is a poor prognostic feature for response to surgery.