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• Posterior Reversible Encephalopathy Syndrome (PRES) is seen as T1 hypo T2 hyper with sometimes restricted diffusion on DWI, and signal increased in affected regions due to increased diffusion on ADC maps.
• Usually following inadequate autoregulatory response to high blood pressure, that leads to hyperperfusion, thus leading to a break in the blood brain barrier, and hence vasogenic edema, without overt signs of infarction.
• Usually symmetrical and bilateral but not necessarily so and more common in the occipito-parietal regions
• Common causes being severe hypertension, sepsis, drug toxicity