Early DWI reversal in ischemic stroke

Early DWI reversal in ischemic stroke (also referred to as diffusion lesion reversal) is encountered early in the course of ischemic infarction, most frequently in the setting of reperfusion within 3 to 6 hours of onset .

DWI reversal is defined as the interval disappearance of the initially-visible increased DWI signal on repeat MRI scan. In the vast majority of cases it is transient and the abnormal DWI signal returns. That is, it does not represent true reversal (i.e. the region of the brain initially demonstrating reduced ADC values goes on to infarct regardless of whether early DWI reversal is demonstrated) .

It should be noted that in other clinical contexts (e.g. hemiplegic migraine, seizure, transient ischemic attack and transient global amnesia) permanent diffusion lesion reversal, without progression to permanent lesion has been rarely encountered .

Note: Early DWI reversal should not be confused with ADC pseudonormalization which occurs later in the evolution of ischemic stroke.