Discordant ADC and DWI signal evolution in hyperacute stroke: implications for early imaging interpretation.

Here we report the first human observation of an imaging pattern in early hyperacute ischemic stroke, in which restricted diffusion is detectable on ADC maps before it becomes appreciable on DWI. The pattern—an ADC/DWI mismatch—was incidentally captured in a thalamic infarct during MRI obtained after a transient ischemic attack in a different vascular territory, enabling observation at an early hyperacute stage. Quantitative measurements at three time points demonstrated falling relative ADC and slower-rising relative DWI signal, aligning with thresholds for visual detectability. Although anticipated by animal data, this dissociation has not, to our knowledge, been documented in humans. Recognition of this putative earliest stage of ischemia may refine stroke diagnosis and inform MRI acquisition and interpretation protocols.