Failure to demonstrate peri-infarct depolarizations by repetitive MR diffusion imaging in acute human stroke

Background and Purpose-Peri-infarct depolarizations (PIDs) have been demons trated with diffusion-weighted MRT. (DWI) in experimental stroke and are re garded as an important mechanism of ischemic injury. We tested the hypothes is that PIDs are of relevance for the early enlargement of human brain infa rcts. Methods-Ten stroke patients were investigated by repetitive imaging of the apparent diffusion coefficient (ADC) in the acute phase (7 patients) or sub acute phase (3 patients) of developing cortical infarction. In each patient , 20 ADC maps were obtained from serially measured echo-planar DWI (interva l of 45 seconds). Data analysis focused on the potential spatial and tempor al ADC changes, including structured qualitative analysis, calculation of s ubtraction images, serial analysis of regions of interest positioned in the infarct core and border, and calculation of hemispheric lesion areas, depe nding on various ADC thresholds ranging between 0 and 800 mum(2)/s. Results-Data analysis was unable to disclose any time-dependent changes in ADC that would resemble PID. In ischemic regions, the ADC reduction signifi cantly progressed from the infarct border (555+/-96 mum(2)/s) to the infarc t core (431+/-101 mum(2)/s, P<0.01). Conclusions-By using an MRI protocol with high temporal resolution and elab orated postprocessing, we were unable to demonstrate a pattern of diffusion changes that would be indicative of PID in human stroke. Experimental infa rction and human stroke may differ in the detectability of PID.