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Failure to demonstrate peri-infarct depolarizations by repetitive MR diffusion imaging in acute human stroke
1Department of Neurology, Klinikum Mannheim, Ruprecht Karls University Heidelberg, Germany. Tobias.Back@lrz.uni-muenchen.de
Background And Purpose:
Peri-infarct depolarizations (PIDs) have been demonstrated with diffusion-weighted MRI (DWI) in experimental stroke and are regarded as an important mechanism of ischemic injury. We tested the hypothesis that PIDs are of relevance for the early enlargement of human brain infarcts.
Methods:
Ten stroke patients were investigated by repetitive imaging of the apparent diffusion coefficient (ADC) in the acute phase (7 patients) or subacute phase (3 patients) of developing cortical infarction. In each patient, 20 ADC maps were obtained from serially measured echo-planar DWI (interval of 45 seconds). Data analysis focused on the potential spatial and temporal ADC changes, including structured qualitative analysis, calculation of subtraction images, serial analysis of regions of interest positioned in the infarct core and border, and calculation of hemispheric lesion areas, depending on various ADC thresholds ranging between 0 and 800 microm(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 significantly progressed from the infarct border (555+/-96 microm(2)/s) to the infarct core (431+/-104 microm(2)/s, P:<0.01).
Conclusions:
By using an MRI protocol with high temporal resolution and elaborated postprocessing, we were unable to demonstrate a pattern of diffusion changes that would be indicative of PID in human stroke. Experimental infarction and human stroke may differ in the detectability of PID.
Insights
Peri-infarct depolarizations (PIDs) were not detected in human stroke patients using advanced MRI. This suggests that PIDs, observed in animal models, may not play a significant role in early human brain infarct enlargement.
Area of Science:
- Neuroscience
- Radiology
- Stroke research
Background:
- Peri-infarct depolarizations (PIDs) are linked to ischemic injury in experimental stroke models.
- Diffusion-weighted MRI (DWI) has previously demonstrated PIDs in animal studies.
Purpose of the Study:
- To investigate the relevance of PIDs in the early enlargement of human brain infarcts.
- To test the hypothesis that PIDs contribute to infarct progression in humans.
Main Methods:
- Ten human stroke patients underwent serial diffusion-weighted MRI (DWI) with high temporal resolution.
- Apparent diffusion coefficient (ADC) maps were analyzed for spatial and temporal changes in infarcting brain tissue.
Main Results:
- No time-dependent ADC changes indicative of PIDs were observed in human stroke patients.
- ADC values significantly decreased from the infarct border to the infarct core, indicating progressive cytotoxic edema.
Conclusions:
- The study failed to demonstrate PIDs in human stroke using a high-resolution MRI protocol.
- Differences in PID detectability may exist between experimental stroke models and human stroke.