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Viability thresholds of ischemic penumbra of hyperacute stroke defined by perfusion-weighted MRI and apparent
L Røhl1, L Ostergaard, C Z Simonsen
1Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark. Lisbeth@pet.auh.dk
Background And Purpose:
The penumbra of ischemic stroke consists of hypoperfused, but not irreversibly damaged, tissue surrounding the ischemic core. The purpose of this study was to determine viability thresholds in the ischemic penumbra, defined as the perfusion/diffusion mismatch in hyperacute stroke, by the use of diffusion- and perfusion-weighted MRI (DWI and PWI, respectively).
Methods:
DWI and PWI were performed in 11 patients
Results:
The post hoc analysis showed that the penumbra progressed to infarction at the following cutoff values: rCBF <0.59 and MTT >1.63. Higher sensitivity and accuracy in predicting outcome of the penumbra were obtained from the rCBF maps compared with the rCBV and MTT maps. The initial rCBV and apparent diffusion coefficient ratios did not differentiate between the part of the penumbra that recovered and the part that progressed to infarction. The mean rCBF ratio was optimal in distinguishing the parts of the penumbra recovering or progressing to infarction.
Conclusions:
The thresholds found in this study by combined DWI/PWI might aid in the selection of patients suitable for therapeutic intervention within 6 hours. However, these hypothesized thresholds need to be prospectively tested at the voxel level on a larger patient sample before they can be applied clinically.
Insights
This study identified specific thresholds using diffusion- and perfusion-weighted MRI (DWI/PWI) to predict ischemic stroke penumbra outcomes. These findings may help select patients for timely therapeutic intervention.
Area of Science:
- Neuroimaging
- Cerebrovascular disease
- Stroke research
Background:
- The ischemic penumbra represents tissue at risk in acute stroke.
- Understanding penumbra viability is crucial for timely intervention.
Purpose of the Study:
- To determine viability thresholds in the ischemic penumbra using diffusion- and perfusion-weighted MRI (DWI/PWI).
- To define the perfusion/diffusion mismatch in hyperacute stroke.
Main Methods:
- DWI and PWI were performed on 11 patients within 6 hours of stroke onset.
- Regions of interest were defined for the ischemic core, penumbra progressing to infarction, and penumbra that recovered.
- Ratios of relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), mean transit time (MTT), and apparent diffusion coefficient were calculated.
Main Results:
- Penumbra progression to infarction was identified at rCBF <0.59 and MTT >1.63.
- Relative cerebral blood flow (rCBF) maps showed higher sensitivity and accuracy in predicting penumbra outcome compared to rCBV and MTT.
- Relative cerebral blood volume (rCBV) and apparent diffusion coefficient ratios did not differentiate between penumbra that recovered or progressed to infarction.
Conclusions:
- Identified thresholds using combined DWI/PWI may assist in selecting patients for therapeutic intervention within 6 hours.
- Prospective, voxel-level testing on larger patient cohorts is necessary before clinical application.