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Updated: Oct 2, 2025
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Use of DWI-FLAIR Mismatch to Estimate the Onset Time in Wake-Up Strokes
Jinfeng Zhang1,2, Na Ta3, Meng Fu1,2
1Department of Neurology, Baotou Central Hospital, Baotou, Inner Mongolia, People's Republic of China.
Purpose:
To compare the MRI characteristics of patients with wake-up ischemic stroke (WUS) and with ischemic stroke with known onset time (clear-onset-time stroke, COS) to clarify the role of diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch in estimating the onset time of WUS patients.
Patients And Methods:
Two hundred patients with acute ischemic stroke were selected for complete brain MRI within six hours of symptom onset, including DWI and FLAIR sequences. The patients were divided into WUS (n = 78) and COS (n = 122) groups, based on whether the time of onset was known. The general conditions and imaging characteristics were collected to compare the DWI-FLAIR mismatch features between the two groups at different time intervals.
Results:
There was no significant difference in the DWI-FLAIR mismatch on MRI within 2 hour after the first found abnormality between the two groups (50.0% vs 71.8%, p = 0.180). With increasing time, the DWI-FLAIR mismatch decreased substantially in the WUS group, while a higher DWI-FLAIR mismatch presence persisted in the COS group within a four-hour interval from the onset of symptoms to the MRI. The DWI-FLAIR mismatch was significantly lower in the WUS group than in the COS group from symptom identification to MRI at 2-3 h, 3-4 h, and 4-5 h intervals (15% vs 60%, 10.5% vs 48%, 6.7% vs 45.4%; p < 0.01).
Conclusion:
Our results suggest that the presence of DWI-FLAIR mismatch within 2 h of the first found abnormality was not significantly different between WUS and COS. Therefore, Patients with WUS within 2 hours after the first detected abnormality may be suitable for intravenous thrombolysis.
Insights
Diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch showed no significant difference in wake-up ischemic stroke (WUS) patients within two hours. This suggests WUS patients identified within two hours may benefit from intravenous thrombolysis.
Area of Science:
- Neurology
- Radiology
- Emergency Medicine
Background:
- Wake-up ischemic stroke (WUS) presents diagnostic challenges due to unknown onset times.
- Diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch is a key imaging biomarker in acute ischemic stroke.
- Accurate time-to-treatment is crucial for effective reperfusion therapies.
Purpose of the Study:
- To compare MRI characteristics between WUS and clear-onset-time stroke (COS) patients.
- To evaluate the utility of DWI-FLAIR mismatch in estimating WUS onset time.
- To identify WUS patients potentially eligible for acute stroke treatments.
Main Methods:
- Retrospective analysis of 200 acute ischemic stroke patients undergoing MRI within six hours of symptom onset.
- Patients categorized into WUS (n=78) and COS (n=122) groups.
- Comparison of DWI-FLAIR mismatch prevalence between groups at various time intervals.
Main Results:
- No significant difference in DWI-FLAIR mismatch within 2 hours post-symptom onset between WUS and COS groups (50.0% vs 71.8%).
- DWI-FLAIR mismatch decreased significantly over time in WUS patients.
- Higher DWI-FLAIR mismatch persisted in COS patients within a 4-hour window.
Conclusions:
- DWI-FLAIR mismatch is not significantly different between WUS and COS within the initial 2 hours.
- WUS patients identified within 2 hours of the first detected abnormality may be candidates for intravenous thrombolysis.
- This finding supports the use of early DWI-FLAIR mismatch assessment for treatment decisions in WUS.
