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Updated: Jun 17, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Fluid-attenuated inversion recovery evolution within 12 hours from stroke onset: a reliable tissue clock?
Martin Ebinger1, Ivana Galinovic, Michal Rozanski
1Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany. martin.ebinger@charite.de
Background And Purpose:
It has recently been proposed that fluid-attenuated inversion recovery (FLAIR) imaging may serve as a surrogate marker for time of symptom onset after stroke. We assessed the hypothesis that FLAIR imaging could be used to decide if an MRI was performed within 4.5 hours from symptom onset or later.
Methods:
All consecutive patients with presumed stroke who underwent an MRI within 12 hours after known symptom onset were included regardless of stroke subtype and severity between May 2008 and May 2009. Blinded to time of symptom onset, 2 raters judged the visibility of lesions on FLAIR. Apparent diffusion coefficient values, lesion volume on diffusion-weighted imaging, and relative signal intensity of FLAIR lesions were determined.
Results:
In 94 consecutive patients with stroke, we found that median time from symptom onset for FLAIR-positive patients (189 minutes; interquartile range, 110 to 369 minutes) was significantly longer compared with FLAIR-negative patients (103 minutes; interquartile range, 75 to 183 minutes; P=0.011). Negative FLAIR had a sensitivity of 46% and a specificity of 79% for allocating patients to a time window of less than 4.5 hours. FLAIR positivity increased with diffusion-weighted imaging lesion volume (P<0.001) but showed no correlation with apparent diffusion coefficient values (P=0.795). There was no significant correlation between relative signal intensity and time from symptom onset (Spearman correlation coefficient -0.152, P=0.128).
Conclusions:
Based on our findings, we cannot recommend the use of FLAIR visibility as an estimate of time from symptom onset within the first 4.5 hours.
Insights
Fluid-attenuated inversion recovery (FLAIR) visibility on MRI is not a reliable marker for estimating stroke onset within 4.5 hours. FLAIR imaging showed low sensitivity and specificity for this crucial time window in stroke patients.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Fluid-attenuated inversion recovery (FLAIR) MRI is being explored as a potential surrogate marker for stroke symptom onset.
- Accurate time of stroke onset is critical for treatment decisions, particularly for thrombolysis within 4.5 hours.
Purpose of the Study:
- To evaluate the hypothesis that FLAIR MRI visibility can accurately determine if a stroke occurred within 4.5 hours of symptom onset.
- To assess the utility of FLAIR imaging in differentiating early ( < 4.5 hours) versus late ( > 4.5 hours) stroke onset.
Main Methods:
- A study included 94 consecutive stroke patients undergoing MRI within 12 hours of symptom onset.
- Two blinded raters assessed FLAIR lesion visibility. Apparent diffusion coefficient (ADC) values, diffusion-weighted imaging (DWI) lesion volume, and FLAIR lesion signal intensity were measured.
Main Results:
- FLAIR-positive patients had a significantly longer median time from symptom onset (189 minutes) compared to FLAIR-negative patients (103 minutes; P=0.011).
- FLAIR negativity showed 46% sensitivity and 79% specificity for identifying patients within the 4.5-hour window.
- FLAIR positivity correlated with DWI lesion volume but not with ADC values or relative signal intensity.
Conclusions:
- FLAIR lesion visibility is not a recommended method for estimating stroke onset within the critical 4.5-hour therapeutic window.
- The study findings do not support the use of FLAIR imaging as a reliable surrogate marker for early stroke detection.
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