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Updated: Dec 11, 2025
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Routine use of FLAIR-negative MRI in the treatment of unknown onset stroke
Malik M Adil1, Marie Luby2, John K Lynch2
1National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, B1D733 MSC 1063, 10 Center Drive, Bethesda, United States; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, United States.
Background:
Treatment of FLAIR-negative stroke in patients presenting in an unknown time window has been shown to be safe and effective. However, implementation can be challenging due to the need for hyper-acute MRI screening. The purpose of this study was to review the routine application of this practice outside of a clinical trial.
Methods:
Patients presenting from 3/1/16 to 8/22/18 in a time window <4.5 h from symptom discovery but >4.5 h from last known normal were included if they had a hyper-acute MRI performed. Quantitative assessment based on the MR WITNESS trial and qualitative assessment based on the WAKE-UP trial were used to grade the FLAIR images. The MR WITNESS trial used a quantitative assessment of FLAIR change where the fractional increase in signal change had to be <1.15, whereas the WAKE-UP trial used a visual assessment requiring the absence of marked FLAIR signal changes.
Results:
During the study period, 136 stroke patients presented and were imaged in the specified time window. Of these, 17 (12.5%) received IV tPA. Three patients had hemorrhage on 24-h MRI follow up; none had an increase in NIHSS ≥4. Of the 119 patients who were screened but not treated, 18 (15%) were eligible based on FLAIR quantitative assessment and 55 (46%) were eligible based on qualitative assessment. In all cases where patients were not treated, there was an identifiable exclusion based on trial criteria. During the study period, IV tPA utilization was increased by 5.6% due to screening and treating patients with unknown onset stroke.
Conclusions:
Screening stroke patients in an unknown time window with MRI is practical in a real-world setting and increases IV tPA utilization.
Insights
Hyper-acute MRI screening for stroke patients with unknown onset is safe and practical. This real-world approach successfully increased the utilization of intravenous thrombolysis (IV tPA) in eligible patients.
Area of Science:
- Neurology
- Emergency Medicine
- Radiology
Background:
- Stroke treatment in unknown time windows is safe but requires hyper-acute MRI.
- Clinical trial implementation of MRI screening presents challenges.
- This study evaluated the real-world application of MRI screening for unknown time window strokes.
Purpose of the Study:
- To review the routine application of hyper-acute MRI screening for stroke patients presenting in an unknown time window.
- To assess the practicality and effectiveness of this practice outside of a clinical trial setting.
Main Methods:
- Retrospective review of stroke patients presenting between March 2016 and August 2018.
- Inclusion criteria: presentation within 4.5 hours of symptom discovery but >4.5 hours from last known normal, with hyper-acute MRI.
- FLAIR image assessment using quantitative (MR WITNESS) and qualitative (WAKE-UP) criteria.
Main Results:
- 136 patients were included; 17 (12.5%) received IV tPA.
- 119 patients were screened but not treated; eligibility varied by assessment method (15% quantitative, 46% qualitative).
- IV tPA utilization increased by 5.6% due to screening and treating unknown onset stroke patients.
Conclusions:
- Real-world MRI screening of stroke patients with unknown time windows is practical.
- This screening strategy effectively increases IV tPA utilization in eligible stroke patients.
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