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Published on: September 25, 2019
Relative FLAIR Signal Intensities over Time in Acute Ischemic Stroke: Comparison of Two Methods
Ann-Christin Ostwaldt1, Ivana Galinovic1, Benjamin Hotter1
1Center for Stroke Research Berlin (CSB), Charité Universitätsmedizin Berlin, Germany.
Background And Purpose:
Visibility of lesions on fluid attenuated inversion recovery (FLAIR) images appears indicative of the time window in acute ischemic stroke. We compared two published methods for calculation of relative FLAIR signal intensities (rSI) regarding their association with time from symptom onset in a longitudinal fashion.
Methods:
We prospectively included patients receiving serial MRI examinations between 4.5 and 35 hours from symptom onset. FLAIR rSI was determined using two methods: a whole regions-of-interest (ROI) method and a hotspot method, selecting only a single area of visually highest signal. Signal intensity (rSI) was calculated relative to the contralateral side for each time point.
Results:
We included 21 patients with 3-6 MRI examinations on the first 2 days after stroke onset. FLAIR rSI determined with both methods shows a linear association with time from onset, although the hotspot results showed higher variability. Both methods with their previously published thresholds are reliable for identifying patients outside the 4.5 hours time window.
Conclusion:
Both methods show a similar performance, and might be a suitable help for the visual assessment of FLAIR lesion visibility.
Insights
Fluid attenuated inversion recovery (FLAIR) lesion visibility on MRI helps determine the time window in acute ischemic stroke. Two methods for calculating FLAIR signal intensity reliably identify patients outside the 4.5-hour window.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Lesion visibility on FLAIR MRI is a key indicator for the time window in acute ischemic stroke.
- Assessing the time from symptom onset is critical for acute ischemic stroke treatment decisions.
Purpose of the Study:
- To compare two methods for calculating relative FLAIR signal intensities (rSI).
- To evaluate the association of these methods with time from symptom onset in acute ischemic stroke patients.
- To determine the reliability of these methods in identifying patients outside the 4.5-hour time window.
Main Methods:
- Prospective inclusion of patients with serial MRI examinations between 4.5 and 35 hours post-symptom onset.
- Calculation of FLAIR rSI using a whole regions-of-interest (ROI) method and a hotspot method.
- Signal intensity was normalized relative to the contralateral side for each time point.
Main Results:
- 21 patients with 3-6 MRI examinations within the first 2 days post-stroke were included.
- Both FLAIR rSI calculation methods demonstrated a linear association with time from symptom onset.
- The hotspot method exhibited higher variability compared to the whole ROI method.
- Both methods, using established thresholds, proved reliable for excluding patients beyond the 4.5-hour window.
Conclusions:
- Both compared methods for FLAIR rSI calculation exhibit similar performance in acute ischemic stroke.
- These methods can serve as valuable aids for the visual assessment of FLAIR lesion visibility.
- FLAIR lesion visibility is a reliable indicator for estimating time from symptom onset in acute ischemic stroke.
