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Updated: Jun 13, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Diffusion-weighted MRI in acute stroke within the first 6 hours: 1.5 or 3.0 Tesla?
1AP-HP, Urgences Cérébro-Vasculaires, Université Pierre et Marie Curie, Paris VI, Hôpital Pitié-Salpêtrière, Paris, France. charlotte.rosso@gmail.com
Objectives:
To compare the sensitivity and specificity of 1.5-T and 3.0-T diffusion-weighted MRI (DWI) to detect hyperacute ischemic stroke lesions.
Methods:
We blindly reviewed the DWI of 135 acute stroke patients and 34 controls performed at 1.5 T (n = 108) or 3.0 T (n = 61). The stroke patients all had subsequently proved carotid territory ischemic stroke and were imaged within the first 6 hours after stroke onset. Four readers (2 neuroradiologists and 2 stroke neurologists) blinded to clinical data and magnetic field strength recorded the presence of ischemic lesions on DWI and apparent diffusion coefficient (ADC) maps if necessary. Sensitivity, specificity, and false-negative rates were computed. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and DWI contrasts were calculated at both field strengths.
Results:
The accuracy of DWI in stroke diagnosis was superior at 1.5 T (98.8%) than at 3.0 T (90.9%, p = 0.03). The sensitivity decreased from 99.1% at 1.5 T to 92.5% at 3.0 T (p = 0.06) and the specificity from 97.8% to 84.1% (p = 0.002). ADC map readings did not improve accuracy, sensitivity, or specificity. The false-negative rate was 0.6% at 1.5 T and 6.1% at 3.0 T. Type of readers, stroke severity, and type of the coil did not affect diagnosis value. SNR and CNR were significantly higher at 3 T (p < 0.0001) but DWI contrast was lower (p = 0.04).
Conclusions:
Blind reading by 4 experts of a large series of images shows that 1.5-T diffusion-weighted MRI (DWI) is better than 3.0-T DWI for the imaging of hyperacute stroke during the therapeutic window of thrombolysis.
Insights
1.5-T diffusion-weighted MRI (DWI) demonstrates superior accuracy and sensitivity for detecting hyperacute ischemic stroke lesions compared to 3.0-T DWI. This finding is crucial for timely diagnosis and treatment within the thrombolysis window.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Diffusion-weighted MRI (DWI) is essential for diagnosing acute ischemic stroke.
- Magnetic field strength (1.5 T vs. 3.0 T) may influence DWI performance.
- Optimizing imaging for hyperacute stroke detection is critical for therapeutic interventions.
Purpose of the Study:
- To compare the diagnostic accuracy, sensitivity, and specificity of 1.5-T and 3.0-T DWI for detecting hyperacute ischemic stroke.
- To evaluate the impact of magnetic field strength on DWI performance in the early hours of stroke onset.
Main Methods:
- Retrospective analysis of DWI scans from 135 acute ischemic stroke patients and 34 controls.
- Scans were performed at 1.5 T (n=108) or 3.0 T (n=61) within 6 hours of stroke onset.
- Four blinded readers assessed lesion detection; quantitative metrics like SNR and CNR were calculated.
Main Results:
- 1.5-T DWI showed higher diagnostic accuracy (98.8%) than 3.0-T DWI (90.9%, p=0.03).
- Sensitivity was higher for 1.5-T (99.1%) vs. 3.0-T (92.5%), and specificity was significantly higher for 1.5-T (97.8%) vs. 3.0-T (84.1%, p=0.002).
- False-negative rates were lower for 1.5-T (0.6%) compared to 3.0-T (6.1%).
Conclusions:
- 1.5-T DWI is more effective than 3.0-T DWI for imaging hyperacute ischemic stroke within the thrombolysis window.
- Despite higher SNR/CNR at 3.0 T, lower DWI contrast impacts diagnostic performance.
- Expert readers confirmed the superiority of 1.5-T DWI in this critical diagnostic scenario.
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