The Value of MRI in Transient Ischemic Attack/Minor Stroke Following a Negative CT for Predicting Subsequent Stroke
Matthieu Robitaille, Marcel Émond, Mukul Sharma, Ariane Mackey, Pierre-Gilles Blanchard, et al.
Canadian Journal of Emergency Medicine (CJEM), March 2025
Conclusion:
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MRI adds diagnostic and prognostic value beyond CT in TIA/minor stroke.
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The Canadian TIA Score helps prioritize MRI use:
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Medium-risk patients benefit most from MRI for further stratification.
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High-risk patients need urgent management regardless of MRI.
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Low-risk patients with positive MRI may need further evaluation despite overall low score.
Methods:
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Design: Pre-planned substudy of the Canadian TIA Score cohort
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Setting: 13 Canadian EDs over 11 years
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Population: 1,048 patients with TIA/minor stroke, normal CT, and MRI <7 days
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Stratification: By Canadian TIA Score (low, medium, high risk)
Key Findings:
Acute Infarction on MRI:
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Overall: 330/1048 (31.5%) had infarction
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By TIA Score:
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Low-risk: 130/844 (15.4%)
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Medium-risk: 754/2480 (30.4%)
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High-risk: 162/324 (50.0%)
90-Day Stroke Rates (Positive MRI):
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Low-risk: 10.0%
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Medium-risk: 22.3%
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High-risk: 24.7%
90-Day Stroke Rates (Negative MRI):
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Low-risk: 0.9%
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Medium-risk: 1.3%
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High-risk: 4.9%
Robitaille, M., Émond, M., Sharma, M., Mackey, A., Blanchard, P.G., Nemnom, M.J., Sivilotti, M.L., Stiell, I.G., Stotts, G., Lee, J. and Worster, A., 2025. The value of MRI in transient ischemic attack/minor stroke following a negative CT for predicting subsequent stroke. Canadian Journal of Emergency Medicine, pp.1-6.