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Diffusion-negative stroke: a report of two cases
P Y Wang1, P B Barker, R J Wityk
1Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Abstract:
Diffusion-weighted MR imaging is generally thought to be highly sensitive for the diagnosis of acute stroke. We report two cases of hyperacute stroke with absence of changes on diffusion-weighted images within 4 hours of symptom onset. Follow-up studies, performed 4 days later, showed infarction in regions compatible with the clinical presentation and (in one case) with the initial perfusion deficit. These cases indicate that normal findings on diffusion-weighted images in patients with suspected cerebral ischemia do not rule out impending infarction.
Insights
Diffusion-weighted imaging (DWI) is crucial for acute stroke diagnosis. However, these two hyperacute stroke cases show DWI may appear normal within 4 hours, highlighting the need for careful clinical correlation.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diffusion-weighted MR imaging (DWI) is a cornerstone for detecting acute ischemic stroke.
- Its high sensitivity is generally accepted for early stroke diagnosis.
Observation:
- Two cases of hyperacute stroke presented with normal DWI findings within 4 hours of symptom onset.
- Initial perfusion imaging in one case revealed deficits not yet visible on DWI.
Findings:
- Absence of signal changes on DWI does not exclude early-stage cerebral infarction.
- Follow-up MRI 4 days later confirmed infarction in both cases.
Implications:
- Clinicians should consider potential infarction even with normal DWI in hyperacute stroke scenarios.
- DWI findings should be interpreted alongside clinical presentation and perfusion data.
- This challenges the universal assumption of DWI's immediate sensitivity in all acute stroke presentations.