Abstract
Even though history taking and neurological exam are paramount to diagnose stroke, the crucial differentiation between hemorrhagic and ischemic syndromes relies entirely on diagnostic neuroimaging, such as computed tomography (CT) and magnetic resonance imaging (MRI). The principal advantage of CT over MRI is its availability and speed. However, MRI provides better diagnostic data. For instance, MRI permits earlier detection of ischemic changes and better lesion conspicuity. The extension of irreversible damage and tissue at risk of infarction can be delineated with the combination of the diffusion and perfusion-weighted MRI sequences. MRI of patients with acute ischemic stroke often shows a discrepancy between the size and localization of the perfusion and diffusion abnormalities. A perfusion-diffusion mismatch refers to instances in which the diffusion lesion is smaller than the related perfusion defect. This discrepancy signals the presence of hypoperfused tissue at risk for infarction, and is deemed to be useful for guiding therapy. The purpose of this article is to discuss the utility and diagnostic merits of CT and MRI during acute stroke, providing examples in which neuroimages helped clarifying the clinical problem and guided management (Acta Neurol Colomb 2006;22:31-41).
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