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We investigated whether a nonspatial working memory (WM) task would activate dorsolateral prefrontal cortex (DLPFC) and whether activation would be correlated with WM load. Using functional magnetic resonance imaging we measured regional brain signal changes in 12 normal subjects performing a continuous performance, choice reaction time task that requires(More)
Diffusion-weighted MRI can rapidly detect acute cerebral ischemic injury as hyperintense signal changes, reflecting a decline in the apparent diffusion coefficient (ADC) of water through brain parenchyma, whereas ADC is elevated in the chronic stage because of increased extracellular water content. To determine the time course of these ADC changes, we(More)
BACKGROUND Identifying tissue at risk for infarction is important in deciding which patients would benefit most from potentially harmful therapies and provides a way to evaluate newer therapies with regard to the amount of ischemic tissue salvaged. OBJECTIVE To operationally define and characterize cerebral tissue at risk for stroke progression. METHODS(More)
We aimed to determine the frequency and time course of the enlargement of ischemic cerebral lesions following human stroke and to study the effect of the state of perfusion on lesion enlargement. Acute lesion volumes were measured on diffusion-weighted magnetic resonance images and compared with lesion volumes measured on T2-weighted images at 7 days or(More)
Diffusion-weighted magnetic resonance imaging detects ischemic injury within minutes after onset, and has been used to demonstrate drug efficacy in animal models of stroke. In 50 patients diagnosed with acute ischemic stroke (<24-hour duration) within the middle cerebral artery territory, lesion volume was measured by diffusion-weighted imaging. Thirty-four(More)
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