Differential Prognosis of Isolated Cortical Swelling and Hypoattenuation on CT in Acute Stroke

Abstract

Background and Purpose-The Alberta Stroke Program Early CT Score (ASPECTS) is a validated method of assessing parenchymal ischemic changes, including focal swelling and hypoattenuation. The hypothesis that these signs result from different pathophysiological processes was tested by comparing CT with diffusion and perfusionweighted MRI. Methods-MRI and CT were performed, within 2 hours of each other, in 30 ischemic stroke patients Ͻ17 hours after symptom onset. Relative apparent diffusion coefficient, relative cerebral blood flow, and relative cerebral blood volume were calculated for individual cortical ASPECTS regions. Regional infarction was assessed on days 3 to 5. Results-Isolated focal swelling was seen in 25 ASPECTS cortical regions from 6 patients.

Accuracy of the Alberta Stroke Program Early CT Score during the First 3 Hours of Middle Cerebral Artery Stroke: Comparison of Noncontrast CT, CT Angiography Source Images, and CT Perfusion

“…Thus, we believe our initial assumption to consider only a region with low CBV was valid. Similarly, a recommendation 14,15 was recently put forth to consider only a region of hypoattenuation (infarct core) and not focal cortical swelling (likely penumbra) in the scoring of ASPECTS on noncontrast CT (a recommendation that was adopted in this study).…”

“…For the whole-brain CTA source images and noncontrast CT datasets, the raters evaluated each ASPECTS region for parenchymal hypoattenuation, 14,15 compared with the mirror region in the contralateral hemisphere. Adjustments in optimal window width and center level settings 16 were used to maximize detection of subtle differences between normal and abnormal brain during the hyperacute stroke period.…”

Diffusion-Weighted Magnetic Resonance Imaging May Underestimate Acute Ischemic Lesions

“…17 In the present study, early ischemic changes on CT included both parenchymal hypoattenuation and cortical swelling. 18 Acute DWI changes were defined as relative hyperintensity, including slight or small hyperintense lesions.…”

Advanced neuroimaging in acute ischemic stroke: extending the time window for treatment

“…44 Both PET and MR imaging studies suggest that areas of hypoattenuation on CT scans represent decreased CBV that could be a indicator of the infarct core, whereas areas of sulcal effacement have been shown to represent areas of increased CBV that may correlate with the penumbra that could be saved with thrombolytic therapy. 8,17,44 Computed tomography perfusion scanning is more sensitive than noncontrast CT in identifying ischemic stroke in patients presenting less than 12 hours after ischemic stroke symptom onset and in detecting the extension of the infarction. 54 A large rapid bolus of iodine-based contrast material is injected during continuous rapid scanning of one or multiple slices at fixed time interval and the wash-in and wash-out of the bolus can be analyzed by a computer.…”