Acute stroke assessment with CT: do we need multimodal evaluation?

PURPOSE: To assess detection of stroke and prediction of extent of infarction with multimodal computed tomographic (CT) evaluation (unenhanced CT, perfusion CT, and CT angiography) in patients suspected of having acute stroke. MATERIALS AND METHODS: Forty-four consecutive patients with a mean National Institutes of Health Stroke Scale score of 10.45 and suspected of having ischemic stroke of the anterior circulation were examined with multi-detector row CT within 8 hours (mean, 3.05 hours) of onset of symptoms. All evaluations were performed with the knowledge that acute stroke was suspected but without detailed clinical information. The extent of ischemia or final infarction on the baseline unenhanced CT scan and follow-up images was assessed with the Alberta Stroke Program Early CT score. Different perfusion maps and follow-up images were assessed to determine the percentage of the ischemia-affected hemisphere. Each component, as well as the multimodal CT evaluation, was compared with follow-up unenhanced CT scans or magnetic resonance images after a mean time of 2.32 days. RESULTS: Multimodal CT revealed true-positive findings in 30 of 41 patients and true-negative findings in three, resulting in a sensitivity of 78.9%. Unenhanced CT, CT angiography, and perfusion CT showed sensitivities of 55.3%, 57.9%, and 76.3%, respectively. In eight patients, small infarctions (mean size, 1.47 cm) that were proved at follow-up were missed with all modalities at initial multimodal CT. With perfusion CT, four of these small infarctions were missed within the white matter of the section levels. Maps of cerebral blood flow showed the best correlation with the final size of infarction with an r(2) value of 0.71. CONCLUSION: The presented multimodal CT evaluation improves detection rate and prediction of the final size of infarction in comparison with unenhanced CT, CT angiography, and perfusion CT alone.

MOSAIC: Multimodal Stroke Assessment Using Computed Tomography: novel diagnostic approach for the prediction of infarction size and clinical outcome.

BACKGROUND AND PURPOSE: With new CT technologies, including CT angiography (CTA), perfusion CT (PCT), and multidetector row technique, this method has regained interest for use in acute stroke assessment. We have developed a score system based on Multimodal Stroke Assessment Using CT (MOSAIC), which was evaluated in this prospective study. METHODS: Forty-four acute stroke patients (mean age, 63.8 years) were enrolled within a mean of 3.0+/-1.9 hours after symptom onset. The MOSAIC score (0 to 8 points) was generated by results of the 3 sequential CT investigations: (1) presence and amount of early signs of infarction on noncontrast CT (NCCT; 0 to 2 points), (2) stenosis (>50%) or occlusion of the distal internal carotid or middle cerebral artery on CTA (0 to 2 points), and (3) presence and amount of reduced cerebral blood flow on 2 adjacent PCT slices (0 to 4 points). The predictive value of the MOSAIC score was compared with each single CT component with respect to the final size of infarction and the clinical outcome 3 months after stroke by use of the modified Rankin Scale (mRS) and the Barthel Index (BI). RESULTS: Among the CT components, PCT showed the best correlation to infarction size (r=0.75) and clinical outcome (r=0.60 to 0.62) compared with NCCT (r=0.43 to 0.58) and CTA (r=0.47 to 0.71). The MOSAIC score showed consistently higher correlation factors (r=0.67 to 0.78) and higher predictive values (0.73 to 1.0) than all single CT components with respect to outcome measures. A MOSAIC score <4 predicted independence with 89% to 96% likelihood (mRS /=90); a MOSAIC score <5 predicted fair outcome with 96% to 100% likelihood (mRS /=60). CONCLUSIONS: The MOSAIC score based on multidetector row CT technology is superior to NCCT, CTA, and PCT in predicting infarction size and clinical outcome in hyperacute stroke.