Purpose: To evaluate the feasibility and prognostic accuracy of penumbra assessment by perfusion-CT before intravenous thrombolytic treatment within 3 hours of stroke onset.
Methods and Materials: Viable ischemic tissue and infarct were assessed on admission by perfusion-CT, with measurement of the penumbra volume/penumbra+infarct volume ratio (Lausanne Stroke Index LSI). Perfusion-CT was followed by CT-angiography (CTA) to assess vessel patency, both examinations being performed before intravenous thrombolytic treatment with rtPA. Diffusion-weighted imaging (DWI) and MR-angiography (MRA) were obtained within 6 hours and 4 days later.
Results: Thrombolytic treatment was initiated within 148+-30 minutes in 35 patients, while perfusion-CT and CTA were performed within 114+-45 minutes of stroke onset. Penumbra was found in 31 (89%) patients (mean LSI = 66%+-23%) and internal carotid artery/middle cerebral artery occlusion in 27 (77%). Fourteen patients (40%) had a favorable outcome (3-month NIHSS <=1), with arterial reopening on MRA in over half the patients (57%; positive predictor of outcome, multivariate analysis: p=0.001). A strong correlation was found between admission penumbra (mean LSI, 73%+-18%) and 24-hour NIHSS improvement (70.5%+-16.5%; p<0.001), with equivalent perfusion-CT-predicted infarct and final DWI infarct.
Conclusion: Viable tissue versus predicted infarct can be measured by perfusion-CT within 3 hours of stroke onset and before intravenous thrombolysis, allowing early prediction of clinical improvement and infarct size associated with arterial reopening. (Philips Medical Systems collaborated in the development of the perfusion-CT software in which data of the study was processed.)
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