Usefulness of triphasic perfusion computed tomography for intravenous thrombolysis with tissue-type plasminogen activator in acute ischemic stroke

Background: Intravenous thrombolysis for acute ischemic stroke has been investigated in several clinical trials without enough information on collateral blood flow and perfusion deficit in the ischemic areas. The therapeutic time window varies from patient to patient depending on these factors. Triphasic perfusion computed tomography (TPCT) can provide this information as reliably as conventional angiography. Objective: To assess the safety and efficacy of thrombolysis within 3 or 7 hours of stroke onset according to the extent of perfusion deficit on TPCT. Methods: In 46 patients with acute middle cerebral artery (MCA) territory stroke, TPCT was performed with power injector-controlled, intravenous administration of contrast media after taking precontrast CT scans; Sequential scans of early, middle, and late phases were performed. The entire procedure took 5 minutes. Depending on collateral blood flow, the perfusion deficit on TPCT was graded as "severe perfusion deficit" or "moderate perfusion deficit." Twenty-nine patients were excluded based on clinical, laboratory, and TPCT findings. Seventeen patients were treated with an intravenous recombinant tissue-type plasminogen activator, 0.9 mg/kg. The 17 treated patients were divided into 2 groups: group 1 with small severe perfusion deficit (less than or equal to 33% of the presumed MCA territory) and group 2 with medium-sized severe perfusion deficit (>33% but less than or equal to 50% of the presumed MCA territory). The 13 patients in group 1 were treated within 7 hours of onset and the 4 patients in group 2 were treated within 3 hours. Results: Initial mean National Institutes of Health Stroke Scale score was 12.1 (range, 6.0-20.0) in group 1 and 19.0 (range, 18.0-21.0) in group 2. The initial score correlated better with the total extent of model-ate perfusion deficit and severe perfusion deficit than that of severe perfusion deficit alone. Mean time lapse to thrombolysis was 4.2 hours (range, 1.5-7.0 hours) in group I and 2.2 hours (range, 1.9-2.5 hours) in group 2. Fight patients (47%), 7 from group 1 and 1 from group 2, improved by dr points or more from baseline Stroke Scale score within 24 hours of thrombolysis. Patients with moderate perfusion deficit of 50% or more of MCA territory (n=4) had a better chance of early improvement than did those (n=13) with moderate perfusion deficit of less than 50% (4 of 4 vs 4 of 13). No fatal hemorrhage occurred. Only 1 patient (6%) had symptomatic small basal ganglia hemorrhage after thrombolysis. Conclusions: Thrombolysis can be safely performed within 3 or 7 hours of stroke onset according to the extent of severe perfusion deficit on TPCT. A larger extent of moderate perfusion deficit on TPCT may predict early improvement after thrombolysis.