Early Changes of Tissue Perfusion after tPA in Hyperacute Ischemic Stroke

Background and Purpose—It is hypothesized that tPA rescues brain tissue by improving perfusion. In this study, we aimed to examine acute regional perfusion changes and how they influence infarction and clinical outcome. Methods—Three sequential MR scans were performed in 15 tPA-treated patients within 3.5 (tp1), at 6 hours (tp2), and at 1 month (tp3) after stroke onset. “Hypoperfusion ” was defined if MTT prolongation was> a threshold (four thresholds: 3, 4, 5, and 6 seconds). Four ROIs were classified: 1) “Reperfusion ” – hypoperfused at tp1, normal at tp2; (2) “Non-reperfusion ” – hypoperfused at tp1 and tp2; (3) “Normal perfusion ” – normal at tp1 and tp2; and (4) “New hypoperfusion ” – normal at tp1 and hypoperfused at tp2. Risk of infarction was calculated within each ROI. Associations between tissue perfusion changes and clinical variables were evaluated using step-wise multiple linear regressions. Moreover, the association between NIHSS changes and perfusion alterations was assessed using linear mixed effect models. Results—Regardless of the MTT threshold chosen, the risk of infarction in non-reperfused regions (40–68%, thresholds 3–6 seconds) was higher than reperfused regions (9–30%, P< 0.05)