Reperfusion Beyond 6 Hours Reduces Infarct Probability in Moderately Ischemic Brain Tissue.
BACKGROUND AND PURPOSE
We aimed to examine perfusion changes between 3 and 6 and 6 and 24 hours after stroke onset and their impact on tissue outcome.


METHODS
Acute ischemic stroke patients underwent perfusion magnetic resonance imaging at 3, 6, and 24 hours after stroke onset and follow-up fluid-attenuated inversion recovery at 1 month to assess tissue fate. Mean transit time prolongation maps (MTTp=MTT-[median MTT of contralateral hemisphere]) were obtained at 3 (MTTp3 h), 6 (MTTp6 h), and 24 hours (MTTp24 h). Perfusion changes between 3 and 6 hours (ΔMTTp3_6) and 6 and 24 hours (ΔMTTp6_24) were calculated. A 2-step analysis was performed to evaluate the impact of ΔMTTp3_6 and ΔMTTp6_24 on tissue fate. First, a voxel-based multivariable logistic regression was performed for each individual patient with MTTp3 h, ΔMTTp3_6, and ΔMTT6_24 as independent variables and tissue fate as outcome. Second, Wilcoxon signed-rank tests on logistic regression coefficients were performed across patients to evaluate whether ΔMTTp3_6 and ΔMTT6_24 had significant impact on tissue fate for varying severities of baseline perfusion.


RESULTS
Perfusion change was common during both time periods: 85% and 81% of patients had perfusion improvement during 3- to 6- and 6- and 24-hour time intervals, respectively. ΔMTT3_6 significantly influenced 1-month infarct probability across a wide range of baseline perfusion (MTTp 0-15 s). ΔMTT6_24 also impacted 1-month infarct probability, but its influence was restricted to tissue with milder baseline ischemia (MTTp 0-10 s).


CONCLUSIONS
Brain tissue with mild to moderate ischemia can be salvaged by reperfusion even after 6 hours. Such tissue could be targeted for intervention beyond current treatment windows.
['An|Hongyu|H|', 'Ford|Andria L|AL|', 'Eldeniz|Cihat|C|', 'Chen|Yasheng|Y|', 'Vo|Katie D|KD|', 'Zhu|Hongtu|H|', 'Powers|William J|WJ|', 'Lin|Weili|W|', 'Lee|Jin-Moo|JM|']
D000368:Aged D002545:Brain Ischemia D002544:Cerebral Infarction D006801:Humans D018810:Magnetic Resonance Angiography D008875:Middle Aged D011446:Prospective Studies D015424:Reperfusion D020521:Stroke D013997:Time Factors
reperfusion brain stroke tissue outcome ischemia MR perfusion imaging