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Stroke. 2016 Jan;47(1):99-105. doi: 10.1161/STROKEAHA.115.010656. Epub 2015 Nov 19.

Reperfusion Beyond 6 Hours Reduces Infarct Probability in Moderately Ischemic Brain Tissue.

Author information

1
From the Mallinckrodt Institute of Radiology (H.A., C.E., K.D.V., J.-M.L.) and Department of Neurology (A.L.F., Y.C., J.-M.L.), Washington University, School of Medicine; and Department of Biostatistics (H.Z.), Department of Neurology (W.J.P., W.L.), and Department of Radiology (W.L.), University of North Carolina at Chapel Hill.
2
From the Mallinckrodt Institute of Radiology (H.A., C.E., K.D.V., J.-M.L.) and Department of Neurology (A.L.F., Y.C., J.-M.L.), Washington University, School of Medicine; and Department of Biostatistics (H.Z.), Department of Neurology (W.J.P., W.L.), and Department of Radiology (W.L.), University of North Carolina at Chapel Hill. leejm@neuro.wustl.edu weili_lin@med.unc.edu.

Abstract

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.

KEYWORDS:

MR perfusion imaging; brain; ischemia; reperfusion; stroke; tissue outcome

PMID:
26585394
PMCID:
PMC4696879
DOI:
10.1161/STROKEAHA.115.010656
[Indexed for MEDLINE]
Free PMC Article

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