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Clinically Relevant Reperfusion in Acute Ischemic Stroke: MTT Performs Better than Tmax and TTP

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Abstract

While several MRI parameters are used to assess tissue perfusion during hyperacute stroke, it is unclear which is optimal for measuring clinically relevant reperfusion. We directly compared mean transit time (MTT) prolongation (MTTp), time-to-peak (TTP), and time-to-maximum (Tmax) to determine which best predicted neurological improvement and tissue salvage following early reperfusion. Acute ischemic stroke patients underwent three MRIs: <4.5 h (tp1), at 6 h (tp2), and at 1 month after onset. Perfusion deficits at tp1 and tp2 were defined by MTTp, TTP, or Tmax beyond four commonly used thresholds. Percent reperfusion (%Reperf) was calculated for each parameter and threshold. Regression analysis was used to fit %Reperf for each parameter and threshold as a predictor of neurological improvement [defined as admission National Institutes of Health Stroke Scale (NIHSS)–1 month NIHSS (∆NIHSS)] after adjusting for baseline clinical variables. Volume of reperfusion, for each parameter and threshold, was correlated with tissue salvage, defined as tp1 perfusion deficit volume–final infarct volume. Fifty patients were scanned at 2.7 and 6.2 h after stroke onset. %Reperf predicted ∆NIHSS for all MTTp thresholds, for Tmax >6 s and >8 s, but for no TTP thresholds. Tissue salvage significantly correlated with reperfusion for all MTTp thresholds and with Tmax >6 s, while there was no correlation with any TTP threshold. Among all parameters, reperfusion defined by MTTp was most strongly associated with ∆NIHSS (MTTp >3 s, P = 0.0002) and tissue salvage (MTTp >3 s and 4 s, P < 0.0001). MTT-defined reperfusion was the best predictor of neurological improvement and tissue salvage in hyperacute ischemic stroke.

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Sources of Funding

This study was supported by grants from National Institutes of Health NIH 5P50NS055977 (to JML) and K23 NS069807 (to AF) and from Washington University Institute of Clinical and Translational Sciences grant UL1 TR000448 from the National Center for Advancing Translational Sciences of the National Institutes of Health.

Compliance with Ethics Requirements

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008. Informed consent was obtained from all patients for being included in the study.

Conflict of Interest

None of the authors have any financial relationships with the National Institutes of Health who funded this research and all the authors declare that they have no conflicts of interest.

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Authors and Affiliations

  1. Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA

    Andria L. Ford & Jin-Moo Lee

  2. Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

    Hongyu An & Weili Lin

  3. Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada

    Linglong Kong

  4. Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

    Hongtu Zhu

  5. Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA

    Katie D. Vo & Jin-Moo Lee

  6. Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

    William J. Powers

Authors
  1. Andria L. Ford
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  2. Hongyu An
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  3. Linglong Kong
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  4. Hongtu Zhu
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  5. Katie D. Vo
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  6. William J. Powers
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  7. Weili Lin
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  8. Jin-Moo Lee
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Corresponding authors

Correspondence to Weili Lin or Jin-Moo Lee.

Additional information

Andria L. Ford and Hongyu An contributed equally to the manuscript

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Ford, A.L., An, H., Kong, L. et al. Clinically Relevant Reperfusion in Acute Ischemic Stroke: MTT Performs Better than Tmax and TTP. Transl. Stroke Res. 5, 415–421 (2014). https://doi.org/10.1007/s12975-014-0325-2

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  • DOI: https://doi.org/10.1007/s12975-014-0325-2

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