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Abstract
Acute ischemic stroke represents a major cause of long-term adult disability. Accurate prognostication of post-stroke functional outcomes is invaluable in guiding patient care, targeting early rehabilitation efforts, selecting patients for clinical research, and conveying realistic expectations to families. The involvement of specific brain regions by acute ischemia can alter post-stroke recovery potential. Understanding the influences of infarct topography on neurologic outcomes holds significant promise in prognosis of functional recovery. In this review, we discuss the recent evidence of the contribution of infarct location to patient management decisions and functional outcomes after acute ischemic stroke.
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Affiliation(s)
- Mark R Etherton
- 1 Harvard Medical School, Boston, MA, USA.,2 Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Natalia S Rost
- 1 Harvard Medical School, Boston, MA, USA.,2 Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Ona Wu
- 1 Harvard Medical School, Boston, MA, USA.,3 Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
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2
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Song S, Bokkers RPH, Luby M, Edwardson MA, Brown T, Shah S, Cox RW, Saad ZS, Reynolds RC, Glen DR, Cohen LG, Latour LL. Temporal similarity perfusion mapping: A standardized and model-free method for detecting perfusion deficits in stroke. PLoS One 2017; 12:e0185552. [PMID: 28973000 PMCID: PMC5626465 DOI: 10.1371/journal.pone.0185552] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 09/14/2017] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Interpretation of the extent of perfusion deficits in stroke MRI is highly dependent on the method used for analyzing the perfusion-weighted signal intensity time-series after gadolinium injection. In this study, we introduce a new model-free standardized method of temporal similarity perfusion (TSP) mapping for perfusion deficit detection and test its ability and reliability in acute ischemia. MATERIALS AND METHODS Forty patients with an ischemic stroke or transient ischemic attack were included. Two blinded readers compared real-time generated interactive maps and automatically generated TSP maps to traditional TTP/MTT maps for presence of perfusion deficits. Lesion volumes were compared for volumetric inter-rater reliability, spatial concordance between perfusion deficits and healthy tissue and contrast-to-noise ratio (CNR). RESULTS Perfusion deficits were correctly detected in all patients with acute ischemia. Inter-rater reliability was higher for TSP when compared to TTP/MTT maps and there was a high similarity between the lesion volumes depicted on TSP and TTP/MTT (r(18) = 0.73). The Pearson's correlation between lesions calculated on TSP and traditional maps was high (r(18) = 0.73, p<0.0003), however the effective CNR was greater for TSP compared to TTP (352.3 vs 283.5, t(19) = 2.6, p<0.03.) and MTT (228.3, t(19) = 2.8, p<0.03). DISCUSSION TSP maps provide a reliable and robust model-free method for accurate perfusion deficit detection and improve lesion delineation compared to traditional methods. This simple method is also computationally faster and more easily automated than model-based methods. This method can potentially improve the speed and accuracy in perfusion deficit detection for acute stroke treatment and clinical trial inclusion decision-making.
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Affiliation(s)
- Sunbin Song
- NIH/NINDS, Human Cortical Physiology and Neurorehabilitation Section, Bethesda, Maryland, United States of America
| | - Reinoud P. H. Bokkers
- Department of Radiology, Medical Imaging Center, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
| | - Marie Luby
- NIH/NINDS, Stroke Branch, Bethesda, Maryland, United States of America
| | | | - Tyler Brown
- NIH/NINDS, Stroke Branch, Bethesda, Maryland, United States of America
| | - Shreyansh Shah
- NIH/NINDS, Stroke Branch, Bethesda, Maryland, United States of America
| | - Robert W. Cox
- NIH/NIMH, Scientific and Statistical Computing Core, Bethesda, Maryland, United States of America
| | - Ziad S. Saad
- NIH/NIMH, Scientific and Statistical Computing Core, Bethesda, Maryland, United States of America
| | - Richard C. Reynolds
- NIH/NIMH, Scientific and Statistical Computing Core, Bethesda, Maryland, United States of America
| | - Daniel R. Glen
- NIH/NIMH, Scientific and Statistical Computing Core, Bethesda, Maryland, United States of America
| | - Leonardo G. Cohen
- NIH/NINDS, Human Cortical Physiology and Neurorehabilitation Section, Bethesda, Maryland, United States of America
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3
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Meijs M, Christensen S, Lansberg MG, Albers GW, Calamante F. Analysis of perfusion MRI in stroke: To deconvolve, or not to deconvolve. Magn Reson Med 2015; 76:1282-90. [PMID: 26519871 DOI: 10.1002/mrm.26024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 08/28/2015] [Accepted: 09/30/2015] [Indexed: 11/06/2022]
Abstract
PURPOSE There is currently controversy regarding the benefits of deconvolution-based parameters in stroke imaging, with studies suggesting a similar infarct prediction using summary parameters. We investigate here the performance of deconvolution-based parameters and summary parameters for dynamic-susceptibility contrast (DSC) MRI analysis, with particular emphasis on precision. METHODS Numerical simulations were used to assess the contribution of noise and arterial input function (AIF) variability to measurement precision. A realistic AIF range was defined based on in vivo data from an acute stroke clinical study. The simulated tissue curves were analyzed using two popular singular value decomposition (SVD) based algorithms, as well as using summary parameters. RESULTS SVD-based deconvolution methods were found to considerably reduce the AIF-dependency, but a residual AIF bias remained on the calculated parameters. Summary parameters, in turn, show a lower sensitivity to noise. The residual AIF-dependency for deconvolution methods and the large AIF-sensitivity of summary parameters was greatly reduced when normalizing them relative to normal tissue. CONCLUSION Consistent with recent studies suggesting high performance of summary parameters in infarct prediction, our results suggest that DSC-MRI analysis using properly normalized summary parameters may have advantages in terms of lower noise and AIF-sensitivity as compared to commonly used deconvolution methods. Magn Reson Med 76:1282-1290, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Midas Meijs
- Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Soren Christensen
- Stanford Stroke Center, Stanford University School of Medicine, Stanford, California, USA
| | - Maarten G Lansberg
- Stanford Stroke Center, Stanford University School of Medicine, Stanford, California, USA
| | - Gregory W Albers
- Stanford Stroke Center, Stanford University School of Medicine, Stanford, California, USA
| | - Fernando Calamante
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia. .,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia. .,Department of Medicine, Austin Health and Northern Health, University of Melbourne, Melbourne, Australia.
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Lv Y, Margulies DS, Cameron Craddock R, Long X, Winter B, Gierhake D, Endres M, Villringer K, Fiebach J, Villringer A. Identifying the perfusion deficit in acute stroke with resting-state functional magnetic resonance imaging. Ann Neurol 2013; 73:136-40. [PMID: 23378326 DOI: 10.1002/ana.23763] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 08/20/2012] [Accepted: 08/31/2012] [Indexed: 11/06/2022]
Abstract
Temporal delay in blood oxygenation level-dependent (BOLD) signals may be sensitive to perfusion deficits in acute stroke. Resting-state functional magnetic resonance imaging (rsfMRI) was added to a standard stroke MRI protocol. We calculated the time delay between the BOLD signal at each voxel and the whole-brain signal using time-lagged correlation and compared the results to mean transit time derived using bolus tracking. In all 11 patients, areas exhibiting significant delay in BOLD signal corresponded to areas of hypoperfusion identified by contrast-based perfusion MRI. Time delay analysis of rsfMRI provides information comparable to that of conventional perfusion MRI without the need for contrast agents.
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Affiliation(s)
- Yating Lv
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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5
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Liu JR, Jensen-Kondering UR, Zhou JJ, Sun F, Feng XY, Shen XL, Deuschl G, Jansen O, Herdegen T, Meyne J, Zhao Y, Eschenfelder C. Transient filament occlusion of the middle cerebral artery in rats: does the reperfusion method matter 24 hours after perfusion? BMC Neurosci 2012; 13:154. [PMID: 23272656 PMCID: PMC3546945 DOI: 10.1186/1471-2202-13-154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/19/2012] [Indexed: 11/20/2022] Open
Abstract
Background There are two widely used transient middle cerebral artery occlusion (MCAO) methods, which differ in the use of unilateral or bilateral carotid artery reperfusion (UNICAR and BICAR). Of the two methods, UNICAR is easier to perform. This study was designed to comprehensively compare the two reperfusion methods to determine if there are any differences in outcomes. Results The UNICAR and BICAR groups each included 9 rats. At baseline, the average pO2 was 20.54 ± 9.35 and 26.43 ± 7.39, for the UNICAR and BICAR groups, respectively (P = 0.519). Changes in pO2, as well as other physiological parameters measured within the ischemic lesion, were similar between the UNICAR and BICAR groups during 90 min of MCAO and the first 30 min of reperfusion (all P > 0.05). Furthermore, both the Bederson score and Garcia score, which are used for neurological assessment, were also similar (both P > 0.05). There were also no significant differences in T2WI lesion volume, DWI lesion volume, PWI lesion volume, or TTC staining infarct volume between the two groups (all P > 0.05). Conclusion UNICAR and BICAR have similar capability for inducing acute brain ischemic injury and can be considered interchangeable up to 24 hours after reperfusion.
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Affiliation(s)
- Jian-Ren Liu
- Department of Neurology, University of Schleswig-Holstein, Campus Kiel, Christian-Albrechts-University Kiel, Kiel, Germany.
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Warach S, Al-Rawi Y, Furlan AJ, Fiebach JB, Wintermark M, Lindstén A, Smyej J, Bharucha DB, Pedraza S, Rowley HA. Refinement of the Magnetic Resonance Diffusion-Perfusion Mismatch Concept for Thrombolytic Patient Selection. Stroke 2012; 43:2313-8. [DOI: 10.1161/strokeaha.111.642348] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
The DIAS-2 study was the only large, randomized, intravenous, thrombolytic trial that selected patients based on the presence of ischemic penumbra. However, DIAS-2 did not confirm the positive findings of the smaller DEDAS and DIAS trials, which also used penumbral selection. Therefore, a reevaluation of the penumbra selection strategy is warranted.
Methods—
In post hoc analyses we assessed the relationships of magnetic resonance imaging–measured lesion volumes with clinical measures in DIAS-2, and the relationships of the presence and size of the diffusion-perfusion mismatch with the clinical effect of desmoteplase in DIAS-2 and in pooled data from DIAS, DEDAS, and DIAS-2.
Results—
In DIAS-2, lesion volumes correlated with National Institutes of Health Stroke Scale (NIHSS) at both baseline and final time points (
P
<0.0001), and lesion growth was inversely related to good clinical outcome (
P
=0.004). In the pooled analysis, desmoteplase was associated with 47% clinical response rate (n=143) vs 34% in placebo (n=73;
P
=0.08). For both the pooled sample and for DIAS-2, increasing the minimum baseline mismatch volume (MMV) for inclusion increased the desmoteplase effect size. The odds ratio for good clinical response between desmoteplase and placebo treatment was 2.83 (95% confidence interval, 1.16–6.94;
P
=0.023) for MMV >60 mL. Increasing the minimum NIHSS score for inclusion did not affect treatment effect size.
Conclusions—
Pooled across all desmoteplase trials, desmoteplase appears beneficial in patients with large MMV and ineffective in patients with small MMV. These results support a modified diffusion-perfusion mismatch hypothesis for patient selection in later time-window thrombolytic trials.
Clinical Trial Registration—
URL:
http://www.clinicaltrials.gov
. Unique Identifiers: NCT00638781, NCT00638248, NCT00111852.
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Affiliation(s)
- Steven Warach
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Yasir Al-Rawi
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Anthony J. Furlan
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Jochen B. Fiebach
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Max Wintermark
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Annika Lindstén
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Jamal Smyej
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - David B. Bharucha
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Salvador Pedraza
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
| | - Howard A. Rowley
- From the Seton/University of Texas Southwestern Clinical Research Institute of Austin, TX (S.W.); Signen Biomedical Consulting FZE, United Arab Emirates (Y.A.); Department of Neurology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH (A.J.S.); Center for Stroke Research Berlin, Charité Universitätsmedizin, Berlin, Germany (J.B.F.); Department of Radiology, University of Virginia, Charlottesville, VA (M.W.); H. Lundbeck A/S, Valby, Denmark (A.L., J.S.); Forest
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Boutelier T, Kudo K, Pautot F, Sasaki M. Bayesian hemodynamic parameter estimation by bolus tracking perfusion weighted imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2012; 31:1381-1395. [PMID: 22410325 DOI: 10.1109/tmi.2012.2189890] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A delay-insensitive probabilistic method for estimating hemodynamic parameters, delays, theoretical residue functions, and concentration time curves by computed tomography (CT) and magnetic resonance (MR) perfusion weighted imaging is presented. Only a mild stationarity hypothesis is made beyond the standard perfusion model. New microvascular parameters with simple hemodynamic interpretation are naturally introduced. Simulations on standard digital phantoms show that the method outperforms the oscillating singular value decomposition (oSVD) method in terms of goodness-of-fit, linearity, statistical and systematic errors on all parameters, especially at low signal-to-noise ratios (SNRs). Delay is always estimated sharply with user-supplied resolution and is purely arterial, by contrast to oSVD time-to-maximum TMAX that is very noisy and biased by mean transit time (MTT), blood volume, and SNR. Residue functions and signals estimates do not suffer overfitting anymore. One CT acute stroke case confirms simulation results and highlights the ability of the method to reliably estimate MTT when SNR is low. Delays look promising for delineating the arterial occlusion territory and collateral circulation.
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Affiliation(s)
- Timothé Boutelier
- Department of Research and Innovation, Olea Medical, 13600 La Ciotat, France. timothe.
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Nagakane Y, Christensen S, Ogata T, Churilov L, Ma H, Parsons MW, Desmond PM, Levi CR, Butcher KS, Davis SM, Donnan GA. Moving beyond a single perfusion threshold to define penumbra: a novel probabilistic mismatch definition. Stroke 2012; 43:1548-55. [PMID: 22499579 DOI: 10.1161/strokeaha.111.643932] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The mismatch lesion volumes defined by perfusion-weighted imaging exceeding diffusion-weighted imaging have been used as a marker of ischemic penumbral tissue. Defining the perfusion lesion by thresholding has shown promise as a practical tool; several positron emission tomography studies have indicated a more probabilistic relationship between perfusion and infarction. Here, we used a randomized controlled trial dataset of tissue-type plasminogen activator 3 to 6 hours after stroke to: (1) quantify the relationship between severity of hypoperfusion (measured by Tmax) and risk of infarction; (2) exploit this relationship to present a novel definition of mismatch based on infarct probabilities rather than dichotomies; and (3) examine the treatment response in the subgroup of patients with mismatch by the new definition. METHODS Patients from the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) were included. Baseline perfusion-weighted imaging and 90-day T2-weighted imaging were coregistered. Perfusion-weighted imaging lesion volumes were divided into 10 Tmax delay strata, and infarct risk was defined as the fraction of the tissue at a given Tmax strata that progressed to infarction by day 90. RESULTS Sixty-two patients were studied. Infarct risk was an increasing function of Tmax for all subgroups, including the whole cohort. The probabilistic approach outperformed all Tmax thresholds, with exception of the Tmax ≥ 10 threshold, for which it was only favored by a trend. CONCLUSIONS Infarct risk and treatment effect increased with severity of perfusion abnormalities. This suggests that a severity-weighted mismatch definition may define penumbral tissue more accurately.
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Affiliation(s)
- Yoshinari Nagakane
- National Stroke Research Institute, Florey Neuroscience Institutes, Austin Health, University of Melbourne, Victoria 3053, Australia.
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9
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Heiss WD. The ischemic penumbra: correlates in imaging and implications for treatment of ischemic stroke. The Johann Jacob Wepfer award 2011. Cerebrovasc Dis 2011; 32:307-20. [PMID: 21921593 DOI: 10.1159/000330462] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The concept of the ischemic penumbra was formulated 30 years ago based on experiments in animal models showing functional impairment and electrophysiological disturbances with decreasing flow to the brain below defined values (the threshold for function) and irreversible tissue damage with the blood supply further decreased (the threshold for infarction). The perfusion range between these thresholds was termed 'penumbra', and restitution of flow above the functional threshold was able to reverse the deficits without permanent damage. However, in further experiments, the dependency of the development of irreversible lesions on the interaction of the severity and duration of critically reduced blood flow was established - proving that the lower the flow, the shorter the time for efficient reperfusion. Therefore, infarction develops from the core of ischemia to the areas of less severe hypoperfusion. The propagation of irreversible tissue damage is characterized by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusional disturbances. Waves of depolarizations, the peri-infarct spreading depression-like depolarizations, inducing activation of ion pumps and liberation of excitatory transmitters, have dramatic consequences as drastically increased metabolic demand cannot be satisfied in regions with critically reduced blood supply. The translation of experimental concept into the basis for efficient treatment of stroke requires non-invasive methods by which regional flow and energy metabolism can be repeatedly investigated to demonstrate penumbra tissue that can benefit from therapeutic interventions. Positron emission tomography (PET) allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction. From these variables, clear definitions of irreversible tissue damage and critically perfused but potentially salvageable tissue (i.e. the penumbra) can be achieved in animal models and stroke patients. Additionally, further tracers can be used for early detection of irreversible tissue damage, e.g. by the central benzodiazepine receptor ligand flumazenil. However, PET is a research tool and its complex logistics limit clinical routine applications. As a widely applicable clinical tool, perfusion/diffusion-weighted (PW/DW) MRI is used, and the 'mismatch' between the PW and the DW abnormalities serve as an indicator of the penumbra. However, comparative studies of PW/DW-MRI and PET have pointed to an overestimation of the core of irreversible infarction as well as of the penumbra by MRI modalities. Some of these discrepancies can be explained by unselective application of relative perfusion thresholds, which might be improved by more complex analytical procedures. Heterogeneity of the MRI signatures used for the definition of the mismatch are also responsible for disappointing results in the application of PW/DW-MRI for the selection of patients for clinical trials. As long as a validation of the mismatch selection paradigm is lacking, its use as a surrogate marker of outcome is limited.
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Carrera E, Jones PS, Alawneh JA, Klærke Mikkelsen I, Cho TH, Siemonsen S, Guadagno JV, Mouridsen K, Ribe L, Hjort N, Fryer TD, Carpenter TA, Aigbirhio FI, Fiehler J, Nighoghossian N, Warburton EA, Ostergaard L, Baron JC. Predicting Infarction Within the Diffusion-Weighted Imaging Lesion. Stroke 2011; 42:1602-7. [DOI: 10.1161/strokeaha.110.606970] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Emmanuel Carrera
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - P. Simon Jones
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Josef A. Alawneh
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Irene Klærke Mikkelsen
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Tae-Hee Cho
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Suzanne Siemonsen
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Joseph V. Guadagno
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Kim Mouridsen
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Lars Ribe
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Niels Hjort
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Tim D. Fryer
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - T. Adrian Carpenter
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Franklin I. Aigbirhio
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Jens Fiehler
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Norbert Nighoghossian
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Elizabeth A. Warburton
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Leif Ostergaard
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
| | - Jean-Claude Baron
- From the Department Clinical Neurosciences (E.C., P.S.J., J.A., J.V.G., E.A.W., J.C.B.), Cambridge University, Cambridge, UK; CFIN (I.K.-M., K.M., L.R., N.H., L.O.), Aarhus University, Aarhus, Denmark; Hopital Neurologique (T.H.C., N.N.), Creatis UMR 5515-Inserm U630, Lyon, France; the Neuroradiology Department (S.S., J.F.), University Medical Center, Hamburg, Germany; Wolfson Brain Imaging Centre (T.D.F., T.A.C., F.I.A.), Cambridge University, Cambridge, UK; and INSERM U894 (J.C.B.), Paris, France
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11
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Fiebach JB, Galinovic I. Uncertainties in the Assessment of Cortical Flow by Perfusion-Weighted Imaging in Acute Stroke: Finding the ‘True Negatives’ rather than Prognosticating the ‘True Positives’. Cerebrovasc Dis 2011. [DOI: 10.1159/000329311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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12
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Abstract
The 'penumbra' is a concept coined in animal experiments suggesting that functionally impaired tissue can survive and recover if sufficient reperfusion is re-established within a limited time period, which depends on the level of residual flow. In an ischaemic territory, irreversible damage progresses over time from the centre of the most severe flow reduction to the periphery with less disturbed perfusion. This centrifugal progression of irreversible tissue damage is characterised by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusion disturbances. Waves of depolarisations, the peri infarct spreading depressions, inducing activation of ion pumps and liberation of excitatory transmitters play an important role in the drastically increased metabolic demand during reduced oxygen supply causing hypoxic tissue changes and lactacidosis, which further damage the tissue. Positron emission tomography allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction, which can be used to identify regions with a critical reduction in these physiologic variables as indicators of penumbra and irreversible damage within ischaemic territories in animal models and patients with stroke. These positron emission tomography methods require arterial blood sampling and due to the complex logistics involved, are limited for routine application. Therefore, newer tracers were developed for the noninvasive detection of irreversible tissue damage (flumazenil) and of hypoxic tissue changes (fluoromisonidazole). As a widely applicable clinical tool, diffusion/perfusion-weighted magnetic resonance imaging is used; the 'mismatch' between perfusion and diffusion changes serves as a surrogate marker of the penumbra. However, in comparative studies of magnetic resonance imaging and positron emission tomography, diffusion-weighted imaging showed a high false-positive rate of irreversible damage, and the perfusion-weighted-diffusion-weighted mismatch overestimated the penumbra as defined by positron emission tomography. Advanced analytical procedures of magnetic resonance imaging data may improve the reliability of these surrogate markers but should be validated with quantitative procedures.
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13
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Zaro-Weber O, Moeller-Hartmann W, Heiss WD, Sobesky J. MRI perfusion maps in acute stroke validated with 15O-water positron emission tomography. Stroke 2010; 41:443-9. [PMID: 20075355 DOI: 10.1161/strokeaha.109.569889] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Perfusion-weighted imaging maps are used to identify hypoperfusion in acute ischemic stroke. We evaluated maps of cerebral blood flow (CBF), cerebral blood volume, mean transit time, and time to peak (TTP) in acute stroke by comparison with positron emission tomography. METHODS Perfusion-weighted imaging and positron emission tomography were performed in 26 patients with acute ischemic stroke (median 18.5 hours after stroke onset, 65 minutes between MRI and positron emission tomography). The perfusion-weighted imaging-derived maps of CBF, cerebral blood volume, mean transit time, and TTP delay were compared with quantitative positron emission tomography CBF. A receiver-operating characteristic curve analysis identified the best perfusion-weighted imaging map and threshold to identify hypoperfusion <20 mL/100 g/min, a widely used measure of penumbral flow. RESULTS Individual regression analysis of positron emission tomography CBF and perfusion-weighted imaging values were strong for CBF and TTP delay and weaker for mean transit time and cerebral blood volume, but the pooled analysis showed a large variance. Receiver-operating characteristic curve analysis identified TTP and CBF maps as most predictive (median area under the curve=0.94 and 0.93). Penumbral flow thresholds were <21.7 mL/100 g/min (CBF), <1.5 mL/100 g (cerebral blood volume), >5.3 seconds (mean transit time), and >4.2 seconds (TTP). TTP and CBF maps reached sensitivity/specificity values of 91%/82% and 89%/87%. CONCLUSIONS In our sample, maps of CBF, TTP, and mean transit time yielded a good estimate of penumbral flow. The performance of TTP maps was equivalent to deconvolution techniques using an arterial input function. For all maps, the application of a predefined threshold is mandatory and calibration studies will enhance their use in acute stroke therapy as well as in clinical stroke trials.
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Affiliation(s)
- Olivier Zaro-Weber
- Department of Neurology, University of Cologne, Max Planck Institute for Neurological Research, Gleueler Str 50, 50931 Cologne, Germany.
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14
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Christensen S, Mouridsen K, Wu O, Hjort N, Karstoft H, Thomalla G, Röther J, Fiehler J, Kucinski T, Østergaard L. Comparison of 10 perfusion MRI parameters in 97 sub-6-hour stroke patients using voxel-based receiver operating characteristics analysis. Stroke 2009; 40:2055-61. [PMID: 19359626 DOI: 10.1161/strokeaha.108.546069] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Perfusion-weighted imaging can predict infarct growth in acute stroke and potentially be used to select patients with tissue at risk for reperfusion therapies. However, the lack of consensus and evidence on how to best create PWI maps that reflect tissue at risk challenges comparisons of results and acute decision-making in trials. Deconvolution using an arterial input function has been hypothesized to generate maps of a more quantitative nature and with better prognostic value than simpler summary measures such as time-to-peak or the first moment of the concentration time curve. We sought to compare 10 different perfusion parameters by their ability to predict tissue infarction in acute ischemic stroke. METHODS In a retrospective analysis of 97 patients with acute stroke studied within 6 hours from symptom onset, we used receiver operating characteristics in a voxel-based analysis to compare 10 perfusion parameters: time-to-peak, first moment, cerebral blood volume and flow, and 6 variants of time to peak of the residue function and mean transit time maps. Subanalysis assessed the effect of reperfusion on outcome prediction. RESULTS The most predictive maps were the summary measures first moment and time-to-peak. First moment was significantly more predictive than time to peak of the residue function and local arterial input function-based methods (P<0.05), but not significantly better than conventional mean transit time maps. CONCLUSIONS Results indicated that if a single map type was to be used to predict infarction, first moment maps performed at least as well as deconvolved measures. Deconvolution decouples delay from tissue perfusion; we speculate this negatively impacts infarct prediction.
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Affiliation(s)
- Søren Christensen
- Center of Functionally Integrative Neuroscience, Department of Neuroradiology, Aarhus University Hospital, Building 30, Nørrebrogade 44, 8000 Aarhus C, Denmark.
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15
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Siemonsen S, Fitting T, Thomalla G, Horn P, Finsterbusch J, Summers P, Saager C, Kucinski T, Fiehler J. T2' imaging predicts infarct growth beyond the acute diffusion-weighted imaging lesion in acute stroke. Radiology 2008; 248:979-86. [PMID: 18647849 DOI: 10.1148/radiol.2483071602] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To show that measurement of the transverse relaxation time that characterizes signal loss caused by local susceptibilities (T2') is sensitive to an increased deoxyhemoglobin concentration in the brain, indicating tissue at risk for infarction. MATERIALS AND METHODS The study was approved by the local institutional review board; patients or their guardians provided informed consent. Magnetic resonance (MR) imaging was performed within 6 hours of symptom onset and again 1-11 days thereafter in 100 consecutive stroke patients, all of whom received intravenous thrombolytic therapy (mean age, 67 years). The MR imaging protocol included diffusion- and perfusion-weighted imaging for determination of apparent diffusion coefficient (ADC) and time to peak (TTP), along with quantitative T2 and T2* imaging. T2' maps were calculated and visually compared with ADC and TTP lesions by two independent observers. RESULTS A T2'>ADC mismatch was observed by reader 1 in 73 (73%) of 100 patients, and by reader 2 in 65 (65%) patients. Respective sensitivities of T2'>ADC and of TTP>ADC mismatches for later infarct growth were 0.87 and 0.98 for reader 1 and 0.78 and 0.98 for reader 2, with respective specificities of 0.42 and 0.04 for reader 1 and 0.46 and 0.04 for reader 2. The odds ratios for infarct growth in the presence of a T2'>ADC mismatch were 4.59 (reader 1 P = .002) and 3.10 (reader 2 P = .012), while the odds ratios for TTP>ADC mismatch were 2.22 (reader 1 P = .606) and 1.73 (reader 2 P > .999). CONCLUSION The presence of a T2'>ADC mismatch is a more specific predictor of infarct growth than is TTP>ADC mismatch and hence may be of clinical value in patient selection for acute stroke therapies in the future.
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Affiliation(s)
- Susanne Siemonsen
- Department of Neuroradiology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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16
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Lansberg MG, Thijs VN, Bammer R, Olivot JM, Marks MP, Wechsler LR, Kemp S, Albers GW. The MRA-DWI mismatch identifies patients with stroke who are likely to benefit from reperfusion. Stroke 2008; 39:2491-6. [PMID: 18635861 DOI: 10.1161/strokeaha.107.508572] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND PURPOSE The aim of this exploratory analysis was to evaluate if a combination of MR angiography (MRA) and diffusion-weighted imaging (DWI) selection criteria can be used to identify patients with acute stroke who are likely to benefit from early reperfusion. METHODS Data from DEFUSE, a study of 74 patients with stroke who received intravenous tissue plasminogen activator in the 3- to 6-hour time window and underwent MRIs before and approximately 4 hours after treatment were analyzed. The MRA-DWI mismatch model was defined as (1) a DWI lesion volume less than 25 mL in patients with a proximal vessel occlusion; or (2) a DWI lesion volume less than 15 mL in patients with proximal vessel stenosis or an abnormal finding of a distal vessel. Favorable clinical response was defined as an improvement on the National Institutes of Health Stroke Scale score of at least 8 points between baseline and 30 days or a National Institutes of Health Stroke Scale score </=1 at 30 days. RESULTS Twenty-seven of 62 patients (44%) had an MRA-DWI mismatch. There was a differential response to early reperfusion based on MRA-DWI mismatch status. Reperfusion was associated with an increased rate of a favorable clinical response in patients with an MRA-DWI mismatch (OR, 12.5; 95% CI, 1.8 to 83.9) and a lower rate in patients without mismatch (OR, 0.2; 95% CI, 0.0 to 0.8). CONCLUSIONS The MRA-DWI mismatch model appears to identify patients with stroke who are likely to benefit from reperfusion therapy administered in the 3- to 6-hour time window after symptom onset. The criteria established for the MRA-DWI mismatch model in this study require validation in an independent cohort.
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Affiliation(s)
- Maarten G Lansberg
- Stanford Stroke Center, 701 Welch Road, Suite B325, Palo Alto, CA 94304-9705, USA.
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17
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Wintermark M, Lau BC, Chien J, Arora S. The anterior cerebral artery is an appropriate arterial input function for perfusion-CT processing in patients with acute stroke. Neuroradiology 2007; 50:227-36. [DOI: 10.1007/s00234-007-0336-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 10/18/2007] [Indexed: 10/22/2022]
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Kane I, Carpenter T, Chappell F, Rivers C, Armitage P, Sandercock P, Wardlaw J. Comparison of 10 Different Magnetic Resonance Perfusion Imaging Processing Methods in Acute Ischemic Stroke. Stroke 2007; 38:3158-64. [DOI: 10.1161/strokeaha.107.483842] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Several methods are available to assess the magnetic resonance perfusion lesion in acute ischemic stroke. We tested 10 of these to compare perfusion lesion sizes and to assess the relation to clinical scores and final infarct extent.
Methods—
We recruited patients with acute ischemic stroke, performed diffusion- and perfusion-weighted imaging, and recorded stroke severity at baseline, final infarct size on T2-weighted imaging at ≥1 month, and Rankin Scale score at 3 months. We calculated 10 perfusion parameters (6 of mean transit time, MTT; 3 of cerebral blood flow; 1 of cerebral blood volume; 7 relative and 3 quantitative), measured the perfusion-weighted imaging lesion and diffusion/perfusion mismatch volumes, and compared each with clinical and radiologic outcomes.
Results—
Among 32 patients, the median perfusion lesion volume varied from 0 to 14 882 voxels (
P
<0.0001); the proportion of patients with mismatch varied from 9% to 72% (
P
<0.05), depending on the perfusion parameter. Five measures of relative MTT were associated with baseline National Institutes of Health Stroke Scale score; 1 (arrival time fitted) was also associated with clinical outcome. Final infarct size was most strongly associated with MTT measures, including arrival time fitted. There was no advantage of quantitative perfusion measures and no relation between mismatch presence/absence and infarct expansion with any of the 10 perfusion measures.
Conclusions—
Perfusion lesion size differs markedly depending on the parameter calculated. Relative perfusion parameters performed as well as quantitative ones. Some parameters (mainly representing MTT measures) were correlated with clinical scores; others were correlated with final infarct size; and arrival time fitted was correlated with both. These findings should be validated in other datasets. A consensus is required on which perfusion measurement and processing methods should be used.
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Affiliation(s)
- Ingrid Kane
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Trevor Carpenter
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Francesca Chappell
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Carly Rivers
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Paul Armitage
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Peter Sandercock
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
| | - Joanna Wardlaw
- From the Division of Clinical Neurosciences (I.K., T.C., F.C., P.A., P.S., J.W.), Western General Hospital, Edinburgh, Scotland, and the Clinical Trials Research Unit (C.R.), Leeds, England
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19
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Messé SR, Kasner SE, Chalela JA, Cucchiara B, Demchuk AM, Hill MD, Warach S. CT-NIHSS mismatch does not correlate with MRI diffusion-perfusion mismatch. Stroke 2007; 38:2079-84. [PMID: 17540971 DOI: 10.1161/strokeaha.106.480731] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE MRI diffusion-perfusion mismatch may identify patients for thrombolysis beyond 3 hours. However, MRI has limited availability in many hospitals. We investigated whether mismatch between the Alberta Stroke Program Early CT Score (ASPECTS) and the NIH Stroke Scale (NIHSS) correlates with MRI diffusion-perfusion mismatch. METHODS We retrospectively analyzed a cohort of consecutive acute ischemic stroke patients who underwent MRI and CT at admission. NIHSS was performed by the admitting physician. MRI and CT were reviewed by 2 blinded expert raters. Degree of MRI mismatch was defined as present (> 25%) or absent (<25%). Univariate and multivariate analyses were performed to determine characteristics associated with MRI mismatch. Probability of MRI mismatch was calculated for all combinations of ASPECTS and NIHSS cutoff scores. RESULTS Included in the analysis were 143 patients. Median NIHSS on admission was 4 (IQR, 2 to 10); median ASPECTS was 10 (IQR, 9 to 10). Median time to completion of MRI and CT was 4.5 (2.5 to 13.9) hours after onset. CT and MRI were separated by a median of 35 (IQR, 29 to 44) minutes. MRI mismatch was present in 41% of patients. In multivariate analysis, only shorter time-to-scan (OR, 0.96 per hour; 95% CI, 0.92 to 1.0; P=0.043) was associated with MRI mismatch. There was no combination of NIHSS and ASPECTS thresholds that was significantly associated with MRI mismatch. CONCLUSIONS ASPECTS-NIHSS mismatch did not correlate with MRI diffusion-perfusion mismatch in this clinical cohort. MRI mismatch was associated with decreasing time from stroke onset to scan.
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Affiliation(s)
- Steven R Messé
- Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA.
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20
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Abstract
Imaging continues to have a huge impact on the understanding of the ischemic penumbra and the management of acute stroke. Determinants of penumbral tissue fate, such as age, hyperglycemia, hematocrit, and oxygen concentration, are increasingly being recognized using neuroimaging. The significance of the penumbra in the white matter and in posterior circulation stroke is also becoming clearer. Neuroimaging is also making invaluable contributions to clinical decision making in acute stroke, especially in relation to reperfusion therapies in the 3- to 6-hour time window. Despite ongoing questions over the choice of parameters to identify the penumbra and their respective clinical usefulness, imaging is gaining widespread use in acute stroke management. However, definitive evidence of its benefit is still lacking. This review explores the recent progress and controversies relating to imaging of the penumbra.
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Abstract
PURPOSE OF REVIEW To review the techniques for imaging cerebral blood flow and metabolism following injury to the brain. RECENT FINDINGS Xenon enhanced computerized tomography (Xenon CT), CT perfusion and single photon emission CT provide measurements of cerebral perfusion, while positron emission tomography (PET), and magnetic resonance imaging and spectroscopy (MRI and MRS) are able to assess both perfusion and cerebral metabolism. Xenon CT and CT perfusion are readily available and have proved useful in a variety of causes of brain injury. PET is an extremely useful research tool for defining cerebral physiology, but is limited in its availability. Despite the continuing development of MRI and MRS imaging, the scanning environment remains hostile for critically ill patients, and further research is required before the techniques become generally available. SUMMARY Imaging of cerebral blood flow and metabolism has been shown to be useful following a variety of causes of brain injury, as it can help to define the cause and extent of injury, identify appropriate treatments and predict outcome. Imaging based on CT techniques (Xenon CT and CT perfusion) can be implemented easily in most hospital centres, and are able to provide quantitative perfusion data in addition to structural images.
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Affiliation(s)
- Jonathan P Coles
- University Department of Anaesthesia, Addenbrooke's Hospital, Cambridge, UK.
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22
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Abstract
Thrombolytic therapy has led to a higher proportion of patients presenting to hospital early, and this, with parallel developments in imaging technology, has greatly improved the understanding of acute stroke pathophysiology. Additionally, MRI, including diffusion-weighted imaging (DWI) and gradient echo, or T2*, imaging is important in understanding basic structural information--such as distinguishing acute ischaemia from haemorrhage. It has also greatly increased sensitivity in the diagnosis of acute cerebral ischaemia. The pathophysiology of the ischaemic penumbra can now be assessed with CT or MRI-based perfusion imaging techniques, which are widely available and clinically applicable. Pathophysiological information from CT or MRI increasingly helps clinical trial design, may allow targeted therapy in individual patients, and may extend the time scale for reperfusion therapy.
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Affiliation(s)
- Keith W Muir
- Division of Clinical Neurosciences, University of Glasgow, Institute of Neurological Sciences, Southern General Hospital, Glasgow
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