Can the Ischemic Penumbra Be Identified on Noncontrast CT of Acute Stroke?

Background and Purpose— Early ischemic changes on noncontrast CT in acute stroke include both hypoattenuation and brain swelling, which may have different pathophysiological significance. Methods— Noncontrast CT and CT perfusion brain scans from patients with suspected acute stroke <6 hours after onset were reviewed. Five raters independently scored noncontrast CTs blind to clinical data using the Alberta Stroke Program Early CT Score (ASPECTS). Each ASPECTS region was scored as hypodense or swollen. A separate reviewer measured time to peak and cerebral blood volume in each ASPECTS region on CT perfusion. Time to peak and cerebral blood volume were compared for each region categorized as normal, hypodense, or isodense and swollen. Results— Scans of 32 subjects a median 155 minutes after onset yielded 228 regions with both CT perfusion and noncontrast CT data. Isodense swelling was associated with significantly higher cerebral blood volume (P=0.016) and with penumbral perfusion (posttest:pretest likelihood ratio 1.44 [95% CI: 0.68 to 2.90]), whereas hypodensity was associated with more severe time to peak delay and with core perfusion (likelihood ratio 3.47 [95% CI: 1.87 to 6.34]). Neither isodense swelling nor hypodensity was sensitive for prediction of perfusion pattern, but appearances were highly specific (87.2% and 91.0% for penumbra and core, respectively). Intrarater agreement was good or excellent, but interrater agreement for both hypodensity and swelling was poor. Conclusions— Regions exhibiting hypoattenuation are likely to represent the infarct core, whereas regions that are isodense and swollen have increased cerebral blood volume and are more likely to signify penumbral perfusion. Although noncontrast CT is not sensitive for detection of core and penumbra, appearances are specific. Some information on tissue viability can therefore be obtained from noncontrast CT.

[1]  J. Sobesky,et al.  Early x-ray hypoattenuation of brain parenchyma indicates extended critical hypoperfusion in acute stroke. , 2000, Stroke.

[2]  S. Warach,et al.  The Desmoteplase in Acute Ischemic Stroke Trial (DIAS): A Phase II MRI-Based 9-Hour Window Acute Stroke Thrombolysis Trial With Intravenous Desmoteplase , 2005, Stroke.

[3]  R. von Kummer.  Early major ischemic changes on computed tomography should preclude use of tissue plasminogen activator. , 2003, Stroke.

[4]  V. Glauche,et al.  Correlation of Apparent Diffusion Coefficient and Computed Tomography Density in Acute Ischemic Stroke , 2002, Stroke.

[5]  W. Heiss,et al.  Early Ischemic Edema on Cerebral Computed Tomography: Its Relation to Diffusion Changes and Hypoperfusion within 6 h after Human Ischemic Stroke , 2006, Cerebrovascular Diseases.

[6]  S M Davis,et al.  Identification of major ischemic change. Diffusion-weighted imaging versus computed tomography. , 1999, Stroke.

[7]  G. Ferguson,et al.  Autoregulation of cerebral blood flow during controlled hypotension in baboons , 1976, Journal of neurology, neurosurgery, and psychiatry.

[8]  P. Lyden.  Early major ischemic changes on computed tomography should not preclude use of tissue plasminogen activator. , 2003, Stroke.

[9]  A. Demchuk,et al.  Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy. ASPECTS Study Group. Alberta Stroke Programme Early CT Score. , 2000, Lancet.

[10]  Reto Meuli,et al.  Perfusion-CT Assessment of Infarct Core and Penumbra: Receiver Operating Characteristic Curve Analysis in 130 Patients Suspected of Acute Hemispheric Stroke , 2006, Stroke.

[11]  M. van Lookeren Campagne,et al.  Correlation of apparent diffusion coefficient and computed tomography density in acute ischemic stroke. , 2003, Stroke.

[12]  A. Buchan,et al.  Selection of Acute Ischemic Stroke Patients for Intra-Arterial Thrombolysis With Pro-Urokinase by Using ASPECTS , 2003, Stroke.

[13]  D Petersen,et al.  Interobserver agreement in assessing early CT signs of middle cerebral artery infarction. , 1996, AJNR. American journal of neuroradiology.

[14]  Sabbir Siddique,et al.  Perfusion computed tomography: Prediction of final infarct extent and stroke outcome , 2005, Annals of neurology.

[15]  G. Donnan,et al.  Increased blood volume maintains viability in tissue with isolated focal swelling on CT in acute stroke , 2005 .

[16]  W Hacke,et al.  Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk. , 1994, AJNR. American journal of neuroradiology.

[17]  Klaus Sartor,et al.  Comparison of Perfusion Computed Tomography and Computed Tomography Angiography Source Images With Perfusion-Weighted Imaging and Diffusion-Weighted Imaging in Patients With Acute Stroke of Less Than 6 Hours’ Duration , 2004, Stroke.

[18]  J. Grotta,et al.  Lack of clinical significance of early ischemic changes on computed tomography in acute stroke. , 2001, JAMA.

[19]  Brian Silver,et al.  Importance of Early Ischemic Computed Tomography Changes Using ASPECTS in NINDS rtPA Stroke Study , 2005, Stroke.

[20]  Werner Hacke,et al.  MRI versus CT-based thrombolysis treatment within and beyond the 3 h time window after stroke onset: a cohort study , 2006, The Lancet Neurology.

[21]  Michael D Hill,et al.  Extent of Early Ischemic Changes on Computed Tomography (CT) Before Thrombolysis: Prognostic Value of the Alberta Stroke Program Early CT Score in ECASS II , 2006, Stroke.

[22]  Steven Warach,et al.  Dose Escalation of Desmoteplase for Acute Ischemic Stroke (DEDAS): Evidence of Safety and Efficacy 3 to 9 Hours After Stroke Onset , 2006, Stroke.

[23]  A. Demchuk,et al.  Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy , 2000, The Lancet.

[24]  C. Levi,et al.  CT perfusion source images improve identification of early ischaemic change in hyperacute stroke , 2006, Journal of Clinical Neuroscience.

[25]  M. Wiesmann,et al.  Dynamic CT perfusion imaging of acute stroke. , 2000, AJNR. American journal of neuroradiology.

[26]  A. Mendelow,et al.  Early computed-tomography abnormalities in acute stroke , 1997, The Lancet.

[27]  R. Higashida,et al.  Computed Tomographic Findings in Patients Undergoing Intra-arterial Thrombolysis for Acute Ischemic Stroke due to Middle Cerebral Artery Occlusion: Results From the PROACT II Trial , 2002, Stroke.

[28]  F. Gillespie,et al.  Measurement of regional cerebral blood-flow during carotid ligation. , 1966, Lancet.

[29]  R. Knab,et al.  Cerebral perfusion impairment correlates with the decrease of CT density in acute ischaemic stroke , 2004, Neuroradiology.

[30]  C. Weiller,et al.  Outcome and Symptomatic Bleeding Complications of Intravenous Thrombolysis Within 6 Hours in MRI-Selected Stroke Patients: Comparison of a German Multicenter Study With the Pooled Data of ATLANTIS, ECASS, and NINDS tPA Trials , 2006, Stroke.

[31]  E. Kim,et al.  CT sign of brain swelling without concomitant parenchymal hypoattenuation: comparison with diffusion- and perfusion-weighted MR imaging. , 2005, Radiology.

[32]  L Bozzao,et al.  Early prediction of irreversible brain damage after ischemic stroke at CT. , 2001, Radiology.

[33]  Michael Forsting,et al.  Brain Tissue Water Uptake after Middle Cerebral Artery Occlusion Assessed with CT , 2004, Journal of neuroimaging : official journal of the American Society of Neuroimaging.

[34]  R. Gonzalez,et al.  CT Angiography With Whole Brain Perfused Blood Volume Imaging: Added Clinical Value in the Assessment of Acute Stroke , 2002, Stroke.