Cor et Vasa Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/crvasa Přehledový článek | Review article Role of CT perfusion in acute stroke management Stephan A. Municha,d,e, Hakeem J. Shakir,a,d, Kenneth V. Snydera,b,c,d,e,f a Department of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA b Department of Radiology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA c Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA d Department of Neurosurgery, Gates Vascular Institute at Kaleida Health, Buffalo, NY, USA e Department of Neurosurgery, Rush University Medical Center, Chicago, IL, USA f Toshiba Stroke and Vascular Research Center, University at Buffalo, State University of New York, Buffalo, NY, USA ARTICLE INFO SOUHRN Article history: Akutní ischemická cévní mozková příhoda (CMP) je celosvětově jednou z hlavních příčin invalidity dospělých Received: 22. 12. 2015 osob. Moderní endovaskulární léčba akutních ischemických CMP je založena na použití vyspělých zobra- Accepted: 14. 1. 2016 zovacích metod a vyhledávání tkání, které lze ještě zachránit. Na rozdíl od nekontrastní výpočetní tomo- Available online: 11. 2. 2016 grafi e (CT) nebo tradiční magnetické rezonance nabízí CT zobrazení perfuze mozku (CTP) aktivní pohled na fyziologii mozkové vaskulatury s jejími četnými parametry. Přes omezení různých zařízení a analytického softwaru používaných ke kvantitativnímu hodnocení rozsahu ischemie a penumbry představuje CTP vyni- Klíčová slova: kající nástroj pro neurointervencionisty. Rychlost, s níž lze získat CT skeny perfuze, spolu se schopností této Cévní mozková příhoda metody predikovat vznik infarktu mohou zkrátit dobu do provedení potřebné intervence. I když každá zo- Intervence brazovací metoda má své výhody a nevýhody, představuje podle našich zkušeností použití CTP v kombinaci Penumbra s klinickým vyšetřením účinný nástroj pro vyhledávání pacientů vhodných pro endovaskulární výkon. Perfuzní CT © 2016, ČKS. Published by Elsevier sp. z o.o. All rights reserved. ABSTRACT Acute ischemic stroke is a leading cause of adult disability worldwide. Modern endovascular treatment for acute ischemic stroke is predicated on advanced imaging modalities and the identifi cation of salvageable tissue. Unlike noncontrast computed tomographic (CT) imaging or traditional magnetic resonance imaging, CT perfusion (CTP) imaging offers an active view of cerebrovascular physiology with multiple parameters involved. Though limited by the different equipment and analytic software used to quantitatively assess the Keywords: extent of ischemia and penumbra, CTP imaging nevertheless serves as an excellent tool for neurointerven- CT perfusion tionists. The rapidity by which CT perfusion may be obtained coupled with its potential for predicting infarct Intervention can lead to faster intervention times. Although each imaging modality offers its own set of advantages and Penumbra disadvantages, we fi nd from our experience that CTP utilized in conjunction with a clinical examination Stroke leads to an effective model for identifying patients suitable for endovascular intervention. Address: Kenneth V. Snyder, MD, PhD, University at Buffalo Neurosurgery 100 High Street, Suite B4 Buffalo, NY 14203, USA, e-mail: [email protected] DOI: 10.1016/j.crvasa.2016.01.008 Please cite this article as: S.A. Munich, et al., Role of CT perfusion in acute stroke management, Cor et Vasa 58 (2016) e215–e224 as published in the online version of the Cor et Vasa available at http://www.sciencedirect.com/science/article/pii/S0010865016000102 226_233_Prehledovy clanek Snyder.indd 226 6.4.2016 9:38:25 S. A. Munich, H. J. Shakir, K. V. Snyder 227 Introduction and differentiation of these regions versus those with po- tentially salvageable tissue (ischemic penumbra) is critical Acute ischemic stroke affects approximately 795,000 per- in the evaluation of patients with acute ischemic stroke. sons each year, resulting in an annual cost of $17.5 billion [1]. It remains the leading cause of adult long-term di- sability, with more than 50% of patients requiring dis- Early imaging evaluation charge to a rehabilitation facility. Intravenous (IV) tissue plasminogen activator (tPA) remains the only treatment In the National Institute of Neurologic Disorders and for acute ischemic stroke approved by the U.S. Food & Stroke (NINDS) trial [10], patients presenting with acute Drug Administration. However, given the strict eligibility ischemic stroke underwent a noncontrast computed to- criteria, this treatment is administered to only a minority mographic (CT) scan of the head to exclude intracranial of patients, with less than 10% of stroke patients recei- hemorrhage and evaluate for completed infarctions prior ving IV-tPA [2]. to the administration of IV tPA. Due to its rapidity and Endovascular intervention is ushering in a new wave widespread availability, this technique has remained the of stroke treatment. The recent publication of 5 rando- mainstay of the radiographic evaluation of acute ische- mized, controlled studies has demonstrated its benefi cial mic stroke patients. Although very sensitive for the de- effects on reperfusion and clinical outcome in patients tection of hemorrhage, a noncontrast head CT scan lacks with proximal, anterior-circulation occlusion [3–7]. Not the sensitivity for early detection of ischemic stroke (i.e., limited by the strict eligibility criteria of IV tPA, endo- within the fi rst 3–4 h after a stroke has occurred). vascular treatment has expanded the number of patients The European Cooperative Acute Stroke Study (ECASS) undergoing treatment for acute ischemic stroke. trial excluded patients in whom “parenchymal hypoden- The treatment of patients presenting with acute ische- sity, and/or effacement in more than 33% of the middle mic stroke has its foundation on identifi cation and reper- cerebral artery (MCA) territory” was present [11]. These fusion of the ischemic penumbra. Astrup et al. [8] fi rst in- fi ndings are considered indicative of completed infarct troduced the term “ischemic penumbra” in 1981 as “tissue and, therefore, are not useful in identifying salvageable within the thresholds of functional impairment (electrical tissue. This concept was formalized with the creation of failure) and morphological integrity (ion pump failure) the Alberta Stroke Programme Early CT Score (ASPECTS) that has the capacity to recover if perfusion is improved”. in 2000, which was developed in an effort to predict out- Conversely, tissue in which blood fl ow falls below these come of hyperacute stroke [12]. This score divides the thresholds is considered to have completed infarction and, MCA territory into 6 territories, with each assigned one therefore, is refractory to reperfusion [9]. Identifi cation point (Fig. 1). One point is subtracted for each area de- Fig. 1 – Schematic illustrations of head CT scans demonstrating ASPECTS collateral scoring. Reproduced with permission from http://www.aspectsinstroke.com/collateral-scoring/training-cases/13681c2226/ (accessed 11. 12. 2015). 226_233_Prehledovy clanek Snyder.indd 227 6.4.2016 9:38:32 228 Role of CT perfusion in acute stroke management Fig. 2 – Normal computed tomographic perfusion (CTP) imaging study. Upper left, noncontrast head CT scan without evidence of any abnormality. Notice the symmetry in color for each component of the CT perfusion maps (remaining images), indicating normal fl ow without any evidence of large-vessel occlusion. Fig. 3 – CTP imaging study showing a right-sided middle cerebral artery (MCA) stroke without any salvage- able penumbra. Of the six-image panel, the upper right image represents time to peak (TTP), which indica- tes a delay in blood fl ow to the region of the brain seen as bright red on the color map. The upper middle component of the six-image panel represents cerebral blood volume (CBV). Notice the dark blue within that image, which highlights signifi cant core infarct and large volume loss. Regions of irreversibly infarcted tissue show matched areas of decreased CBF and TTP. No stroke intervention was offered for this patient. monstrating early ischemic changes (e.g., focal swelling mia. In other words, it predicts tissue that is already is- or parenchymal hypoattenuation). Though the ASPECTS chemic. correlated with the presenting National Institutes of He- Invoking the mantra that “time is brain,” the ideal alth Stroke Scale (NIHSS) score and predicted functional imaging study in the triage of patients presenting with outcome, it remains unable to predict impending ische- symptoms of acute ischemic stroke would be: (1) rapid, (2) 226_233_Prehledovy clanek Snyder.indd 228 6.4.2016 9:38:42 S. A. Munich, H. J. Shakir, K. V. Snyder 229 accurate, (3) capable of identifying and differentiating ti- fact that the blood is taking alternative (i.e., collateral) ssue at risk, but salvageable, from tissue that is already routes to supply the territory [22]. These fi ndings are con- infarcted and at risk for hemorrhage with reperfusion. As sistent with intact, but stressed, autoregulation in which mentioned, although a noncontrast head CT scan can be vasodilation and recruitment occur. Consequently, CBF obtained rapidly, this imaging modality is relatively ina- is typically >30% of that in the normal, contralateral he-