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Stroke Magnetic Resonance Imaging Techniques in the Evaluation of Stroke and Neurovascular Disease Marco Essig 1 and Lawrence Tanenbaum 2 1. Professor of Radiology, Department of Neuroradiology, University Hospital Erlangen, Germany; 2. Associate Professor of Radiology, Department of Radiology, Mount Sinai Hospital, New York, US Abstract Early intervention remains vital in the management of acute stroke. The goals of imaging techniques are to establish a diagnosis as early as possible and to obtain accurate information about the intracranial vasculature and brain perfusion to guide therapeutic decision- making. Magnetic resonance imaging (MRI) and contrast-enhanced magnetic resonance angiography (CE-MRA) are valuable techniques in the evaluation of acute stroke and can provide diagnostic information on the underlying pathophysiological changes. Gadolinium-based contrast agents (GBCAs) facilitate the diagnosis of ischaemic stroke by accentuating abnormal flow kinetics and the diagnosis of non- ischaemic stroke by assisting in the detection and characterisation of intracranial aneurysms and arteriovenous malformations (AVMs). Contrast agents may also be employed in the characterisation of vascular atherosclerotic plaque. Gadobutrol (Gadovist®, Gadavist®) is a high relaxivity contrast agent which combines an excellent safety profile and proven high efficacy. As the only high concentration contrast media it allows to inject at a small and compact bolus, which has a direct impact on the performance of MRA or perfusion MRI procedure. Keywords Gadolinium-based contrast agents, gadobutrol, Gadovist, neurovascular imaging, stroke Disclosure: Lawrence Tanenbaum is a speaker for Bayer HealthCare and Marco Essig is a consultant for Bayer HealthCare. Received: 18 February 2013 Accepted: 11 April 2013 Citation: European Neurological Review, 2013;8(1):14–20 Correspondence: Lawrence Tanenbaum, 50 Murray Street, NY, NY, 10007, US. E: Support: The publication of this article was supported by Bayer HealthCare. The views and opinions expressed are those of the authors and not necessarily those of Bayer HealthCare. Stroke is the second most common cause of death and a major cause of disability worldwide. Because of the ageing population, the burden of stroke is likely to increase during the next 20 years, especially in developing countries. 1 The majority (85  %) of strokes are ischaemic: patients present with asymptomatic bruits, transient ischaemic attacks (TIA) or manifest neurological symptoms. A TIA is a transient neurological deficit lasting from a few seconds to a few hours. Reversible ischaemic neurological deficit (RIND) is often included within the category of stroke and is a neurological deficit that lasts longer than 24 hours but less than 3 days and results in complete recovery. Prolonged reversible ischaemic neurological deficits (PRIND) may last for up to 7 days. Non-ischaemic or haemorrhagic stroke is associated with higher mortality rates than ischaemic stroke. 2 Patients present with intracerebral or subarachnoid haemorrhage, causes of which include hypertension, intracranial aneurysms, arteriovenous malformations (AVMs), dural arteriovenous fistulas (DAVF), or cerebral amyloid angiopathy. The first stage in the evaluation of patients with acute stroke is to elucidate the nature and aetiology of stroke (haemorrhage or infarction), identify infarcted and threatened tissue and visualise thrombi (see Table 1). 3 Neurovascular imaging techniques can assess these parameters within minutes of the patient arriving at the hospital and allow accurate diagnosis, prompt initiation of appropriate treatment, characterisation of disease progression and monitoring of the response to interventions. 14 Computed tomography (CT) has traditionally been the mainstay of imaging patients with acute stroke but its sensitivity for early infarction is less than ideal and it cannot accurately define the infarct core. It is also subject to substantial inter-rater variability in interpretation and magnetic resonance imaging (MRI) has demonstrated superiority for detection of acute intracranial haemorrhage. 4,5 Traditionally, to obtain vascular and perfusion information with CT, multiple injections have been required although newer techniques have enabled the simultaneous acquisition of CT-perfusion and CT-angiography. 6 MRI techniques are becoming increasingly used in the diagnosis of stroke and enable identification of the infarct core and the relationship to the typically larger volume of ischaemic tissue (penumbra) (see Figure 1). Magnetic Resonance Imaging of Stroke A number of MRI techniques are used in stroke diagnosis. These are defined in Table 2. The imaging regimen in acute stroke includes diffusion weighted imaging (DWI), T2 and fluid attenuated inversion recovery (FLAIR) weighted imaging, gradient recalled echo imaging (GRE) or susceptibility- weighted imaging (SWI) and magnetic resonance angiography (MRA), followed by physiological assessment with perfusion weighted imaging (PWI). 7 Stroke evaluation protocols should include a combination of DWI and PWI, because together they define the location and extent of ischaemia and infarction within minutes of onset. In addition, when performed in series, they can provide information about the pattern of evolution of the ischaemic lesion and treatment monitoring. 8 © Touch M Edical ME d ia 2013