The Origin and Role of Thromboembolism in the Pathogenesis of Ischaemic Stroke

Ischaemic stroke is usually due to occlusion of a cerebral artery by thrombus. However, it is often difficult to identify the source of thrombus, or to confirm thrombus as a cause of ischaemic stroke. Moreover, it is debated whether thrombosis plays any role in certain types of stroke such as lacunar stroke. In preliminary studies, the investigators have evaluated a novel clinical grade thrombus-specific radiotracer, 18F-GP1, which has a high specificity for the glycoprotein IIb/IIIa receptor on activated platelets. The investigations have demonstrated that 18F-GP1 is highly sensitive to in vivo thrombus formation and demonstrates avid binding to thrombus associated with myocardial infarction, pulmonary embolism and aortic bioprosthesis. This study will use this imaging approach to define the role and origin of thrombus in patients with ischaemic stroke, cryptogenic stroke and lacunar stroke.The investigators will also assess its added clinical value in assessing patients with ischaemic stroke.

Inclusion Criteria: * Males and females ≥18 years old * Diagnoses of acute ischaemic stroke (within 21 days of symptom onset) as per American Heart and Stroke Association guidelines Exclusion Criteria: * Inability or unwillingness to provide informed written consent (ie lack capacity) * Inability to undergo the scanning protocol including ability to transfer onto the scanner * Women of child- bearing potential in whom pregnancy cannot be excluded * Contraindication to PET-CT scanning including estimated glomerular filtration rate \