Patients with stroke have a 25x higher risk of cardiovascular complications within the first 30 days of the event compared to individuals without stroke. The mechanisms behind these complications are not well understood. Evidence suggests that inflammation plays a central role. With the present proof-of-concept prospective cohort study, the investigators aim to demonstrate that patients develop cardiac inflammation after stroke by performing positron emission tomography (PET) magnetic resonance imaging (MRI) of the heart within 15 days after stroke. As a secondary aim, the investigators will evaluate whether post-stroke cardiac inflammation persists at 3 months after stroke. The control group will be comprised of age- and sex-matched individuals without stroke.

Inclusion Criteria:

• Age ≥18 years willing to cons Age ≥18 years willing to consent
• Patients with acute ischemic stroke in the right or left MCA territory, admitted to University Hospital, London Health Sciences Centre (LHSC) or evaluated at LHSC's Urgent TIA and Stroke Prevention Clinic. Acute ischemic stroke is defined as acute onset focal symptoms matching an acute brain infarct documented on a Head CT or on diffusion weighted imaging (DWI) MRI of the brain showing restricted diffusion.
• Willing to consent.

Exclusion Criteria:

• History of known heart disease defined as known atrial fibrillation, prior myocardial infarction, coronary artery disease, heart failure, prior cardiovascular surgery or percutaneous intervention
• Stroke in the previous 3 months before the qualifying stroke.
• High-sensitivity Troponin-T (HS-TnT) >100 ng/L on routine standard of care acute stroke bloodwork.
• Clinically or neurologically unstable patients as per the treating physician.
• Ongoing infection or recent infection within the previous 3 months.
• Surgery within 3 months before the stroke.
• Concurrent inflammatory conditions (connective tissue diseases, rheumatological disease, etc.) or use of anti-inflammatory medications.
• Contraindications to the use of gadolinium (e.g., pregnancy, stage IV renal insufficiency)
• Subjects will be excluded if they fail the St. Joseph's Health Care standard MRI screening questionnaire. Briefly, this questionnaire screens for: Heart Pacemakers / Wires, Aneurysm Clips, Shunt / Surgical Clips, Shrapnel / Bullets, Dentures or Metal braces, Intra-Uterine Device, Heart Valves, Ear Implants, Prostheses, Medication Patches (Nicoderm, Habitrol, Transderm-Nitro, etc.), Claustrophobia, History of a head or eye injury involving metal fragments. Patients with an eGFR < 40 will be excluded, as impaired renal function places the patient at a higher risk for a rare reaction to Gd-DTPA, the MRI contrast agent.

The study population will comprise 4 patients with acute ischemic stroke in the right MCA territory involving the insular cortex, 4 patients in the left MCA territory involving the insular cortex, and 4 age- and sex-matched individuals presenting with acute stroke symptoms but no evidence of stroke on brain MRI.