Stroke affects over 125,000 people each year in the UK and leaves at least 50% disabled. After a first stroke, there is a significant risk of recurrence (around 5-10% over the first year). While there are benefits from addressing general risk factors such as exercise, weight and smoking, selecting the best treatments for preventing a further stroke depends on understanding the underlying mechanism. Most strokes results from a blood clot causing a blockage in a blood vessel in the brain ("ischaemic" strokes, about 85% of cases). The clot may originate in the heart, the major blood vessels supplying the head, or result from disease of the small blood vessels in the brain itself (around 25% of cases each), and in around 25% of people a cause cannot be determined (sometimes because more than one exists). Different treatments are given depending on cause (for example, anticoagulant medication for clots from the heart, surgery for some arising from large arteries in the neck).

Current investigations involve multiple tests spread across different hospital departments, and commonly take several weeks to be completed. This may contribute to a high rate of strokes of uncertain cause, and may delay the start of the best treatment.

This trial will investigate the value of a single comprehensive scan to look at the heart and major blood vessels (using CT scanning) in a pilot study, comparing the classification of causes of stroke and the time to starting treatments with routine care, in a randomised study of patients with recent stroke or transient ischaemic attack (TIA, a short-lived stroke episode).

Inclusion Criteria:

• Clinical diagnosis of ischaemic stroke or TIA
• Male or non-pregnant female≥18 years of age.
• Informed consent.

Exclusion Criteria:

• Known impaired renal function precluding contrast Computed Tomography (CT).
• Contraindications to MRI scans
• Known severe hypersensitivity to iodine based contrast media for CT or gadolinium based contrast agents for MRI.
• Severe concurrent medical condition that would prevent participation in study procedures (e.g. severe pulmonary oedema or severe septicemia) or with life expectancy ≤ 1 months.