CT Clock Tool Feasibility Study

Interruption of blood supply to the brain from a blocked blood vessel causes ischaemic stroke. This leads to symptoms relating to the areas of brain affected. For example, people with stroke may suddenly have trouble moving their arms, legs or face, and may find it hard to speak or lose consciousness. There are treatments available to open up the blocked blood vessel: * Thrombolysis involves injecting a medicine to break down the blood clot causing the blockage. * Thrombectomy means pulling the blood clot out through a tiny tube placed within the blood vessel. Both treatments can help restore blood supply to the brain and reverse the symptoms caused by stroke. These treatments are usually only offered when there is a clear onset time for stroke symptoms. However, for around 20% of strokes, the time of onset is unknown. Patients may wake up with symptoms, be confused or be found collapsed. So that treatment can be available to more people, the investigators have developed a method to estimate when an ischaemic stroke began, the CT Clock Tool. This method involves taking measurements from the brain imaging that most patients with stroke routinely get on arrival at hospital (CT or CAT scanning). In other words, no extra tests are needed to use the method; the investigators seek to make better use of existing tests. In this study, the aim is to understand whether it is feasible to use the CT Clock Tool method in the real world. For example, can doctors correctly use the tool during their normal work to produce accurate estimates for the onset time of stroke? The results of this study will be used to plan a future clinical trial for testing the safety of the CT Clock Tool when it is used to treat patients.