Diagnosis of stroke on neuroimaging

“Scan all immediately” strategy improves outcomes and reduces costs Stroke is the clinical syndrome of rapid onset of focal, or sometimes global, cerebral deficit with a vascular cause, lasting more than 24 hours or leading to death.1 Eighty per cent of strokes are ischaemic, 15% are due to intracerebral haemorrhage, and 5% to subarachnoid haemorrhage. Correct diagnosis is important because treatments for ischaemic stroke2 may be contraindicated in intracerebral haemorrhage.3 The diagnosis requires imaging of the brain.4 But which imaging—computed tomography or magnetic resonance—how quickly should it be done, should this include imaging cerebral blood flow, and what is the most cost effective approach? The average general hospital (catchment population 250 000-500 000) will see two to three patients with stroke per day. Many patients have poor airway control, are confused, or are unable to communicate. Routine imaging for most patients must therefore be quick (speed is of the essence for patients, salvaging their brain, and for the radiology department), practical, readily available, and yield the key diagnostic information. There is, however, no imaging technique that does all ofthese perfectly. Computed tomography scanning is practical, quick (a few minutes to scan a brain), widely available, and easy to use in ill patients. It accurately identifies intracerebral haemorrhage as soon as it has occurred, but the technique has limitations. Intracerebral haemorrhage will be misinterpreted as ischaemic stroke if computed tomography is not done within 10-14 days after stroke.5 Delays in seeking medical …