Stroke

Diagnosis

Diagnosis of stroke

Sudden onset of neurological deficits generally indicates a vascular cause, although seizures, specifically focal impaired awareness seizures or a postictal state, can also produce sudden onset of symptoms¹. Rapid access to MRI is a common limitation, and some patients are unable to have an MRI due to metallic implants or agitation. Advanced brain imaging can now be used to identify salvageable brain tissue in patients and to select those who are likely to benefit from reperfusion beyond traditional time windows².

The diagnosis of stroke requires differentiation from common mimics including migraine, seizures, vestibular disturbances, metabolic disturbances and functional disorders, and is assisted by neuroimaging². Globally, imaging usually involves CT, but MRI is the first-line imaging modality in a minority of centers worldwide².

• Non-contrast CT²
  Non-contrast CT of the brain has close to 100% sensitivity for the detection of intraparenchymal and extra-axial hemorrhage.
• CT angiography and perfusion²
  CT angiography is highly accurate for the detection of arterial stenosis and occlusion. Intravenous injection of iodinated contrast agent can be used to assess the cerebral vasculature via either a static acquisition (CT angiography) or a time-resolved series (CT perfusion).
• MRI²
  Diffusion MRI assesses the random motion of water molecules and is the most sensitive imaging modality for the detection of acute ischemia. Perfusion MRI is similar to CT perfusion — an intravenous gadolinium contrast bolus is tracked through the cerebral circulation and images are processed to form maps of contrast arrival delay and blood flow.