CT is still the method of choice for the fast and reliable evaluation of patients with stroke. The first step is to exclude intracranial haemorrhage. Non-enhanced CT (NECT) performed within the first six hours after onset of symptoms may show subtle "early signs" of ischaemic stroke, indicating irreversible brain damage. If irreversible damage of brain tissue has not yet occurred and the patient is admitted within four hours after the onset of symptoms, thrombolysis is a therapeutic option. However, NECT fails to reliably differentiate between brain with sufficient and insufficient perfusion. This differentiation is essential in deciding whether the patient can undergo thrombolysis. Thrombolysis might be harmful if the patient presents with large areas of non-perfused brain. CT-perfusion (CTP) was introduced to improve the evaluation of insufficiently perfused brain, so-called "tissue at risk". Evaluation of the large extracranial and intracranial vessels assuring brain perfusion can be performed safely and non-invasively using CT-angiography (CTA).
In this patient, neither CTP nor NECT - performed immediately after admission and repeated 24 hours later - showed any evidence of ischaemic stroke. In contrast, CTA revealed a high degree stenosis of the right ICA as a probable reason for the patients' symptoms.
In conclusion, with the recent introduction of multislice CT, comprehensive imaging of stroke became possible. Multislice CT combines the information of non-enhanced CT (NECT), CTP and CTA within 15 minutes.