Stroke is a serious life-threatening medical condition that happens when blood supply to a part of the brain is severely compromised. More than 100,000 strokes happen in the UK every year. The average age for stroke across the UK varies, with a median age of 77 (interquartile range 67 to 85 years). A quarter of strokes happen in people of working age. Stroke is a leading cause of disability and one of the most common causes of early death in the UK.
Treatment of stroke depends on the cause, the length of time the blood supply to brain has been compromised and the severity of the damage caused by the stroke. In ischaemic stroke (the most common type), when blood supply to the brain gets blocked by a clot, treatments aim to restore blood flow by dispersing the clot with an intravenous injection of a clot-busting drug (thrombolysis) and mechanically removing the clot (thrombectomy). Thrombolysis needs to be started within 4.5 hours of onset of stroke symptoms. Thrombectomy should be offered as soon as possible to people who were last known to be well within the last 6 hours, or considered as soon as possible for people who were last known to be well between the last 6 and 24 hours. In the less common type of stroke, intracerebral haemorrhage, when a weakened blood vessel in the brain bursts and blood leaks into soft brain tissues, these treatments would be harmful and should not be offered.
CT brain scans are used to help guide treatment choice. In people with a suspected acute stroke, a non-enhanced CT scan is used first to determine if the stroke is ischaemic so that thrombolysis can start. In people with confirmed ischaemic stroke, CT angiography is then used to confirm the presence of a clot and to assess if it is a large vessel occlusion (a clot in a location where it could be removed by thrombectomy). When the impact of stroke is likely to be more severe because the blood supply to the brain has been reduced for a longer time (between 6 and 24 hours), CT perfusion is used to assess if there is the potential to salvage brain tissue by doing a thrombectomy.
Software with artificial intelligence (AI)-derived algorithms can be used to analyse CT brain scan images from people with suspected acute stroke to detect and report imaging abnormalities or findings. The result of this analysis is intended to support the scan review and reporting by a trained healthcare professional. By identifying, quantifying and highlighting stroke-related changes in the brain, the AI-derived algorithms may support clinical decisions about suitability of an appropriate time-sensitive treatment. Using the software in the radiology pathway may lead to quicker review of scans by a multi-site clinical team, improved decisions about treatment, expedited patient transfer, faster access to the correct treatment and improved patient outcomes. Some software has features that can prioritise the review of stroke CT scans.
Accipio is a software with AI-derived algorithms. It detects and analyses intracranial haemorrhage on non-enhanced CT brain scans and large vessel occlusions on CT angiography brain scans. The cost of Accipio is not known. The company says that the Accipio suite is CE marked as a class IIa medical device. The technology has been discontinued since January 2022.
Aidoc is a software platform that includes AI-derived stroke-related algorithms Aidoc ICH and Aidoc LVO. Aidoc ICH detects intracranial haemorrhage on non-enhanced brain CT scans. Aidoc LVO detects large vessel occlusions on CT angiography brain scans. The platform also includes Aidoc Mobile, a communication component to help communication between healthcare professionals in the stroke pathway. The manufacturer estimates that the licence fee for Aidoc for centres doing up to 45,000 CT brain scans per year is around £24,800 per year. For centres doing more than 45,000 CT brain scans per year, the licence fee is estimated as to be around £32,900 per year.
As well as the individual software package, Aidoc has partnered with icometrix (see section 2.13) for a 'stroke solution' (AIDOC ICH for detecting intracranial haemorrhage on non-enhanced CT brain scans, AIDOC LVO for detecting large vessel occlusion on CT angiography brain scans, and icobrain ctp for CT perfusion brain scan analysis in ischaemic stroke). The company says that Aidoc software is a CE-marked (class I medical device) AI triage and notification platform.
BioMind is a software that includes AI-derived algorithms for detecting, locating and assessing the severity of intracerebral haemorrhage on non-enhanced CT brain scans. The cost of BioMind is not known. The company says that BioMind is a CE-marked AI-derived platform (class unknown).
BrainScan CT is a software with AI-derived algorithms. It detects and locates intracerebral haemorrhage and acute ischaemic stroke on non-enhanced CT brain scans. The cost of BrainScan CT is not known. The company says that BrainScan CT is a CE-marked (class IIa medical device) AI-derived platform.
Cercare Perfusion is a software with AI-derived‑ algorithms for CT and MRI brain scans. It uses data on tissue oxygenation to identify suspected stroke lesions. It provides an overview of brain tissue status on CT perfusion brain scans. The cost of Cercare Perfusion is not known. The company says that Cercare Perfusion is a CE‑marked AI-derived platform (class unknown).
CINA Head is a software platform that includes AI-derived algorithms CINA‑ICH, CINA‑LVO and CINA‑ASPECTS. CINA‑ICH detects intracranial haemorrhage on non-enhanced CT brain scans and prioritises them on the radiologist's worklist. CINA‑ASPECTS analyses non-enhanced CT brain scans to help characterise early ischaemic brain tissue injury. CINA‑LVO detects and prioritises the review of large vessel occlusions on CT angiography brain scans. Assuming a minimum of 1,000 scans a year, cost ranges from around EUR 7.08 per scan for centres doing up to 5,000 CT brain scans a year to around EUR 5.27 per scan for centres doing over 20,000 CT brain scans a year. The company says that the technology is CE marked (class I medical device).
CT Perfusion 4D is a software with AI-derived algorithms. It provides an overview of brain tissue status on CT perfusion brain scans. The cost of CT Perfusion 4D is not known. The company says that CT Perfusion 4D is a CE‑marked medical device (class unknown).
e-Stroke is a software platform with AI-derived‑ algorithms e-‑ASPECTS, e‑CTA and e‑CTP. e‑ASPECTS detects acute ischaemic stroke on non-enhanced CT brain scans. e‑CTA detects and locates large vessel occlusions on CT angiography brain scans. e‑CTP analyses CT perfusion brain scans to provide information about brain tissue status. The cost of the software licence for a comprehensive stroke centre is around £30,000 per year and for an acute stroke centre around £15,000 per year. The company says that e-Stroke is CE marked (class IIa medical device).
icobrain ct is a software platform that includes the AI-derived algorithm icobrain ctp for analysing CT perfusion brain scans to determine the presence of potentially salvageable brain tissue in ischaemic stroke. The cost of icobrain ct ranges from around £20,000 to around £45,000 per year depending on volume. As well as the individual software package, icometrix has partnered with Aidoc on a 'stroke solution' (see section 2.6). The company says that icobrain ct is CE marked (class I medical device).
Neuro Solution is a software with AI-derived algorithms. It detects intracranial haemorrhage on non-enhanced CT brain scans. Until November 2021, this technology was known as Zebra-Med (Zebra Medical Vision). The cost of Neuro Solution is not known. The company says that Neuro Solution is CE marked (class I medical device).
qER is a software with AI-derived algorithms for detecting intracerebral haemorrhage and areas of brain tissue death (infarct) on non-enhanced CT brain scans. The cost of qER is not known. The company says that qER is a CE‑marked triage and notification medical device (class unknown).
RapidAI is a software platform that includes AI-derived stroke-related algorithms Rapid ICH, Rapid ASPECTS, Rapid CTA, Rapid LVO and Rapid CTP for analysing CT brain scans. Rapid ICH detects intracerebral haemorrhage on non-enhanced CT brain scans. RAPID ASPECTS assists in assessing the extent of disease on non-enhanced CT brain scans from people who have ischaemic stroke caused by a large vessel occlusion. Rapid CTA and RAPID LVO detect and locate large vessel occlusions on CT angiography brain scans. Rapid CTP analyses CT perfusion brain scans to give information about salvageable brain tissue. RapidAI is provided on an annual subscription fee basis. An average cost per centre is around £20,000 per year. The company says that RapidAI is CE marked (class IIa medical device).
Viz is a software platform that includes AI-derived stroke-related algorithms Viz ICH, Viz LVO and Viz CTP. Viz ICH detects intracranial haemorrhage on non-enhanced CT brain scans. Viz LVO detects large vessel occlusions on CT angiography brain scans. Viz CTP analyses CT perfusion brain scans to provide information about salvageable brain tissue. The cost of the software for a comprehensive stroke centre is in the region of around £30,000 per year and for a primary stroke centre around £15,000 per year. The company says that Viz is CE marked as a class I medical device.
Non-enhanced CT brain scans may be reviewed by a radiologist, specialist radiologist, diagnostic radiographer, stroke physician or emergency medicine physician, depending on availability of staff. CT angiography and CT perfusion brain scans are more likely to be reviewed by a radiologist, neuroradiologist or an interventional neuroradiologist, who specialise in interpretation of these scans. Image sharing between sites is based on current NHS practice (without use of the technologies being assessed as part of this guidance).