Author: Dr Peter Brotchie, Radiologist, St Vincent’s Hospital, Melbourne 

Have you ever wondered about the challenges of detecting acute infarcts that have been missed clinically? These infarcts can be particularly difficult to detect when they are unsuspected as they can be small and subtle. In this blog, we’ll explore this topic in more detail and highlight the importance of detecting the unsuspected infarct in the acute stage. 

Recognising a covert ischemic stroke in the early phase is important as even small infarcts indicate that the patient is at risk of further infarcts, usually within the next few days or weeks.  Early detection enables acute management with preventative therapy that has been shown to dramatically reduce the risk of further infarction. Moreover, when stroke is diagnosed swiftly, patients can be monitored appropriately for neurological progression of stroke syndromes or stroke-related complications.  

Detecting CBI crucial to managing acute ischaemic stroke risk 

Although acute ischaemic stroke (AIS) will be treated urgently when diagnosed, not all strokes are detected clinically. In fact, an unsuspected stroke or covert brain infarction (CBI) is by far the most frequent incidental finding on brain imaging, outweighing all other incidental findings combined. CBI has a prevalence of 10% to 30% in healthy elderly populations and 30% to 50% in populations with elevated cardiovascular risk. The incidence and prevalence of CBI by far exceed the numbers for overt acute ischaemic stroke (AIS)1.   

Detection of CBI is essential, with clear evidence for an increased risk of subsequent AIS in patients with known CBI. The risk is highest in the days following the CBI and can be reduced with appropriate medication 2. 

Non-contrast CT brain studies can detect subtle signs of ischaemia  

Non-contrast CT of the brain remains a cornerstone in diagnosing unsuspected acute infarcts. Its speed, safety, and cost-effectiveness make it indispensable in the emergency setting. Importantly, CT is sensitive to early changes in brain tissue that occur during ischaemic strokes. While it may not detect infarcts in their very early stages, it can often reveal subtle signs including brain oedema, parenchymal hypoattenuation, and loss of grey-white matter differentiation—all indicators that ischemia may be occurring. 

 Accurate detection of subtle changes allows physicians to begin treatment and further diagnostic investigations promptly. However, by their very nature, these subtle changes can be difficult to detect. Long busy shifts, fatigue, and staff shortages – all common in emergency departments – can exacerbate this issue.  

AI-powered support for the triage process 

Annalise Enterprise CTB is a comprehensive product capable of detecting a wide variety of clinical findings, not just intracranial haemorrhage. It can play a pivotal role in triaging patients with unsuspected strokes. By quickly identifying acute infarcts, healthcare providers can determine the appropriate level of care and transfer patients to facilities equipped with specialized stroke care units if needed. 

This triage process ensures patients receive the most appropriate and timely care, which can significantly impact their outcomes. Annalise Enterprise CTB complements the CTB study with its sensitivity for detecting acute infarcts that may be clinically unsuspected. Its full value is realised in its role in triage, expediting patient care and improving overall outcomes for individuals who have had a stroke. 

Note: Annalise Enterprise CTB is  CE marked as class IIb under EU Medical Device Regulation (EU MDR) and has been approved for clinical use in Singapore. 

 

1 ref: Vol. 51, No. 8, Covert Brain Infarction, 2020; 2597–2606 

2 Timpone et al., AJR 2023; 221:1-13