Arterial spin labeling (ASL) is a non-invasive MRI technique to measure cerebral blood flow (CBF). This review provides a practical guide and overview of the clinical applications of ASL of the brain, as well its potential pitfalls. The technical and physiological background is also addressed. At present, main areas of interest are cerebrovascular disease, dementia and neuro-oncology. In cerebrovascular disease, ASL is of particular interest owing to its quantitative nature and its capability to determine cerebral arterial territories. In acute stroke, the source of the collateral blood supply in the penumbra may be visualised. In chronic cerebrovascular disease, the extent and severity of compromised cerebral perfusion can be visualised, which may be used to guide therapeutic or preventative intervention. ASL has potential for the detection and follow-up of arteriovenous malformations. In the workup of dementia patients, ASL is proposed as a diagnostic alternative to PET. It can easily be added to the routinely performed structural MRI examination. In patients with established Alzheimer’s disease and frontotemporal dementia, hypoperfusion patterns are seen that are similar to hypometabolism patterns seen with PET. Studies on ASL in brain tumour imaging indicate a high correlation between areas of increased CBF as measured with ASL and increased cerebral blood volume as measured with dynamic susceptibility contrast-enhanced perfusion imaging. Major advantages of ASL for brain tumour imaging are the fact that CBF measurements are not influenced by breakdown of the blood–brain barrier, as well as its quantitative nature, facilitating multicentre and longitudinal studies.

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The unprecedented COVID-19 pandemic has resulted in rapidly evolving best practices for transmission reduction, diagnosis, and treatment. A regular influx of new information has upended traditionally static hospital protocols, adding additional stress and potential for error to an already overextended system. To help equip frontline emergency clinicians with up-to-date protocols throughout the evolving COVID-19 crisis, our team set out to create a dynamic digital tool that centralized and standardized resources from a broad range of platforms across our hospital. Using a design thinking approach, we rapidly built, tested, and deployed a solution using simple, out-of-the-box web technology that enables clinicians to access the specific information they seek within moments. This platform has been rapidly adopted throughout the emergency department, with up to 70% of clinicians using the digital tool on any given shift and 78.6% of users reporting that they “agree” or “strongly agree” that the platform has affected their management of COVID-19 patients. The tool has also proven easily adaptable, with multiple protocols being updated nearly 20 times over two months without issue. This paper describes our development process, challenges, and results to enable other institutions to replicate this process to ensure consistent, high-quality care for patients as the COVID-19 pandemic continues its unpredictable course.