Computed Tomography Angiogram of the Aortic Arch and Circle of Willis (CTArch-CoW) scans are commonly ordered in the Emergency Department to diagnose stroke and cerebrovascular disease1,2,3. Where strokes and cerebrovascular disease represent the third most common cause of death in Australia, imaging is a necessary step in the clinical diagnostic algorithm and to design management strategies4. We assessed risk stratification and diagnostic yield of CTArch-CoWs when balanced with contrast risks and radiation exposure in line with established guidelines.

A retrospective audit of 160 consecutive CTArch-CoW scans was completed for patients presenting to the Gosford and Wyong Hospital Emergency Department during 31 days from the 1st - 31st of January 2021. Referrals for CTArch-CoW scans included a brief clinical history online including age, gender, symptoms, clinical query, past medical history and urgency of scan. Demographic data including scan date, age, gender and hospital site was collected. Retrospective analysis of referral clinical history provided was performed. Referral reasons recorded included Tranexamic Attack (TIA), Cerebrovascular Accident...

An average of 5.2 scans were completed daily, average patient age was 66 years and 59.4% were female (13 of standard child-bearing age between 18-45 years). Number of patients below 45 years was 25 (15.63%), and 10 (6.25%) were below 35. The most common referral clinical history was neurological symptoms (78, 48.75%), stroke (46,28.75%), CVA (23,14.38%), TIA (22,13.75%), headache (20,12.5%), SAH (11,6.88%), carotid dissection (9,5.63%), vertebral dissection (7,4.38%), trauma (6,3.75%) and metastases (1,0.63%). There was a comparatively low positive finding rate14, where twenty (12.50%) CTArch-CoWs...

Where CT investigation is recommended for rapid stroke diagnosis3,9,14,15 clinical decisions should include consideration of how findings will impact immediate management, such as detecting an intravascular thrombus amenable to lysis, presence of salvageable tissue or haemorrhage9. We recommend careful assessment of current guidelines and risk stratification, where diagnostic yield should be evaluated against radiation exposure, contrast risks and cost efficacy.

Australian Radiation Protection and Nuclear Safety Agency [homepage on the Internet]. Australia: Australian Government; [updated 2018 July 1; cited 2021 Mar 11]. Current Australian national diagnostic reference levels for multi detector computed tomography. Available from: https://www.arpansa.gov.au/research-and-expertise/surveys/national-diagnostic-reference-level-service/current-australian-drls/mdct Han A, Yoon DY, Chang SK, et al. Accuracy of CT angiography in the assessment of the circle of Willis: comparison of volume-rendered images and digital subtraction angiography. Acta Radiologica. 2011 [cited 2021 Mar 11]; 52(8): p889-93. Available from: https://journals.sagepub.com/doi/10.1258/ar.2011.110223 Barr JD. Cerebral angiography in the assessment of acute...