Supplementary Material for: Accuracy of Reporting the Hyperdense Middle Cerebral Artery Sign as a Function of Clinical Experience

Background/Aim: The hyperdense middle cerebral artery sign (HMCAS) is a useful clinical sign in the management of acute stroke and may alter time-critical decisions within an emergency setting. Though gold standards have been published, these are rarely used in clinical practice and scans tend to be reported subjectively. It is therefore possible that the level of experience of the doctor reporting the scan may impact on the accuracy of the reporting and hence patient management. This study was designed to evaluate the accuracy in detecting HMCAS across doctors with varying levels of experience. Methods: Forty doctors were recruited into four categories of experience. Each subject received a brief computer-based tutorial on how to identify an HMCAS and was then asked to report on the presence or absence of an HMCAS in 19 pre-prepared CT scans using a standardised viewing template. Results: The mean (±SE) percentage correct scores increased with experience from 76.8 ± 3.69 among interns and residents to 90.1 ± 2.23 (neurologists and radiologists; p < 0.01). Sensitivity and specificity as well as positive and negative predictive values all increased with experience. In addition, more experienced clinicians were better able to distinguish scans which met the radiological criteria for HMCAS from those which only just failed to do so. Conclusions: Experienced neurologists and radiologists consistently and accurately reported the presence or absence of HMCAS, whereas less experienced clinicians tended to over-report the presence of HMCAS. This may have implications for the acute management of thromboembolic stroke.