Aneurysm Diameter Measurement: A Challenging and Frustrating Task

Abstract

Diameter is the stronger predictor of abdominal aortic aneurysm (AAA) rupture and related death. In the past decades, the expansion of screening and of surveillance programmes for AAA detection and management as well as the remarkable evolution in imaging technology, especially after the introduction of endovascular aneurysm repair (EVAR), has notably increased our training in measuring an AAA. Nevertheless, it is challenging and frustrating to see that we still do not know how to calculate reliably an aneurysm diameter and the related risk of rupture. This is a worrying awareness for the effectiveness and safety of surveillance and screening management of AAA. There are a number of reasons making diameter measurements inaccurate especially with ultrasound that is today the exclusive technique to screen and survey most AAA. Recent metaanalyses of the literature have shown that inter-observer reproducibility for measurement of AAA with ultrasound is often poor, varying from 1.6 to 7.5 mm.1 However, many of these results are related to studies performed in the nineties. Hopefully, technology has developed since. Nevertheless, a corresponding improvement in reproducibility of measurements has not yet occurred, as shown by recent data from the Viborg Vascular (VIVA) screening trial published in this issue of EJVES. This study suggested that an additional important but usually ignored source of difference in measurements of AAA diameter on ultrasound is cardiac cycle.2 By reviewing ultrasound video recorded in a group of 603 AAAs enrolled in the VIVA trial, Grondal et al. showed an average mean AAA diameter of 41.6 mm when measured in systole and 39.63 mm when measured in diastole. The mean difference of about 2 mm seems clinically irrelevant but this implied a 5% difference of the overall AAA diameter that should be added to intraand inter-operator variability in measurements.2 Furthermore, difference in diameter measurements may double when two different operators perform calculations, one during the