The reproducibility of measuring maximum abdominal aortic aneurysm diameter from ultrasound images

BACKGROUND: Accurate repeat assessment of the diameter of an abdominal aortic aneurysm (AAA) is important. This study investigated the reproducibility of different methods of measuring AAA diameter from ultrasound images. METHODS: Fifty AAA patients were assessed by ultrasound. Maximum AAA diameter was measured independently by three trained observers on two separate occasions using a standardised protocol. Five diameters were measured from each scan, three in the anterior-posterior (AP) and two in the transverse (TV) plane, including inner-to-inner (ITI), outer-to-outer (OTO) and leading edge-to-leading edge (LETLE). Intra- and inter-observer reproducibility were reported as reproducibility coefficients. Statistical comparison of methods was performed using linear mixed effects models. RESULTS: Intra-observer reproducibility coefficients (AP LETLE 2.2 mm; AP ITI 2.4 mm; AP OTO 2.6 mm) were smaller than inter-observer reproducibility coefficients (AP LETLE 4.6 mm: AP ITI 4.5; and AP OTO 4.8 mm). There was no statistically significant difference in intra-observer reproducibility of three types of measurements performed in the AP plane. Measurements obtained in the TV plane had statistically significant worse intra-observer reproducibility than those performed in the AP plane. CONCLUSIONS: This study suggests that the comparison of maximum AAA diameter between repeat images is most reproducibly performed by a single trained observer measuring diameters in the AP plane.