Reproducibility of abdominal aortic aneurysm diameter measurement and growth evaluation on axial and multiplanar computed tomography reformations

Abstract

Purpose: Compare different methods measuring abdominal aortic aneurysm (AAA) maximal diameter (Dmax) and its progression on multi-detector computed tomography scan (MDCT). Materials and Methods: Forty AAA patients with 2 MDCT acquired at different time (baseline and follow-up) were included. Three observers measured AAA diameters by 7 different methods: on axial images (antero-posterior, transverse, maximal and short axis) and on multi-planar reformation (MPR) images (coronal, sagittal and orthogonal). Diameter measurement and progression were compared over time for the 7 methods. Reproducibility of measurement methods was assessed by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Results: Dmax measured on axial slices at baseline and follow-up (FU) MDCTs was larger than that measured with use of orthogonal method (p=0.00001), whereas Dmax with the orthogonal method was larger than for all other measurement methods (p≤0.0001). The highest inter-observer ICCs were obtained for the orthogonal and transverse method (0.972) at baseline and for orthogonal and sagittal MPR at FU (0.973 and 0.977). Interobserver ICC of the orthogonal method to document AAA progression was higher (ICC=0.833) than measurements taken on axial images (ICC=0.662-0.780) and single plane MPRs (0.772-0.817). Conclusion: AAA Dmax measured on MDCT axial slices overestimates aneurysm size. Diameter measured by the orthogonal method is more reproducible, especially to document AAA progression.