Clinical validation of a software for quantitative follow-up of abdominal aortic aneurysm maximal diameter and growth by CT angiography

Purpose To compare the reproducibility and accuracy of abdominal aortic aneurysm (AAA) maximal diameter (D-max) measurements using segmentation software, with manual measurement on double-oblique MPR as a reference standard. Materials and methods The local Ethics Committee approved this study and waived informed consent. Forty patients (33 men, 7 women; mean age, 72 years, range, 49–86 years) had previously undergone two CT angiography (CTA) studies within 16 ± 8 months for follow-up of AAA ≥35 mm without previous treatment. The 80 studies were segmented twice using the software to calculate reproducibility of automatic D-max calculation on 3D models. Three radiologists reviewed the 80 studies and manually measured D-max on double-oblique MPR projections. Intra-observer and inter-observer reproducibility were calculated by intraclass correlation coefficient (ICC). Systematic errors were evaluated by linear regression and Bland–Altman analyses. Differences in D-max growth were analyzed with a paired Student's t-test. Results The ICC for intra-observer reproducibility of D-max measurement was 0.992 (≥0.987) for the software and 0.985 (≥0.974) and 0.969 (≥0.948) for two radiologists. Inter-observer reproducibility was 0.979 (0.954–0.984) for the three radiologists. Mean absolute difference between semi-automated and manual D-max measurements was estimated at 1.1 ± 0.9 mm and never exceeded 5 mm. Conclusion Semi-automated software measurement of AAA D-max is reproducible, accurate, and requires minimal operator intervention

Impact of contrast injection and stent-graft implantation on reproducibility of volume measurements in semiautomated segmentation of abdominal aortic aneurysm on computed tomography

Purpose To assessthe impact of contrast injection and stent-graft implantation on feasibility, accuracy, and reproducibilityof abdominal aortic aneurysm (AAA) volume and maximaldiameter (D-max) measurements using segmentation software. Materials and methods CT images of 80 subjects presentingAAA were divided into four equal groups: with or without contrast enhancement, and with or without stent-graft implantation. Semiautomated software was used to segment the aortic wall, once by an expert and twice by three readers. Volume and D-max reproducibility was estimated by intraclass correlation coefficients (ICC), and accuracy was estimated between the expert and the readers by mean relative errors. Results All segmentations were technically successful. Themean AAA volume was 167.0±82.8 mL and the mean D-max 55.0±10.6 mm. Inter- and intraobserver ICCs for volume andD-max measurements were greater than 0.99. Mean relative errors between readers varied between −1.8±4.6 and 0.0± 3.6 mL. Mean relative errors in volume and D-max measurements between readers showed no significant difference between the four groups (P≥0.2). Conclusion The feasibility, accuracy, and reproducibility of AAA volume and D-max measurements using segmentation software were not affected by the absence of contrast injection or the presence of stent-graft