Maximal aneurysm diameter follow-up is inadequate after endovascular abdominal aortic aneurysm repair

Background: follow-up after endovascular abdominal aortic aneurysm repair (EAR) generally consists of serial diameter measurements. A size change after EAR, however, is the consequence of alterations of the excluded aneurysm sac volume. Objective: to assess the agreement between diameter measurements and volume measurements after endovascular aneurysm repair. Patients and methods: from 53 consecutive patients scheduled for EAR, follow-up of at least 6 months was available in 35 patients. CTA was performed on all patients at discharge, at 6 months and yearly thereafter. The resulting 113 datasets were processed on a workstation in a blinded and random older. Maximal aneurysm diameter (DMAX) was measured along the central lumen line. Total aneurysm volume was measured by manual segmentation. All measurements of an individual patient were compared with each other, resulting in 149 comparisons. The significance of individual size changes was classified based on the 95% confidence limits of the intra-observer variability, using difference-of-means analysis. DMAX changes were compared to volume changes. Results: in 37% of the comparisons, discordance was found between DMAX and volume measurements. A decrease in aneurysm size was missed using DMAX in 14% of cases and an increase in 19% of cases. Conclusion: aneurysm size changes after EAR are not noticed using maximal diameter measurements in over one-third of cases.