Decision-making in follow-up after endovascular aneurysm repair based on diameter and volume measurements: a blinded comparison

Objective: to assess whether volume, in addition to diameter, measurements facilitate decision-making after endovascular aneurysm repair (EVAR). Material/Methods: patients (n = 82) with an immediately post-EVAR, and at least one follow-up (3-60 months), computed tomographic angiogram (CTA) were studied. The actual and all preceding proportional sac size changes were recorded. The resulting 347 diameter and 347 volume data were placed in random order and reviewed by three blinded observers who then recommended one of three treatment policies: "good/wait", "uncertain/intensify follow-up" or "not good/further diagnostics (Dx) or intervention (Rx)". The observers were instructed to consider changes of 10% relevant, One observer reviewed the graphs twice. Results: the interobserver agreements (kappa) for the diameter were 0.92, 0.81 and 0.76 and for volumes 0.91, 0.88 and 0.86. The intra-observer agreement was 0.93 for both diameter and volume. Volume data resulted in significantly more "good/wait" decisions out to 36 months. Diameter data resulted in more "not good/Dx or Rx"-decisions out to 36 months (all p < 0.005). Conclusion: post-EVAR aneurysm sac volume data appears to provide earlier reassurance, reduce unnecessary interventions and to be more sensitive to secondary problems than diameter data alone.