title: Maximum Diameter of Native Abdominal Aortic Aneurysm Measured by Angio-Computed Tomography: Reproducibility and Lack of Consensus Impacts on Clinical Decisions.
abstract: BACKGROUND
  Computed tomography angiography (CTA) is the reference technique for the measurement of native maximum abdominal aortic aneurysm (AAA) diameter when surgery is being considered. However, there is a wide choice available for the methodology of maximum AAA diameter measurement on CTA, and to date, no consensus has been reached on which method is best. We analyzed clinical decisions based on these various measures of native maximum AAA diameter with CTA, then analyzed their reproducibility and identified the method of measurement yielding the highest agreement in terms of patient management.
  
  
  METHODS
  Three sets of measures in 46 native AAA were obtained, double-blind by three radiologists (J, S, V) on orthogonal planes, curved multiplanar reconstructions, and semi-automated-software, based on the AAA-lumen centerline. From each set, the clinical decision was recorded as follows: "Follow-up" (if all diameters <50 mm), "ambiguous" (if at least one diameter <50 mm AND at least one ≥50 mm) or "Surgery " (if all diameters ≥50 mm). Intra- and interobserver agreements in clinical decisions were compared using the weighted Kappa coefficient.
  
  
  RESULTS
  Clinical decisions varied according to the measurement sets used by each observer, and according to intra and interobserver (lecture#1) reproducibility. Based on the first reading of each observer, the number of AAA proposed for surgery ranged from 11 to 24 for J, 5 to 20 for S, and 15 to 23 for V. The rate of AAAs classified as "ambiguous" varied from 11% (5/46) to 37% (17/46). The semi-automated method yielded very good intraand interobserver agreements in clinical decisions in all comparisons (Kappa range 0.83-1.00).
  
  
  CONCLUSIONS
  The semi-automated method seems to be appropriate for native AAA maximum diameter measurement on CTA. In the absence of AAA outer-wallbased software more robust for complex AAA, clinical decisions might best be made with diameter values obtained using this technique.
authors.affiliation: Department of Radiology, University Hospital Reims, Hôpital Robert Debré, Reims, France.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Mora
authors.affiliation: Department of Radiology, University Hospital Reims, Hôpital Robert Debré, Reims, France.
authors.forename: Claude D
authors.initials: CD
authors.lastname: Marcus
authors.affiliation: Clinical Research Unit, University Hospital Reims, Hôpital Robert Debré, Reims, France.
authors.forename: Coralie M
authors.initials: CM
authors.lastname: Barbe
authors.affiliation: EA3920, Department of Cardiology, University Hospital Besancon, Besançon, France.
authors.forename: Fiona B
authors.initials: FB
authors.lastname: Ecarnot
authors.affiliation: Department of Internal Medicine and Vascular Medicine, Pavillon M, Hospices Civils de Lyon, University Hospital Edouard Herriot, Lyon, France; Faculty of Medicine and Maieutic Charles Merieux, Claude Bernard Lyon 1 University, Oullins, France.
authors.forename: Anne L
authors.initials: AL
authors.lastname: Long
keywords: Abdominal aortic aneurysm; Computed tomography; Reproducibility