title: Automated software supported versus manual aorto-iliac diameter measurements in CT angiography of patients with abdominal aortic aneurysms: assessment of inter- and intraobserver variation.
abstract: BACKGROUND
  Open surgical or endovascular abdominal aortic aneurysm (AAA) relies on precise preprocedual imaging. Purpose of this study was to assess inter- and intraobserver variation of software-supported automated and manual multi row detector CT angiography (MDCTA) in aortoiliac diameter measurements before AAA repair.
  
  
  METHODS
  Thirty original MDCTA data sets (4 x 2mm collimation) of patients scheduled for endovascular AAA repair were studied on a dedicated software capable of creating two-dimensional reformatted planes orthogonal to the aortoiliac center-line. Measurements were performed twice with afour-week interval between readings. Data were analysed by two blinded readers at random order Two different measurement methods were performed: reader-assisted freehand wall-to-wall measurement and semi-automatic measurement.
  
  
  RESULTS
  Aortoiliac diameters were significantly underestimated by the semi-automatic method as compared to reader-assisted measurements (p < 0.0031). Intraobserver variability of AAA diameter calculation was not significant (p > 0. 15) for reader-assisted measurements except for the diameter of the left common iliac artery in reader 2 (p = 0.0045) and it was not significant (p > 0. 14) using the semi-automatic method. Interobserver variability was not significant for AAA diameter measurements using the reader-assisted method and for proximal neck analysis with the semiautomatic method (p > 0.27). Relevant interobserver variation was observed for semi-automatic measurement of maximum AAA (p = 0.0007) and iliac artery diameters (p = 0.024).
  
  
  CONCLUSIONS
  Dedicated MDCTA software provides a useful tool to minimize aortoiliac diameter measurement variation and to improve imaging precision before AAA repair. For reliable AAA diameter analysis the reader-assisted freehand measurement method is recommended to be applied to a set of reformatted CT data as provided by the software used in this study.
authors.affiliation: Swiss Cardiovascular Center, Divisions of Angiology, Inselspital, University Hospital, Bern, Switzerland. nicolas.diehm@insel.ch
authors.forename: N
authors.initials: N
authors.lastname: Diehm
authors.forename: I
authors.initials: I
authors.lastname: Baumgartner
authors.forename: A
authors.initials: A
authors.lastname: Silvestro
authors.forename: P
authors.initials: P
authors.lastname: Herrmann
authors.forename: J
authors.initials: J
authors.lastname: Triller
authors.forename: J
authors.initials: J
authors.lastname: Schmidli
authors.forename: D D
authors.initials: DD
authors.lastname: Do
authors.forename: H-P
authors.initials: HP
authors.lastname: Dinkel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology*; D001185:Artificial Intelligence; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation