title: Intraobserver and interobserver variability of 64-row computed tomography abdominal aortic aneurysm neck measurements.
abstract: BACKGROUND
  Integrity of the abdominal aortic aneurysm (AAA) neck is crucial for the long-term success of endovascular AAA repair (EVAR). However, suitable tools for reliable assessment of changes in small aortic volumes are lacking. The purpose of this study was to assess the intraobserver and interobserver variability of software-enhanced 64-row computed tomographic angiography (CTA) AAA neck volume measurements in patients after EVAR.
  
  
  METHODS
  A total of 25 consecutive patients successfully treated by EVAR underwent 64-row follow-up CTA in 1.5-mm collimation. Manual CTA measurements were performed twice by three blinded and independent readers in random order with at least a 4-week interval between readings. Maximum and minimum transverse aortic neck diameters were measured twice on two different levels within the proximal neck. Volumetry of the proximal aortic neck was performed by using dedicated software. Variability was calculated as 1.96 SD of the mean arithmetic difference according to Bland and Altman. Two-sided and paired t tests were used to compare measurements. P values <.05 were considered to indicate statistical significance.
  
  
  RESULTS
  Intraobserver agreement was excellent for dedicated aneurysmal neck volumetry, with mean differences of less than 1 mL (P > .05), whereas it was poor for transverse aortic neck diameter measurements (P < .05). However, interobserver variability was statistically significant for both neck volumetry (P < .005) and neck diameter measurements (P < .015).
  
  
  CONCLUSIONS
  The reliability of dedicated AAA neck volumetry by using 64-row CTA is excellent for serial measurements by individual readers, but not between different readers. Therefore, studies should be performed with aortic neck volumetry by a single experienced reader.
authors.affiliation: Division of Clinical and Interventional Angiology, Swiss Cardiovascular Center, Inselspital, University Hospital of Bern, Bern, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Diehm
authors.forename: Ralph
authors.initials: R
authors.lastname: Kickuth
authors.forename: Brigitta
authors.initials: B
authors.lastname: Gahl
authors.forename: Dai-Do
authors.initials: DD
authors.lastname: Do
authors.forename: Jürg
authors.initials: J
authors.lastname: Schmidli
authors.forename: Henning
authors.initials: H
authors.lastname: Rattunde
authors.forename: Iris
authors.initials: I
authors.lastname: Baumgartner
authors.forename: Florian
authors.initials: F
authors.lastname: Dick
mesh_terms: D000368:Aged; D017130:Angioplasty; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery; D001027:Aortography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012984:Software; D013557:Switzerland; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome