title: Sixty-four-detector CT angiography of infrarenal aortic neck length and angulation: prospective analysis of interobserver variability.
abstract: OBJECTIVE
  To quantify the interobserver variability of abdominal aortic aneurysm (AAA) neck length and angulation measurements.
  
  
  METHODS
  A total of 25 consecutive patients scheduled for endovascular AAA repair underwent follow-up 64-row computed tomographic (CT) angiography in 0.625-mm collimation. AAA neck length and angulation were determined by four blinded, independent readers. AAA neck length was defined as the longitudinal distance between the first transverse CT slice directly distal to the lowermost renal artery and the first transverse CT slice that showed at least a 15% larger outer aortic wall diameter versus the diameter measured directly below the lowermost renal artery. Infrarenal AAA neck angulation was defined as the true angle between the longitudinal axis of the proximal AAA neck and the longitudinal axis of the AAA lumen as analyzed on three-dimensional CT reconstructions.
  
  
  RESULTS
  Mean deviation in aortic neck length determination was 32.3% and that in aortic neck angulation was 32.1%. Interobserver variability of aortic neck length and angulation measurements was considerable: in any reader combination, at least one measurement difference was outside the predefined limits of agreement.
  
  
  CONCLUSIONS
  Assessment of the longitudinal extension and angulation of the infrarenal aortic neck is associated with substantial observer variability, even if measurement is carried out according to a standardized protocol. Further studies are mandatory to assess dedicated technical approaches to minimize variance in the determination of the longitudinal extension and angulation of the infrarenal aortic neck.
authors: Baptist Cardiac and Vascular Institute, Miami, Florida, USA. diehm@gmx.ch
authors: Nicolas
authors: N
authors: Diehm
authors: Barry T
authors: BT
authors: Katzen
authors: Shaun
authors: S
authors: Samuels
authors: Constantino
authors: C
authors: Pena
authors: Alex
authors: A
authors: Powell
authors: Florian
authors: F
authors: Dick
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging*; D001027:Aortography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*