title: Interobserver variability in physician-modified endograft planning by comparison with a three-dimensional printed aortic model.
abstract: BACKGROUND
  With the increasing application of fenestrated and physician-modified endografting for aneurysm repair, there is increasing concern about the accuracy of vessel position measurements based on computed tomography scans. Inaccuracies in measurements may result in a "window-shutter" or "eclipsing" phenomenon whereby the fenestration may not overlie the vessel ostium completely. We hypothesized that vessel position measurements from reconstructed imaging do not represent the true vessel position as obtained from a three-dimensional (3D) printed physical model of the visceral aortic segment.
  
  
  METHODS
  Medical 3D modeling software was used to develop the 3D reconstructions, which were then exported to the 3D printing software. This allowed 3D models to be physically generated. The distances to the top and bottom and the angle of each of the celiac, superior mesenteric, right renal, and left renal arteries were recorded. These same measurements were obtained by each of the blinded reviewers in addition to the aortic diameter at the midpoint of each of these vessels. Measurements were compared with intraclass correlation coefficient, nonparametric Spearman rank correlation test, and one-sample t-test to assess accuracy and precision. Statistical significance was set at P < .05 for all tests.
  
  
  RESULTS
  Both the individual measurements and the average of the measurements were statistically accurate (significant) for the bottom of the superior mesenteric artery and the top and bottom of both the right and left renal arteries. There was variability and inaccuracy in all visceral vessel angles and in the bottom of the celiac artery (the top and the angle of the celiac artery were the arbitrary referents).
  
  
  CONCLUSIONS
  Whereas the visceral vessel orifices are largely accurately assessed and measured, the vessel angles are not. This may lead to an eclipsing phenomenon, which may contribute to branch or fenestrated vessel failure and therefore reintervention. Further efforts should assess the clinical significance of the eclipsing phenomenon and should target accurate and appropriate fenestration construction to prevent long-term morbidity.
authors.affiliation: Department of Vascular Surgery, Greenville Health Systems, Greenville, SC.
authors.forename: Issam
authors.initials: I
authors.lastname: Koleilat
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC.
authors.forename: Michael
authors.initials: M
authors.lastname: Jaeggli
authors.affiliation: Department of Vascular Surgery, Greenville Health Systems, Greenville, SC.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Ewing
authors.affiliation: Department of Vascular Surgery, Greenville Health Systems, Greenville, SC. Electronic address: mandroes@ghs.org.
authors.forename: Mark
authors.initials: M
authors.lastname: Androes
authors.affiliation: Department of Bioengineering, Clemson University, Clemson, SC.
authors.forename: Dan T
authors.initials: DT
authors.lastname: Simionescu
authors.affiliation: Department of Vascular Surgery, Greenville Health Systems, Greenville, SC.
authors.forename: John
authors.initials: J
authors.lastname: Eidt
mesh_terms: D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery*; D001027:Aortography / Q000379:methods*; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D000072226:Computed Tomography Angiography; D017076:Computer-Aided Design; D016208:Databases, Factual; D057510:Endovascular Procedures / Q000295:instrumentation*; D006801:Humans; D008953:Models, Anatomic; D015588:Observer Variation; D066230:Patient-Specific Modeling; D010820:Physicians; D011237:Predictive Value of Tests; D066330:Printing, Three-Dimensional; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012189:Retrospective Studies