title: CT artifacts of the proximal aortic neck: an important problem in endograft planning.
abstract: OBJECTIVE
  To describe the imaging error introduced by noncircular abdominal aortic aneurysm (AAA) necks in axial and reformatted computed tomographic (CT) images and discuss the potential implications for aortic endografting.
  
  
  METHODS
  The records of 120 endograft patients with preoperative CT axial scans and subsequent 3-dimensional (3D) computerized reconstructions were reviewed. Maximum and minimum infrarenal aortic neck diameters were measured from axial CT scans and 3D reformatted slices at the same point on the vessel. Diameter measurements were made at the largest point within the 10-mm segment of vessel below the lowest renal artery. Excluded were aneurysms with proximal neck minimum diameters >30 mm, neck lengths < 15 mm, or angulation > 75 degrees measured on the axial CT slice.
  
  
  RESULTS
  Measuring from reformatted CT slices, 86 (71.6%) cases had < or = 2-mm differences between maximal and minimal neck diameters, comprising the "round neck" group A. In 34 (28.4%) cases, the neck was not round: 26 (21.7%) had diameter differences between 2 and 4 mm (group B) and 8 (6.7%) had a > 4-mm difference (group C; range 4.1-8.1 mm). Although AAA diameter, neck length, and neck angle progressively increased as the difference between neck maximum and minimum diameters grew, i.e., greater eccentricity, these trends did not reach statistical significance. Mean infrarenal neck maximum diameter was significantly larger in group C (30.2 +/- 3.4 mm) compared to groups A (23.0 +/- 2.9 mm, p = 0.0002) and B (23.8 +/- 3.6 mm, p = 0.0003). Hence, 28.4% of AAAs had a noncircular aortic neck of varying degree, and 6.7% had an eccentricity factor that may have clinical significance.
  
  
  CONCLUSIONS
  This study confirms the importance of selecting an endoprosthesis sized 15% to 20% larger than the infrarenal aortic neck diameter. Three-dimensional reconstruction using reformatted CT slices perpendicular to the flow lumen is an important tool that offers enhanced accuracy of infrarenal aortic neck evaluation.
authors.affiliation: Jobst Vascular Center, Toledo, Ohio 43606, USA.
authors.forename: Boonprasit
authors.initials: B
authors.lastname: Kritpracha
authors.forename: Jeremy
authors.initials: J
authors.lastname: Wolfe
authors.forename: Hugh G
authors.initials: HG
authors.lastname: Beebe
mesh_terms: D000792:Angiography / Q000379:methods*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery; D016477:Artifacts; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011182:Postoperative Care; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012042:Registries; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*