title: The abdominal aortic aneurysm sac after endoluminal exclusion: a medium-term morphologic follow-up based on volumetric technology.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the role of three-dimensional spiral computed tomographic angiography (SCTA) for the assessment of the feasibility and results of endoluminal repair of infrarenal abdominal aortic aneurysm.
  
  
  METHODS
  Laboratory studies: Phantom glass aneurysms, filled with contrast, underwent SCTA. The correlation between SCTA and laboratory measurements of linear dimensions and volumes was highly accurate (r(2) = 1.0).
  
  
  METHODS
  From the first 7 patients that were suitable for endoluminal repair, the correlation between SCTA and angiocatheter measurements was 0.85 to 0.99 (P <.04), but there was poor agreement between individual values. As determined from the measurements by 2 experienced investigators, intraobserver and interobserver errors for volume calculation in 12 randomly chosen scans from a total of 120 scans were 5.7 and 4.4 mL, respectively (range of volumes, 100-403 mL). The conditions of 53 patients were judged suitable for endoluminal repair of which 30 patients reached 1 year or more follow-up. The median aneurysm neck length and diameter were 24.5 mm (range, 11.5-60.8 mm) and 23.4 mm (18.3-31.5 mm), respectively. The fate of the sac after endografting by two techniques (pre-expanded polytetrafluoroethylene [PTFE] fixed with Palmaz stents and endografts) was defined with three-dimensional SCTA.
  
  
  RESULTS
  The sac volume after endografting by pre-expanded PTFE (n = 12 patients) showed a significant median increase (P =.02) from 129 mL before surgery to 141 mL at 5 days after the operation with no change at 6 (139 mL), 12 (137 mL), and 18 (159 mL) months later. With the endografts (n = 18), there was an initial increase in median volume at 5 days (179-194 mL; P =.02) and then a significant shrinkage at 6 (148 mL; P =.012) and 12 (94.9 mL; P =.02) months.
  
  
  CONCLUSIONS
  Three-dimensional SCTA has been validated and is both precise and reliable. Interobserver and intraobserver errors are within acceptable ranges. Angiocatheter measurements are less accurate and may give misleading information when used for patient selection and endograft construction. The sac volume increased after endografting and later shrank in patients who were treated with endografts, but not in those patients treated with pre-expanded PTFE. We propose that three-dimensional SCTA should be regarded as the gold standard for linear and volumetric measurement for infrarenal abdominal aortic aneurysm.
authors.affiliation: Vascular Unit and Department of Imaging, University College London Hospitals, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Singh-Ranger
authors.forename: T
authors.initials: T
authors.lastname: McArthur
authors.forename: M D
authors.initials: MD
authors.lastname: Corte
authors.forename: W
authors.initials: W
authors.lastname: Lees
authors.forename: M
authors.initials: M
authors.lastname: Adiseshiah
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015588:Observer Variation; D019047:Phantoms, Imaging; D011138:Polytetrafluoroethylene; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D011138:Polytetrafluoroethylene