title: Endovascular AAA repair: classification of aneurysm sac volumetric change using spiral computed tomographic angiography.
abstract: OBJECTIVE
  To classify and analyze the volumetric changes seen on spiral computed tomographic angiography (CTA) following endovascular abdominal aortic aneurysm (AAA) repair.
  
  
  METHODS
  Fifty patients (46 men; mean age 71 years, range 51-83) with >1 year of imaging follow-up were retrospectively selected. The volume of the aneurysm sac was calculated on standard CT workstations to obtain plots of volume changes over time. For the purpose of this study, a 10% change in sac volume was considered significant.
  
  
  RESULTS
  Over a mean 32-month follow-up, 256 CTA scans were performed; initial mean sac volume was 259 mL and initial mean AAA diameter was 6.5 cm. Six distinct patterns of volume change were recognized: group Ia (28 patients, 56%): progressive reduction in aneurysm sac volume; group Ib (3 patients, 6%): transient initial increase then same as Ia; group II (4 patients, 8%): no significant change; group IIIa (5 patients, 10%): late increase in volume; group IIIb (8 patients, 16%): progressive increase in volume; and group IV (2 patients, 4%): late reduction in volume after secondary intervention. Group III changes were associated with endoleak types I and III (p<0.0001).
  
  
  CONCLUSIONS
  This classification system of spiral CTA volumetric changes features 6 patterns with recognized clinical significance and predictive value for endoleaks. Group I is the ideal outcome when the aneurysm sac shrinks and often completely disappears, while group III is associated with types I and type III endoleak and should prompt further investigation. Long-term volumetric analysis of all patients is advised.
authors: Department of Clinical Radiology, Queens Medical Center, University Hospital, Nottingham, UK.
authors: John G
authors: JG
authors: Pollock
authors: Simon J
authors: SJ
authors: Travis
authors: Simon C
authors: SC
authors: Whitaker
authors: Ian R
authors: IR
authors: Davidson
authors: Roger H S
authors: RH
authors: Gregson
authors: Brian R
authors: BR
authors: Hopkinson
authors: Peter W
authors: PW
authors: Wenham
authors: Shane T
authors: ST
authors: MacSweeney
mesh_terms: D000368:Aged; D000792:Angiography; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000628:therapy*; D019917:Blood Vessel Prosthesis Implantation; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015607:Stents; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods