title: Temporal changes of aortic neck morphology in abdominal aortic aneurysms.
abstract: OBJECTIVE
  This study characterized temporal changes in the infrarenal aortic aneurysm neck in patients with small, untreated abdominal aortic aneurysms (AAA).
  
  
  METHODS
  Patients with infrarenal AAA who had contrast-enhanced computed tomography (CT) scans separated by >6 months were identified and their images reviewed. Infrarenal neck diameter and length were measured along with aneurysm diameter. Comparisons between the interval CT scans were made and analysis of factors affecting neck changes performed.
  
  
  RESULTS
  Sixty patients met inclusion criteria with an imaging interval of 3.8 years (median, 3.4 years; range, 0.75-9.6 years). During the interval, there was an increase in proximal and distal neck diameters of 1.1 mm (SD, 2.2) (0.28 mm/y) and 1.0 mm (SD, 3.0) (0.26 mm/y), respectively. During the same interval, the neck length decreased by 4 mm (SD, 11) (1 mm/y). A neck length of <15 mm was present in 10 patients (17%) at the initial imaging. Four of the remaining 50 patients experienced an interval decrease in neck length to <15 mm, all of whom had initial lengths of 15 to 20 mm. Medications had no association with changes in neck morphology; however, diabetes correlated with a slower rate of neck shortening (P = .001).
  
  
  CONCLUSIONS
  The natural history of the aneurysm neck is one of expansion and shortening that will not affect most patients under surveillance. Patients with marginal neck lengths (range, 15-20 mm) at the initial imaging are more likely to experience loss of neck length that may negatively affect endovascular suitability.
authors.affiliation: San Antonio Military Vascular Surgery Service, Wilford Hall United States Air Force Medical Center, San Antonio, Tex, USA.
authors.forename: Brandon W
authors.initials: BW
authors.lastname: Propper
authors.forename: Todd E
authors.initials: TE
authors.lastname: Rasmussen
authors.forename: W Tracey
authors.initials: WT
authors.lastname: Jones
authors.forename: Shaun M
authors.initials: SM
authors.lastname: Gifford
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Burkhardt
authors.forename: W Darrin
authors.initials: WD
authors.lastname: Clouse
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D002908:Chronic Disease; D015331:Cohort Studies; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D019370:Observation; D011336:Probability; D011856:Radiographic Image Enhancement / Q000379:methods*; D012077:Renal Artery; D012189:Retrospective Studies; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media