title: Contrast inhomogeneity in CT angiography of the abdominal aortic aneurysm.
abstract: BACKGROUND
  If undetected, infrarenal Abdominal Aortic Aneurysm (AAA) growth can lead to rupture, a high-mortality complication. Some AAA patients exhibit inhomogeneous luminal contrast attenuation at first-pass CT angiography (CTA). This study assesses the association between this observation and aneurysm growth.
  
  
  METHODS
  Sixty-seven consecutive pre-repair AAA CTAs were included in this retrospective study. The "Gravitational Gradient" (GG), defined as the ratio of the mean attenuation in a region-of-interest placed posteriorly to that in a region-of-interest placed anteriorly within the lumen of the aortic aneurysm on a single axial slice, and the maximum aneurysm diameter were measured from each CT data set. "AAA Contrast Inhomogeneity" was defined as the absolute value of the difference between the GG and 1.0. Univariate and multivariate logistic regression was used to assess the association of aneurysm growth >0.4 and >1.0 cm/year to AAA Contrast Inhomogeneity, aneurysm diameter, patient characteristics and cardiovascular co-morbidities.
  
  
  RESULTS
  AAA Contrast Inhomogeneity was not correlated to aneurysm diameter (p = 0.325). In multivariable analysis that included initial aneurysm diameter and AAA Contrast Inhomogeneity, both factors were significantly associated with rapid aneurysm growth (initial diameter: p = 0.029 and 0.011, and, AAA Contrast Inhomogeneity: p = 0.045 and 0.048 for growth >0.4 cm/year and >1 cm/year respectively).
  
  
  CONCLUSIONS
  AAA Contrast Inhomogeneity is a common observation in first-pass CTA. It is associated with rapid aneurysm growth, independent of aneurysm diameter.
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: George
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Andreas A
authors.initials: AA
authors.lastname: Giannopoulos
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Ayaz
authors.initials: A
authors.lastname: Aghayev
authors.affiliation: Department of Radiology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Rohatgi
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Imanzadeh
authors.affiliation: Cardiovascular Centre, Guy's and St Thomas NHS Foundation Trust, London, UK.
authors.forename: Antonios P
authors.initials: AP
authors.lastname: Antoniadis
authors.affiliation: Department of Radiology, Juntendo University, Tokyo, Japan.
authors.forename: Kanako K
authors.initials: KK
authors.lastname: Kumamaru
authors.affiliation: Cardiovascular Division, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Yiannis S
authors.initials: YS
authors.lastname: Chatzizisis
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Ruth
authors.initials: R
authors.lastname: Dunne
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Steigner
authors.affiliation: Department of Radiology, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Hanley
authors.affiliation: Division of Vascular Surgery, Brigham & Women's Hospital, Boston, MA, USA.
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Gravereaux
authors.affiliation: The Ottawa Hospital Research Institute and Department of Radiology, The University of Ottawa, Ontario, ON, Canada.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Rybicki
authors.affiliation: Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA. Electronic address: dmitsouras@partners.org.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Mitsouras
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging*; D001027:Aortography / Q000379:methods*; D000072226:Computed Tomography Angiography; D018450:Disease Progression; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Abdominal aortic aneurysm; Aneurysm growth; CT angiography; Contrast inhomogeneity; Risk stratification