title: In vivo quantification of murine aortic cyclic strain, motion, and curvature: implications for abdominal aortic aneurysm growth.
abstract: OBJECTIVE
  To develop methods to quantify cyclic strain, motion, and curvature of the murine abdominal aorta in vivo.
  
  
  METHODS
  C57BL/6J and apoE(-/-) mice underwent three-dimensional (3D) time-of-flight MR angiography to position cardiac-gated 2D slices at four locations along the abdominal aorta where circumferential cyclic strain and lumen centroid motion were calculated. From the 3D data, a centerline through the aorta was created to quantify geometric curvature at 0.1-mm intervals. Medial elastin content was quantified with histology postmortem. The location and shape of abdominal aortic aneurysms (AAAs), created from angiotensin II infusion, were evaluated qualitatively.
  
  
  RESULTS
  Strain waveforms were similar at all locations and between groups. Centroid motion was significantly larger and more leftward above the renal vessels than below (P < 0.05). Maximum geometric curvature occurred slightly proximal to the right renal artery. Elastin content was similar around the circumference of the vessel. AAAs developed in the same location as the maximum curvature and grew in the same direction as vessel curvature and motion.
  
  
  CONCLUSIONS
  The methods presented provide temporally and spatially resolved data quantifying murine aortic motion and curvature in vivo. This noninvasive methodology will allow serial quantification of how these parameters influence the location and direction of AAA growth.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California 94305-5431, USA. cgoergen@stanford.edu
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Goergen
authors.forename: Kyla N
authors.initials: KN
authors.lastname: Barr
authors.forename: Diem T
authors.initials: DT
authors.lastname: Huynh
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Eastham-Anderson
authors.forename: Gilwoo
authors.initials: G
authors.lastname: Choi
authors.forename: Maj
authors.initials: M
authors.lastname: Hedehus
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Dalman
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Connolly
authors.forename: Charles A
authors.initials: CA
authors.lastname: Taylor
authors.forename: Philip S
authors.initials: PS
authors.lastname: Tsao
authors.forename: Joan M
authors.initials: JM
authors.lastname: Greve
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001012:Aorta, Abdominal / Q000503:physiopathology*; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology*; D001057:Apolipoproteins E / Q000235:genetics; D004549:Elastin / Q000378:metabolism; D005838:Genotype; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009038:Motion; D013997:Time Factors
chemical_list: D001057:Apolipoproteins E; D000804:Angiotensin II; D004549:Elastin