title: Respiratory-induced 3D deformations of the renal arteries quantified with geometric modeling during inspiration and expiration breath-holds of magnetic resonance angiography.
abstract: OBJECTIVE
  To quantify renal artery deformation due to respiration using magnetic resonance (MR) image-based geometric analysis.
  
  
  METHODS
  Five males were imaged with contrast-enhanced MR angiography during inspiratory and expiratory breath-holds. From 3D models of the abdominal aorta, left and right renal arteries (LRA and RRA), we quantified branching angle, curvature, peak curve angle, axial length, and locations of branch points.
  
  
  RESULTS
  With expiration, maximum curvature changes were 0.054 ± 0.025 mm(-1) (P < 0.01), and curve angle at the most proximal curvature peak increased by 8.0 ± 4.5° (P < 0.05) in the LRA. Changes in maximum curvature and curve angles were not significant in the RRA. The first renal bifurcation point translated superiorly and posteriorly by 9.7 ± 3.6 mm (P < 0.005) and 3.5 ± 2.1 mm (P < 0.05), respectively, in the LRA, and 10.8 ± 6.1 mm (P < 0.05) and 3.6 ± 2.5 mm (P < 0.05), respectively, in the RRA. Changes in branching angle, axial length, and renal ostia locations were not significant.
  
  
  CONCLUSIONS
  The LRA and RRA deformed and translated significantly. Greater deformation of the LRA as compared to the RRA may be due to asymmetric anatomy and mechanical support by the inferior vena cava. The presented methodology can extend to quantification of deformation of diseased and stented arteries to help renal artery implant development.
authors.affiliation: Department of Surgery, Stanford University, Stanford, California, USA.
authors.forename: Ga-Young
authors.initials: GY
authors.lastname: Suh
authors.forename: Gilwoo
authors.initials: G
authors.lastname: Choi
authors.forename: Mary T
authors.initials: MT
authors.lastname: Draney
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Herfkens
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Dalman
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D062485:Breath Holding; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D045853:Exhalation / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D001239:Inhalation / Q000502:physiology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008954:Models, Biological; D012077:Renal Artery / Q000033:anatomy & histology* / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Renal artery; geometric modeling; magnetic resonance angiography; respiratory deformation; vascular implants
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