title: Fully automated tool to identify the aorta and compute flow using phase-contrast MRI: validation and application in a large population based study.
abstract: OBJECTIVE
  To assess if fully automated localization of the aorta can be achieved using phase contrast (PC) MR images.
  
  
  METHODS
  PC cardiac-gated MR images were obtained as part of a large population-based study. A fully automated process using the Hough transform was developed to localize the ascending aorta (AAo) and descending aorta (DAo). The study was designed to validate this technique by determining: (i) its performance in localizing the AAo and DAo; (ii) its accuracy in generating AAo flow volume and DAo flow volume; and (iii) its robustness on studies with pathological abnormalities or imaging artifacts.
  
  
  RESULTS
  The algorithm was applied successfully on 1884 participants. In the randomly selected 50-study validation set, linear regression shows an excellent correlation between the automated (A) and manual (M) methods for AAo flow (r = 0.99) and DAo flow (r = 0.99). Bland-Altman difference analysis demonstrates strong agreement with minimal bias for: AAo flow (mean difference [A-M] = 0.47 ± 2.53 mL), and DAo flow (mean difference [A-M] = 1.74 ± 2.47 mL).
  
  
  CONCLUSIONS
  A robust fully automated tool to localize the aorta and provide flow volume measurements on phase contrast MRI was validated on a large population-based study.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA.
authors.forename: Akshay
authors.initials: A
authors.lastname: Goel
authors.forename: Roderick
authors.initials: R
authors.lastname: McColl
authors.forename: Kevin S
authors.initials: KS
authors.lastname: King
authors.forename: Anthony
authors.initials: A
authors.lastname: Whittemore
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Peshock
mesh_terms: D000465:Algorithms; D001011:Aorta / Q000033:anatomy & histology* / Q000502:physiology*; D001027:Aortography / Q000379:methods*; D001783:Blood Flow Velocity / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D001811:Blood Volume Determination / Q000379:methods; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods / Q000592:standards; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software / Q000592:standards*; D012986:Software Validation
keywords: aorta; automatic; localization; phase contrast; segmentation