title: Balloon Valvuloplasty to Predict X-ray Projection Angles that are Perpendicular to Cardiovascular Structures: A TAVI Patient Feasibility Study.
abstract: OBJECTIVE
  The purpose of this work is to describe methods to measure the 3D angular orientation of cardiovascular structures based on a planar image of a valvuloplasty balloon. These methods facilitate X-ray beam alignment with respect to the anatomy of interest.
  
  
  BACKGROUND
  X-ray beam projections which are perpendicular to the long axis of cardiovascular structures are required to support interventional procedures, including transcatheter aortic valve implant (TAVI).
  
  
  METHODS
  During the TAVI procedure, the 3D angular orientation of the LVOT of 10 patients was measured from a single planar image of an aortic valvuloplasty balloon and the continuous range of X-ray projection angles which are aligned with the aortic valve plane were calculated (research method). Misalignment of the X-ray beam and TAVI valve frame was measured from images of the deployed valve. The accuracy of the research method was compared to clinical standard method to determine appropriate X-ray projection angles, which utilized CT and aortography.
  
  
  RESULTS
  Using the clinical standard method, the median misalignment of the X-ray beam and TAVI valve frame was 8.6° (range 2.6° to 21°). Misalignment was reduced to 2.5° (range 0° to 10°) using the research method.
  
  
  CONCLUSIONS
  The 3D angular orientation of cardiovascular structures can be measured accurately from a single X-ray projection image of a known cardiovascular device contained within the anatomy of interest. For TAVI procedures, improved X-ray beam alignment may help facilitate procedural success. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Cardivascular Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Fetterly
authors.affiliation: Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Kevin
authors.initials: K
authors.lastname: Greason
authors.affiliation: Cardivascular Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Verghese
authors.initials: V
authors.lastname: Mathew
mesh_terms: D059925:Anatomic Landmarks; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000601:surgery*; D001027:Aortography / Q000379:methods*; D063126:Balloon Valvuloplasty / Q000295:instrumentation; D000072226:Computed Tomography Angiography; D005240:Feasibility Studies; D006350:Heart Valve Prosthesis; D006801:Humans; D021621:Imaging, Three-Dimensional; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D065467:Transcatheter Aortic Valve Replacement / Q000295:instrumentation; D016896:Treatment Outcome
keywords: aortic balloon valvuloplasty; aortography; transcatheter aortic valve implant