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SU‐C‐18C‐02: Specifcation of X‐Ray Projection Angles Which Are Aligned with the Aortic Valve Plane From a Planar Image of a Valvuloplasty Balloon Inflated Across the Aortic Valve
Author(s) -
Fetterly K,
Mathew V
Publication year - 2014
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4887836
Subject(s) - fluoroscopy , aortic valvuloplasty , aortic valve , orientation (vector space) , medicine , balloon , physics , biomedical engineering , radiology , aortic valve stenosis , geometry , surgery , mathematics
Purpose: Transcatheter aortic valve replacement (TAVR) procedures provide a method to implant a prosthetic aortic valve via a minimallyinvasive, catheter‐based procedure. TAVR procedures require use of interventional fluoroscopy c‐arm projection angles which are aligned with the aortic valve plane to minimize prosthetic valve positioning error due to x‐ray imaging parallax. The purpose of this work is to calculate the continuous range of interventional fluoroscopy c‐arm projection angles which are aligned with the aortic valve plane from a single planar image of a valvuloplasty balloon inflated across the aortic valve. Methods: Computational methods to measure the 3D angular orientation of the aortic valve were developed. Required inputs include a planar x‐ray image of a known valvuloplasty balloon inflated across the aortic valve and specifications of x‐ray imaging geometry from the DICOM header of the image. A‐priori knowledge of the species‐specific typical range of aortic orientation is required to specify the sign of the angle of the long axis of the balloon with respect to the x‐ray beam. The methods were validated ex‐vivo and in a live pig. Results: Ex‐vivo experiments demonstrated that the angular orientation of a stationary inflated valvuloplasty balloon can be measured with precision less than 1 degree. In‐vivo pig experiments demonstrated that cardiac motion contributed to measurement variability, with precision less than 3 degrees. Error in specification of x‐ray geometry directly influences measurement accuracy. Conclusion: This work demonstrates that the 3D angular orientation of the aortic valve can be calculated precisely from a planar image of a valvuloplasty balloon inflated across the aortic valve and known x‐ray geometry. This method could be used to determine appropriate c‐arm angular projections during TAVR procedures to minimize x‐ray imaging parallax and thereby minimize prosthetic valve positioning errors.