title: Assessment of three-dimensional stent-graft dynamics by using fluoroscopic roentgenographic stereophotogrammetric analysis.
abstract: OBJECTIVE
  To validate the use of fluoroscopic roentgenographic stereophotogrammetric analysis (FRSA) for its feasibility and accuracy for measuring the three-dimensional dynamic motion of stent grafts.
  
  
  METHODS
  A digital biplane fluoroscopy setup was calibrated (Siemens Axiom Artis dBc). Stereo images were acquired of a static aortic model with a stent graft in different axial positions, imposed by a micromanipulator. The three-dimensional measurement error of FRSA was determined by comparing FRSA measurements with the micromanipulator. An aortic model with a stent graft was constructed and connected to an artificial circulation with a physiological flow and pressure profile. Markers were added to the spine (tantalum spherical markers; diameter 1 mm) and stent (welding tin; diameter 1 mm). The three-dimensional measurement precision was determined by measuring the position of a single (stable) spine marker during two pulsatile cycles. Finally, three-dimensional stent marker motion was analyzed with a frame rate of 30 images per second, including three-dimensional marker position (change), diameter change, and center of circle position change.
  
  
  RESULTS
  The mean error of FRSA measurement of displacement was 0.003 mm (SD, 0.019 mm; maximum error, 0.058 mm). A very high precision of position measurement was found (SD, 0.009-0.015 mm). During pulsatile motion, the position (changes) of the markers could be assessed in the x, y, and z directions, as well as the stent diameter change and center of circle position change.
  
  
  CONCLUSIONS
  FRSA has proven to be a method with very high accuracy and temporal resolution to measure three-dimensional stent-graft motion in a pulsatile environment. This technique has the potential to contribute significantly to the knowledge of stent-graft behavior after endovascular aneurysm repair and improvements in stent-graft design. The technique is ready for clinical testing.
authors.affiliation: Department of Surgery, Division of Vascular Surgery, Leiden University Medical Center, Leiden, The Netherlands. o.koning@jbz.nl
authors.forename: Olivier H J
authors.initials: OH
authors.lastname: Koning
authors.forename: Bart L
authors.initials: BL
authors.lastname: Kaptein
authors.forename: Eric H
authors.initials: EH
authors.lastname: Garling
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Hinnen
authors.forename: Jaap F
authors.initials: JF
authors.lastname: Hamming
authors.forename: Edward R
authors.initials: ER
authors.lastname: Valstar
authors.forename: J H
authors.initials: JH
authors.lastname: van Bockel
mesh_terms: D000818:Animals; D001011:Aorta; D001696:Biomechanical Phenomena; D001807:Blood Vessel Prosthesis; D003198:Computer Simulation; D005471:Fluoroscopy; D006801:Humans; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D009068:Movement; D010780:Photogrammetry; D011673:Pulsatile Flow; D015607:Stents; D034421:Sus scrofa