title: Measurement of in vitro and in vivo stent geometry and deformation by means of 3D imaging and stereo-photogrammetry.
abstract: OBJECTIVE
  To quantify variability of in vitro and in vivo measurement of 3D device geometry using 3D and biplanar imaging.
  
  
  METHODS
  Comparison of stent reconstruction is reported for in vitro coronary stent deployment (using micro-CT and optical stereo-photogrammetry) and in vivo pulmonary valve stent deformation (using 4DCT and biplanar fluoroscopy). Coronary stent strut length and inter-strut angle were compared in the fully deployed configuration. Local (inter-strut angle) and global (dog-boning ratio) measures of stent deformation were reported during stent deployment. Pulmonary valve stent geometry was assessed throughout the cardiac cycle by reconstruction of stent geometry and measurement of stent diameter.
  
  
  RESULTS
  Good agreement was obtained between methods for assessment of coronary stent geometry with maximum disagreement of +/- 0.03 mm (length) and +/- 3 degrees (angle). The stent underwent large, non-uniform, local deformations during balloon inflation, which did not always correlate with changes in stent diameter. Three-dimensional reconstruction of the pulmonary valve stent was feasible for all frames of the fluoroscopy and for 4DCT images, with good correlation between the diameters calculated from the two methods. The largest compression of the stent during the cardiac cycle was 6.98% measured from fluoroscopy and 7.92% from 4DCT, both in the most distal ring.
  
  
  CONCLUSIONS
  Quantitative assessment of stent geometry reconstructed from biplanar imaging methods in vitro and in vivo has shown good agreement with geometry reconstructed from 3D techniques. As a result of their short image acquisition time, biplanar methods may have significant advantages in the measurement of dynamic 3D stent deformation.
authors.affiliation: 2 Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield - UK.
authors.forename: Iwona
authors.initials: I
authors.lastname: Zwierzak
authors.forename: Daria
authors.initials: D
authors.lastname: Cosentino
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Narracott
authors.forename: Philipp
authors.initials: P
authors.lastname: Bonhoeffer
authors.forename: Vanessa
authors.initials: V
authors.lastname: Diaz
authors.forename: John W
authors.initials: JW
authors.lastname: Fenner
authors.forename: Silvia
authors.initials: S
authors.lastname: Schievano
mesh_terms: D000328:Adult; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation*; D057176:Compassionate Use Trials; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D056973:Four-Dimensional Computed Tomography; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008422:Materials Testing; D061330:Multidetector Computed Tomography; D010780:Photogrammetry; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011664:Pulmonary Valve / Q000000981:diagnostic imaging / Q000503:physiopathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D015607:Stents; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome; D055114:X-Ray Microtomography