title: Spatial distribution and temporal evolution of scattering centers by optical coherence tomography in the poly(L-lactide) backbone of a bioresorbable vascular scaffold.
abstract: BACKGROUND
  Scattering centers (SC) are often observed with optical coherence tomography (OCT) in some struts of bioresorbable vascular scaffolds (BVS). These SC might be caused by crazes in the polymer during crimp-deployment (more frequent at inflection points) or by other processes, such as physiological loading or hydrolysis (eventually increasing with time). The spatial distribution and temporal evolution of SC in BVS might help to understand their meaning.
  
  
  RESULTS
  Three patients were randomly selected from 12 imaged with Fourier-domain OCT at both baseline and 6 months in the ABSORB cohort B study (NCT00856856). Frame-by-frame analysis of the SC distribution was performed using spread-out vessel charts, and the results from baseline and 6 months were compared. A total of 4,328 struts were analyzed. At baseline and follow-up all SC appeared at inflection points. No significant difference was observed between baseline and 6 months in the number of SC struts (14.9 vs. 14.5%, P=0.754) or in the distribution of SC. The proportion and distribution of SC did not vary substantially among the patients analyzed.
  
  
  CONCLUSIONS
  The SC observed in OCT imaging of the BVS are located exclusively at inflection points and do not increase with time. These findings strongly suggest that SC are caused by crazes in the polymer during crimp-deployment, ruling out any major role of hydrolysis or other time-dependent processes.
authors: Erasmus Medical Centre, Thoraxcentre, Interventional Cardiology Department, Rotterdam, The Netherlands.
authors: Juan Luis
authors: JL
authors: Gutiérrez-Chico
authors: Maria D
authors: MD
authors: Radu
authors: Roberto
authors: R
authors: Diletti
authors: Alexander
authors: A
authors: Sheehy
authors: Mary Beth
authors: MB
authors: Kossuth
authors: James P
authors: JP
authors: Oberhauser
authors: Thierry
authors: T
authors: Glauser
authors: Joel
authors: J
authors: Harrington
authors: Richard J
authors: RJ
authors: Rapoza
authors: Yoshinobu
authors: Y
authors: Onuma
authors: Patrick W
authors: PW
authors: Serruys
mesh_terms: D020341:Absorbable Implants; D015906:Angioplasty, Balloon, Coronary; D057791:Cardiac Imaging Techniques / Q000379:methods; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000628:therapy*; D054855:Drug-Eluting Stents; D000068338:Everolimus; D005500:Follow-Up Studies; D006801:Humans; D006868:Hydrolysis; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D011091:Polyesters; D011474:Prosthesis Design; D012042:Registries; D020123:Sirolimus / Q000031:analogs & derivatives / Q000627:therapeutic use; D041623:Tomography, Optical Coherence / Q000379:methods*
chemical_list: D007166:Immunosuppressive Agents; D011091:Polyesters; C033616:poly(lactide); D000068338:Everolimus; D020123:Sirolimus