title: Head to head comparison of optical coherence tomography, intravascular ultrasound echogenicity and virtual histology for the detection of changes in polymeric struts over time: insights from the ABSORB trial.
abstract: OBJECTIVE
  To analyse and to compare the changes in the various optical coherence tomography (OCT), echogenicity and intravascular ultrasound virtual histology (VH) of the everolimus-eluting bioresorbable scaffold (ABSORB) degradation parameters during the first 12 months after ABSORB implantation. In the ABSORB study, changes in the appearance of the ABSORB scaffold were monitored over time using various intracoronary imaging modalities. The scaffold struts exhibited a progressive change in their black core area by OCT, in their ultrasound derived grey level intensity quantified by echogenicity, and in their backscattering ultrasound signal, identified as "pseudo dense-calcium" (DC) by VH.
  
  
  RESULTS
  From the ABSORB Cohort B trial 35 patients had paired OCT, echogenicity and VH assessment at baseline and at six- (n=18) or 12-months follow-up (n=17). Changes in OCT strut core area, hyperechogenicity and VH-derived DC were analysed and compared at the various time points. At six months, the change (median[IQR]) in OCT strut core area was -7.2% (-14.0-+0.9) (p=0.053), in hyperechogenicity -12.7% (-33.7-+1.4) (p=0.048) and VH-DC 22.1% (-10.8-+48.8) (p=0.102). At 12 months, all the imaging modalities showed a decrease in the various parameters considered (OCT: -12.2% [-17.5--1.9], p=0.093; hyperechogenicity -24.64% [-36.6--16.5], p=0.001; VH-DC: -24.66% [-32.0--7.0], p=0.071). However, the correlation between the relative changes in these parameters was statistically poor (Spearman's rho <0.4).
  
  
  CONCLUSIONS
  OCT, echogenicity and VH were able to detect changes in the ABSORB scaffold struts, although the correlation between those changes was poor. This is likely due to the fact that each imaging modality interrogates different material properties on different length scales. Further studies are needed to explore these hypotheses.
authors: Thoraxcenter, Erasmus MC, 'sGravendijkwal 230, Rotterdam, The Netherlands.
authors: Salvatore
authors: S
authors: Brugaletta
authors: Josep
authors: J
authors: Gomez-Lara
authors: Nico
authors: N
authors: Bruining
authors: Maria D
authors: MD
authors: Radu
authors: Robert-Jan
authors: RJ
authors: van Geuns
authors: Leif
authors: L
authors: Thuesen
authors: Dougal
authors: D
authors: McClean
authors: Jacques
authors: J
authors: Koolen
authors: Stephan
authors: S
authors: Windecker
authors: Robert
authors: R
authors: Whitbourn
authors: James
authors: J
authors: Oberhauser
authors: Richard
authors: R
authors: Rapoza
authors: John A
authors: JA
authors: Ormiston
authors: Hector M
authors: HM
authors: Garcia-Garcia
authors: Patrick W
authors: PW
authors: Serruys
mesh_terms: D020341:Absorbable Implants; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000379:methods*; D003324:Coronary Artery Disease / Q000628:therapy*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology*; D000068338:Everolimus; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives; D054457:Tissue Scaffolds; D041623:Tomography, Optical Coherence; D018084:Ultrasonography, Interventional
chemical_list: D000068338:Everolimus; D020123:Sirolimus