title: Ex vivo assessment of vascular response to coronary stents by optical frequency domain imaging.
abstract: OBJECTIVE
  This study sought to examine the capability of optical frequency domain imaging (OFDI) to characterize various morphological and histological responses to stents implanted in human coronary arteries.
  
  
  BACKGROUND
  A precise assessment of vascular responses to stents may help stratify the risk of future adverse events in patients who have been treated with coronary stents.
  
  
  METHODS
  Fourteen human stented coronary segments with implant duration ≥ 1 month from 10 hearts acquired at autopsy were interrogated ex vivo by OFDI and intravascular ultrasound (IVUS). Comparison with histology was assessed in 134 pairs of images where the endpoints were to investigate: 1) accuracy of morphological measurements; 2) detection of uncovered struts; and 3) characterization of neointima.
  
  
  RESULTS
  Although both OFDI and IVUS provided a good correlation of neointimal area with histology, the correlation of minimum neointimal thickness was inferior in IVUS (R(2) = 0.39) as compared with OFDI (R(2) = 0.67). Similarly, IVUS showed a weak correlation of the ratio of uncovered to total stent struts per section (RUTSS) (R(2) = 0.24), whereas OFDI maintained superiority (R(2) = 0.66). In a more detailed analysis by OFDI, identification of individual uncovered struts demonstrated a sensitivity of 77.9% and specificity of 96.4%. Other important morphological features such as fibrin accumulation, excessive inflammation (hypersensitivity), and in-stent atherosclerosis were characterized by OFDI; however, the similarly dark appearance of these tissues did not allow for direct visual discrimination. The quantitative analysis of OFDI signal reflections from various in-stent tissues demonstrated distinct features of organized thrombus and accumulation of foamy macrophages.
  
  
  CONCLUSIONS
  The results of the present study reinforce the potential of OFDI to detect vascular responses that may be important for the understanding of long-term stent performance, and indicate the capability of this technology to serve as a diagnostic indicator of clinical success.
authors.affiliation: CVPath Institute, Gaithersburg, Maryland 20878, USA.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakano
authors.forename: Marc
authors.initials: M
authors.lastname: Vorpahl
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Otsuka
authors.forename: Masanori
authors.initials: M
authors.lastname: Taniwaki
authors.forename: Saami K
authors.initials: SK
authors.lastname: Yazdani
authors.forename: Aloke V
authors.initials: AV
authors.lastname: Finn
authors.forename: Elena R
authors.initials: ER
authors.lastname: Ladich
authors.forename: Frank D
authors.initials: FD
authors.lastname: Kolodgie
authors.forename: Renu
authors.initials: R
authors.lastname: Virmani
mesh_terms: D000328:Adult; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects* / Q000295:instrumentation*; D001344:Autopsy; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D006965:Hyperplasia; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D015607:Stents; D013997:Time Factors; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology*; D018084:Ultrasonography, Interventional