title: Tissue Characterization of In-Stent Neointima Using Optical Coherence Tomography in the Late Phase After Bare-Metal Stent Implantation--An Ex Vivo Validation Study.
abstract: BACKGROUND
  We performed an ex vivo study to investigate optical coherence tomography (OCT) imaging for differentiating several types of neointimal tissue during the later phases after bare-metal stent (BMS) implantation as compared with histologic results.
  
  
  RESULTS
  OCT imaging was performed in 6 autopsy hearts for 10 BMS with implant duration >4 years. OCT qualitative neointimal tissue characterization was based on tissue structure and classified as homogeneous pattern, heterogeneous pattern with visible struts, or heterogeneous pattern with invisible struts. Corresponding histological analyses of each 2-mm cross-section of the entire BMS were performed. Of 81 cross-sections, histological analysis revealed that the homogeneous pattern of neointima on OCT (n=39) contained smooth muscle cells with collagen, indicating high neointimal maturity. The heterogeneous patterns with visible struts (n=35) contained different tissues, including a proteoglycan-rich myxomatous matrix or dense calcified plate deposition. The heterogeneous patterns with invisible struts (n=7) included neointimal lipid/necrotic core formation, accumulation of foam cells, or microcalcification scattering. Of the 66 cross-sections containing large microvessels within the neointima on histology, only 6 (9%) were visualized by OCT.
  
  
  CONCLUSIONS
  The present study confirmed the potential use of OCT in differentiating several types of neointima after BMS implantation. The image interpretation of OCT, based on visualization of stent struts, enables identification of several types of neointimal tissues, including in-stent fibroatheroma formation, more accurately.
authors.affiliation: Cardiovascular Division, Hyogo College of Medicine.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Shibuya
authors.forename: Kenichi
authors.initials: K
authors.lastname: Fujii
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hao
authors.forename: Takahiro
authors.initials: T
authors.lastname: Imanaka
authors.forename: Ten
authors.initials: T
authors.lastname: Saita
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukunaga
authors.forename: Kojiro
authors.initials: K
authors.lastname: Miki
authors.forename: Hiroto
authors.initials: H
authors.lastname: Tamaru
authors.forename: Machiko
authors.initials: M
authors.lastname: Nishimura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Horimatsu
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Naito
authors.forename: Hatsue
authors.initials: H
authors.lastname: Ishibashi-Ueda
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hirota
authors.forename: Tohru
authors.initials: T
authors.lastname: Masuyama
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005487:Foam Cells / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000473:pathology*; D009336:Necrosis; D058426:Neointima / Q000378:metabolism / Q000473:pathology*; D015607:Stents; D041623:Tomography, Optical Coherence