title: Volumetric characterization of human coronary calcification by frequency-domain optical coherence tomography.
abstract: BACKGROUND
  Coronary artery calcification (CAC) presents unique challenges for percutaneous coronary intervention. Calcium appears as a signal-poor region with well-defined borders by frequency-domain optical coherence tomography (FD-OCT). The objective of this study was to demonstrate the accuracy of intravascular FD-OCT to determine the distribution of CAC.
  
  
  RESULTS
  Cadaveric coronary arteries were imaged using FD-OCT at 100-μm frame interval. Arteries were subsequently frozen, sectioned and imaged at 20-μm intervals using the Case Cryo-Imaging automated system(TM). Full volumetric co-registration between FD-OCT and cryo-imaging was performed. Calcium area, calcium-lumen distance (depth) and calcium angle were traced on every cross-section; volumetric quantification was performed offline. In total, 30 left anterior descending arteries were imaged: 13 vessels had a total of 55 plaques with calcification by cryo-imaging; FD-OCT identified 47 (85%) of these plaques. A total of 1,285 cryo-images were analyzed and compared with corresponding co-registered 257 FD-OCT images. Calcium distribution, represented by the mean depth and the mean calcium angle, was similar, with excellent correlation between FD-OCT and cryo-imaging respectively (mean depth: 0.25±0.09 vs. 0.26±0.12mm, P=0.742; R=0.90), (mean angle: 35.33±21.86° vs. 39.68±26.61°, P=0.207; R=0.90). Calcium volume was underestimated in large calcifications (3.11±2.14 vs. 4.58±3.39mm(3), P=0.001) in OCT vs. cryo respectively.
  
  
  CONCLUSIONS
  Intravascular FD-OCT can accurately characterize CAC distribution. OCT can quantify absolute calcium volume, but may underestimate calcium burden in large plaques with poorly defined abluminal borders.
authors.affiliation: Harrington Heart and Vascular Institute, University Hospitals Case Medical Center, Case Western Reserve University.
authors.forename: Emile
authors.initials: E
authors.lastname: Mehanna
authors.forename: Hiram G
authors.initials: HG
authors.lastname: Bezerra
authors.forename: David
authors.initials: D
authors.lastname: Prabhu
authors.forename: Eric
authors.initials: E
authors.lastname: Brandt
authors.forename: Daniel
authors.initials: D
authors.lastname: Chamié
authors.forename: Hirosada
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Guilherme F
authors.initials: GF
authors.lastname: Attizzani
authors.forename: Satoko
authors.initials: S
authors.lastname: Tahara
authors.forename: Nienke
authors.initials: N
authors.lastname: Van Ditzhuijzen
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Fujino
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Kanaya
authors.forename: Gregory
authors.initials: G
authors.lastname: Stefano
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Madhusudhana
authors.initials: M
authors.lastname: Gargesha
authors.forename: David
authors.initials: D
authors.lastname: Wilson
authors.forename: Marco A
authors.initials: MA
authors.lastname: Costa
mesh_terms: D000368:Aged; D002118:Calcium; D003324:Coronary Artery Disease / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000378:metabolism / Q000473:pathology; D041623:Tomography, Optical Coherence; D061205:Vascular Calcification / Q000378:metabolism / Q000473:pathology
chemical_list: D002118:Calcium