title: Identification and quantification of macrophage presence in coronary atherosclerotic plaques by optical coherence tomography.
abstract: OBJECTIVE
  Vulnerable plaques are characterized by a high macrophage content. We investigated the optical coherence tomography (OCT) capability of identifying coronary plaque macrophage presence using tissue property indexes.
  
  
  RESULTS
  Fifteen epicardial coronary arteries were imaged by OCT and subsequently analysed by histology. Correlating OCT-histological sections were identified and regions of interest (ROIs) were selected on both atherosclerotic plaques and normal appearing vessel tracts. OCT-derived tissue property indexes named normalized standard deviation (NSD), signal attenuation, and granulometry index were applied on ROIs to identify inflamed ROIs defined as a macrophage percentage >10 by histology. Forty-three paired samples (OCT frame and histology section) were considered suitable as ROIs for analysis. Eleven out of 43 ROIs were considered inflamed and the remaining 32 ROIs were non-inflamed on the basis of histological count of macrophage percentage. All OCT-derived tissue property indexes were positively correlated with macrophage percentage (P = 0.0001 for all). Receiver operating characteristic curve analysis showed that NSD, granulometry index, and signal attenuation had a significant area under the curve (area = 0.906, 0.804, and 0.793, respectively). A two-step algorithm requiring to first apply NSD with a cut-off value of 0.0570 followed by granulometry index was able to identify an inflamed ROI with a sensitivity of 100% and a specificity of 96.8%.
  
  
  CONCLUSIONS
  OCT was able to identify and quantify macrophage presence in coronary artery specimens using tissue property indexes. NSD and granulometry index showed the highest accuracy in identifying a significant plaque inflammation, especially if used together in a two-step algorithm.
authors.affiliation: Interventional Cardiology Unit, San Giovanni Addolorata Hospital, Via dell'Amba Aradam 8, 00184 Rome, Italy CLI Foundation, Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Di Vito
authors.affiliation: Centre for Inherited Cardiovascular Diseases, Policlinico San Matteo, Pavia, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Agozzino
authors.affiliation: CLI Foundation, Rome, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Marco
authors.affiliation: CLI Foundation, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ricciardi
authors.affiliation: Centre for Inherited Cardiovascular Diseases, Policlinico San Matteo, Pavia, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Concardi
authors.affiliation: CLI Foundation, Rome, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Romagnoli
authors.affiliation: Interventional Cardiology Unit, San Giovanni Addolorata Hospital, Via dell'Amba Aradam 8, 00184 Rome, Italy CLI Foundation, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Gatto
authors.affiliation: Centre for Inherited Cardiovascular Diseases, Policlinico San Matteo, Pavia, Italy.
authors.forename: Giordano
authors.initials: G
authors.lastname: Calogero
authors.affiliation: GVM Care and Research, Maria Cecilia Hospital, Ettore Sansavini Health Science Foundation, Cotignola, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Tavazzi
authors.affiliation: Centre for Inherited Cardiovascular Diseases, Policlinico San Matteo, Pavia, Italy.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Arbustini
authors.affiliation: Interventional Cardiology Unit, San Giovanni Addolorata Hospital, Via dell'Amba Aradam 8, 00184 Rome, Italy CLI Foundation, Rome, Italy fprati@hsangiovanni.roma.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Prati
mesh_terms: D000368:Aged; D003331:Coronary Vessels / Q000473:pathology* / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000648:ultrastructure*; D008297:Male; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D012372:ROC Curve; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D020858:Tissue and Organ Harvesting; D041623:Tomography, Optical Coherence / Q000379:methods*; D014463:Ultrasonography
keywords: macrophage; normalized standard deviation; optical coherence tomography; vulnerable plaque