title: Determination of adequate coronary stent expansion using StentBoost, a novel fluoroscopic image processing technique.
abstract: OBJECTIVE
  We tested the hypothesis that the use of motion-corrected fluoroscopic images results in enhanced coronary stent visualization and improved detection of inadequate stent expansion.
  
  
  BACKGROUND
  Intravascular ultrasound (IVUS) more accurately detects inadequate stent expansion when compared with coronary angiography. Stent under-expansion is associated with stent restenosis and thrombosis. Developing a technique to improve fluoroscopic-based assessment of stent expansion is desirable.
  
  
  METHODS
  We analyzed measurements of 48 coronary stents implanted in 30 patients using quantitative coronary angiography (QCA), IVUS, and StentBoost (SB), a novel fluoroscopic image processing technique. Correlations of stent diameter between the modalities were determined. Using established IVUS criteria for adequate stent deployment, we assessed the diagnostic test characteristics of SB to detect inadequate stent expansion.
  
  
  RESULTS
  Correlations of minimum stent diameter were highest between IVUS and SB (r=0.75; P<0.0001) when compared with QCA and IVUS (r=0.65; P<0.0001), and QCA and SB (r=0.49; P=0.0004). IVUS and SB demonstrated a small difference in minimum stent diameter, 0.043 mm (95% CI: 0.146-0.061 mm). The correlation between IVUS and SB was lower for vessels with intimal calcification (r=0.57; P=0.002) when compared with vessels with deeper calcification (r=0.84; P<0.0001). A SB minimum diameter of <2.5 mm predicted inadequate stent expansion by IVUS with 88% sensitivity, 70% specificity, and a positive likelihood ratio of 2.9.
  
  
  CONCLUSIONS
  SB had superior correlations for stent expansion measured by IVUS when compared with QCA. A minimum stent diameter by SB measurement<2.5 mm is associated with inadequate stent expansion using IVUS criteria.
authors.affiliation: Division of Cardiology, Department of Medicine, University of California, San Francisco, California, USA.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Mishell
authors.forename: Kalpesh T
authors.initials: KT
authors.lastname: Vakharia
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Ports
authors.forename: Yerem
authors.initials: Y
authors.lastname: Yeghiazarians
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Michaels
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000628:therapy*; D005260:Female; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D015641:Radiography, Interventional; D015607:Stents; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional