title: Contrast enhancement of coronary arteries in cardiac surgery: a new multispectral stereoscopic camera technique.
abstract: OBJECTIVE
  During open heart surgery, the myocardium usually provides sufficient visual contrast with both epicardial veins and arteries. However, visibility of coronary arteries may occasionally be impaired due to, e.g., intra-myocardial course of coronary arteries, increased epicardial fat, epicardial post-surgical adhesions, or pericarditis. Seen within the near infra-red range, coronary arteries show higher contrasts in relation to the myocardium than coronary veins. Hence, we developed a non-contact stereo-optical camera to selectively enhance coronary arteries by combining visible and near infra-red images. In this paper we present our first results on porcine and human hearts.
  
  
  METHODS
  Two CMOS-cameras, with apochromatic lenses and dual-band LED-arrays, -captured visible colour (visible range, or VIS, 400-780nm) and near infra-red grey-scale (near infra-red range, or NIR, 910-920nm) images by sequentially switching between LED-array emission bands. Data was recorded by computer and processed off-line. Arterial NIR contrasts were algorithmically distinguished from shadows and specular reflections. Detected arteries were selectively enhanced and back-projected into the stereoscopic VIS-colour-image using either a 3D-display or conventional shutter glasses.
  
  
  RESULTS
  Our technique visualised coronary vasculature and allowed to identify concealed parts of coronary arteries using off-line processing. Raw VIS & NIR images were real-time, processing took < 15s after filming.
  
  
  CONCLUSIONS
  The applied principle works, but needs further development.
authors.affiliation: Erasmus MC, Thorax Center, Rotterdam.
authors.forename: F P
authors.initials: FP
authors.lastname: Wieringa
authors.forename: F
authors.initials: F
authors.lastname: Mastik
authors.forename: D J G M
authors.initials: DJ
authors.lastname: Duncker
authors.forename: A J J C
authors.initials: AJ
authors.lastname: Bogers