title: Contrast harmonic intravascular ultrasound: a feasibility study for vasa vasorum imaging.
abstract: OBJECTIVE
  We sought to investigate feasibility of vasa vasorum imaging using the novel technique of contrast harmonic intravascular ultrasound.
  
  
  METHODS
  Prototype intravascular ultrasound (IVUS) instrumentation was developed for the sensitive detection of micro-bubble contrast agents. The technique, "harmonic" imaging, involves transmitting ultrasound at 20 MHz (fundamental) and detecting contrast signals at 40 MHz (second harmonic). Phantom experiments were conducted to investigate the detection of a small vessel in the wall surrounding a larger vessel. In vivo experiments were conducted in atherosclerotic rabbit abdominal aortas.
  
  
  RESULTS
  The phantom experiments showed improved small vessel detection in harmonic mode relative to fundamental mode. For the in vivo experiments, harmonic imaging enabled the visualization of contrast agent outside the aortic lumen through a statistically significant (P < 0.001) enhancement of image power, consistent with the detection of adventitial microvessels. These microvessels were not detected in fundamental imaging mode.
  
  
  CONCLUSIONS
  These results indicate the feasibility of contrast harmonic intravascular ultrasound as a new technique for vasa vasorum imaging.
authors.affiliation: Biomedical Engineering Dept., Thoraxcenter, Erasmus Medical Centre, Rotterdam, The Netherlands. d.goertz@erasmusmc.nl
authors.forename: David E
authors.initials: DE
authors.lastname: Goertz
authors.forename: Martijn E
authors.initials: ME
authors.lastname: Frijlink
authors.forename: Dennie
authors.initials: D
authors.lastname: Tempel
authors.forename: Luc C A
authors.initials: LC
authors.lastname: van Damme
authors.forename: Robert
authors.initials: R
authors.lastname: Krams
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Schaar
authors.forename: Folkert J
authors.initials: FJ
authors.lastname: Ten Cate
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
authors.forename: Nico
authors.initials: N
authors.lastname: de Jong
authors.forename: Antonius F W
authors.initials: AF
authors.lastname: van der Steen
mesh_terms: D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D005466:Fluorocarbons; D006801:Humans; D045423:Microbubbles; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011817:Rabbits; D018084:Ultrasonography, Interventional / Q000295:instrumentation* / Q000379:methods; D014651:Vasa Vasorum / Q000000981:diagnostic imaging*; D014684:Venae Cavae / Q000000981:diagnostic imaging
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren