title: Contrast-enhanced intravascular ultrasound: validation of a new technique for delineation of the vessel wall boundary.
abstract: OBJECTIVE
  We evaluated a new technique for delineation of the vessel wall surface during intravascular ultrasound imaging using echogenic contrast agents.
  
  
  BACKGROUND
  Intravascular ultrasound is used for detection of complex vessel wall structures after catheter-based interventions; however, differentiation between the lumen and these wall structures can be difficult.
  
  
  METHODS
  In 12 anesthetized dogs, intracoronary ultrasound was performed during intracoronary bolus injection (3 and 6 ml) of different contrast agents (hand-agitated saline solution, standard iohexol, sonicated iohexol, hand-agitated iohexol, SHU 454, SHU 508). Contrast intensity was quantified by videodensitometry, and contrast homogeneity was assessed qualitatively (grade 0 to 3).
  
  
  RESULTS
  Peak contrast intensities for SHU 454 and SHU 508 (mean [+/- SD] 48 +/- 9 and 36 +/- 6 U, respectively) were higher compared with standard, sonicated or agitated iohexol (16 +/- 3, 28 +/- 7 and 20 +/- 3 U, respectively) or with agitated saline solution (17 +/- 4 U); intensities were higher for 6 ml compared with that for 3 ml. Contrast homogeneity was higher for SHU 508 (mean [+/- SD] 3.0 +/- 0) and SHU 454 (2.7 +/- 0.5) compared with the other agents (standard iohexol 1.2 +/- 0.4, sonicated iohexol 2.0 +/- 0.5, agitated iohexol 1.8 +/- 0.6, agitated saline solution 1.0 +/- 0.4). Exact delineation of the vessel wall surface was possible in 100% of SHU 508 and in 88% of SHU 454 injections compared with 13% of agitated iohexol and 8% of sonicated iohexol injections. Accurate surface delineation was never achieved with standard iohexol or agitated saline solution. Shadowing of parts of the vessel wall by contrast material occurred at peak intensity of 75% of SHU 508 and 46% of SHU 454 injections but not with the other agents. No adverse physiologic reactions were noted, except for transient negative inotropic effects after 6 ml of SHU 508.
  
  
  CONCLUSIONS
  This preliminary study shows that delineation of the vessel wall boundary using echogenic contrast agents during intravascular ultrasound is safe and feasible. Because of higher contrast intensity and homogeneity, SHU 454 and SHU 508 are superior to other agents.
authors.affiliation: Cardiovacular Research Institute, University of California at San Francisco.
authors.forename: D
authors.initials: D
authors.lastname: Hausmann
authors.forename: K
authors.initials: K
authors.lastname: Sudhir
authors.forename: W L
authors.initials: WL
authors.lastname: Mullen
authors.forename: P J
authors.initials: PJ
authors.lastname: Fitzgerald
authors.forename: T A
authors.initials: TA
authors.lastname: Ports
authors.forename: W G
authors.initials: WG
authors.lastname: Daniel
authors.forename: P G
authors.initials: PG
authors.lastname: Yock
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000494:pharmacology; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects; D007472:Iohexol / Q000494:pharmacology; D011134:Polysaccharides / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508; D007472:Iohexol; D012965:Sodium Chloride; C040642:SHU 454