title: Imaging and quantification of myocardial perfusion using real-time three-dimensional echocardiography.
abstract: OBJECTIVE
  We tested the feasibility of real-time three-dimensional echocardiographic (RT3DE) perfusion imaging and developed and validated an algorithm for volumetric analysis of myocardial contrast inflow. The study included three protocols wherein perfusion was measured: 1) in an ex-vivo model of controlled global coronary flow, 2) in an in-vivo model during regional perfusion variations, and 3) in humans during pharmacologically induced hyperemia.
  
  
  BACKGROUND
  The RT3DE technology offers an opportunity for myocardial perfusion imaging without multi-slice reconstruction and repeated contrast maneuvers.
  
  
  METHODS
  Electrocardiographically triggered harmonic RT3DE datasets were acquired (Philips 7500) while infusion of Definity was initiated and reached a steady state. Protocol 1 was performed in nine isolated rabbit hearts and included three coronary flow levels. In protocol 2, changes in regional perfusion caused by partial left anterior descending artery occlusion were measured in five pigs. In protocol 3, adenosine-induced changes in perfusion were measured in eight normal volunteers. Myocardial video-intensity (MVI) was measured over time in three-dimensional (3D) slices to calculate peak contrast inflow rate (PCIR). In pigs, PCIR was measured on a regional basis and validated against microspheres.
  
  
  RESULTS
  The RT3DE imaging allowed selection of slices for perfusion analysis in rabbit hearts, pigs, and humans. Administration of contrast resulted in clearly visible and quantifiable changes in MVI. In rabbits, The PCIR progressively decreased with coronary flow (p < 0.0001). In pigs, coronary occlusion caused a 59 +/- 26% decrease in PCIR exclusively in the left anterior descending artery territory (p < 0.05) in agreement with microspheres. In humans, adenosine increased PCIR to 198 +/- 57% of baseline (p < 0.05).
  
  
  CONCLUSIONS
  Contrast-enhanced RT3DE imaging provides the basis for volumetric imaging and quantification of myocardial perfusion.
authors.affiliation: Noninvasive Cardiac Imaging Laboratory, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Eran
authors.initials: E
authors.lastname: Toledo
authors.forename: Roberto M
authors.initials: RM
authors.lastname: Lang
authors.forename: Keith A
authors.initials: KA
authors.lastname: Collins
authors.forename: Georgeanne
authors.initials: G
authors.lastname: Lammertin
authors.forename: Ursula
authors.initials: U
authors.lastname: Williams
authors.forename: Lynn
authors.initials: L
authors.lastname: Weinert
authors.forename: Gil
authors.initials: G
authors.lastname: Bolotin
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Coon
authors.forename: Jai
authors.initials: J
authors.lastname: Raman
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: Jacobs
authors.forename: Victor
authors.initials: V
authors.lastname: Mor-Avi
mesh_terms: D000241:Adenosine; D000328:Adult; D000818:Animals; D001810:Blood Volume; D003287:Contrast Media; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D019560:Echocardiography, Three-Dimensional; D005466:Fluorocarbons; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D011817:Rabbits; D013552:Swine; D017725:Ventricular Pressure
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; D000241:Adenosine; C042852:perflutren