title: Counter-propagating wave interaction for contrast-enhanced ultrasound imaging.
abstract: Most techniques for contrast-enhanced ultrasound imaging require linear propagation to detect nonlinear scattering of contrast agent microbubbles. Waveform distortion due to nonlinear propagation impairs their ability to distinguish microbubbles from tissue. As a result, tissue can be misclassified as microbubbles, and contrast agent concentration can be overestimated; therefore, these artifacts can significantly impair the quality of medical diagnoses. Contrary to biological tissue, lipid-coated gas microbubbles used as a contrast agent allow the interaction of two acoustic waves propagating in opposite directions (counter-propagation). Based on that principle, we describe a strategy to detect microbubbles that is free from nonlinear propagation artifacts. In vitro images were acquired with an ultrasound scanner in a phantom of tissue-mimicking material with a cavity containing a contrast agent. Unlike the default mode of the scanner using amplitude modulation to detect microbubbles, the pulse sequence exploiting counter-propagating wave interaction creates no pseudoenhancement behind the cavity in the contrast image.
authors.affiliation: Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands. renaud_gu@yahoo.fr
authors.forename: G
authors.initials: G
authors.lastname: Renaud
authors.forename: J G
authors.initials: JG
authors.lastname: Bosch
authors.forename: G L
authors.initials: GL
authors.lastname: Ten Kate
authors.forename: V
authors.initials: V
authors.lastname: Shamdasani
authors.forename: R
authors.initials: R
authors.lastname: Entrekin
authors.forename: N
authors.initials: N
authors.lastname: de Jong
authors.forename: A F W
authors.initials: AF
authors.lastname: van der Steen
mesh_terms: D016477:Artifacts; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D003287:Contrast Media; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D045423:Microbubbles; D017711:Nonlinear Dynamics; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media